BPK 105 Midterm Exam Questions and Answers | Simon Fraser University | Fall 2025/2026 Update | 100% Correct

Comprehensive BPK 105 Midterm Exam Study Guide – Simon Fraser University. Includes full questions and detailed answers from Modules 1–2 (Chapters 1–2). Covers key physiology concepts such as the definition and goals of physiology, organ systems and their functions, homeostasis and feedback mechanisms, types of chemical bonds, classifications of chemical reactions, properties of water, and comparisons of carbohydrates, lipids, proteins, and nucleic acids. Perfect for SFU BPK 105 students preparing for the midterm or reviewing core human physiology topics. Updated for Fall 2025/2026 – 100% correct and verified. BPK 105 Midterm Exam Downloaded by Mike Splendid () Module 1: Chapter 1 (1.1-1.5) & Chapter 2 Define physiology including its major goals. [3 marks] Physiology is the study of the processes and functions of the body. The major goals of studying physiology are 1) to understand and predict the body’s responses to stimuli and 2) to understand how the body maintains internal conditions within a narrow range of values in the presence of continually changing internal and external environments. Define the term “organ system.” List the nine organ systems that will be discussed in this course (see Course Objectives in the Syllabus), choose two of them and describe their general functions and components. [6 marks] The organ system is a group of organs classified as a unit because of a common function or set of functions. There are 11 organ systems-integumentary, skeletal, muscular, lymphatic, respiratory, digestive, nervous, endocrine, cardiovascular, urinary, and reproductive. 1) Integumentary System- Gives protection, regulates temp, prevents water loss, helps produce vitamin D. Consist of skin, hair, nails, and sweat glands. 2) Skeletal System- Give protections and support, lets the body move and produces bloods cells, stores minerals and fats. Consists of bones with the associated cartilages, ligaments, and joints. 3) Muscular System- Gives body movements, maintains posture, and produces body heat. Consists of muscles attached to the skeleton by tendons. 4) Lymphatic System- Removes foreign substances from the blood and lymph, fights against disease. Consists of the lymphatic vessels, lymph nodes, and other lymphatic organs. 5) Respiratory System- Exchange’s oxygen and carbon dioxide between the blood and the air and regulates the ph. Consists of lung and respiratory passages. 6) Digestive System- Mechanical and chemical process of digestion, absorption of nutrients, and eliminates waste. Consists of mouth, esophagus, stomach, intestine, and accessory organs. 7) Nervous System- Major regulatory system that can sense sensations and control movements, physiological process, and intellectual functions. Consists of the brain, spinal cord, nerves, and sensory receptors. 8) Endocrine- Major regulatory system that influences metabolism, growth, reproduction. Consists of glands, such as pituitary, that secretes hormones. 9) Cardiovascular System- Transports nutrients, waste products, gases, and hormones throughout the body; has to do immune response and reg of body temperature. Consists of heart, blood vessels, and blood. 10) Urinary System- removes waste products from the blood and regulates blood ph, ion balance, and water balance. Consists of kidneys, urinary bladder, and ducts that carry urine.BPK 105 Midterm Exam Downloaded by Mike Splendid () 11) Female Reproductive System- Produces oocytes, fertilization and fetal development; produces milk for newborns, hormones that influence sexual functions and behaviours. Consists of ovaries, vagina, uterus, mammary glands, and associated structures. 12) Male Reproductive- Produces and transfers sperm cells to the female and produces hormones that influences sexual functions and behaviours. Consists of testes, accessory structures, ducts, and penis. Name and describe the type of feedback that is utilized to maintain homeostasis. Provide a detailed physiological example of this type of feedback. Use this example to describe homeostasis and its importance. [4 marks] Homeostasis (the same) - is the state in which the internal environment of the body remains relatively stable by responding appropriately to changes. If the fluid surrounding cells deviates from homeostasis, the cells do not function normally and may even die. Disease disrupts homeostasis and sometimes results in death. Modern medicine attempts to understand disturbances in homeostasis and works to re-establish a normal range of values This is important because it helps control the inside of the body to stay somewhat steady. The type of feedback that is utilized to maintain homeostasis is negative-feedback mechanisms. In this case negative = to decrease (an example of this maintaining normal body temperature). Most negative feedback systems have three components: 1) a receptor – detects stimuli, 2) control center – receives input, 3) an effector – that changes variables. Differentiate between ionic, covalent and hydrogen bonds. Include an example of each. [5 marks] An ion is an atom that carries an electrical charge due to its loss or gain of electrons, and when a chemical bond occurs from the attraction of two oppositely charged ions an ionic bond is created. An example of ionic bonding can be seen in sodium chloride (NaCl) when the positive sodium (Na+) and the oppositely negatively charged chloride (Cl-) are formed together through their opposite charges using ionic bonding thus creating sodium chloride (NaCl). A covalent bond is another form of a chemical bond that is created when two separate atoms have one or more pairs of shared electrons. This bonding results in the creation of a molecule. An example of this can be seen in the formation of a hydrogen molecule which occurs when two positively charged nuclei of separate hydrogen atoms electrons are attracted to one another. Ultimately the sharing of the electrons between the nuclei which are being connected by the covalent bond makes the hydrogen molecule. Unlike an ionic and covalent bond, the hydrogen bond is not a chemical bond. This is because in a hydrogen bond there is no transference or sharing of electrons between the atoms of polar molecules. This is significant because in a hydrogen bond a polar molecule that has both a positive and negative end, the positive end is weakly attracted to a negative end of another polar molecule. This attraction is weaker as compared to those found in covalent and ionic bonds. The main example of this weaker hydrogen bonding can be seen in water molecules. In a water molecule, the positively charged hydrogen which is weakly attracted to a negatively charged oxygen is held together by a hydrogen bond ultimately create the water molecule.BPK 105 Midterm Exam Downloaded by Mike Splendid () Describe the three classifications of chemical reactions. Include a specific example of each type. [6 marks] Classifications of Chemical Reactions: Synthesis Reactions- two or more reactions to form a complex product. (A+B----->AB) ( A-P-P + Pi ----> A-P-P-P ) ADP + Phosphate Group ----> ATP Decomposition Reactions- reactants are broke up into smaller, less complex products. (A-P-P-P ----> A-P-P + Pi) ATP--- > ADP + Phosphate Group Exchange Reactions- combination of decomposition reaction and a synthesis reaction. AB + CD--- > AC + BD ( HCl + NaOH--- > NaCl +H2O) Draw the reaction catalyzed by Carbonic Anhydrase. Use this reaction to describe how the body compensates for a rise in hydrogen ions in the blood. Define, then use, the following terms in your description, pH, buffer, reversible reaction and equilibrium. [6 marks] The reaction between CO2 and H2O is catalyzed by an enzyme, called carbonic anhydrase, which is found in red blood cells and on the surface of capillary epithelial cells. The enzyme accelerates the rate at which the reaction proceeds in either direction. The higher the concentration of CO2, the lower the pH becomes. This is because a greater amount of H2CO3 is formed, which forms a greater amount of H+ and HCO3 −. An increase in H+ concentration lowers the pH. However, the reaction is reversible. If CO2 levels decline, the equilibrium shifts in the opposite direction. That is, H+ and HCO3 − combine to form H2CO3, which then forms CO2 and H2O, and the pH increases. Recently evidence has been found on Mars to indicate there were once bodies of water there. Describe four important properties of water that are essential to the functioning of living organisms. [6 marks] 1. Stabilizing body temperature. Because heat energy causes not only movement of water molecules, but also disruption of hydrogen bonds, water can absorb large amounts of heat and remain at a stable temperature. Blood, which is mostly water, is warmed deep in the body and then flows to the surface, where the heat is released. In addition, water evaporation in the form of sweat results in significant heat loss from the body. 2. Providing protection. Water is an effective lubricant. For example, tears protect the surface of the eye from the rubbing of the eyelids. Water also forms a fluid cushion around organs, which helps protect them from damage. The fluid that surrounds the brain is an example. 3. Facilitating chemical reactions. Most of the chemical reactions necessary for life do not take place unless the reacting molecules are dissolved in water. For example, NaCl must dissociate in water into Na+ and Cl− before those ions can react with other ions. Water alsoBPK 105 Midterm Exam Downloaded by Mike Splendid () directly participates in many chemical reactions. For example, during the digestion of food, large molecules and water react to form smaller molecules. 4. Transporting substances. Many substances dissolve in water and can be moved from place to place as the water moves. For example, blood transports nutrients, gases, and waste products within the body Compare and contrast the structure and functional roles of carbohydrates and lipids. Include a general description of these organic molecules in your discussion. [6 marks] Carbohydrates and lipids play an important role in our body’s chemistry. Carbohydrates are made up of three distinct atoms: a) carbon, b) hydrogen and c) oxygen. Likewise, lipids also contain these three atoms but also comprise of other minor elements such as phosphorus and nitrogen which distinguish them from carbohydrates. The function of carbohydrates in the body is the use and or storage of energy. The building blocks that makeup carbohydrates include monosaccharides which can be utilized as an energy source. While one of the functions of lipids is also energy, lipids also serve functions in the structure and regulation of the body. The building blocks of lipids consist of glycerol and fatty acids. The fats can be kept in the body and broken down when in the need of energy. The energy produced by the fats in lipids is twice that produced by carbohydrates. Other examples of lipids such as phospholipids, eicosanoids, and steroids all play a role in the earlier mentioned functions of lipids. For example, phospholipids are integral to the cell membrane structure. While steroids work to regulate many other physiological processes within the body like testosterone and estrogen for example. Compare and contrast the structure and functional roles of proteins and nucleic acids. Include a general description of these organic molecules in your discussion. [6 marks] All proteins contain carbon, hydrogen, oxygen, and nitrogen, and most have some sulfur. The building blocks of proteins are amino acids, which are organic acids containing an amine group (–NH2), a carboxyl group, and a side chain designated by the symbol R. Regulation: Enzymes control the rate of chemical reactions. Hormones regulate many physiological processes (e.g., insulin affects glucose transport into cells). Structure: Collagen fibers form a structural framework in many parts of the body. Energy: Proteins can be broken down for energy; per unit of weight, they yield the same energy as carbohydrates. Contraction: Actin and myosin in muscle are responsible for muscle contraction. Transport: Hemoglobin transports O2 in the blood. Protection: Antibodies and complement protect against microorganisms and other foreign substances. The nucleic acids are large molecules composed of carbon, hydrogen, oxygen, nitrogen, and phosphorus. Both DNA and RNA consist of basic building blocks called nucleotides. Each nucleotide is composed of a sugar (monosaccharide) to which a nitrogenous organic base and a phosphate group are attached. Regulation: DNA directs the activities of the cell. Heredity: Genes are pieces of DNA that can be passed from one generation to the next. Gene expression: RNA is involved in gene expression.BPK 105 Midterm Exam Downloaded by Mike Splendid () Describe the role of an enzyme in a chemical reaction. Use and define the appropriate terminology in your description. Briefly describe the other factors affect the rate of chemical reactions? [7 marks] Enzymes increase the rate of chemical reactions by lowering the activation energy which is the energy necessary to start a chemical reaction example: heat in the form of a spark is required to start the reaction between oxygen and gasoline most of the chemical reactions that occur in the body have high activation energies, which are decreased by enzymes lowered activation energies enable reactions to proceed at rates that sustain life 3D shape of enzymes is critical for their normal function lock-and-key model of an enzyme and those of the reactants very close to one another reduces the activation energy for the reaction because the enzyme and the reactants must fit together, enzymes are very specific for the reactions they control, and each enzyme controls only one type of chemical reaction after reaction takes place, the enzyme is released and can be used again bodies chemical events are regulated primarily by mechanisms that control either the concentration or the activity of enzymes the rate at which enzymes are produced in cells or whether the enzymes are in an active or inactive form determines the rate of each chemical reaction. Module 2: Chapter 3 (3.1-3.6) Describe the functions of the Nucleus, Nucleolus, Cytoplasm, Rough Endoplasmic Reticulum, and Ribosome. [5 marks] • Nucleus: Contains genetic material (DNA) as well as the nucleoli. • Nucleolus: Subunit of ribosomes are made within this structure. • Cytoplasm: Cellular material surrounding the nucleus, contains many different organelles and is enclosed by cell membrane (plasma). • Rough endoplasmic reticulum has ribosomes attached to the surface, site of protein synthesis. • Ribosomes: Site of protein synthesis. Describe the functions of the Secretory Vesicle, Lysosome, Mitochondria, Cell Membrane and Gogli Apparatus. [5 marks] • Secretory Vesicle: small, membrane-bound sac that transports or stores minerals within cells. They pinch off from the Gogli apparatus and move to the surface of the cell. • Lysosome: membrane-bound vesicles formed from the Gogli apparatus. They contain a variety of enzymes that function as intracellular digestive systems. • Mitochondria: are small organelles with inner and outer membranes separated by a space. • Gogli Apparatus consists of closely packed stacks of curved, membrane-bound sacs. It collects, modifies, packages, and distributes proteins and lipids manufactures by the ER. • Cell Membrane: or plasma membrane is the outermost component of a cell. Encloses the cytoplasm and forms the boundary between material inside the cel and martial outside.BPK 105 Midterm Exam Downloaded by Mike Splendid () Describe separately, the effects of placing a red blood cell in a hypertonic, an isotonic and a hypotonic solution. Be sure to define the three terms in your answer and describe the driving force behind what you would observe in each case. [5 marks] When placing a red blood cell in a hypertonic solution the red blood cells will shrieval up or crenation because the solution usually has a higher concentration of solutes and lower concentration of water relative to the cytoplasm. Water will then move by osmosis from the cell into the hypertonic solution causing the cell to shrink. An isotonic solution will cause a red blood cell to stay the same because the concentration of different solutes and water are the same on both sides of the membrane. Hypotonic solution will cause a red blood cell to swell or lysis because the solution will normally have a lower concentration of water relative to the cytoplasm. The solution has less osmotic pressure there for the water move by osmosis into the cell causing it to swell. Sodium ions can move through the membrane into the cell by diffusion through channels but require active transport to move out of the cell. Describe these methods of movement across the membrane and clearly describe why we observe these differences for sodium movement. [4 marks] Diffusion: moves substances into or out of cells from an area of higher concentration to and area of lower concentration. The movement withe the concentration gradient, metabolic energy in the form of ATP is not required. Figure 3.8 Active transport: moves substances across the cell membrane from regions of lower concentration to those of higher concentration against concentration gradient. It requires energy in the form of ATP, if ATP is not available active transport stops. Figure 3.9 Absorbing glucose into the cells of the small intestine after digestion requires the use of secondary active transport. To move this same glucose out of the cell to be taken up the circulation utilizes facilitated diffusion. Describe these methods of movement across the membrane and clearly describe why we observe these differences for glucose movement. [4 marks] Secondary Active Transport- involves the active transport of one substance, such as Na+, across the cell membrane, establishing a concentration gradient. The diffusion of that transported substance down its concentration gradient provides the energy to transport a second substance, such as glucose, across the cell membrane. In co-transport, the diffusing substance moves in the same direction as the transported substance; in counter transport, the diffusing substance moves in a direction opposite to that of the transported substance. Provide an overview of the process of transcription. Explain what would happen if one nucleotide within the DNA sequence was changed. Why is this potentially important to physiological function? [4 marks] First step in gene expression: a) The strand of the DNA molecule separates from each other. One DNA strand serves as a template for mRNA synthesis. b) Nucleotides that will form mRNA pair with DNA nucleotides according to the base-pair combinations. Thus, the sequence ofBPK 105 Midterm Exam Downloaded by Mike Splendid () nucleotides in the template DNA strand determines the sequence of nucleotides in mRNA. An enzyme joins the nucleotides of mRNA together. c) As nucleotides are added, an mRNA molecule is formed. Provide an overview of the process of translation. Explain what would happen if the body was missing one of the twenty kinds of amino acids. [5 marks] Translation is one of the two types of gene expression used in our body. By utilizing the information present in the mRNA, translation uses that information to synthesize protein. This process occurs in the ribosomes, in which during translation the sequence of codons in the mRNA bind to the ribosomes. From there the anticodons of the tRNA bind to the codons of the mRNA. This allows for an enzyme to form a peptide bond between amino acids that are bound in the tRNA. Once this bond is formed the ribosomes then move down the mRNA processing each codon separately and then placing the tRNA and mRNA in their respective places to form a polypeptide chain. Once this chain is formed the translation is complete. This polypeptide chain is what becomes a protein molecule. A protein consists of many amino acids and if the body were missing one of the twenty kinds of amino acids it would be quite detrimental. Although there are only 20 amino acids, a combination of many unique proteins with their own functions and structures can be created through these 20 amino acids. These proteins have many important functions within the body. For example, some proteins regulate the rate of chemical reactions, while others such as structural proteins provide the basis for many of the body’s tissues, while some are responsible for muscle contraction. If the body is unable to produce a complete protein due to the lack of a missing amino acid(s) it can negatively affect the body’s growth, tissue repair and be the cause of other negative symptoms. Briefly describe the life cycle of a cell including differentiation. (You do not need to include the detailed stages of mitosis). [4 marks] 1. The cell cycle consists of a series of events that produce new cells for growth and for tissue repair. 2. The two phases of the cell cycle are interphase and cell division. 3. DNA replicates during interphase, the nondividing phase of the cell cycle. 4. Cell division occurs through mitosis, which is divided into four stages: ∙ Prophase—each chromosome consists of two chromatids joined at the centromere. ∙ Metaphase— chromosomes align at the center of the cell. ∙ Anaphase—chromatids separate at the centromere and migrate to opposite poles. ∙ Telophase—the two new nuclei assume their normal structure, and cell division is completed, producing two new daughter cells. Differentiation, the process by which cells develop specialized structures and functions, results from the selective activation and inactivation of DNA sections. Describe the four main functions of the cell, describe an example of each of these functions that was discussed in this module’s readings. [6 marks]BPK 105 Midterm Exam Downloaded by Mike Splendid () • Cell metabolism and energy use- The chemical reactions that occur within cells are collectively called cell metabolism. Energy releases during metabolism is used for cell activities, such as the synthesis of new molecules, muscle contraction, and heat production, which helps maintain body temperature. • Synthesis of molecule- Cell synthesize various types of molecules, including proteins, nucleic acids, and lipids. The different cells of the body do not all produce the same molecules. Therefore, the structural and functional characteristics of cells are determined by the types of molecules they produce. • Communication- Cells produce and receive chemicals and electrical signals that allow them to communicate with one another. For example, nerve cells communicate with one another and with muscle cells, causing muscle cells to contract. • Reproduction and inheritance- Each cell contains a copy of the genetic information of the individual. Specialized cells (sperm cells and oocytes) transmit that genetic information to the next generation. Module 3: Chapter 7 (7.1-7.4) Describe the functions of the muscular system, include whether it is skeletal, smooth or cardiac muscle involved. [7 marks] • Movement of the body - involves the skeletal muscles to contract for overall movement of the body. • Maintenance of posture - involves the skeletal muscles that is constantly maintaining tone which keeps us standing and sitting upright. • Respiration - muscles of the thorax which involve skeletal and smooth muscles carry out breathing movements. • Production of body heat - involves skeletal muscles that when contract heat is given off by product which is critical for body temperature. • Communication - involves skeletal muscles that takes part in all aspects of communication. • Constriction of organs and vessels - involves smooth muscles which when contracted within the walls of internal organs and vessels causes those structures to constrict that helps mix food and water in the digestive tract, propel secretions from organs and regulate blood flow. • Contraction of the heart - involves cardiac muscle that when contracted causes the heart to beat propelling blood to all parts of the body. Describe resting membrane potential. Include the distribution of ions and charge across the membrane, the state of ion channels (open or closed), and concentration and electrical gradients that exist. [4 marks] Resting membrane potential occurs because there is an uneven distribution of ions across the cell membrane. Na+ channels and some, but not all, K+ diffuses down its concentration gradient through the open K+ channels, making the inside of the cell membrane negatively charged compared to the outside.BPK 105 Midterm Exam Downloaded by Mike Splendid () Describe an action potential (depolarization and repolarization) following stimulation of a muscle cell. Include the movement of ions and charge across the membrane, the state of ion channels (open or closed), and concentration and electrical gradients that exist. [6 marks] It begins with a stimulated muscle fiber or nerve call. -Causing Na+ channels to open quickly. -Membrane becomes very permeable to Na+, because Na+ concentration is greater outside the cell then compared to the inside. -Charge inside cell membrane is negative. -Na+ quickly diffuses down its concentration gradient, towards negative charges into the cell. -Inside of the cell membrane is now more positive then compared to the outside. This change is called depolarization. -Near the end of depolarization Na+ channels close, additional K+ channels open. -The chance for Na+ to enter the cell go down and the chance for K+ to leave the cell increases. -That causes the inside of the cell membrane to become more negative then the outside. -More K+ channels close. -The charge across the membrane goes backs to resting condition -The change back to resting potential is called repolarization. -The quick change between depolarization and repolarization is called action potential. What is the role of the sodium potassium exchange pump in an excitable muscle cell? What would happen if the sodium potassium exchange pump stopped working? [3 marks] The sodium-potassium pump requires ATP to move Na+ out of the cell and K+ into the cell. The concentration gradients for Na+ and K+, established by the sodium-potassium pump, are essential in maintaining the resting membrane potential. To make sure that an uneven distribution of potassium and sodium is maintained across the cell membrane. When the muscle fiber is not being stimulated and remains at rest, the job of the sodium potassium exchange pump is to transport the sodium from inside to outside the cell and transport potassium from outside to inside the cell in order to maintain a more negative charge inside the cell than out. Works by opening more potassium channels to account for the extra positively charged sodium that enters the cell when the muscle fiber or cell is stimulated. If the sodium potassium exchange pump stopped working the muscle cell would not be able to repolarize and return to its negative charge. This would in turn mean that the cell could not aid in the muscle fiber's contraction. Depending on how many of the excitable muscle cells were affected, the muscle could potentially be unable to move. Describe the functional steps that occur at the neuromuscular junction. Begin with motor neuron stimulation and end with muscle action potential. What is the role of acetylcholinesterase? What would happen if its function were blocked? Describe what would happen if the receptor sites for acetylcholine were blocked by a poison such as curare (See Clinical Impact). [7 marks] The neuromuscular junction is a synaptic junction between a muscle fiber and a nerve Axon. These neuromuscular junctions can be found near the center of a muscle fiber. A motor unit(s) which consists of a single motor neuron and all the skeletal muscle fibers are what help make up a single muscle. Depending on the number of fibers present in a motor unit muscle the controlBPK 105 Midterm Exam Downloaded by Mike Splendid () you have on the muscle varies. If you have more fibers in a muscle unit, the less control you have over the muscle while if you have fewer fibers the more control you have over that particular muscle. Moreover, the neuromuscular junction contains several axon terminals (or presynaptic terminal) located in the muscle fibers sarcolemma. The synaptic cleft can be found between the space of the presynaptic terminal and the muscle fiber membrane. Each of these presynaptic terminals contains many small vesicles called the synaptic vesicle which hold the neurotransmitter acetylcholine. at the presynaptic terminal where an action potential arrives which causes calcium (Ca2+) channels to open. Once these channels are open calcium ions can enter the presynaptic terminal to begin releasing the neurotransmitter acetylcholine between synaptic vesicles and the presynaptic cleft. The acetylcholine begins to diffuse across the synaptic cleft which then binds the acetylcholine receptor sites to sodium (Na+) channels in the muscle fiber cell membrane. This combination creates a more permeable cell membrane resulting in an action potential. The role of acetylcholinesterase is to rapidly breakdown the acetylcholine that has been released into the synaptic cleft between the muscle fibers of a neuron. If the function of acetylcholinesterase is blocked the transmission of an action potential that is found across neuromuscular junctions can be severely impacted. For example, if this function were blocked something very integral to human life such as respiration could be hindered due to the inhibition of proper contraction and relaxing of the lungs. If the receptor sites for acetylcholine were blocked by poison such as curare Receptors would be blocked from activation. This would result in the muscles being incapable of contracting in necessary situations such as response to nervous simulations and is known as something called flaccid paralysis. But in calculated doses curare has been researched for its role in relaxing muscles for surgical and medical purposes by blocking the role of acetylcholine in neuromuscular synapses. Describe the sliding filament model of muscle contraction. Describe which regions of the sarcomere change in length. Why does the A-band stay the same length when the sarcomere shortens? [5 marks] Muscle contractions are a very crucial aspect of body movement. The sliding filament model of muscle contractions is a process in which actin myofilaments slide past myosin myofilaments when a muscle is contracted. In the process of contraction, the sarcomere is shortened when actin myofilaments on each side are moved into the H zone of the muscle. Although, the sarcomere is shortened in this process the lengths of the actin and myofilaments remain the same. The same is true for the A bands which are the same in length as the myosin myofilaments, hence as the myosin myofilaments length does not change nor does the A bands length during contraction. Contrarily, when the muscles are relaxed the sarcomeres get lengthened due to the opposite force of muscles or that of gravity. Describe cross bridge movement during muscle contraction. Begin with action potential in the muscle and end with relaxation. What happens if ATP is not available? [6 marks] The action potential causes the membranes of the sarcoplasmic reticulum adjustment to the T tubules to become more permeable to Ca2+, and Ca2+ diffuses into the sarcoplasm. The Ca2+ binds to troponin molecules attached to the actin myofilaments. The binding causes tropomyosinBPK 105 Midterm Exam Downloaded by Mike Splendid () molecules to move into a groove along the actin molecules, exposing attachment sites on the actin myofilaments bind to the head of the myosin myofilaments to form cross-bridges between the actin and myosin myofilaments. If ATP is not available causes your muscles to become rigid and will cause a condition called rigor Morris. ATP provides the energy required for muscle contraction and exercise performance to continue. Describe the three energy systems that can produce ATP. Include the type of activity that will result in ATP being produced predominantly by each of the energy systems. [6 marks] Aerobic respiration: requires 02, breaks down glucose to produce ATP, C02, and H20. A type of actively that will produce ATP using this energy system is resting muscles or any muscles that are undergoing long-term exercise like long-distance running. Anaerobic respiration: does not require 02, breakdown of glucose to yield ATP and lactic acid. A type of activity that will produce ATP using this energy system is sprinting. Creatine phosphate: provides storage for energy that can be used quickly to help maintain the right amount of ATP in contracting muscle fiber. Creatine phosphates will store the ATP until it is needed so say you are sprinting it will then use the ATP to run for 2-3 minutes at top speed. Compare and contrast the characteristics of smooth, skeletal, and cardiac muscle. [6 marks] SKELETAL -attached to bone -long, cylindrical cells -multiple, peripheral nuclei -no special features -has striations -not autorhythmic -voluntary control -moves the whole body CARDIAC -heart -branched cells -usually single, central nucleus -special feature: intercalated disks -has striations -is autorhythmic -involuntary control -contract heart to propel blood through the body SMOOTH -walls or hollow organs, blood vessels, and glands -spindle-shaped cells -singe, central nucleus -no striationsBPK 105 Midterm Exam Downloaded by Mike Splendid () -is autorhythmic -involuntary control -compress organs, ducts, tubes, etc. Autorhythmic: periodic spontaneous contraction. Module 4: Chapter 8 (8.1-8.6, 8.8-8.10, 8.14-8.15) Describe each of the general functions of the nervous system. [5 marks] • Receiving sensory input- snoopy receptors monitor numerous external and internal stimuli. (vision, hearing, and taste) • Integrating information- the brain and spinal cord are the major organs for processing sensory input and initiating responses. • Controlling muscles and glands- skeletal muscles normally contract only when stimulated by the nervous system. • Maintaining homeostasis- the nervous system plays an important role in maintaining homeostasis. Depends on the nervous systems ability to detect, interpret and respond to changes in internal and external conditions. • Establishing and maintaining mental activity- the brain is the centre of mental activity, including consciousness, memory, and thinking. Briefly describe all the divisions and subdivisions of the Nervous System. [9 marks] The sensory division of the peripheral nervous system (PNS) detects stimuli and conducts action potentials to the central nervous system (CNS). The CNS interprets incoming action potentials and initiates action potentials that are conducted through the motor division (purple) to produce a response. The motor division is divided into the somatic nervous system and the autonomic nervous system. CNS (central nervous system) consists of brain and spinal cord brain is housed within the braincase; the spinal cord is in vertebral column. PNS (peripheral nervous system) consists of all the nerves and ganglia outside CNS [divided into sensory + motor]collects info from inside and on the surface of the body and relays it by way of sensory neurons to the CNS, where one of three results is possible: The information is ignored, triggers a reflex, or is evaluated more extensively PNS links CNS with the various parts of the body carries info about the different tissues of the body to the CNS. sensory/afferent div conducts APs from sensory receptors to CNS sensory division, or afferent (toward) division, of PNS neurons that transmit action potentials from the periphery to the CNS = sensory neurons motor/efferent (away) div conducts APs from CNS to effector organs (muscles and glands) MOTOR NEURONS can be further subdivided based on the type of effector being innervated [somatic, autonomic] Motor neurons in PNS relay information from the CNS to muscles andBPK 105 Midterm Exam Downloaded by Mike Splendid () glands neurons that transmit action potentials from the CNS toward the periphery are called motor neurons regulate activity in those structures. Somatic transmits APs from CNS to skeletal muscles. Autonomic transmits APs from CNS to cardiac and smooth muscle and glands. - Divided into sympathetic vs parasympathetic. - The sympathetic and parasympathetic divisions can each produce both stimulatory and inhibitory effects. - sympathetic division stimulates smooth muscle contraction in blood vessel walls and inhibits smooth muscle contraction in lung airway walls. - Parasympathetic division stimulates contraction of the urinary bladder and inhibits contraction of the heart. sympathetic stimulation of the heart causes an increase in heart rate, whereas parasympathetic stimulation causes a decrease in heart rate. - When both divisions innervate a single organ, the sympathetic division tends to play a major role during physical activity or stress, whereas the parasympathetic division has more influence during resting conditions. Enteric nervous system (ENS) unique subdivision of the peripheral nervous system. ENS has both sensory and motor neurons contained wholly within the digestive tract. ENS can function without input from the CNS or other parts of the PNS normally integrated with the CNS by sensory neurons and ANS motor neurons. Compare and contrast the structure and functional roles of neurons (nerve cells) and neuroglia (glial cells). Be sure to describe four types of neuroglia (excluding Ependymal cells) in your discussion. [6 marks] A neurons job is to perform action potentials and consists of the cell body, dendrites, and axon. Neuroglia is the glue. They are the support cells of the nervous system; they protect, nourish, and insulate the axon. The neuroglia is related closely to a neuron because it forms around the axon of the neuron. Both a neuron and neuroglia are cells that are make up the nervous system and without both of these types of cells our nervous system would not function properly. There a multiply different types of neuroglia cells with different functions. Astrocytes have many branches and will help the cell support its structure, as well as helping the neuronal signalling stay constant. Microglia which is small and moves around, helps the central nervous system for getting infected as well as being able to absorb infections and bacteria in response to inflammation. Oligodendrocytes which will form a myelin sheath around an axon and will also cover the parts for the axon that are open and are unmyelinated. Explain how a myelinated axon can conduct a signal faster than an unmyelinated axon of similar diameter. Use and define appropriate terminology in your explanation. [4 marks] Axons that process neurons have a specialized layer called myelin sheaths that wrap around the axons of some neurons. Myelin sheaths are formed by the oligodendrocytes in the central nervous system (CNS) and by the Schwann cells in the peripheral nervous system (PNS). The axons that have these myelin sheaths are known as myelinated axons. These myelinated axonsBPK 105 Midterm Exam Downloaded by Mike Splendid () contain myelin which is a great insulator that helps prevent most ion movement across the cell membrane, Furthermore, about every millimeter in the oligodendrocyte segments or between the Schwann cells there are gaps known as nodes of Ranvier. At these nodes, ion movement can occur and due to the myelination of an axon the speed and efficiency of the action potential increases. However, an unmyelinated axon that does not have myelin sheaths have axons that sit on indentations found in the oligodendrocytes of the CNS and the Schwann cells of the PNS. Which result in a slower speed and efficiency of action potential. Define reflex. Draw a diagram of a reflex arc that would result in muscle contraction following the stimulation of a pain receptor in the skin. What type of reflex is this? Label the five components of the reflex arc in your diagram and the components of the spinal cord. [8 marks]. Reflex is an action which we can not control in response to a stimulus that is applied to the peripheral nervous system and transmitted to the central nervous system. A reflex helps a person react to a stimulus more quickly then they would be able to if there conscious thought was taking place. Describe the roles of the cerebellum and basal nuclei in the control and modification of movement. [5 marks] Cerebellum is connected to the brainstem and is located near the bottom of the brain. Cerebellum helps maintain balance, muscle tone, and in coordinating fine motor movement. Basal nuclei are a group of related nuclei the two main ones being the corpus striatum and substantia nigra. These two nuclei are involved in planning, organizing, and coordinating motor movements like picking a small object up with your fingers, and your posture. These two are connected in many ways an excellent example are toddlers, when you are young you are just forming you fine motor movements and your brain is developing. When you first start walking you are very unbalanced and not able to go very far because your cerebellum is not fully developed. Also, you are not able to grip, grab, and hold things very well because you are just developing you fine motor movements causing you to drop things often. As your brain develops you are able to do all those things that use to be so hard when you were a toddler. Use the heart and lungs as physiological examples to compare and contrast the sympathetic and parasympathetic divisions of the autonomic nervous systems. Include the structure and function of each division in your discussion. [8 marks] The autonomic nervous system (ANS) plays an integral role within our bodies. The ANS contains information about the motor neurons that carry action potentials from the CNS to the periphery and contains both the parasympathetic and sympathetic divisions of the ANS. The sympathetic nervous system is one of the subdivisions of the ANS that has preganglionic nerve cells bodies which are used in prepping the body for immediate physical activity. This subdivision is found in the thoracic and lumbar areas of the spinal cord. The sympathetic subdivision is also known as the fight or flight response system as the increased activity in these neutrons will prepare an individual for physical activities. This is achieved as the axons of the preganglionic neuron’s travel through the ventral roots and venture to either the sympathetic chain ganglia or collateral ganglia. Preganglionic neurons synapse with postganglionic neuronsBPK 105 Midterm Exam Downloaded by Mike Splendid () in the collateral ganglia and the postganglionic neurons in the collateral ganglia venture to its targeted tissues to its respective regions. While the second subdivision the parasympathetic nervous system which has preganglionic neurons is found in the brainstem and sacral region of the spinal cord involves the use of involuntary functions in the body such as urination and digestion. The parasympathetic division stimulates involuntary activities of the body at rest as the axons of the preganglionic neurons spread out through the spinal nerves to terminal ganglia which are located near effector organs. The vagus nerve parts to provide parasympathetic innervation to the heart, the lungs, the liver, and the stomach and other digestive organs. Two physiological examples that can be used to compare and contrast the sympathetic and parasympathetic divisions of the autonomic nervous systems are the heart and lungs. Firstly, the heart is a muscular organ that is vital for life as it pumps blood throughout the body. The lungs are the primary organs of respiration with one on each side of the body left and right. Both these integral organs utilize both the sympathetic and parasympathetic divisions of the ANS. The heart utilizes the parasympathetic division to decrease heart rate while the lungs use it for constriction of the bronchioles. The heart utilizes the sympathetic divisions to increase heart rate and force of contraction of the heart, while the lungs use it for dilation of the bronchioles. Module 5: Chapter 9 Define sensory perception and differentiate between general and special senses, listing examples of each. [5 marks] General senses have receptors that are distributed over a large part of the body. general senses are divided into two groups: the somatic senses and the visceral senses. Somatic senses provide information about various internal organs, primarily involving pain and pressure. Special senses are more specialized in structure and are localized to specific parts of the body. The general senses include touch, pressure, pain, temperature, vibration, itch, and proprioception. The special senses are small, taste, sight, hearing, and balance. Sensory receptors are sensory nerve endings or specialized cells capable of responding to stimuli by developing action potentials. Different receptors respond to different stimuli. For instance, mechanoreceptors receptors respond to mechanical stimuli, such as bending or stretching of receptors. Chemoreceptors respond to chemicals, such as odor molecules. Photoreceptors respond to light. Thermoreceptors respond to light. Nociceptors respond to stimuli that results in the sensation of pain. Describe the five types of receptors involved in responding to both general and special senses. Provide a specific example of where each is utilized. [7.5 marks] - Mechanoreceptors respond to mechanical stimuli, such as the bending or stretching of receptors. - Chemoreceptors respond to chemicals. For example, odor molecules bind to chemoreceptors, allowing us to perceive smells. - Photoreceptors respond to light. - Thermoreceptors respond to temperature changes. - Nociceptors (to injure) respond to stimuli that result in the sensation of pain.BPK 105 Midterm Exam Downloaded by Mike Splendid () How does a local anesthetic such as freezing at the dentist, function to block the perception of pain? [1 mark] Local anesthesia blocks the perception of pain through the injection of chemical anesthetics near a sensory receptor or nerve, which results in reduced pain sensation. How does rubbing your elbow after hitting it on a door relieve the pain? [2 marks] Rubbing your elbow after hitting on a door relieves the pain because rubbing the skin in the area of an injury stimulates the tactile receptors, which send action potentials along the sensory axons to the spinal cord. According to gate control theory these action potentials "close the gate" and inhibit action potentials carried to the brain by the spinothalamic tract. The spinothalamic tract relays pain sensations to the brain. So, inhibiting and synapsing with neurons that gives rise to the spinothalamic tract eliminated the sensation of pain. When someone is experiencing a heart attack, they often perceive the pain to be originating from their left arm or shoulder. Describe why this occurs. Define appropriate terminology in your answer. [2 marks] This occurs because of a phenomenon known as referred pain where pain is perceived to originate in a region of the body that is not the source of the pain stimulus. We often sense referred pain when deeper structures, such as internal organs are damaged or inflamed. This occurs because sensory neurons from the superficial area to which the pain is referred and the neurons from the deeper area where the pain stimulation originates converge onto the same ascending neurons in the spinal cord. then the brain can’t distinguish between the two sources of pain stimuli, and the painful sensation is referred to the most superficial structures innervated. What is the role of mucus in the detection of smell? Describe the pathway from odorant molecule binding to a receptor to the olfactory bulb. What happens after you have been exposed to an odorant for a long time? [5 marks] Mucus keeps the nasal epithelium moist, traps and dissolves airborne molecules, and facilitates the removal of molecules and particles from the nasal epithelium. Airborne odorants become dissolved in the mucus on the surface of the epithelium and bind to receptor molecules on the membrane of the specialized cilia. The binding of the odorant to the receptor initiates action potentials which are then conducted to the olfactory cortex of the cerebrum by the sensory neurons. Describe how you sense sugar after licking an ice cream cone. Include the structures and their functions in your description. [3 marks] Taste buds are also distributed throughout other areas of the mouth and pharynx, such as on the palate, the root of the tongue, and the epiglottis. Each taste bud consists of two types of cells. Specialized epithelial cells form the exterior supporting capsule of each taste bud, and the interior consists of about 40 taste cells. Each taste cell contains hairlike processes, called taste hairs, that extend through a tiny opening in the surrounding stratified epithelium, called a taste pore. Dissolved molecules or ions bind to receptors on the taste hairs and initiate actionBPK 105 Midterm Exam Downloaded by Mike Splendid () potentials, which sensory neurons carry to the insula of the cerebral cortex. The facial nerve (anterior two-thirds of the tongue), glossopharyngeal nerve (posterior one-third of the tongue), and vagus nerve (root of the tongue) all carry taste sensations. The trigeminal nerve carries tactile sensations from the anterior two thirds of the tongue. The chorda tympani from the facial nerve (carrying taste input) joins the trigeminal nerve. Describe the process and importance of light refraction in the eye. Describe the changes that occur during accommodation (focusing light on the retina) when focusing on a close object. Include the anatomy of the eye that accomplishes each of these functions. [6 marks] The visual system comprises of the eyes, their accessory structures, and sensory neurons. Visual input such as the information of light, dark, colour, and movement are what allow us to see. Of these visuals, a main input is the information of light. A very fundamental component of light is that it can be refracted or otherwise known as bent which is ultimately what allows us to see the way we do. This is because in refraction as light passes through a less dense to denser transparent substance, the light rays refract. Depending on whether the lens is concave or convex how the light refracts is changed. If the lens is concave the light rays are bent allowing it to diverge as it passes through the lens, if the lens is convex the light rays converge in which they cross. This cross point is known as the focal point and the convergence of light is known as focusing. The focal point and focussing allow the object we are viewing to be focussed invertedly on the retina allowing us to see. Another integral aspect in seeing is accommodation, our eye lens adjusts or adapts in the form of increasing the thickness and convexity to allow for a focus on an object in the retina as it moves closer to the eye. As mentioned above the main changes that are observed in accommodation one focusing on a close object or the change of thickness and roundness or convexity of the lens. When an object is moved closer to the eye the ciliary muscles in the eye contract closer to the lens due to the parasympathetic stimulation. This movement lowers the tension of the suspensory ligaments of the lens which then adapts to a more rounded shape due to its elastic nature. This rounded shape allows for a more convex surface which creates more refraction of light to focus on the object moving closer to the eye. Describe the effect of light on rhodopsin. How is light changed into an electrical signal? (please see the study guide in Canvas for more detail) [4 marks] 1. retinal attached inside opsin to make rhodopsin. 2. light activates rhodopsin by causing retinal to change shape, which causes opsin to change shape. 3. the change in rhodopsin's shape stimulates a response in the rod cell that result in vision 4. following rhodopsin activation, retinal detaches from opsin 5. energy from ATP is required to bring retinal back to its original form 6. retinal attaches to opsin to form rhodopsin (return to step 1) Describe all the changes a sound wave goes through before it becomes a fluid wave within the perilymph of the cochlea. Include the relevant anatomy in your description. [4 marks] Before sound waves become a fluid in the perilymph, sound waves in the air are picked up by the external auricle and then directed into the external auditory canal. They travel through theBPK 105 Midterm Exam Downloaded by Mike Splendid () external auditory canal before coming into contact with the thin tympanic membrane (or eardrum). This membrane separates the external ear from the middle ear, and the vibrations felt in the membrane are transmitted further inwards, causing the three auditory ossicles (malleus, incus, and stapes) to start vibrating, furthering the vibrations deeper into the ear. Once the vibrations are transmitted to the last bone, the stapes, they then travel through the base of the stapes to the oval window as the two are connected. As this transition occurs there is a 20-fold amplification of the vibrations due to the dramatic decrease in area, however two small muscle serve to help mute the strong vibrations and protect the delicate structure of the inner ear. Finally, the vibrations in the foot plate cause the perilymph in scala vestibule to begin vibrating, carrying the fluid vibrations deeper towards the inner ear. Describe how a wave in the parilymph fluid of the cochlea leads to an electrical signal in the cochlear nerve. Include relevant anatomical details. How do we distinguish that a sound is either loud or soft? High pitched or low pitched? [6 marks] Waves in the perilymph fluid are vibrations in the base of the stapes. These waves push the perilymph against the membrane of the round window. The waves then proceed to vibrate the endolymph. This leads to the displacement of the basilar membrane and the movement of the hair cells on the membrane. The microvilli of the hair cells are implanted in the tectorial membrane and are therefore forced to bend with the movement of the basilar membrane. The bent hair cells stimulate action potentials in the cochlear nerves. This is how waves in the perilymph fluid result in an electrical signal in the cochlea nerve. Due to the uneven length of the basilar membrane (being narrowed near the oval window and wider near the cochlea) the regions of the membrane vary in thickness in length. This variation makes higher pitched sounds distort the basilar membrane and stimulate the hair cells near the oval window and lower pitched sounds distort the basilar membrane and stimulate the hair cells near the apex of the cochlea. The higher a sound wave's amplitude, the more distorted the basilar membrane, the more stimulated the hair cells become therefore the higher the volume and vice versa. Define static equilibrium and describe the structure and function of the components of the inner ear that determine it. [4 marks] Static equilibrium is one of two main components of the sense of balance and the structures and components that help with the static equilibrium in the ear include the vestibule. The vestibule is a small cavity or space at the entry of the year and is involved in determining the head's position comparative to gravity. The structures and components that help with the static equilibrium in the ear include the vestibule. The vestibule can be separated into two chambers: 1) the utricle 2) the saccule, both contain specialized areas of epithelium called the maculae which are surrounded by endolymph. These maculae contain hair cells and the tips of the microvilli of these cells are rooted in a gelatinous mass, also known as the otolithic membrane. This membrane is weighted by particles that are made up of protein and calcium carbonate called the otoliths. In response to gravity, the weighted gelatinous mass moves accordingly, bending the hair cell microvilli and starting action potentials in the associated neurons. From here the action potentials from these neurons are taken to the axons in the vestibular area of theBPK 105 Midterm Exam Downloaded by Mike Splendid () vestibulocochlear nerve to the brain. Here they are then translated as a shift of change in the position of the head. Define dynamic equilibrium and describe the structure and function of the components of the inner ear that determine it. How is that we are able to detect movement in any direction? [5 marks] Static equilibrium is associated with vestibules and is involved in evaluating head position relative to gravity. The vestibule of the inner ear is divided into 2 chambers: utricle and saccule. Each chamber has specialized patches of epithelium called maculae surrounded by endolymph. The maculae have hair cells, and tips of microvilli of cells are embedded in a gelatinous mass called the otolithic membrane, weighted by otoliths (particles or protein and calcium carbonate). The mass moves in response to gravity, bending hair cell microvilli and initiating action potentials in associated neurons. The action potentials from neurons are carried by axons of the vestibular portion of the vestibulo-cochlear nerve to the brain, where they're interpreted as a change in head position. Module 6: Chapter 10 Briefly describe the regulatory functions of the endocrine system. [5 marks] 1. regulates metabolism 2. control of food intake and digestion 3. tissue development 4. regulates the solute concentration of the blood 5. water balance 6. heart rate and blood pressure regulation 7. control of blood glucose levels and other nutrients 8. control of reproductive functions 9. uterine contractions and milk release 10. immune system regulation It’s composed of endocrine glands and specialized endocrine cells located throughout the body. The endocrine gland secretes minute amounts of chemical messengers called hormones into the blood stream rather than ducts. These hormones then travel away from their source and thought the bloodstream to specific sites called target tissues or effectors, where they produce a coordinated response of target tissue. Describe each of the different functional classifications of chemical messengers. Provide an example of each and the function of each example (use glossary). [8 marks] There are different functional classifications of intercellular chemical signals. The first category are autocrine chemical messengers, which work to stimulate the same cell that originally secreted it. For example, when there is an area of infection inside the body, it needs numerous white blood cells to fight it off. The White blood cells have autocrine chemical messengers enabling them to stimulate their own replication to increase their numbers. The second category is paracrine chemical messengers, which enable cells to secrete a signal locally into extracellular fluid, allowing other cells nearby to pick up and be affected by the signal. For example, when histamine is released by a white blood cell, nearby blood vessels are stimulated and begin vasodilation. The third classification uses Neurotransmitters, which are secreted with action potentials by neurons in synaptic clefts in order to activate adjacent neurons or other cells. Acetylcholine is an example of a neurotransmitter that signals the beginning or muscle contractions in motor neurons throughout the body. Finally, the last classification is endocrineBPK 105 Midterm Exam Downloaded by Mike Splendid () chemical messengers, which are signals that are secreted into the bloodstream by glands and cells and have the capability to be carried throughout the body to affect cells that are distance from the original source. Growth hormone is secreted by the pituitary gland into the bloodstream and carried all over the body to stimulate growth in bones, muscles, and other organs. Differentiate between protein and lipid derived hormones. Provide two examples of each along with their functions. [7 marks] Lipid derived hormones travel in the blood stream and will attach to binding proteins, proteins that are transporting hormones. The rate that lipid derived hormones are eliminated from the circulation becomes less likely, and their life span will range from a few days to up(as long as) several weeks. If there is no binding protein, the lipid derived hormones would diffuse very quickly out of the capillaries and be eliminated by enzymes of the liver and lungs or be removed from the body through the kidneys. Circulating hydrolytic enzymes can also metabolize free lipid derived hormones. The breakdown products are then excreted in the urine or the bile. Protein hormones or water-soluble hormones can dissolve in blood, most circulating as free hormones meaning most of them dissolve right into the bloodstream and are delivered to their target tissue without attaching to a binding protein. Many water-soluble hormones are fairly large, and don't readily diffuse through the walls of the capillaries; causing them to diffuse from blood into tissue spaces more slowly. The capillaries of organs are regulated by protein hormones and are normally very ports. Other water-soluble hormones are pretty small and require attachment to a large protein to avoid being filtered out of the blood. Water-soluble hormones, such as protein, peptides, and amino acids derivatives, have fairly shot half-lives because the are quickly degraded by enzymes, called proteases, within the bloodstream. The kidneys then remove the hormone breakdown products from the blood. Target cells also kill water-soluble hormones when the hormones are internalized through endocytosis. Water-soluble hormones are more stable in the circulation than others. Many times, proteins and peptides hormones have a carbohydrate attached to them, or their terminal ands are changed. The change helps protect them from activity to a greater extent then water-soluble hormones lacking such change. Describe the concept of receptor site specificity using any two hormones as an example. Describe the concept of target tissues. Why are these concepts so important? [4 marks] Receptor site is the portion of each receptor molecule where a hormone bind. The shape and chemical characteristics of each receptor site allow only a specific type of hormone to bind it. The chance for each type of hormone to bind to one type of receptor, and not to others, is called specificity. Example: insulin binds to insulin receptor, but not receptors for thyroid hormones. Some hormones such as epinephrine, can bind to a "family" of receptors that are structurally similar. Hormones that travel a distance from their source through the bloodstream to specific site called target tissue or effectors, where they produce a coordinated response of the target tissue.BPK 105 Midterm Exam Downloaded by Mike Splendid () Receptor site specificity is an important concept because without it, our bodies would not be able to properly function. Receptor sites are made specifically to bind to one type of hormone because it only requires on type of function and stimulation. If all receptor sites were able to bind to all the different types of hormones, our cells would be in a chaotic turmoil. For example, two hormones such as insulin and prolactin are only able to bind to their individual specific receptor sites. If prolactin were to bind on to an insulin receptor site and vice versa, our body wouldn't know how to correctly respond to correct its imbalance and maintain homeostasis. Describe the three types of stimuli that regulate hormone secretion, provide an example for each method from the list of hormones in the module objectives. Include the specific stimulus and site of release as well as the impact on the target organ for each example you use. [7 marks] 1. Humoral: when blood borne molecules can directly stimulate the release of some hormones. These hormones are sensitive to blood levels of a particular substance, such as glucose, calcium, or sodium. Ex.