This is a comprehensive glossary of terms related to Animal Physiology, organized alphabetically from A to Z. Each term is briefly defined in the context of animal physiology, covering key concepts, processes, systems, and structures.
- Absorption: The process by which nutrients, water, or other substances are taken up by cells or tissues, typically in the digestive system.
- Acclimatization: Physiological or behavioral adjustments by an animal to adapt to environmental changes, such as temperature or altitude.
- Action Potential: A rapid change in the electrical potential across a cell membrane, especially in neurons or muscle cells, enabling signal transmission.
- Active Transport: The movement of substances across a cell membrane against a concentration gradient, requiring energy (usually ATP).
- Adaptation: A physiological or structural trait that enhances an animal’s survival and reproduction in its environment.
- Adipose Tissue: Specialized connective tissue that stores fat, serving as an energy reserve and insulator.
- Adrenal Gland: An endocrine gland producing hormones like cortisol and adrenaline, which regulate stress responses and metabolism.
- Aerobic Respiration: The process of producing energy (ATP) in cells using oxygen, primarily in mitochondria.
- Allostasis: The process of achieving stability through physiological or behavioral change in response to environmental challenges.
- Alveoli: Tiny air sacs in the lungs where gas exchange (oxygen and carbon dioxide) occurs.
- Amino Acids: Organic molecules that serve as building blocks of proteins, essential for physiological functions.
- Amylase: An enzyme in saliva or pancreatic secretions that breaks down starches into sugars.
- Anaerobic Respiration: Energy production without oxygen, often producing lactic acid or ethanol as byproducts.
- Anatomy: The study of the physical structure of animals, closely related to physiology.
- Antibody: A protein produced by the immune system to neutralize pathogens like bacteria or viruses.
- Antidiuretic Hormone (ADH): A hormone that regulates water retention by increasing kidney reabsorption of water.
- Apoptosis: Programmed cell death, a controlled process to eliminate damaged or unnecessary cells.
- Artery: A blood vessel that carries oxygenated blood away from the heart to tissues.
- Assimilation: The incorporation of absorbed nutrients into an animal’s cells or tissues.
- Autonomic Nervous System: The part of the nervous system controlling involuntary functions like heart rate and digestion.
- Axon: A long projection of a neuron that conducts electrical impulses away from the cell body.
B
- Basal Metabolic Rate (BMR): The rate of energy expenditure by an animal at rest, reflecting basic physiological functions.
- Bile: A digestive fluid produced by the liver and stored in the gallbladder, aiding fat emulsification and absorption.
- Bioenergetics: The study of energy flow and transformation in living organisms.
- Blood: A fluid connective tissue that transports oxygen, nutrients, and wastes, and supports immune functions.
- Blood Pressure: The force exerted by blood against the walls of blood vessels, critical for circulation.
- Bone: A rigid connective tissue providing structural support, protection, and mineral storage.
- Bowman’s Capsule: A structure in the nephron of the kidney where blood filtration begins.
- Bradycardia: A slower-than-normal heart rate, often seen in highly fit animals or during rest.
- Bronchi: The main airways branching from the trachea into the lungs, facilitating air movement.
- Buffer: A system (e.g., bicarbonate in blood) that maintains pH stability by neutralizing acids or bases.
C
- Capillary: The smallest blood vessel, where gas, nutrient, and waste exchange occurs between blood and tissues.
- Cardiac Muscle: Specialized involuntary muscle tissue in the heart, responsible for pumping blood.
- Cardiovascular System: The organ system comprising the heart and blood vessels, responsible for blood circulation.
- Cartilage: A flexible connective tissue providing support and cushioning in joints and other structures.
- Cell Membrane: A semi-permeable barrier surrounding cells, regulating the movement of substances.
- Central Nervous System (CNS): The brain and spinal cord, coordinating physiological and behavioral responses.
- Chemoreceptor: A sensory receptor detecting chemical changes, such as oxygen or carbon dioxide levels in blood.
- Cholecystokinin (CCK): A hormone stimulating bile release and pancreatic enzyme secretion for digestion.
- Chyme: The semi-liquid mixture of partially digested food and gastric juices in the stomach.
- Cilia: Hair-like structures on cell surfaces, aiding movement or filtration (e.g., in respiratory tracts).
- Circadian Rhythm: A biological clock regulating physiological processes over a 24-hour cycle.
- Coagulation: The process of blood clotting to prevent excessive bleeding.
- Collagen: A structural protein in connective tissues, providing strength and elasticity.
- Countercurrent Exchange: A mechanism (e.g., in fish gills or bird lungs) maximizing efficient exchange of heat or gases.
- Cortex: The outer layer of an organ, such as the adrenal cortex or cerebral cortex, with specialized functions.
- Cranial Nerves: Nerves originating from the brain, controlling sensory and motor functions of the head and neck.
- Cytokine: Small proteins involved in immune signaling, coordinating inflammation and immune responses.
- Cytoplasm: The gel-like substance within cells, housing organelles and facilitating biochemical reactions.
D
- Defecation: The elimination of undigested waste (feces) from the digestive tract.
- Dendrite: A branched extension of a neuron receiving electrical signals from other neurons.
- Depolarization: A change in a cell’s membrane potential, making it less negative, often triggering an action potential.
- Diaphragm: A muscle separating the thoracic and abdominal cavities, aiding respiration in mammals.
- Diffusion: The passive movement of molecules from an area of higher to lower concentration.
- Digestion: The breakdown of food into smaller molecules for absorption and energy production.
- Diuretic: A substance or hormone increasing urine production, affecting fluid balance.
- Dorsal: Referring to the back or upper surface of an animal’s body.
- Duodenum: The first section of the small intestine, where significant digestion and nutrient absorption occur.
E
- Ectotherm: An animal that relies on external environmental conditions to regulate body temperature (e.g., reptiles).
- Effector: A muscle, gland, or organ that carries out a physiological response to a stimulus.
- Electrocardiogram (ECG): A recording of the heart’s electrical activity, used to assess cardiac function.
- Electrolyte: A charged molecule (e.g., sodium, potassium) critical for nerve and muscle function.
- Endocrine System: A system of glands secreting hormones into the bloodstream to regulate bodily functions.
- Endotherm: An animal that generates internal heat to maintain body temperature (e.g., mammals, birds).
- Enzyme: A protein catalyst speeding up biochemical reactions in physiological processes.
- Epithelium: A tissue layer lining organs and surfaces, involved in protection, secretion, and absorption.
- Erythrocyte: A red blood cell responsible for oxygen transport via hemoglobin.
- Esophagus: A muscular tube transporting food from the mouth to the stomach.
- Estrogen: A sex hormone regulating reproductive physiology and secondary sexual characteristics in females.
- Excretion: The elimination of metabolic waste products, such as urea or carbon dioxide.
- Exocrine Gland: A gland secreting products (e.g., sweat, saliva) through ducts to external surfaces or cavities.
- Extracellular Fluid: Fluid outside cells, including plasma and interstitial fluid, maintaining homeostasis.
F
- Facilitated Diffusion: Passive transport of molecules across a cell membrane via specific protein channels.
- Feces: Waste material eliminated from the digestive tract during defecation.
- Feedback Loop: A regulatory mechanism where the output of a process influences its continuation (e.g., negative or positive feedback).
- Filtration: The process of separating substances (e.g., in kidneys) based on size or charge.
- Follicle-Stimulating Hormone (FSH): A hormone regulating reproductive processes, such as gamete production.
- Fovea: A region in the retina with high visual acuity, critical for detailed vision.
G
- Gallbladder: An organ storing and concentrating bile for fat digestion.
- Gamete: A reproductive cell (sperm or egg) involved in sexual reproduction.
- Ganglion: A cluster of nerve cell bodies, often in the peripheral nervous system.
- Gastrin: A hormone stimulating gastric acid secretion for digestion.
- Gastrointestinal Tract: The digestive system’s tubular structure, from mouth to anus.
- Glial Cell: A non-neuronal cell supporting and protecting neurons in the nervous system.
- Glomerulus: A network of capillaries in the kidney where blood filtration occurs.
- Glucagon: A pancreatic hormone raising blood glucose levels by promoting glycogen breakdown.
- Glycogen: A stored form of glucose in the liver and muscles, used for energy.
- Gonad: A reproductive organ (testis or ovary) producing gametes and sex hormones.
H
- Hematopoiesis: The formation of blood cells in bone marrow or other tissues.
- Hemoglobin: A protein in red blood cells binding oxygen for transport.
- Hepatic Portal System: A venous system transporting nutrient-rich blood from the digestive tract to the liver.
- Histamine: A compound involved in immune responses, inflammation, and gastric acid secretion.
- Homeostasis: The maintenance of stable internal conditions (e.g., temperature, pH) despite external changes.
- Hormone: A chemical messenger secreted by endocrine glands, regulating physiological processes.
- Hydrolysis: A chemical reaction breaking down molecules using water, critical in digestion.
- Hyperplasia: An increase in cell number, often in response to physiological demands.
- Hypertrophy: An increase in cell size, often in muscle tissue due to exercise or stress.
- Hypothalamus: A brain region regulating hunger, thirst, temperature, and hormone release.
I
- Immune System: A network of cells, tissues, and organs defending against pathogens and disease.
- Inflammation: A localized immune response to injury or infection, involving redness, heat, and swelling.
- Innervation: The supply of nerves to a tissue or organ, enabling sensory or motor functions.
- Insulin: A pancreatic hormone lowering blood glucose by promoting cellular uptake.
- Interneuron: A neuron connecting sensory and motor neurons, facilitating signal integration.
- Interstitial Fluid: Fluid surrounding cells, facilitating nutrient and waste exchange.
- Intestine: The organ responsible for nutrient absorption and waste formation in the digestive system.
- Ion Channel: A membrane protein allowing selective passage of ions, critical for nerve and muscle function.
- Isotonic: A solution with equal solute concentration to a cell’s cytoplasm, preventing water movement.
J
- Joint: A structure connecting bones, allowing movement or stability.
- Juxtaglomerular Apparatus: A kidney structure regulating blood pressure and filtration via renin release.
K
- Keratin: A tough protein in skin, hair, and nails, providing structural support.
- Kidney: An organ filtering blood, regulating fluid balance, and producing urine.
- Krebs Cycle: A metabolic pathway in mitochondria producing energy (ATP) from glucose.
L
- Lactation: The production and secretion of milk by mammary glands for offspring nourishment.
- Larynx: The voice box, involved in sound production and air passage to the lungs.
- Leukocyte: A white blood cell involved in immune defense.
- Ligament: A connective tissue band connecting bones, stabilizing joints.
- Lipase: An enzyme breaking down fats into fatty acids and glycerol.
- Liver: A vital organ involved in detoxification, metabolism, and bile production.
- Loop of Henle: A kidney nephron structure concentrating urine and conserving water.
- Lung: An organ facilitating gas exchange between air and blood.
- Lymph: A fluid containing immune cells, transported through the lymphatic system.
- Lymphatic System: A network of vessels and nodes supporting immune function and fluid balance.
M
- Macrophage: An immune cell engulfing pathogens and debris via phagocytosis.
- Mast Cell: An immune cell releasing histamine during allergic or inflammatory responses.
- Mechanoreceptor: A sensory receptor detecting mechanical stimuli, such as pressure or vibration.
- Medulla: The inner region of an organ (e.g., adrenal medulla) or the lower brainstem controlling vital functions.
- Melatonin: A hormone from the pineal gland regulating sleep-wake cycles.
- Membrane Potential: The electrical charge difference across a cell membrane, critical for nerve and muscle function.
- Metabolism: The sum of chemical reactions in an organism, supporting energy and growth.
- Mitochondrion: A cellular organelle producing ATP via aerobic respiration.
- Motor Neuron: A neuron transmitting signals from the CNS to muscles or glands.
- Mucous Membrane: A tissue lining body cavities, secreting mucus for protection and lubrication.
- Muscle: A tissue type (skeletal, smooth, or cardiac) enabling movement, posture, or organ function.
- Myelin: A fatty sheath around axons, speeding up nerve impulse conduction.
- Myoglobin: A muscle protein storing oxygen for use during contraction.
N
- Nephron: The functional unit of the kidney, filtering blood and forming urine.
- Nerve: A bundle of axons transmitting electrical signals throughout the body.
- Neuron: A specialized cell transmitting electrical and chemical signals in the nervous system.
- Neurotransmitter: A chemical (e.g., dopamine, acetylcholine) transmitting signals between neurons.
- Nociceptor: A sensory receptor detecting pain or harmful stimuli.
- Norepinephrine: A hormone and neurotransmitter involved in stress responses and arousal.
O
- Olfaction: The sense of smell, mediated by olfactory receptors in the nasal cavity.
- Oogenesis: The process of egg (ovum) formation in female animals.
- Organ: A structure composed of multiple tissues performing specific physiological functions.
- Osmoregulation: The regulation of water and solute balance to maintain homeostasis.
- Osmosis: The passive movement of water across a semi-permeable membrane.
- Ovary: The female gonad producing eggs and sex hormones like estrogen.
- Oxytocin: A hormone promoting labor, lactation, and social bonding.
P
- Pancreas: An organ producing digestive enzymes and hormones like insulin and glucagon.
- Parathyroid Hormone (PTH): A hormone regulating calcium and phosphate levels in blood.
- Peristalsis: Rhythmic muscle contractions moving food through the digestive tract.
- Phagocytosis: The engulfing of particles or pathogens by immune cells.
- Photoreceptor: A sensory cell detecting light, critical for vision.
- Pituitary Gland: The “master gland” regulating other endocrine glands via hormone secretion.
- Plasma: The liquid component of blood, transporting nutrients, hormones, and wastes.
- Platelet: A blood cell fragment involved in clotting and wound repair.
- Pleura: A membrane surrounding the lungs, reducing friction during breathing.
- Proprioceptor: A sensory receptor detecting body position and movement.
- Prostaglandin: A lipid compound mediating inflammation, pain, and other physiological responses.
- Pulmonary: Relating to the lungs or respiratory system.
- Pupil: The opening in the iris regulating light entry into the eye.
- Pyruvate: A molecule produced during glycolysis, entering the Krebs cycle for energy production.
Q
- Quaternary Structure: The arrangement of multiple protein subunits in a functional complex.
R
- Receptor: A protein or cell detecting specific stimuli (e.g., hormones, light, or pressure).
- Reflex: An involuntary, rapid response to a stimulus, mediated by the nervous system.
- Renin: An enzyme from the kidneys regulating blood pressure via the renin-angiotensin system.
- Respiration: The process of gas exchange, including breathing and cellular energy production.
- Reticular Formation: A brainstem region regulating arousal, sleep, and vital functions.
- Retina: The light-sensitive layer of the eye, containing photoreceptors.
- Ribosome: A cellular structure synthesizing proteins based on genetic instructions.
S
- Saliva: A digestive fluid containing enzymes like amylase, aiding food breakdown.
- Sarcolemma: The membrane surrounding muscle fibers, regulating contraction signals.
- Sarcomere: The contractile unit of skeletal and cardiac muscle.
- Secretion: The release of substances (e.g., hormones, enzymes) by cells or glands.
- Sensory Neuron: A neuron transmitting environmental or internal stimuli to the CNS.
- Serotonin: A neurotransmitter regulating mood, sleep, and appetite.
- Sinoatrial Node: The heart’s pacemaker, initiating electrical impulses for contraction.
- Skeletal Muscle: Voluntary muscle tissue enabling movement and posture.
- Smooth Muscle: Involuntary muscle in organs, controlling processes like digestion.
- Spermatogenesis: The process of sperm production in male animals.
- Sphincter: A ring of muscle controlling the passage of substances (e.g., in the digestive tract).
- Spinal Cord: A CNS structure transmitting signals between the brain and body.
- Spleen: An organ filtering blood, storing immune cells, and recycling red blood cells.
- Steroid: A lipid-based hormone (e.g., cortisol, testosterone) regulating metabolism and reproduction.
- Stomach: A digestive organ mixing food with gastric juices for breakdown.
- Sympathetic Nervous System: A division of the autonomic nervous system activating “fight or flight” responses.
- Synapse: The junction where neurons communicate via neurotransmitters.
T
- Tachycardia: A faster-than-normal heart rate, often due to stress or exercise.
- Tendon: A connective tissue attaching muscle to bone, transmitting force.
- Testis: The male gonad producing sperm and testosterone.
- Thermoreceptor: A sensory receptor detecting temperature changes.
- Thermoregulation: The maintenance of optimal body temperature via physiological or behavioral means.
- Thymus: An immune organ where T-cells mature, critical for adaptive immunity.
- Thyroid Gland: An endocrine gland producing hormones (e.g., thyroxine) regulating metabolism.
- Tissue: A group of similar cells performing a specific function (e.g., muscle, epithelial).
- Tonicity: The effect of a solution’s solute concentration on cell volume (e.g., isotonic, hypotonic).
- Trachea: The windpipe, conducting air to the lungs.
- Triglyceride: A fat molecule stored in adipose tissue, used for energy.
- Tropism: A directional growth or movement response to a stimulus, often in simpler animals.
- Tubule: A small tube in organs (e.g., kidney nephrons) facilitating transport or filtration.
U
- Urea: A nitrogenous waste product excreted in urine, formed in the liver.
- Ureter: A tube transporting urine from the kidney to the bladder.
- Urethra: A tube excreting urine from the bladder to the exterior.
- Urine: A liquid waste product filtered by the kidneys, containing urea and excess water.
V
- Vagus Nerve: A cranial nerve regulating heart rate, digestion, and other autonomic functions.
- Vasoconstriction: The narrowing of blood vessels, increasing blood pressure.
- Vasodilation: The widening of blood vessels, reducing blood pressure and increasing blood flow.
- Vein: A blood vessel returning deoxygenated blood to the heart.
- Ventricle: A heart chamber pumping blood into arteries or lungs.
- Venule: A small vein collecting blood from capillaries.
- Vestibular System: The inner ear structures regulating balance and spatial orientation.
- Villus: A finger-like projection in the small intestine, increasing surface area for nutrient absorption.
- Viscera: Internal organs, especially those in the abdominal cavity.
- Vitamin: An organic compound required in small amounts for physiological functions.
W
- White Blood Cell: A leukocyte involved in immune defense (e.g., lymphocytes, neutrophils).
- Womb: The uterus, where embryonic development occurs in mammals.
X
- Xenobiotic: A foreign chemical (e.g., drug, pollutant) metabolized or detoxified by the body.
- Xiphoid Process: A small cartilaginous structure at the base of the sternum, relevant to anatomy.
Y
- Yolk: A nutrient-rich substance in eggs, supporting embryonic development in oviparous animals.
- Yolk Sac: A membrane in embryos, providing nutrients before placental development.
Z
- Zona Pellucida: A glycoprotein layer surrounding the egg, involved in fertilization.
- Zymogen: An inactive enzyme precursor, activated for digestion or other functions.
