teas-6-science-anatomy-and-physiology-guide

teas-6-science-anatomy-and-physiology-guide TEAS 6 Science Anatomy and Physiology Guide. ANATOMY AND PHYSIOLOGY Endocrine System Gland/Organ Hormone Secreted Function Hypothalamus Releasing/Inhibiting hormones Stimulate Pituitary Anterior Pituitary (base of brain; controls growth and development Adrenocorticotropic Hormone (ACTH) Stimulate adrenal cortex to secrete glucocorticoids Thyroid Stimulating Hormone (TSH) Stimulate the Thyroid gland Follicle Stimulating Hormone (FSH) Stimulates production of ova (females) and sperm (males) Luteinizing Hormone (LH) Stimulates Ovaries (females) and Testes (males) Prolactin Stimulates milk production Growth Hormone (GH) Stimulates growth (bones) and metabolic functions Posterior Pituitary (back of anterior pituitary) Antidiuretic Hormone (ADH) Promotes retention of water by the kidneys Oxytocin Stimulates contraction of uterus and mammary gland cells Pineal Gland (center of brain) Melatonin Sleep cycles; biorhythms Thyroid (neck; hormones regulate growth, development, and metabolism) Triiodothyronine (T3) Metabolism Thyroxine (T4) Metabolism and temperature Calcitonin Inhibits release of Calcium from bones Parathyroid (4 glands on Thyroid) Parathyroid Hormone (PTH) Stimulates release of calcium from bones, back into blood. Thymus (lymphoid organ that produces T-Cells) Thymosin Stimulates T-Cell Development Adrenal Glands (Above Kidneys; regulate HR, BP, and other functions) See below See below Adrenal Cortex (stimulates fight or flight response) Cortisol/Glucocorticoids Stress response; Increase blood glucose, Decrease immune response; metabolism Aldosterone Regulates Na content in blood Adrenal Medulla (stimulates fight or flight response) Epinephrine Fight Norepinephrine Flight Ovaries (female gonads) Estrogen Stimulates egg maturation, controls 2ndary sex TEAS 6 Science characteristics Progesterone Prepares uterus to receive fertilized egg Testes (male gonads) Testosterone Regulates sperm production and 2ndary sex characteristics Kidneys Erythropoietin Response to cellular hypoxia Renin Promotes production of Angiotensin Liver Angiotensin II Vasoconstriction, Increase BP Pancreas Glucagon (Alpha Cells) Increase blood glucose Insulin (Beta Cells) Decrease blood glucose Stomach Gastrin Response to food; stimulates production of gastric juices Intestine Secretin Response to acidity in small intestine; stimulates secretion by liver and pancreas Cholecystokinin Production of Bile Salts Heart Atrial Natriuretic Peptide (ANP) Increase renal Na excretion, decrease ECF Gastrointestinal System Enzyme Production site Release site Carbs Salivary Amylase Salivary Glands Mouth Pancreatic Amylase Pancreas Small Intestine Maltase Small Intestine Small Intestine Protein Pepsin Chief Cells (gastric gland) Stomach Trypsin Pancreas Small Intestine TEAS 6 Science Peptidases Small Intestine Small Intestine Nucleic Acids Nuclease Pancreas Small Intestine Nucleosidase Pancreas Small Intestine Lipids Lipase Pancreas Small Intestine Bile Salt Liver→Gallbladder Small Intestine *Bile is technically not an enzyme, but a salt that emulsifies lipid into fatty droplets. Chief Cells: Covert pepsinogen to pepsin Goblet Cells: Mucus secretions Parietal Cells: HCl production Peyer's Patches: Lymphatic Tissue found in Ileum to protect GI tract from pathogens Integumentary System Epidermis: Most superficial layer of skin; entirely epithelial cells ● Does NOT contain blood vessels ● 5 layers o Stratum Corneum: "Top Layer"- Dead keratinocytes o Stratum Lucidum: "Clear Layer"- Colorless protein eleidin o Stratum Granulosum: "Thin Layer"- granular layer o Stratum Spinosum: "Spiny Layer"- Thickest layer, keratinocytes, immune dendritic cells, sensory cells o Stratum Basale: "Basal Layer"- Bottom layer; contains melanocytes. Dermis: Directly below epidermis; mostly connective tissue ● Contains blood vessels ● Sensory receptors ● Hair follicles ● Sebaceous glands ● Sweat glands ● Elastin and Collagen fibers Hypodermis/SubQ: Connective tissue ● Binds the skin to underlying muscle ● Fat deposits cushion and insulate the body Glands Exocrine: Secrete substances into ducts ● Holocrine: secretory products; whole cells; connected to hair follicle o Sebaceous Glands: secrete sebum: an oily mixture of lipids and proteins; waterproofs skin, protects from pathogens ● Eccrine: Not connected to hair follicle, activated by high body temperature, located throughout the body. A type of sweat gland (sudoriferous gland) in thermoregulation. o Secrete a salty solution of electrolytes and water ▪ NaCl ▪ KHCO3 TEAS 6 Science ▪ Glucose ▪ Antimicrobial Peptides ● Apocrine: Secrete an oily solution (fatty acids, triglycerides, and proteins) o Located in: ▪ Armpits ▪ Groin ▪ Palms ▪ Soles of feet o Secrete (sweat) during anxiety or stress o Body Odor forms from bacteria feeding on apocrine sweat Urinary System Kidney (2): Regulates fluid balance and filters waste from blood ● Receive blood from renal artery (extension of aorta) ● Filter blood ● Reabsorb need materials ● Excrete waste and water via urine ● Renal Cortex: Outer Layer o Contains ~1 million Nephrons (filters) o Glomerulus: Capillary in nephron o Bowman's Capsule: encapsulates the glomerulus ● Renal Medulla: Middle Layer o Proximal Convoluted Tubule: Water, glucose, ions, and other organic molecules are reabsorbed back into the blood stream. o Distal Convoluted Tubule: Urea and drugs are removed from blood. pH in blood is adjusted with H+ ions. ● Renal Pelvis: Inner Layer o Materials arrive as urine from distal convoluted tubule. Reproductive System MALES ● Produce, maintain, and transfer sperm and semen into the female reproductive tract. ● Produce and secrete male hormones. TEAS 6 Science External Organs: Penis, Scrotum, Testes ● Scrotum: Protects testes; keeps optimal temperature for spermatogenesis. ● Testes: Male gonads; produce sperm and testosterone. Internal Organs: Epididymis, Vas Deferens, Ejaculatory Ducts, Urethra, Seminal Vesicles, and Bulbourethral glands ● Epididymis: Stores sperm as it matures ● Vas Deferens: Mature sperm move from epididymis to Vas Deferens to the ejaculatory duct ● Seminal Vesicles: Secrete alkaline fluids with protein and mucus into ejaculatory duct ● Prostate Gland: Secretes a milky white fluid with proteins and enzymes as part of semen ● Bulbourethral (Cowper's) Gland: Secrete a fluid to neutralize the acidity in the urethra Hormones ● FSH: Stimulates spermatogenesis ● LH: Stimulates testosterone production ● Testosterone: Male sex characteristics FEMALES ● Produce ova (oocytes/egg cells) ● Transfer ova to fallopian tubes for fertilization ● Receive sperm from male ● Provide a protective, nourishing environment for developing embryo External Organs: Labia Majora, Labia Minora, Bartholin's Glands, Clitoris ● Labia (both): Close and protect vagina ● Bartholin's Gland: Secrete lubricating fluid ● Clitoris: Contains erectile tissue and nerve endings for sensual pleasure Internal Organs: Ovaries, Fallopian Tubes, Uterus, Vagina ● Ovaries: Female gonads; produce ova, and secrete estrogen and progesterone ● Fallopian Tubes: Carry mature egg toward uterus; site of fertilization ● Uterus: Fertilized egg implants on uterine wall; protects and nourishes developing embryo until birth ● Vagina: Muscular tube from cervix to outside of body; receives semen, is site of intercourse, and birth canal Hormones ● Estrogen: Stimulates egg maturation; female sex characteristics ● Progesterone: Prepares uterus to receive fertilized egg ● FSH: Stimulates oogenesis ● LH: Stimulates estrogen production ● Oxytocin: Stimulates contraction of uterus and mammary gland cells ● Prolactin: Stimulates milk production Immune System TEAS 6 Science Function: Protects the body against invading pathogens including bacteria, viruses, fungi, and protists. Lymphatic System: Lymph, lymph capillaries, lymph vessels, lymph nodes. ● Skeletal muscle contractions move the lymph one way through the lymphatic system to lymphatic ducts o Dump back into venous supply via lymph nodes ● Red marrow- produces blood cells ● Leukocytes- WBC Lymph Nodes: located in neck, armpit, and groin ● Small swellings in the lymphatic system where lymph is filtered and lymphocytes are formed Lymph Tissue: Tonsils, adenoids, thymus, spleen, peyer's patches ● Tonsils: Located in pharynx o Protect against pathogens entering via mouth or throat ● Thymus: Maturation chamber for immune T Cells formed in bone marrow ● Spleen: Cleans blood of dead cells and pathogens ● Peyer's Patches: Located in ileum of Sm. Intestine. o Protects GI tract from pathogens General Immune Defenses ● Skin: Primary barrier (intact) ● Ciliated Mucous Membranes: Cilia protect respiratory system ● Glandular Secretions: Exocrine- destroy bacteria ● Gastric Secretions: Gastric Acid destroys pathogens ● Normal Bacterial Populations: Compete with pathogens in gut and vagina 3 Types of WBC ● Macrophage: Phagocytes that alert T-Cells to the presence of foreign substances o Largest, longest living phagocyte o Engulf and destroy pathogens o Found in lymph ● T Lymphocytes: Directly attack cells infected by viruses and bacteria o Helper T, Killer T, Memory T, Suppressor T ● B Lymphocytes: Target specific bacteria for destruction o Plasma Cells: Antibody production. Other Immune Cells ● Helper T-Cells: Activate B-Cells to make Antibodies and other chemicals ● Suppressor T-Cells: Stop other T-Cells when the battle is over ● Memory T-Cells: Remain in blood on alert incase invader attacks again ● Killer/Cytotoxic T-Cells: Destroy Cells infected with a pathogen, virus, or tumor Leukocytes: WBC- Produced in Red Marrow ● Monocyte o Macrophage o Dendritic Cell: Present antigens to T Cell ● Granulocyte TEAS 6 Science o Neutrophil: Short living phagocyte; responds quick to invaders o Basophil: Alerts body of invasion o Eosinophil: Large, long living phagocyte; Defend against multicellular invaders ● T Lymphocyte ● B Lymphocyte ● Natural Killer Cell Antibody Mediated Response: Response is to an antigen Cellular Mediated Response: Response is to an already infected cell Antigen: Foreign particle that stimulates the immune system ● Typically a protein on the surface of bacteria, virus, or fungi Antibody: A blood protein that counteracts a specific antigen Steps of Immune System 1. Macrophage engulfs antigen and presents fragments of antigen on its surface 2. A Helper T Cell joins the Macrophage 3. Killer/Cytotoxic T Cells and B Cells are activated 4. Killer/Cytotoxic T Cells search and destroy cells presenting the same antigen 5. B Cells differentiate into Plasma Cells and Memory Cells Innate Immune System ● Born with it ● Non Specific response ● EX) Skin, hair, mucus, earwax, secretions, normal flora, antimicrobials, inflammation, interferons, complement, NK Lymphocytes, phagocytes Adaptive Immune System ● Responds to specific antigens ● Vaccinations or previous encounters o Reaction: Cytotoxic T Cells kill pathogen o Prevention: B Cells produce Antibodies ● Activated by Antigen and Helper T Cells ● Helper T Cells activated by Antigen Presenting Cells (APC) Naturally Acquired Active Immunity: Exposure to pathogen without immunization Naturally Acquired Passive Immunity: Occurs during pregnancy and during breast feeding ● Antibodies are passed from mother to child ● Provides protection from infancy to childhood Artificially Acquired Active Immunity: Build immunity via Vaccination Artificially Acquired Passive Immunity: Immunization given during an outbreak or emergency ● Quick, short lived protection ● Antibodies come from another person or animal TEAS 6 Science Skeletal System Function: Movement, Protection, and Metabolism Bone: Hard calcified material that makes up the skeletal system ● Constantly being reorganized ● Synthesize blood and immune cells ● Stores calcium, phosphate, and lipids ● 4 Types: o Long Bones: long compact hollow shafts containing marrow ▪ Ends are spongy with air pockets ▪ EX) Humerus, Ulna, Radius, Tibia, Fibula o Short Bones: Wider than they are long ▪ EX) Metatarsals, Clavicle o Flat Bones: Not hollow, but contain marrow ▪ EX) Scapula, Ribs, Sternum o Irregular Bones: Nonsymmetrical shape ▪ EX) Skull, Knee, Elbow, Vertebra Ligament: Articulates BONE to BONE TEAS 6 Science Tendon: Articulates MUSCLE to BONE Hyaline Cartilage: Covers articulating surface of bones ● Prevents bone on bone grinding Synovial Joint: Contain lubricating synovial fluid ● Pivot Joint: Neck ● Ball and Socket Joint: Hip ● Hinge Joint: Knee Osteocytes: Bone Cells ● Osteoclast: Multinucleate o Removes/absorbs bone tissue during growth and healing ● Osteoblast: Mononucleate o Cells that build bone Periosteum: Fibrous sheath that covers bone and contains nerve and blood vessels Osteon: Cylindrical structure that comprise, synthesize, and compact bone ● Composed of Calcium and phosphate rich Hydroxyapatite embedded in collagen matrix Collagen: Primary structural protein of connective tissue Canaliculi: Small channel or duct in ossified bone Cartilage: Tough, elastic connective tissue found in parts of the body (Ear) Haversian Canal: Channels in bone that contain BV and Nerves Lamellae: Layers of the bone, tissues, or cell walls Lining Cells: Flattened bone cells that come from osteoblasts Volkmann Canal: Channels in bone that transmit BV and communicate with Haversian Canals Bone Disease ● Osteoporosis: causes brittle, fragile bones ● Brittle Bone Disease: Group of Diseases that affect the collagen (defect in the matrix) and results in fragile bones ● Osteoarthritis: Degenerative joint disease ● Rheumatoid Arthritis: Progressive disease the causes joint inflammation and pain Cardiovascular/Circulatory System Function: Movement of blood and lymph around the body, which permits nutrient distribution, waste removal, communication, and protection TEAS 6 Science ● Closed Double loop system o Pulmonary Loop: Deoxygenated blood from Rt. Ventricle to lungs and returns Oxygenated blood to Lt. Atrium o Systemic Loop: Oxygenated blood from Lt. Ventricle to body, returning Deoxygenated blood to Rt. Atrium ● Systole: Contraction of ventricles (heart expels blood) ● Diastole: Relaxation of ventricles (heart refills with blood) ● SA Node: "Pacemaker" controls contractions via electrical signals ● Blood Pressure: Fluid pressure generated by cardiac cycle (sys/dias) Artery: Blood vessel that carries blood AWAY from heart ● Aorta: large artery branching off heart to the rest of the body o Coronary Artery o Carotid Artery o Subclavian Artery o Common Iliac Artery o Renal Artery Vein: Blood vessel that carries blood TO the heart ● Vena Cava- All veins empty here prior to entering the heart o Jugular Vein o Subclavian Vein o Hepatic Portal Vein o Common Iliac Vein o Renal Vein Arteriole: Small artery Venule: Small vein Capillary: Small blood vessel that connects arterioles to venules Heart: Muscle that pumps blood throughout the body Blood: The red liquid that circulates in the arteries and veins ● Carries oxygen to and carbon dioxide from the tissues of the body. ● 4 Main Components: o RBC: Disc shaped cells that carry Hemoglobin and O2 o WBC: Immune defense o Platelets: Clotting cells o Plasma: Liquid portion of blood (mostly water) Disease: Myocardial Infarction: Heart attack; Death of the heart muscle due to inadequate blood supply TEAS 6 Science Stroke: "Brain Attack." Damage to the brain due to inadequate blood supply Aneurysm: Localized abnormal, weak spot on a blood vessel wall that causes an outward bulging, likened to a bubble or balloon. Hemorrhage occurs when it bursts. Atherosclerosis: Narrowing of arteries due to plaque buildup on artery walls Anemia: Not enough healthy RBC Arrhythmia: Abnormal heart rhythm ● Tachycardia: Too fast ● Bradycardia: Too slow Hypertension: High blood pressure. Systole is over 140 mmHg; Diastole is over 90 mmHg Respiratory System Function: transporting O2 from the atmosphere into the body's cells and moving CO2 in the other direction. Lungs: 5 Lobes (2 left, 3 right). Main structure of TEAS 6 Science respiratory system. Alveoli: Tiny air sacs; site of O2 and CO2 exchange. ● Occurs by diffusion (passive transport) Bronchi: The main passageways directly attached to the lungs Bronchiole: Small passages that connect bronchi to alveoli Trachea: Windpipe, connects Larynx to lungs Larynx: Voice box Pharynx: Located behind mouth, also part of GI system Diaphragm: Dome-shaped sheet of muscle and tendon that serves as the main muscle of respiration and plays a vital role in the breathing process Pleura: Membrane around lungs, inside chest cavity Perfusion: Passage of fluid to an organ or tissue Surfactant: A fluid secreted by alveoli; reduces surface tension- Prevent lung collapse Tidal Volume: The amount of air breathed in a normal inhalation or exhalation Ventilation: Movement of air in and out of body via inhalation and exhalation ● Inhalation: Diaphragm contracts downward, ribs push out, lungs fill with air ● Exhalation: Diaphragm relaxes upward, ribs relax, air pushes out ● Hyperventilation: More CO2 than the body can produce (breathing out more than in) ● Hypoventilation: Breathing at an abnormally slow rate, resulting in an increased amount of carbon dioxide in the blood Neuromuscular System Function: Controls voluntary and involuntary movement. Nerve: Long bundles of axons that transmit signals from the CNS ● Electrical impulse from dendrite to axon terminal o Transmitted from cell to cell via neurotransmitters secreted into the synapse from the axon terminal Synapse: The structure that allows neurons to pass signals to other neurons, muscles, or glands Neurotransmitter: A chemical substance that is released from the AXON TERMINAL by the arrival of a nerve impulse ● Diffuses across the SYNAPSE, ● causes the transfer of the impulse to another nerve fiber, a muscle fiber, or some other structure at the DENDRITE of the other cell TEAS 6 Science o Acetylcholine: NT; causes muscle to contract o Dopamine: NT; precursor to epinephrine Central NS: Brain and Spinal Cord Peripheral NS: ● Sensory NS: AFFERENT; send messages TO CNS ● Motor NS: EFFERENT; send messages TO MUSCLES o Somatic NS: Carries information to CNS from senses, and from CNS to skeletal muscles o Autonomic NS: Involuntary; controls actions involving cardiac and smooth muscle ▪ Sympathetic NS: Arouses body; FIGHT or FLIGHT ▪ Parasympathetic NS: Calms body; Rest and Digest Brain: Control center ● 4 Lobes o Frontal Lobe: thinking, organizing, emotions, behavior, personality o Parietal Lobe: perception, making sense, arithmetic, spelling o Temporal: memory, understanding, language o Occipital: vision Brain Anatomy Cerebellum: Balance and coordination Cerebrum: Anterior brain Pons: Brainstem that links medulla and thalamus Medulla Oblongata: Control center for heart and lungs Brainstem: Contains the Pons, Medulla Oblongata, Midbrain Midbrain: Develops from the middle of the embryonic brain Thalamus: Relays sensory information; pain perception TEAS 6 Science Hippocampus: Emotion, memory, ANS Amygdala: Emotions MUSCLES Myosin: THICK FILAMENT; fibrous protein; forms the contractile filaments of muscle cells Actin: THIN FILAMENT; protein involved in motion; works with myosin Sarcomere: Myofibril containing myosin and actin Smooth Muscle: Involuntary muscle, not striated ● Stomach, lung, intestine… Striated Muscle: Voluntary muscle; striated ● Biceps, triceps, gluteus maximus… Cardiac Muscle: Involuntary muscle; striated ● Heart BIOLOGY Macromolecules: Carbohydrate, Lipid, Nucleic Acid, Protein, Enzyme Carbohydrate: Sugars and starches which body breaks down to glucose ● Structural function: cellulose and chitin ● Energy storage: amylose, amylopectin, glycogen ● Recognition molecules: glycoproteins and glycolipids Lipids: Fatty acids and their derivatives that are soluble in water ● H and C and main components ● Fats ● Hydrophobic- thus help separate aqueous compartments ● Store energy (fats, oils, adipose) Protein: Molecules composed of amino acids joined by peptide bonds ● Monomer: amino acids (amino group + carboxylic acid)(20 types) TEAS 6 Science ● Keratin and Collagen (hydrophobic)- not soluble in water, found in structural protein ● Globular proteins are hydrophilic (hemoglobin, antibodies, enzymes) ● Function as transport carries or signal transfer Nucleic Acids: Long molecules made of nucleotides; DNA and RNA ● DNA stores genetic material ● Chromosomes ● RNA is a messenger (mRNA) also rRNA and tRNA Enzymes: Class of protein that catalyze biochemical reactions ● Not consumed in reaction ● Speed up reaction by lowering activation energy ● Exergonic: release energy ● Endergonic: require energy ● Energy is supplied and released as ATP ● Lock and Key (substrate must fit into enzymes active site) DNA and RNA DNA: macromolecule that contains coded instructions for the body to produce proteins ● Nucleotide: the building block of DNA and RNA ● Nitrogenous Base: Adenine, Thymine, Guanine, and Cytosine ● Purines: Adenine and Guanine ● Pyrimidines: Thymine and Cytosine ● Codon: A group of 3 nitrogenous bases used to synthesize amino acids (Synthesized from RNA during TRANSLATION) ● Hydrogen Bonds: Connect a Purine to a Pyrimidine (A-T) and (C-G). Non-covalent, weak. o RNA: Uracil replaces Thymine ● Double Helix structure ● Coded or read 5'→3' ● Sugar(pentose)-Phosphate backbone (deoxyribose and phosphate group- bound to 4 oxygen atoms) DNA Replication DNA Helicase: Unzips and Unwinds DNA strand DNA Primase: Generates RNA Primer. Act as a template for starting point of DNA Replication DNA Polymerase: Synthesize new DNA molecules by adding nucleotides to leading and lagging DNA strands in 5'→3' direction Topoisomerase: Prevents supercoiling DNA Ligase: Joins DNA fragments together by forming phosphodiester bonds between nucleotides Okazaki Fragment: Short, newly synthesized DNA fragments that are formed on the lagging strand Single Strand Binding Protein: Stabilize structure during replication Leading Strand: Replicated continuously in the 3' to 5' direction Lagging Strand: Replicated discontinuously in short sections TEAS 6 Science Cellular Organelles and Structure TEAS 6 Science Mitosis Meiosis TEAS 6 Science CHEMISTRY States of Matter Solid: rock, wood, paper… ● Molecules are packed together in a tight, orderly pattern ● Vibrational motion, not translational motion TEAS 6 Science ● Retains shape ● Retains density Liquid: water, juice, soda… ● Molecules are less ordered than solids, less tightly packed ● Vibrational and translational motion ● Shape is indefinite- takes shape of container ● Retains volume Gas: Oxygen, Methane, Carbon Dioxide… ● Molecules are rapidly moving and spread far apart ● Highly compressible- expands to fill container ● No definite shape ● No definite volume Change in Matter ● Condensation: Gas→ Liquid ● Deposition: Gas→ Solid ● Evaporation: Liquid→Gas ● Freezing: Liquid→ Solid ● Melting: Solid→Liquid ● Sublimation: Solid→Gas Boiling: The transition of liquid to gas when a substance has acquired enough thermal energy. Critical Point: The temperature at which LIQUID and GAS phases have same density. Phase Diagram: A graph of physical states of a substance under varying temperature and pressure. Triple Point: The temperature and pressure at which all 3 phases of a pure substance coexists. Chemical Bonds and Structures Covalent Bond: A chemical bond where electrons are SHARED between atoms (2 NON metals) Ionic Bond: Between 2 metals or a metal and a nonmetal. Complete TRANSFER of electrons Proton: positively charged atomic particle (determines atomic number) Electron: Negatively charged atomic particle- very small and irrelevant to mass of atom. Neutron: Determines isotope. Added to number protons to get atomic mass. No electric charge. Anion: Negatively charged ion Cation: Positively charged ion TEAS 6 Science Atom: The most basic complete unit of an element SCIENTIFIC INQUIRY Scientific Method: I. Identify the problem II. Ask Questions (by conducting research) III. Develop Hypothesis (IF/THEN statement) IV. Conduct Experiment V. Analyze Results TEAS 6 Science VI. Form a Conclusion Independent variable ● The thing you are testing ● "If" statement of the hypothesis ● Cause Dependent Variable ● The thing you are measuring ● "Then" statement of the hypothesis ● Effect Control Variable ● Scientific Constant ● Remains unchanged throughout the experiment *Must be able to replicate data for a successful experiment and must have a large sample