BPK 105 Final Exam Study Guide | Complete Questions and Answers (Modules 7–9) | Fall 2025/2026 Edition | 100% Correct | Simon Fraser University – Human Physiology

Downloaded by Mike Splendid () BPK 105 Final Exam Study Guide | Complete Questions and Answers (Modules 7–9) | Fall 2025/2026 Edition | 100% Correct | Simon Fraser University – Human Physiology Module 7 & 8 1. Describe the process by which more red blood cells are made in response to low oxygen. What nutrients are required for this process, why? - In response to low blood oxygen levels, the kidneys produce erythropoietin, which stimulates red blood cell production in red bone marrow. - Typical causes of low blood oxygen are decreased numbers of red blood cells, decreased or defective hemoglobin, diseases of the lungs, high altitude, inability of the cardiovascular system to deliver blood to tissues, and increased tissue demand for oxygen, as occurs during endurance exercises. - Low blood oxygen levels stimulate red blood cell production by increasing the formation and release of the glycoprotein erythropoietin, primarily by the kidneys (figure 11.4). - Erythropoietin stimulates red bone marrow to produce more red blood cells. The greater number of red blood cells increases the blood’s ability to transport oxygen. This negativefeedback mechanism increases the blood’s capacity to transport oxygen and maintains homeostasis. - Conversely, if blood oxygen levels rise, less erythropoietin is released, and red blood cell production decreases. 2. Draw a flow chart indicating the three stages of clot formation following injury to a blood vessel. Where would there be a problem if the individual was vitamin K deficient? What diagnostic blood test help determine this, what would be a normal value for this test? - Prothrombin time measurement calculates how long it takes for the blood to start clotting, which is normally 9–12 seconds. Prothrombin time is determined by adding thromboplastin to whole plasma. - Thromboplastin is a chemical released from injured tissues that starts the process of clotting (see figure 11.9). Prothrombin time is officially reported as the International Normalized Ratio (INR), which standardizes the time it takes to clot on the basis of the slightly different thromboplastins used by different labs. - Because many clotting factors have to be activated to form fibrin, a deficiency of any one of them can cause the prothrombin time to be abnormal. Vitamin K deficiency, certain liver diseases, and drug therapy can increase prothrombin time. 3. Describe the functions of the heart, including the heart structure responsible for each function. 1. Generating blood pressureDownloaded by Mike Splendid () a. Contractions force blood through blood vessels b. Ventricles forcefulness of contraction determines BP 2. Routing blood a. Heart separates the pulmonary and systemic circulations b. Pulmonary Semilunar valve & Aortic semilunar valve c. Bicuspid and Tricuspid valves 3. Ensuring one way blood flow a. Valves prevent back flow of blood 4. Regulating blood supply a. Changes in rate and force of contraction match blood flow to the changing metabolic needs of the tissues b. AV node and ventricles 4. Trace the flow of blood through the heart. Specify the various chambers, valves, and vessels and the function of each. Draw the approximate location of the sinoatrial (SA) node and Atrioventricular (AV) node. [7 marks] (*note the information for this question is contained in several figures throughout Chapter 12*) - Both atria and both ventricles contract at the same time - Blood enters right atrium through inferior and superior vena cava & coronary sinus - Right atrium contracts through bicuspid valve right ventricle - Right ventricle fills and contracts pulmonary semilunar valve pulmonary trunk - Higher pressure in pulmonary trunk causes backflow of blood and valve closes - Pulmonary trunk branches into pulmonary arteries lungs pulmonary vein - Left atrium tricuspid valve left ventricle aortic semilunar valve 5. Describe the important similarities and differences between cardiac and skeletal muscle cell structure and function. (Action Potential differences will be discussed in Question 7 below). - Cardiac: connect at branching, irregular angles, called intercalated discs - Striated in appearance - Involuntary - Skeletal: arranged in regular, parallel bundles - Striated in appearance - Voluntary 6. Draw the action potential that occurs in cardiac muscle. Label the axis and different phases. Describe which channels are open and closed during each phase, and how they contribute to the shape of the action potential 1. Depolarization Phase - Na+ Channels are open and Ca2+ channels are open - Sodium diffuses into the cell causing the inside of the cell membrane to become more positive (depolarized) - Inside of cell becomes increasingly more positive, represented by the steep increasingDownloaded by Mike Splendid () slope on the shape of the graph 2. Plateau Phase - At peak depolarization Na+ channels close - Small number of K+ channels open to cause repolarization - Ca2+ channels are open, slowing repolarization o Movement of K+ out of the cell is counterbalanced by movement of Ca2+ into the cell - Diffusion of Ca2+ is why cardiac muscle fiber action potential lasts longer and creates a plateau phase 3. Repolarization Phase - Ca2+ channels close - Many K+ channels open and K+ moves out of the cell - Since Ca2+ channels are closed, there is a greater net movement of positive ions out of the cell, causing the inside of the cell to become more negative (repolarized), represented by the dip on the graph 4. Refractory Period - Allow the cardiac muscle to relax 7. What are the major differences between the cardiac action potential and the skeletal muscle action potential? What causes these differences, why is it important for how the heart functions? - Plateau time period found only in cardiac AP gives time for blood to collect in the ventricles before being ejected to the arteries - Plateau makes the action potential and refractory period longer 8. What is the role of the Sinoatrial (SA) node in the heart? Describe the conduction system of the heart. How does this conduction system facilitate the smooth coordinated contraction of the heart that is important for it to function as a pump? The SA node: - Functions as the heart's pacemaker - Produces fast action potentials initiate in the SA node and spread over the atria causing them to contract - Na+ and Ca2+ channels open and close in a rhythmic rate to control heart beat The Conduction System: - Action potentials are initiated in the SA node, which cause the two atria of the heart to contract - Action potentials reach the AV node and spread to the AV bundle o Time it takes for the action potential to spread from the AV node to the AV bundle allows the ventricles of the heart to fill with blood - The AV bundle divides into left and right bundle branches o Tips of these branches have purkinje fibers that extend through the cardiac muscle of the ventricles - Action potentials travel from the AV bundle to the purkinje fibersDownloaded by Mike Splendid () - Action potentials are rapidly delivered to all the cardiac muscle in the ventricles, causing the ventricles to contract - After contractions, the ventricles relax and an action potential originates in the SA node to begin the next cycle of contraction 9. Draw a typical Electrocardiogram (ECG) trace. Label each of the phases and describe the electrical and contractile events in the heart during each phase. - Recording of electrical events that occur in the heart - The P wave: depolarization of the atrial myocardium o Beginning of P wave precedes atrial contraction - QRS complex: results from depolarization of the ventricles and beginning precedes ventricle contraction - T wave: represents repolarization of the ventricles and beginning precedes ventricle relaxation - Repolarization of atria occurs during the QRS wave - PQ interval: the time between the beginning of a P wave QRS complex o Atria contract and begin to relax - QT interval: represents the length of time required for ventricular depolarization and repolarization 10. After six months of training an individual has a lower resting heart rate than she did prior to training when running at the same speed. Her cardiac output, however, is essentially the same. What do you think accounts for this? Define cardiac output and its components in your answer. Do you think her resting HR is different after training? Why? - Cardiac output: the volume of blood pumped by a single ventricle of the heart per minute - Stroke Volume: the volume of blood pumped by one ventricle as a result of single contraction - Heart Rate: the number of times the heart contracts per minute - Trained athlete has a higher stroke volume (volume of blood per beat) than a sedentary person, there for can pump the same amount of blood more efficiently (with less heart beats per minute) - Exercise increases the size of the heart which allows for higher stroke volume - A Sedentary person will have a smaller heart and a smaller stroke volume, so more beats per minuteDownloaded by Mike Splendid () 11. Compare and contrast the structure and function of elastic arteries, muscular arteries and capillaries. List the functions of the circulatory system that each type of vessel contributes to. Arteries - Elastic Arteries: the largest in diameter and have the thickest walls o Have a greater proportion of elastic tissue and smaller proportion of smooth muscle o E.g. aorta and pulmonary trunk o Stretch when ventricles pump blood into them o Elastic recoil prevents blood pressure from falling - Muscular arteries: medium and small sized arteries o Thick walls from smooth muscles o Distributing arteries: smooth muscles enables vessels to control blood flow to specific regions of the body o Vasoconstriction: contraction of the smooth muscles o Vasodilation: relaxation of the smooth muscles - Arterioles: transport blood from small arteries to capillaries o Only one or two layers of circular smooth muscle cells Capillaries - Precapillary sphincters: regulate the blood flow through capillaries - Endothelium: make up capillary walls - Thin walls of capillaries facilitate diffusion between the capillaries and surrounding cells o 0.5-1mm long o Same diameter of a red blood cell (7.5um) - Red blood cells flow through capillaries in single file - Capillary networks more extensive in highly metabolic tissues - Very low BP Veins - Venules: diameter slightly larger than capillaries - Small veins: slightly larger in diameter than venules - Medium sized veins: collect blood from small veins and deliver it to large veins o Three distinct tunics o Elastic fibers and smooth muscle, adventitia (collagen fibers) - Veins are more distensible than arteries because of adventitia - Veins with diameters greater than 2mm contain valves to prevent backflow - Because of veins large diameter, resistance to flow is slow and BP is low 12. Illustrate the changes in blood pressure as you move from the Aorta to the Venae Cavae using standard values for a young adult. Define and label Systolic BP, Diastolic BP and Pulse Pressure. - Refer to figure 13.22 in textbook. - When the ventricles contract, blood is forced into the arteries, and the pressure reachesDownloaded by Mike Splendid () a maximum value called the systolic pressure. - When the ventricles relax, blood pressure in the arteries falls to a minimum value called the diastolic pressure. - The difference between the systolic and diastolic pressures is called the pulse pressure. - A standard blood pressure for a resting young adult male is 120 mm Hg for the systolic pressure and 80 mm Hg for the diastolic pressure, commonly expressed as 120/80. - As blood flows from arteries through the capillaries and veins, blood pressure falls progressively to about 0 mm Hg or even slightly lower by the time blood is returned to the right atrium. In addition, the fluctuations in blood pressure are damped, meaning that the difference between the systolic and diastolic pressures is decreased in the smalldiameter vessels. - The decrease in fluctuations in pressure is the result of increased resistance to blood flow in smaller and smaller vessels. By the time blood reaches the capillaries, the smallest of the vessels, there is no variation in blood pressure, and only a steady pressure of about 30 mm Hg remains (figure 13.22). 13. Describe the movement of fluid out and back into capillaries at the tissue (capillary exchange). Include the forces that drive this process that is necessary for the diffusion of nutrients and dissolved gases (oxygen and carbon dioxide). What is edema, and what causes it? - Nutrients diffuse across capillary walls to interstitial space and waste products diffuse in the opposite direction - Major forces responsible are blood pressure and osmosis o BP forces fluid out of the capillary, osmosis moves fluid into the capillary - Capillary wall works as a selectively permeable membrane that prevents proteins from moving from the capillary into the interstitial space but allows fluid to move across the capillary wall - At arterial end, movement of fluid out of the capillary due to blood pressure is greater than the movement of fluid into the capillary because of osmosis o Net movement of fluid out of the capillary - At venous end, blood pressure is lower than at arterial end because of the resistance to blood flow through the capillary o Movement of fluid out of capillary is less than movement into the capillary due to osmosis o Net movement of fluid into the capillary - Approximately 9/10ths of fluid that leaves the capillary at the arterial end reenters at the venous end and the remaining 1/10t enters the lymphatic circulation - Edema: swelling that results from the disruption in the normal inward and outward directed pressures across the capillary walls o Proteins leak out into interstitial space and inc osmotic pressure o Fluid passes into the interstitial space more rapidly and fluid accumulatesDownloaded by Mike Splendid () 14. Describe the changes in blood flow that occur during the onset of exercise. Include detailed descriptions of the local and nervous control mechanisms. - Blood flow provided to the tissues by the circulatory system is highly controlled and matched closely to the metabolic needs of tissues. Mechanisms that control blood flow through tissues are classified as (1) local control or (2) nervous and hormonal control. Local Control of Blood Flow - Local control of blood flow is achieved by the periodic relaxation and contraction of the precapillary sphincters. - When the sphincters relax, blood flow through the capillaries increases. - When the sphincters contract, blood flow through the capillaries decreases. - The precapillary sphincters are controlled by the metabolic needs of the tissues. - For example, blood flow increases when by-products of metabolism buildup in tissue spaces. - During exercise, the metabolic needs of skeletal muscle increase dramatically, and the by-products of metabolism are produced more rapidly. The precapillary sphincters relax, increasing blood flow through the capillaries. - Other factors that control blood flow through the capillaries are the tissue concentrations of O2 and nutrients, such as glucose, amino acids, and fatty acids (figure 13.25 and table 13.1). Blood flow increases when O2 levels decrease or, to a lesser degree, when glucose, amino acids, fatty acids, and other nutrients decrease. An increase in CO2 or a decrease in pH also causes the precapillary sphincters to relax, thereby increasing blood flow. - In addition to the control of blood flow through existing capillaries, if the metabolic activity of a tissue increases often, additional capillaries gradually grow into the area. The additional capillaries allow local blood flow to increase to a level that matches the metabolic needs of the tissue. For example, the density of capillaries in the well-trained skeletal muscles of athletes is greater than that in skeletal muscles on a typical nonathlete (table 13.1). Nervous and Hormonal Control of Blood Flow - Nervous control of blood flow is carried out primarily through the sympathetic division of the autonomic nervous system. Sympathetic nerve fibers innervate most blood vessels of the body, except the capillaries and precapillary sphincters, which have no nerve supply (figure 13.26). - An area of the lower pons and upper medulla oblongata, called the vasomotor center, continually transmits a low frequency of action potentials to the sympathetic nerve fibers. - As a consequence, the peripheral blood vessels are continually in a partially constricted state, a condition called vasomotor tone. 15. Describe the baroreceptor reflex initiated by a sudden drop in blood pressure. Include the location of receptors and integration centers and how the nervous system responds to this change. Include the influences on the heart (Chapter 12) andDownloaded by Mike Splendid () blood vessels (Chapter 3). - Baroreceptors: stretch receptors that monitor blood pressure in the aorta and the wall of the carotid arteries - Changes in blood pressure result in changing levels of stretch within the vessels and changes the frequency of action potentials of the baroreceptors - Action potentials are transmitted along nerve fibers from the stretch receptors to the brain cardioregulatory center - Cardioregulatory center controls the action potential frequency of the sympathetic and parasympathetic nerve fibers and stimulation of the adrenal gland - When blood pressure decreases, baroreceptors are stimulated at lower frequency which prompts the cardioregulatory center to decrease parasympathetic stimulation and increase sympathetic stimulation and HR and SV increase causing blood pressure to increase - If decrease in BP is large, sympathetic stimulation of adrenal medulla also increases and epinephrine and norepinephrine increase heart rate and stroke volume Module 9 1. Describe the functions of the lymphatic system. Describe the general location and function of the major organs of the lymphatic system. 1. Fluid Balance a. About 30L of fluid pass from capillaries to interstitial space every day but 27L pass from interstitial space back to capillaries b. Extra 3L enters the lymphatic capillaries where it is called lymph c. Lymph contains solutes derived from two sources i. Substances in plasma (ions, nutrients, gases and some proteins) ii. Substances such as hormones, enzymes, waste products derived from cells within the tissues 2. Lipid Absorption a. Absorbs lipids and other substances from the digestive tract b. Lacteals: lymphatic vessels that absorb lipids c. Chyle: lymph passing through vessels that appears white due to lipid content 3. Defense a. Pathogens are filtered from lymph by the lymph nodes from the blood and by the spleen b. Lymphocytes and other cells are capable of destroying pathogens The Tonsils - Three groups of tonsils o Palatine tonsils: located on each side of the posterior opening of the oral cavity and are what is commonly referred to as “the tonsils” o Pharyngeal tonsil: located near the internal opening of nasal cavity o Lingual tonsil: on posterior surface of the tongue - The tonsils perform a protective ring of lymphatic tissue around the openings between the nasal and oral cavities and the pharynxDownloaded by Mike Splendid () - Protect against pathogens and other harmful material entering the nose and mouth The Lymph Nodes - Distributed along various lymphatic vessels - Two functions are performed in the lymph nodes: o Activate the immune system pathogens in the lymph can stimulate lymphocytes in the lymphatic tissue to divide o To remove pathogens from the lymph through the action of macrophages The Spleen - Located in left superior corner of the abdominal cavity - Cells within the spleen detect and respond to foreign substances in the blood and destroy worn-out RBCs - Lymphocytes in the white pulp can be stimulated as they are in lymph nodes - Macrophages in red pulp remove foreign substances and RBCs through phagocytosis - Also functions as a blood reservoir, holding a small volume of blood The Thymus - Located in the mediastinum, the partition that divides the thoracic cavity into left and right parts - Thymus is the site for maturation of T-Cell lymphocytes - Large number of T cells are produced in the thymus 2. Describe the formation and movement of lymph fluid. - Lymph is formed when the interstitial fluid is collected through tiny lymph capillaries (see diagram), which are located throughout the body .....Some fluid (blood plasma) leaks out into the tissues via tiny capillaries, contributing to interstitial fluid, which eventually drains back into the lymphatic system. 3. Discuss the differences between innate (non-specific) and adaptive (specific) immunity. List the white blood cells that are involved in each type of response. Innate Immunity: - Body recognizes and destroys pathogens, but the response is the same each time the body is exposed - Relies on physical barriers (preventing the pathogen from entering the body), Chemical mediators (such as saliva or tears that kill cells or prevent them from entering), White blood cells and the Inflammatory response - Activated by the chemical properties of the pathogen - Monocytes and Neutrophils - Basophils and Mast cells - Natural Killer Cells Adaptive Immunity: - Has specificity and memory - Can recognize specific substances and respond more effectivelyDownloaded by Mike Splendid () - Uses antibody proteins that respond to a specific antigen - Reacts to foreign antigens (antigens introduced from outside the body) and Self-antigens (molecules the body produces to stimulate immune response) - Divided into antibody-mediated immunity (involves lymphocytes B cells and antibody proteins) and Cell-mediated immunity (involves lymphocyte T-cells) 4. Describe the steps of the local inflammatory response to tissue damage caused by bacterial infection, including the roles of the different chemical mediators and white blood cells. - A group of more than 20 proteins found in plasma - Normally circulate the blood in inactive form but can be activated when combining with foreign substances or antibodies - Once activated, promote inflammation and phagocytosis and can directly rupture bacterial cells Interferons - Proteins that protect the body against viral infections - When virus enters cell it produces viral nucleic acids and proteins - Interferons binds to surface of neighboring cells and stimulate those cells to produce antiviral proteins that inhibit viral reproduction by preventing the production of new viral nucleic acids and proteins White Blood Cells: Phagocytic Cells - Neutrophils: small phagocytic cells that are usually first to enter infected tissues from the blood in large numbers o Release chemical signals that increase the inflammatory response by recruiting and activating other immune cells - Macrophages: monocytes that leave the blood, enter tissues and enlarge about 5x o With macrophages form the mononuclear phagocytic system o Can ingest more and larger items that neutrophils o Responsible for most of the phagocytic activity in late stages of infection o May phagocytize pathogens before they can replicate or cause damage Cells of Inflammation - Basophils: motile white blood cells that can leave the blood and enter infected tissues - Mast cells: non-motile cells in connective tissue o Located at points where pathogens may enter the body (skin, lungs, gastrointestinal tract, urogenital tract) - Basophils and mast cells can be activated through innate or adaptive immunity - When activated they release chemicals such as histamine and leukotrienes that produce inflammatory response or activate other mechanisms - Eosinophils: participate in inflammation associated with allergies and asthma Natural Killer CellsDownloaded by Mike Splendid () - Recognize classes of cells such as tumor cells or virus infected cells in general - Use a variety of methods to kill their target cells, including releasing chemicals that damage the cell membranes and cause the cells to lyse The Inflammatory Response 1. Bacteria Enter the tissue a. Damage causes the release or activation of chemical mediators 2. Chemical mediators produce several effects a. Vasodilation increases blood flow and brings phagocytes and other white blood cells to the area b. Phagocytes leave the blood and enter the tissue c. Increased vascular permeability allows fibrinogen and complement to enter the tissues from the blood 3. Phagocytes remove microorganisms and dead tissues and the damaged tissues are repaired 5. What is an antigen, use the details of human blood typing (Section 11.6) to illustrate your knowledge. Use a description of autoimmune disease to describe the ability to differentiate between self and foreign molecules. - Antigen: a substance that elicits a specific immune response in the body o There are foreign antigens and self-antigens - Allergies are caused by foreign antigens o Things such as pollen or certain foods cause allergic reactions o Allergic reactions are an overreaction of the immune system o Antibody-mediated immunity is activated o B-cells are activated and antibodies are produced which bind to the antigens and destroy them - Self-antigens are important when initiating an immune response on unhealthy tissues, such as tumors that occur in the body - Autoimmune disease occurs when self-antigens elicit self-destruction of healthy tissues - Cell-mediated immunity is activated when protecting against self-antigens T-cells 6. Describe cell mediated immunity through a description of the proliferation of helper T cells and cytotoxic T cells. - Antigen presenting cells phagocytize, process and display antigens on the cell’s surface - Antigens are bound to MHC class II molecules which present the processed antigen to the T-cell receptor of the helper T-cell - Costimulation results from interleukin-1 and the CD4 glycoprotein of the helper T-cell - IL-1 stimulates helper T cell to secrete IL-2 and to produce Il-2 receptors - The daughter T cell can be stimulated to divide again if they are exposed to the same antigen that stimulated the parent T cell - The increased number of T cells can facilitate the activation of B cells or effector T cellsDownloaded by Mike Splendid () 7. Describe the structure and function of antibodies. Describe the different effects antibodies have in immunity. Structure of Antibodies - Y shaped molecules consisting of 4 polypeptide chains o Two heavy chains and two light chains - At the end of each arm is the variable region part of the antibody that combines with the antigen o Variable region can join only with a particular antigen (lock and key) - Rest of the antibody is called the constant region o Can activate complement or attach antibodies to cells Effects of Antibodies - Antibodies can affect antigens either directly or indirectly - Direct occur when a single antibody binds to an antigen and inactivates the antigen - Indirect after antibody has attached to the antigen, the constant region of the antibody can activate other mechanisms that destroy the antigen o E.g. activate complement to stimulate inflammation 8. Differentiate between antibody production in primary and secondary responses. Describe the roles of memory B cells and memory T cells. - Primary Response: results from first exposure of a B cell to an antigen o When antigen binds to the antigen-binding receptor on the B cell and the B cell has been activated by a helper T cell, the B cell undergoes several divisions to form plasma cells and memory B cells o Plasma cells produce antibodies o Normally takes about 3-14 days to produce enough antibodies to be effective against the antigen - Memory B cells: responsible for the secondary response o When exposed to the antigen, memory B cells quickly divide to form plasma cells which rapidly produce antibodies o Provides better response than primary response for two reasons: ● The time required to start producing antibodies is less ● More plasma cells and antibodies are produced o Antigen is quickly destroyed, no disease symptoms develop and person is immune o Also includes formation of new memory cells, which protect against additional exposure to a specific antigen 9. Describe the four ways to acquire adaptive immunity providing examples of each. 1. Active Natural Immunity - Results from natural exposure to an antigen - Individual is not immune during first exposure, so symptoms of the disease typically developDownloaded by Mike Splendid () - E.g. catching the flu 2. Active Artificial Immunity - Antigen is purposely introduced into an individual to elicit an immune response in a process called vaccination - Vaccine contains part of a pathogen which is either dead or alive but modified - The pathogen will stimulate an immune response, but not produce symptoms of the disease - Produces immunity against the pathogen - E.g. Getting a tetanus shot 3. Passive Natural Immunity - Occurs when antibodies from a mother are passed to her child across the placenta before birth - The antibodies protect the baby for the first few months of its life once born, but eventually break down, requiring the baby to develop its own immune system - E.g. a baby that is breastfed will receive antibodies from its mom through her breast milk 4. Passive Artificial Immunity - Begins with vaccinating an animal whose immune system produces antibodies in response to the antigen or a human who has immunity through artificial immunity or natural exposure - The antibodies produced in the animal or human are then removed and injected into the recipient who requires immunity - The preferred treatment when not enough time is available to allow the individual to develop their own active immunity - Provides only temporary immunity because antibodies are eventually eliminated by the receiver Module 10 1. Describe the functions of the respiratory system. 1. Regulation of Blood pH a. Can alter blood pH by changing blood CO2 levels 2. Voice Production a. Air movement past vocal cords sound and speech 3. Olfaction a. Airborne molecules must be drawn into the nasal cavity 4. Innate Immunity a. Protects against some microorganisms and other pathogens by preventing them from entering the body or removing them from respiratory surfaces b. Phagocytic cells in the lungs phagocytize most carbon particles and other debris inspired from the air and move them to the lymphatic vessels 5. Breathing provides oxygen needed in cellular respiration to make ATP from glucoseDownloaded by Mike Splendid () increases. 2. Draw and label a diagram of the respiratory system including the detailed anatomy of the lungs (utilize Figures 15.1, 15.5, and 15.7). 3. Describe the pressure changes involved during inspiration and expiration. Include the changes in thoracic volume and specific muscle contractions during one breathing cycle at rest and during exercise. - During inspiration, alveolar pressure is less than atmospheric pressure because the thoracic volume - During expiration, alveolar pressure is greater than atmospheric pressure because the thoracic volume decreases. - Diaphragm always contracts when breathing - Quiet breathing: intercostal muscles contract - Labored breathing: Scalenes and Pectoralis minor contract too 4. Describe surfactant and pleural pressure including their roles of in preventing the collapse of alveoli. Briefly describe infant respiratory disease syndrome (IRDS) in premature infants and why it is critical to treat it effectively. The surface acting agent known as surfactant is a lipoprotein molecule mixture formed through alveolar epithelial secretory cells. They make a single layer on the surface of the fluid layer covering the alveoli to lower pulmonary surface tension. The tension that causes the alveoli to recoil without surfactant will be almost ten times higher than when surfactant is there. However, it lessens the chances of a lung collapsing. Rather, the alveoli will expand when the pleural pressure is lower than the alveolar pressure. The suction effect will cause pleural pressure to be lower than alveolar pressure. Alveoli increases when pleural pressure is smaller than alveolar pressure, however, it is countered by the lungs ability to recoil. Alveoli expand when pleural pressure is low. Meanwhile the opposite, alveoli shrink when pleural pressure is too high. It is crucial to treat premature babies, with IRDS due to the decline in surfactant intake. Only in the seventh month of pregnancy does the infant develop sufficient quantities of surfactant, therefore this occurs often in premature babies. IRDS needs to be managed and dealt with a birth as the infant can die if the lungs do not function properly. 5. Draw and label a graph representing the pulmonary volumes and capacities. Briefly define each of these volumes and capacities below the graph. - Tidal Volume: How much you breathe normally - Inspiratory Reserve Volume: Max you can breathe in on top of Tidal Volume - Expiratory Reserve Volume: Max you can blow out under Tidal VolumeDownloaded by Mike Splendid () - Residual Volume: Air after max blow out (how much remains) - Functional Residual Capacity: How much air after normal breath. (expiratory + residual) - Inspiratory Capacity: How much can you breathe in after normal breath - Vital Capacity: How much you air you can blow after max breathe in. - Total Lung Capacity: How much air can your lungs hold? 6. Describe gas exchange in the pulmonary and systemic circulatory systems for oxygen and carbon dioxide. Include the changes in partial pressures for both of these dissolved gases and the driving force for exchange at each location. What impact would pulmonary edema, an increase in interstitial fluid in the lungs, have on gas exchange? List the other factors could influence the rate of gas exchange at the respiratory membrane. - In pulmonary gas exchange, CO2 enters the alveoli that have low CO2 pressure. O2 enters the bloodstream which has low O2 pressure. In systemic gas exchange O2 moves from hemoglobin to tissue because of high CO2 pressure, low O2 pressure, low pH and high temperature in the tissue. - Pulmonary edema causes the rate of gas exchange to decrease because thicker layers of fluid in alveoli make it hard for O2 to diffuse. 7. Describe the transport of oxygen in circulation. What environmental changes occur as blood enters the active muscle influence the release of oxygen from hemoglobin? How does the release of oxygen differ during exercise? - After Oxygen diffuses from the respiratory membrane into the blood, 98.5% of it combines reversibly with hemoglobin to make oxyhemoglobin. This depends on oxygen's partial pressure. In lungs, pressure is high so oxyhemoglobin forms. In tissues, oxygen is used so partial pressure is low. oxygen diffuses into cells for cellular respiration. At rest, 23% of oxygen picked up by hemoglobin in the lungs is released to the tissues. - 98.5% of oxygen binds reversibly to hemoglobin, 1.5% are in plasma. Muscle contractions means using O2, and producing CO2, low pH, and high temperatures. Invites O2 into tissue from the bloodstream. 8. Describe the various ways carbon dioxide is transported in circulation, including the approximate percentage that is transported in each way. Include the full reaction catalyzed by carbonic anhydrase. How does this equilibrium reaction change between the tissues and the lungs? After goes to blood, CO2 1) 7% dissolved into plasma 2) 23% transported in combination with blood proteins 3) 70% is transported in the form of bicarbonate ions CO2+ H2O <-> H2CO3 <-> H + HCO3 carbon dioxide + water <-> carbonic acid <-> hydrogen ion + bicarbonate ionDownloaded by Mike Splendid () IN TISSUES - Carbonic anhydrase increases rate to form hydrogen ions and bicarbonate ions IN LUNGS - HCO3- & H+ combine to make carbonic acid, which then forms co2 & h2o. The co2 diffuses into alveoli & is expired. 9. Describe the rhythmic control of ventilation. Describe the phases of change in ventilation during exercise. How does exercise training affect ventilation at rest and during exercise? 1. The Medullary Respiratory Center constantly receives stimulation from many sources. 2. When input from these sources reaches a certain threshold, respiratory muscle produces action potential to bring INSPIRATION. 3. Once inspiration begins, more and more neurons are activated (last about 2s). 4. When neurons responsible for stopping inspiration receive input (past a certain threshold), inspiration stops, muscles relax, and step 1 begins. - Exercise causes Immediate increase to 50% or more of total breathing capacity, then gradual increase for another 4-6 minutes until plateauing. - Training helps the brain learn to match breathing with intensity of exercise, so that the respiratory muscles move more efficiently. It also increases vital capacity, and decreases residual volume slightly. 10. Describe the chemical control of ventilation. When are blood oxygen levels important? Describe the step-by-step response to an increase in carbon dioxide in the blood. The body’s cells absorb O2 and emit CO2 during cellular respiration. In breathing one of the most important aspects is the amount of CO2 in the blood. Hypercapnia is when there is a slight rise in CO2 resulting in the individual feeling a strong need to breathe. The difference in pH is involved in how CO2 in the blood activates breathing. The medulla oblongata contains chemoreceptors that are susceptible to subtle variations in H+ concentration. Not only are chemoreceptors important for that, they are essential for preserving blood pH. In order to maintain CO2 levels, the chemoreceptors will signal a slower breathing rate, as the pH of the blood will rise if CO2 levels fall. While blood CO2 rises, blood pH drops becoming more acidic, resulting in chemoreceptors sensing a spike in H+ and indicating faster breathing. The carotid and aortic bodies have O2 responsive chemoreceptors as well. As O2 levels drop a condition called hypoxia, where the chemoreceptors transmit action potentials to the respiratory centre., cause a rise in breathing. Therefore, O2 diffusion from alveoli to blood will improve. Module 11 1. Briefly describe the functions of the digestive system. 1. Ingestion of FoodDownloaded by Mike Splendid () a. Food and water enter the body through the mouth 2. Digestion of Food a. Food is broken down from complex particles to smaller molecules that can be absorbed 3. Absorption of Nutrients a. Epithelial cells that line the small intestine absorb nutrients 4. Elimination of Wastes a. Undigested material plus waste products are excreted as feces 2. Describe the structure and general functional roles of the four tunics (layers) of the digestive tract (Figure 16.2). Briefly highlight the differences between the different organs related to their specialized functions. Mucosa (loose connective tissue, thin layer of smooth muscle) - Consists of three additional layers: mucous epithelium, lamina propria and muscularis mucosae - Key component of absorption as it contains many folds - Cells secrete mucus and other substances like enzymes Submucosa (thick layer of loose connective tissue) - Contains nerves, blood and lymph vessels and small glands - Glands to secrete substances and enzymes - An extensive network of nerve cell processes form an intertwining of nerves and blood vessels (called a nerve plexus) - Nourishes surrounding tissue Muscularis - Consists of two additional layers: smooth muscle and longitudinal smooth muscle - Contract in opposite directions to move food - Has another nerve plexus, and together w/ nerve plexus of submucosa compose the enteric nervous system, which controls movement and secretion within tract Serosa - Consists of a smooth epithelial layer (peritoneum) and connective tissue layer - Serves mainly as protection - Secrets serous fluid to lubricate organs from sticking to e/o 3. Name and describe the three phases of deglutition (swallowing). Include the relevant anatomy involved in each phase. - Voluntary phase o A bolus (mass of food) is formed in the mouth and pushed by the tongue against the hard palate forcing it toward the posterior part of the mouth - Pharyngeal phase o Swallowing is a reflex initiated when a bolus of food stimulates receptors in the oropharynx o Begins with the elevation of the soft palateDownloaded by Mike Splendid () o Pharyngeal constrictor muscles contract and force the food through the pharynx o Epiglottis covers the larynx by the force of the bolus against it - Esophageal phase o Moving of food from the pharynx to the stomach o Moved by muscular contractions of the esophagus in peristaltic waves 4. Describe the cephalic phase of stomach secretion. Include the function, stimulation for release and gland of origin of each secretion. - Taste, smell or thought of food or tactile sensations of food stimulate the medulla oblongata - Action potentials are transmitted to the stomach via the vagus nerve where the enteric plexus neurons are activated - Postganglionic neurons stimulate secretion by parietal and chief cells and stimulate gastrin and histamine secretion by endocrine cells - Gastric is carried through the circulation back to the stomach with it stimulates secretion 5. Describe the intestinal phase of stomach secretion. Describe the hormones and pathways involved in modifying gastric activity. Intestinal phase: - Inhibits gastric secretions - Controlled by the entrance of chyme into the duodenum - The hormone secretin is released from the duodenum in response to low pH o Inhibits gastric secretions - Fatty acids and peptides in the duodenum initiate release of the hormone cholecystokinin o Also inhibits gastric secretions - Further secretion is controlled by negative feedback loops 6. Compare and contrast the structure of the mucosal layers of the stomach and small intestine. What does this tell you about the roles of the stomach and small intestine within the digestive system? Provide a brief description of two specialized structures from each organ’s mucosal layer to support your discussion of its role. The Stomach: - Mucosal surface forms numerous gastric pits o Openings for gastric glands - Mucosa layer has five types of cells o Mucous neck cells: produce mucus o Parietal cells: produce HCl and intrinsic factor o Endocrine cells: produce regulatory chemicals o Chief cells: produce pepsinogen (a precursor for the enzyme pepsin) Small Intestine: Mucosa of the small intestine has 4 cell types o Absorptive cells: have microvilli, produce digestive enzymes and absorb digested foodDownloaded by Mike Splendid () o Goblet cells: produce protective mucus o Granular cells: help protect epithelium from bacteria o Endocrine cells: produce hormones - These cells increase the surface area of the small intestine - Large surface area is important because small intestine is the main site of absorption and digestion of food 7. Describe the control of release and function of each of the secretions from the exocrine pancreas. Exocrine secretions of the pancreas are: - Bicarbonate (HCO3 - ) ions neutralizes the acidic chyme that enters the small intestine and raises the pH, stopping pepsin digestion but provides the ideal environment for pancreatic enzymes to function - Chymotrypsin, trypsin, carboxypeptidase continue protein digestion - Pancreatic amylase: continues polysaccharide digestion - Lipase: digests lipids - Nucleases: digest DNA and RNA into nucleotides Exocrine activity is controlled by hormonal and neural mechanisms: - Acidic chyme in the duodenum stimulates the release of bicarbonate ions - Cholecytokinin stimulates the pancreas to release enzyme-solution - Amino acids and fatty acids in the duodenum stimulate the release of cholecytokinin - Parasympathetic stimulation via the vagus nerve stimulates pancreas secretions and sympathetic stimulation inhibits the secretions 8. Distinguish between the processes of digestion and absorption through definition and description. Where in the gastrointestinal system do they generally take place? Digestion: The process of larger, more complex food molecules being broken down into smaller particles that can be absorbed into circulation. - Takes place in the mouth and stomach and small intestine - Mouth breaks down food into smaller particles by chewing and enzymes in the saliva help digest food - Hydrochloric acid in the stomach activates pepsin which helps digest food - Mixing waves in the stomach mix ingested food with stomach secretions to form chyme - Enzymes in the small intestine break down chyme - Mechanical and chemical digestion Absorption: The process by which epithelial cells absorb these small particles derived from food to use for body functions. - Begins in the stomach where some small molecules can diffuse through the stomach epithelium and into circulation - Absorption primarily takes places in the duodenum and jejunum o Villi, microvilli and circular folds increase the surface area of the small intestine whichDownloaded by Mike Splendid () increases efficiency of absorption 9. Describe the digestion and absorption of carbohydrates through the entire digestive system. Include the site, stimulation and function of important secretions and describe the details of absorption across the cell membrane. - Salivary amylase: begins the digestion of carbohydrates and is secreted into the mouth o Food then passes from the mouth to the stomach where it is mixed with acid that deactivates salivary amylase - Pancreatic amylase continues the digestion of carbohydrates in the duodenum o Breaks down polysaccharides into disaccharides - Disaccharidases: enzymes bound to microvilli in the intestinal epithelium o Break down the disaccharides into monosaccharides - Monosaccharides are then taken up through the epithelial cells and are then transported into the capillaries of the intestinal villi and carried by the hepatic portal vein to the liver o Driven by a Na+ concentration gradient o Diffusion of Na+ down its concentration gradient provides the energy to transport glucose across the cell membrane - Liver cells convert monosaccharides to glucose to be distributed throughout the body 10. Describe the digestion and absorption of lipids through the entire digestive system. Include a detailed description of the roles of the liver and the process of emulsification. Describe the process of lipid absorption and transport. - First step in lipid digestion is emulsification o Large lipid droplets are transformed into smaller droplets by bile salts which are secreted by the liver o Emulsiphication increases the surface area of the lipid droplets making it more likely for them to be exposed by digestive enzymes that can only act on their surface - Lipase: an enzyme secreted by the pancreas that digests lipid molecules - Bile salts collect around the droplets of lipids to form micelles o Hydrophobic ends of the salts stay close to the lipid particles and the hydrophilic ends are directed outward - When a micelle comes in contact with the epithelial cells of the small intestine, the lipids move by process of diffusion from the micelles through the cell membranes of the epithelial cells - Once inside the epithelial cells, the fatty acids and monoglycerides recombine and form triglycerides and are then packaged inside a protein coat o This complex is called a chylomicron or lipoprotein - Chylomicrons leave the epithelial cells by entering the lacteals which carries the lymph to the bloodstream which is then transported to the liver where the lipids are stored, used for energy, or converted to other moleculesDownloaded by Mike Splendid () 11. Describe the digestion and absorption of proteins through the entire digestive system. Include the site, stimulation and function of important secretions and describe the details of absorption across the cell membrane. - Pepsin: an enzyme secreted by the stomach that breaks down proteins into polypeptides - Trypsin, chymotrypsin and carboxypeptidase: enzymes located in the small intestine, produced in the pancreas that continue the digestive process of proteins o Produce small peptides which are further broken down - Peptidases: breaks down polypeptides into tripeptides, dipeptides or amino acids - Absorption of amino acids occurs in the intestinal epithelial cells by Cotransport o Many are taken up by Cotransport with Na+ - Within the intestinal epithelial cells, tripeptides and dipeptides are broken down into amino acids and enter the blood capillaries in the villi and are transported to the liver where they may be released into the bloodstream 12. Approximately 9 L of water enter the digestive tract daily. Where does this water come from, where does it end up, what regulates its movement and what are its functions (see Section 2.4). - 2 L is in food and drinks and the remaining 7 L are from digestive secretions - 92% of that water is absorbed in the large intestine, 7% in the large intestine and 1% leaves in poop - Water can move in either direction by osmosis across the wall of the digestive tract, and the movement is determined osmotic gradients across the epithelium - When chyme is dilute, water moves out of the intestine and into the blood, but if its concentrated, water moves out of the blood and into the small intestine Module 12 1. List the functions of the Urinary Systems. Excretion o Kidneys remove waste products from blood o Waste products: metabolic by-products of cell metabolism or substances absorbed from the intestine o Skin, liver, lungs, and other organs eliminate some waste products, but the waste elimination by these organs are not enough to retain homeostasis Regulation of blood volume and pressure o Kidneys play key role in controlling extracellular fluid volume in the body o Kidneys produce either a large or small volume of urine, depending on hydration in the body ▪ Urine production helps regulate blood volume and pressure Regulation of the concentration of solutes in the blood o Kidneys regulate concentration of major molecules and ions Regulation of extracellular fluid pH o Kidneys excrete variable amounts of hydrogen to regulate extracellular fluid pHDownloaded by Mike Splendid () Regulation of red blood cell synthesis o Kidneys secrete erythropoietin (hormone) which regulates the synthesis of red blood cells in bone marrow Regulation of vitamin D synthesis o Kidneys play key role in controlling blood levels of calcium by regulating the synthesis of vitamin D 2. Draw the structure of the kidney and nephron, including blood flow in the nephron. Use Figure 18.6 as a guide. 3. Illustrate and describe the pressures that influence filtation pressure at the bowmans capsule. What is pushed into the Bowman capsule from the glomerular is the fluid through the filtration membrane by the filtration pressure. Filtration pressure is formed when the forces which move the fluid out of the glomerular capillary into the Bowman capsule are less than the forces moving fluid into the glomerular capillary. The blood pressure in the glomerular capillary is the pressure, where fluid moves from the glomerular capillary through the filtration membrane and into Bowman's capsule because of immense force. (Glomerular capillary pressure) → (Capillary pressure) → (Colloid osmotic pressure) = Filtration pressure Black bottom arrow - glomerular capillary pressure Big purple arrow - capillary pressure Orange arrows - Colloid osmotic pressure 4. Describe the processes of reabsorption that occur as you move through the nephron. Include the main function, the % of filtrate volume and the main substances reabsorbed and in each area of the nephron. If we started with 180L of fluid being filtered, what is the average volume of urine output?Downloaded by Mike Splendid () - As filtrate flows from the Bowman capsule to the distal convoluted tubule and collecting duct, many solutes are reabsorbed o 99% of the original filtrate volume is reabsorbed and enters the peritubular capillaries o The remaining 1% becomes urine - The proximal convoluted tubule is the primary site for reabsorption of solutes and water o Cells of the proximal convoluted tubule have microvilli and mitochondria and are well adapted to transport molecules and ions across the nephron wall by active transport or co transport o Substances transported from the proximal convoluted tubule include proteins, amino acids, glucose and fructose, as well as ions - The proximal convoluted tubule is permeable to water o As solute molecules are transported out into the interstitial fluid, water moves by osmosis in the same direction o The solutes and water then enter the peritubular capillaries - The descending limb of the loop of Henle further concentrates the filtrate o The renal medulla contains very concentrated interstitial fluid that has high amounts of Na, Cl and urea o The thin segment of the descending limb is permeable to water and moderately permeable to solutes o As filtrate passes through the descending limb, water moves out of the nephron by osmosis, and some solutes move into the nephron by diffusion o More water is reabsorbed from the filtrate, and the filtrate is now as concentrated as the interstitial fluid of the medulla - The cells of the thick segment of the ascending limb actively transport Na, K and Cl out of the nephron o the thick segment is not permeable to water o As a result, Na, K and Cl are removed from the filtrate o Due to the removal of these ions, as the filtrate enters the distal convoluted tubule, it is more dilute than the interstitial fluid of the renal cortex - The cells of the distal convoluted tubule and collect duct remove some water and additional solutes o Na and Cl are reabsorbed o 19% of the filtrate volume are reabsorbed by osmosis o The reabsorbed water and solutes from the distal convoluted tubule enter the peritubular capillaries and the vasa recta from the collecting ducts - The reabsorption of water and solutes from the distal convoluted tubule and collecting duct is controlled by hormones 5. Outline the regulation of water and sodium balance by illustrating the response of the Renin-Angiostensin system to a decrease in blood volume. Use a block diagram to illustrate your answer. [6 marks]Downloaded by Mike Splendid () - Refer to figures 13.31 and 18.14 in textbook. Renin-Angiotensin-Aldosterone Mechanism - In response to reduced blood flow, the kidneys release an enzyme called renin into the circulatory system (figure 13.31). Renin acts on the blood protein angiotensinogen to produce angiotensin I. - Another enzyme, called angiotensin-converting enzyme (ACE), found in large amounts in organs, such as the lungs, acts on angiotensin I to convert it to its most active form, angiotensin II. Angiotensin II is a potent vasoconstrictor. - Thus, in response to reduced blood pressure, the kidneys’ release of renin increases the blood pressure toward its normal value. - Angiotensin II also acts on the adrenal cortex to increase the secretion of aldosterone. - Aldosterone acts on the kidneys, causing them to conserve Na+ and water. As a result, the volume of water lost from the blood into the urine is reduced. The decrease in urine volume results in less fluid loss from the body, which maintains blood volume. Adequate blood volume is essential to maintain normal venous return to the heart and thereby maintain blood pressure (see chapter 12). 6. An increase in Antidiuretic hormone (ADH) secretion is found in circulation. Describe what would stimulate an increase in ADH, where ADH is released from and how it influences the nephron. Briefly describe what else may be triggered by the same stimuli? - ADH is secreted by the posterior pituitary gland - ADH changes the permeability of the distal convoluted tubules and collecting ducts to water and causes more water to be reabsorbed from the filtrate - Changes in solute concentration of the urine influence the release of ADH o When solute concentration of the blood increase, ADH is released o Low solute concentration cause the release of ADH to be inhibited - Low blood pressure stimulates and increase of ADH o If baroreceptors detect decreased blood pressure, they will cause ADH to be secreted o ADH promotes an increase in Na+ and water reabsorption from the kidney to bing the blood pressure back up to its normal value 7. Describe the approximate volumes of the body fluid compartments of an adult female (as % of body weight). Include a comparison of the distribution of the major ions within these compartments. - ~50% of total body weight of a female is H2O less than men because females have higher percentage of body fat than males - Water and ions dissolved in it are in two major compartments: (1) intracellular fluid compartment and (2) extracellular fluid compartment. 1. Intracellular compartment: include all the fluids inside the body. Approximately 2/3 of H2O in the body is in this compartment. Intracellular in general has more K+, Ca2+, Mg, phosphate,Downloaded by Mike Splendid () sulphate ions and protein fluid than extracellular. 2. Extracellular fluid compartment: entails all the fluid outside the cell interstitial fluid, plasma within blood vessels, fluid in lymphatic vessels. Within it’s subcompartments, aqueous and vitreous humor of the eye, cerebrospinal fluid etc is included. Extracellular has more Na+, Cl-, an bicarbonate ions. 8. Describe the homeostatic response to a reduction in extracellular calcium concentration. Include the names, actions and sources of the hormones involved. Describe the potential physiological consequences if calcium concentration remained low? - The extracellular concentration of Ca2+, like that of other ions, is maintained with a narrow range. Increases and decreases in the extracellular concentration of Ca2+ have dramatic effects on the electrical properties of excitable tissues. - For example, decreased extracellular Ca2+ concentration make cell membranes more permeable to Na+, thus making them more electrically excitable. Decreased extracellular concentrations of Ca2+ cause spontaneous action potentials in nerve and muscle cells, resulting in hyper excitability and muscle tetany. - Increased extracellular Ca2+ concentrations make cell membranes less permeable to Na+ therefore making them less electrically excitable. Increased extracellular concentrations of Ca2+ inhibit action potentials in nerve and muscle cells, causing a reduction of excitability and either muscle weakness or paralysis. - Parathyroid hormone, secreted by the parathyroid glands, increases extracellular Ca2+ concentrations. The rate of PTH secretion is regulated by the extracellular Ca2+ concentration. - An higher Ca2+ concentration inhibits the secretion of PTH and a reduced Ca2+ concentration stimulates the secretion of PTH. PTH causes osteoclasts to degrade bone and release Ca2+ into the body fluids. - PTH also increases the rate of Ca2+ reabsorption from kidney nephrons. - Vitamin D increases Ca2+ concentration in the blood by increasing the rate of Ca2+ absorption by the intestine. Some vitamin D is consumes in food, and the blood produces the rest. - PTH affects the intestinal uptake of Ca2+ because PTH increases the rate of vitamin D production in the body. - Calcitonin is secreted by the thyroid gland. Calcitonin reduces the blood Ca2+ concentration when it is too high. An elevated blood Ca2+ concentration causes the thyroid gland to secrete calcitonin, and a low blood Ca2+ concentration inhibits calcitonin secretion. - Calcitonin reduces the rate at which bone is broken down and decreases the release of Ca2+ from bone. 9. Draw the series of reversible reactions catalyzed by the enzyme carbonic anhydrase,Downloaded by Mike Splendid () including the names and formulae of the components involved. Describe the compensation that would occur, within this buffer system, if there was an sudden increase in carbon dioxide dissolved in the blood. H2O + CO2 H2CO3 H+ + HCO3 Water + Carbon Dioxide Carbonic Acid Hydrogen ion + Bicarbonate ion - An increase in CO2 concentration would shift the equation to the right - Carbonic anhydrase would convert the excess CO2 into H+ and HCO3 - quickly - quicker than what would happen if the catalyst wasn’t present - This would cause he pH to decrease 10. Describe the homeostatic control of blood pH in response to an increase in blood pH (alkaline, H+ concentration decreases). Include all three mechanisms of control, and a brief discussion of the time course for each type of response mechanism. Due to the rise of pH in the blood rising above 7 this is where alkalosis occurs. The distal tangled tubules of the kidney reduce H+ secretion in the urine and HC03- reabsorption into the blood. The respiratory regulation part in the brain lowers the breathing rate in the lungs, resulting in a rise of CO2 levels in the blood. H+ is released via buffers. The drop of pH levels, causes the body to react in restoring natural pH levels. The kidney is slower to respond to a change in pH levels. However, the reaction time is affected through the urinary and respiratory systems. 11. What could cause Metabolic acidosis? Describe the homeostatic compensations that occur? Metabolic acidosis occurs when the blood is too acidic (pH below 7.35) due to too little bicarbonate, a condition called primary bicarbonate deficiency. At the normal pH of 7.40, the ratio of bicarbonate to carbonic acid buffer is 20:1. If a person’s blood pH drops below 7.35, then he or she is in metabolic acidosis. The most common cause of metabolic acidosis is the presence of organic acids or excessive ketones in the blood. Table 1 lists some other causes of metabolic acidosis. Diarrhea Bicarbonate Uremia Phosphoric, sulfuric, and lactic acids Diabetic ketoacidosis Increased ketones Strenuous exercise Lactic acid Table 1. Common Causes of Metabolic Acidosis and Blood Metabolites Cause MetaboliteDownloaded by Mike Splendid () Methanol Formic acid* Paraldehyde β-Hydroxybutyric acid* Isopropanol Propionic acid* Ethylene glycol Glycolic acid, and some oxalic and formic acids* Salicylate/aspirin Sulfasalicylic acid (SSA)* *Acid metabolites from ingested chemical.