anatomy & physiology

Unit 1: Introduction to Anatomy and Physiology

Anatomy – The study of the structure of organisms and their parts.
Physiology – The study of the functions and processes of living organisms.
Homeostasis – The ability of the body to maintain a stable internal environment.
Anatomical Position – A standard position in which the body stands upright, facing forward, with arms at the sides and palms facing forward.
Sagittal Plane – A vertical plane that divides the body into left and right parts.
Coronal Plane – A vertical plane that divides the body into front (anterior) and back (posterior) portions.
Transverse Plane – A horizontal plane that divides the body into upper and lower parts.
Superior – Toward the head or upper part of the body.
Inferior – Away from the head or toward the lower part of the body.
Anterior – Toward the front of the body.
Posterior – Toward the back of the body.
Medial – Toward the midline of the body.
Lateral – Away from the midline of the body.
Proximal – Closer to the point of attachment or origin.
Distal – Further from the point of attachment or origin.
Cell – The basic structural and functional unit of living organisms.
Tissue – A group of cells with similar structure and function.
Organ – A structure composed of different tissues that work together to perform a specific function.
Organ System – A group of organs that work together to perform a common function.
Organism – A complete living entity composed of several organ systems.
Feedback Mechanism – A process that helps regulate homeostasis by using feedback to adjust systems.
Positive Feedback – A feedback loop that amplifies or intensifies a change.
Negative Feedback – A feedback loop that counteracts a change, maintaining stability.
Cellular Respiration – The process by which cells convert glucose and oxygen into energy (ATP).
Metabolism – The sum of all chemical reactions within the body, including those that break down molecules for energy and those that build up molecules.
Ions – Atoms or molecules with an electrical charge due to the loss or gain of electrons.
Electrolytes – Minerals that carry an electrical charge and are vital for various physiological processes.
Phospholipid – A lipid molecule that forms the structural component of cell membranes.
Homeostatic Imbalance – A condition in which the body's homeostasis is disrupted, leading to disease.
Atom – The smallest unit of an element, consisting of protons, neutrons, and electrons.

Unit 2: Cell and Tissue Structure

Plasma Membrane – The outer boundary of the cell that regulates the passage of materials in and out.
Cytoplasm – The fluid inside the cell that contains the organelles.
Nucleus – The control center of the cell that contains DNA.
Mitochondria – Organelles that produce energy for the cell in the form of ATP.
Ribosomes – Small structures where protein synthesis occurs.
Endoplasmic Reticulum (ER) – A network of membranes involved in protein and lipid synthesis.
Golgi Apparatus – An organelle that modifies, sorts, and packages proteins for secretion.
Lysosome – Organelles that contain enzymes to digest waste materials and cellular debris.
Peroxisome – Organelles that break down fatty acids and detoxify harmful substances.
Cytoskeleton – A network of protein fibers that maintains cell shape and facilitates movement.
Centrosome – The region of the cell that organizes microtubules for cell division.
Nucleolus – The region within the nucleus where ribosomal RNA is produced.
Chromatin – The material in the nucleus that contains DNA and proteins.
Gene – A segment of DNA that codes for a specific protein or trait.
Mitosis – The process of cell division that produces two identical daughter cells.
Meiosis – The type of cell division that produces four genetically distinct gametes (sperm or egg).
Diffusion – The movement of molecules from an area of high concentration to an area of low concentration.
Osmosis – The diffusion of water across a semipermeable membrane.
Active Transport – The movement of molecules against their concentration gradient, requiring energy (ATP).
Endocytosis – The process by which cells engulf large particles or liquids.
Exocytosis – The process by which cells expel materials through vesicles.
Phagocytosis – The engulfing of solid particles by a cell.
Pinocytosis – The ingestion of liquids by a cell.
Tissue – A group of similar cells that perform a specific function.
Epithelial Tissue – Tissue that covers body surfaces and lines cavities.
Connective Tissue – Tissue that provides support, protection, and binds other tissues.
Muscle Tissue – Tissue that contracts and allows movement.
Nervous Tissue – Tissue that transmits electrical signals throughout the body.
Squamous Epithelium – Thin, flat cells that form the outer layer of the skin and line blood vessels.
Cuboidal Epithelium – Cube-shaped cells found in glands and kidney tubules.

Unit 3: Integumentary System

Skin – The largest organ of the body, which provides protection and regulates temperature.
Epidermis – The outermost layer of the skin, composed of stratified squamous epithelium.
Dermis – The layer beneath the epidermis containing blood vessels, nerves, and connective tissue.
Hypodermis – The deepest layer of skin, also called the subcutaneous layer, made of adipose tissue.
Keratinocytes – Cells in the epidermis that produce keratin, a protein that provides strength to the skin.
Melanocytes – Cells in the epidermis that produce melanin, the pigment responsible for skin color.
Stratum Corneum – The outermost layer of the epidermis, consisting of dead keratinized cells.
Stratum Basale – The deepest layer of the epidermis, where new skin cells are produced.
Sebaceous Glands – Glands that produce sebum, an oily substance that lubricates the skin and hair.
Sweat Glands – Glands that secrete sweat to regulate body temperature and excrete waste.
Hair Follicle – The structure in the dermis that produces hair.
Nail Matrix – The area at the base of the nail where new nail cells are formed.
Collagen – A protein in the dermis that provides strength and elasticity to the skin.
Elastin – A protein in the dermis that provides skin with elasticity.
Basal Cell Carcinoma – A type of skin cancer that originates in the basal cells of the epidermis.
Melanoma – A serious type of skin cancer that originates in melanocytes.
Sunburn – Skin damage caused by overexposure to ultraviolet (UV) radiation.
Wrinkles – Skin folds that occur with age due to a decrease in collagen and elastin production.
Alopecia – Hair loss or baldness.
Psoriasis – A chronic skin condition characterized by red, scaly patches on the skin.
Acne – A condition in which hair follicles become clogged with oil and dead skin cells, leading to pimples.
Dermatitis – Inflammation of the skin, often causing redness, swelling, and itching.
Eczema – A condition in which patches of skin become inflamed, itchy, and red.
Rashes – Red, inflamed areas of skin that are often a symptom of an underlying condition.
Burns – Tissue damage caused by heat, chemicals, or radiation.
Blister – A fluid-filled sac formed when the skin is damaged.
Suntan – The darkening of the skin due to increased melanin production in response to UV exposure.
Vasodilation – The widening of blood vessels near the skin surface to release heat.
Vasoconstriction – The narrowing of blood vessels near the skin surface to retain heat.
Hypothermia – A condition caused by prolonged exposure to cold, leading to a dangerously low body temperature.

Unit 4: Skeletal System

Bone – A hard, dense connective tissue that makes up the skeleton and provides support and protection.
Osteocyte – A mature bone cell that maintains the bone matrix.
Osteoblast – A cell that forms new bone tissue.
Osteoclast – A cell that breaks down bone tissue.
Osseous Tissue – Bone tissue, which is a type of dense connective tissue.
Spongy Bone – A type of bone tissue that is less dense and found at the ends of long bones and in the interior of others.
Compact Bone – Dense, hard bone tissue that forms the outer layer of bones.
Periosteum – The membrane that covers the outer surface of bones, except at the joints.
Endosteum – A membrane lining the inner surface of bones, including the medullary cavity.
Medullary Cavity – The hollow space within the diaphysis of long bones that contains bone marrow.
Yellow Bone Marrow – Bone marrow that stores fat and is located in the medullary cavity of long bones.
Red Bone Marrow – Bone marrow that produces blood cells, found in the spongy bone of certain bones.
Ligament – A connective tissue that connects bones to other bones.
Tendon – A connective tissue that connects muscles to bones.
Cartilage – A flexible, semi-rigid connective tissue found in joints, the rib cage, and the ears.
Hyaline Cartilage – The most common type of cartilage, found in the ribs, nose, and joints.
Elastic Cartilage – A type of cartilage that provides flexibility, found in the ear and epiglottis.
Fibrocartilage – A type of cartilage that provides strength, found in intervertebral discs and joints.
Joint – A location where two or more bones meet, allowing movement.
Synovial Joint – A type of joint that allows free movement and is characterized by a synovial cavity filled with fluid.
Hinge Joint – A type of synovial joint that allows movement in one plane, such as the elbow or knee.
Ball-and-Socket Joint – A type of synovial joint that allows movement in multiple directions, such as the shoulder or hip.
Cartilaginous Joint – A joint where bones are connected by cartilage, allowing limited movement.
Fibrous Joint – A joint where bones are connected by fibrous tissue, typically immovable.
Fracture – A break or crack in a bone.
Osteoporosis – A condition where bones become weak and brittle due to a loss of bone density.
Arthritis – Inflammation of the joints, leading to pain and stiffness.
Rheumatoid Arthritis – An autoimmune disorder that causes inflammation and damage to joints.
Osteoarthritis – A degenerative joint disease caused by the breakdown of cartilage in the joints.
Skeletal System – The framework of bones and cartilage that provides support, protection, and movement for the body.

Unit 5: Muscular System

Muscle Tissue – Tissue that contracts to produce movement in the body.
Skeletal Muscle – Muscle tissue that is attached to bones and allows voluntary movement.
Smooth Muscle – Muscle tissue found in the walls of internal organs and blood vessels, allowing involuntary movement.
Cardiac Muscle – Muscle tissue found in the heart that contracts involuntarily to pump blood.
Myofibril – A threadlike structure within muscle fibers that is responsible for muscle contraction.
Sarcomere – The basic functional unit of muscle contraction, composed of actin and myosin filaments.
Actin – A protein filament that interacts with myosin during muscle contraction.
Myosin – A protein filament that interacts with actin during muscle contraction.
Z-Line – The boundary of a sarcomere, where actin filaments are anchored.
Tendon – A connective tissue that attaches muscles to bones.
Neuromuscular Junction – The synapse where a motor neuron communicates with a muscle fiber.
Acetylcholine – A neurotransmitter that is released at the neuromuscular junction to initiate muscle contraction.
Muscle Fiber – A single muscle cell that contracts to generate force.
Fascia – Connective tissue that surrounds muscles and separates muscle groups.
Twitch – A brief contraction of a muscle fiber in response to a single stimulus.
Summation – The process by which multiple muscle contractions combine to produce a stronger contraction.
Tetany – A continuous, sustained muscle contraction.
Muscle Fatigue – A condition in which a muscle loses its ability to contract due to prolonged activity.
Muscle Tone – The continuous, passive contraction of muscles that maintains posture.
Isometric Contraction – A type of muscle contraction in which the muscle length remains the same while tension increases.
Isotonic Contraction – A type of muscle contraction in which the muscle shortens as it contracts.
Concentric Contraction – A type of isotonic contraction where the muscle shortens while contracting.
Eccentric Contraction – A type of isotonic contraction where the muscle lengthens while contracting.
Muscle Hypertrophy – The increase in muscle size due to the enlargement of muscle fibers.
Muscle Atrophy – The decrease in muscle size due to a loss of muscle fibers or their contents.
Sarcoplasm – The cytoplasm of a muscle cell, containing glycogen and other substances necessary for contraction.
Myoglobin – A protein in muscle cells that binds oxygen and stores it for use during contraction.
Calcium Ions – Ions released from the sarcoplasmic reticulum during muscle contraction to initiate the interaction between actin and myosin.
Cross-Bridge – The connection formed between myosin heads and actin filaments during muscle contraction.
Sarcolemma – The cell membrane of a muscle fiber.

Unit 6: Nervous System

Neuron – A specialized cell that transmits electrical impulses in the nervous system.
Dendrite – The branching extensions of a neuron that receive signals from other neurons.
Axon – The long, slender projection of a neuron that transmits electrical impulses away from the cell body.
Myelin Sheath – A fatty layer that insulates the axon and increases the speed of nerve impulse transmission.
Node of Ranvier – Gaps in the myelin sheath where action potentials are regenerated, speeding up nerve transmission.
Synapse – The junction between two neurons where communication occurs.
Neurotransmitter – A chemical messenger that transmits signals across synapses.
Action Potential – A rapid, temporary change in membrane potential that travels along the axon of a neuron.
Resting Potential – The electrical charge difference across the membrane of a neuron when it is not transmitting an impulse.
Depolarization – A decrease in the electrical charge difference across the neuron membrane, triggering an action potential.
Repolarization – The process by which a neuron returns to its resting potential after depolarization.
Reflex Arc – The pathway through which a reflex action occurs, involving sensory and motor neurons.
Central Nervous System (CNS) – The brain and spinal cord, which process and coordinate sensory input and motor output.
Peripheral Nervous System (PNS) – The nerves outside the CNS that transmit signals between the CNS and the rest of the body.
Somatic Nervous System – A division of the PNS that controls voluntary movements of skeletal muscles.
Autonomic Nervous System – A division of the PNS that controls involuntary functions, such as heart rate and digestion.
Sympathetic Nervous System – A part of the autonomic nervous system that prepares the body for "fight or flight."
Parasympathetic Nervous System – A part of the autonomic nervous system that promotes "rest and digest" activities.
Brainstem – The part of the brain that connects to the spinal cord and regulates basic life functions.
Cerebrum – The largest part of the brain, responsible for higher functions like thought, memory, and sensory processing.
Cerebellum – The part of the brain that coordinates movement and balance.
Thalamus – The brain structure that relays sensory information to the appropriate areas of the cerebrum.
Hypothalamus – A region of the brain that controls homeostasis, such as body temperature and hunger.
Spinal Cord – A long, cylindrical structure that transmits nerve impulses between the brain and the rest of the body.
Sensory Neurons – Neurons that carry sensory information from receptors to the CNS.
Motor Neurons – Neurons that carry motor commands from the CNS to muscles and glands.
Interneurons – Neurons that connect sensory and motor neurons within the CNS.
Neuroglia – Supporting cells in the nervous system that provide structural support and nourishment to neurons.
Meninges – Protective membranes that cover the brain and spinal cord.
Cerebrospinal Fluid – The fluid that circulates within the brain and spinal cord, providing cushioning and nutrient support.

Unit 7: Circulatory System

Heart – The muscular organ responsible for pumping blood throughout the body.
Arteries – Blood vessels that carry oxygenated blood away from the heart to the body.
Veins – Blood vessels that carry deoxygenated blood back to the heart.
Capillaries – Small, thin blood vessels where gas exchange occurs between blood and tissues.
Blood – A connective tissue that transports oxygen, nutrients, waste, and immune cells throughout the body.
Plasma – The liquid portion of blood that carries cells, nutrients, and waste products.
Red Blood Cells (RBCs) – Cells in blood that carry oxygen from the lungs to tissues and carbon dioxide from tissues to the lungs.
White Blood Cells (WBCs) – Cells in blood that are part of the immune system and protect the body from infection.
Platelets – Small cell fragments that help with blood clotting.
Hemoglobin – A protein in red blood cells that binds to oxygen and carries it through the bloodstream.
Hematopoiesis – The process of blood cell formation in the bone marrow.
Heart Rate – The number of heartbeats per minute.
Blood Pressure – The force exerted by blood against the walls of the blood vessels.
Systolic Pressure – The higher number in blood pressure, indicating the pressure when the heart contracts.
Diastolic Pressure – The lower number in blood pressure, indicating the pressure when the heart is at rest.
Aorta – The largest artery in the body, carrying oxygen-rich blood from the left ventricle to the body.
Pulmonary Circulation – The pathway through which blood travels from the heart to the lungs and back.
Systemic Circulation – The pathway through which blood travels from the heart to the rest of the body and back.
Coronary Arteries – The arteries that supply blood to the heart muscle.
Atrium – The upper chambers of the heart that receive blood.
Ventricle – The lower chambers of the heart that pump blood to the lungs and the rest of the body.
Valve – Structures in the heart that ensure blood flows in one direction and prevents backflow.
Endocardium – The innermost layer of tissue that lines the chambers of the heart.
Myocardium – The thick middle layer of the heart, composed of cardiac muscle.
Epicardium – The outer layer of the heart that provides protection.
SA Node – The sinoatrial node, the pacemaker of the heart, that initiates the heartbeat.
AV Node – The atrioventricular node, which delays the electrical signal before it passes to the ventricles.
Electrocardiogram (ECG) – A test that measures the electrical activity of the heart.
Arrhythmia – An irregular heartbeat or abnormal heart rhythm.
Atherosclerosis – A condition where fatty deposits build up inside the arteries, leading to reduced blood flow.

Unit 8: Respiratory System

Respiration – The process of taking in oxygen and expelling carbon dioxide.
Lungs – The primary organs of the respiratory system where gas exchange occurs.
Diaphragm – The muscle that separates the thoracic and abdominal cavities and plays a key role in breathing.
Trachea – The windpipe, a tube that connects the throat to the bronchi, allowing air to flow to the lungs.
Bronchi – The two main branches of the trachea that lead to the lungs.
Bronchioles – Smaller branches of the bronchi that lead to the alveoli.
Alveoli – Tiny air sacs in the lungs where gas exchange occurs.
Oxygen – A gas that is essential for cellular respiration and is absorbed in the lungs.
Carbon Dioxide – A waste product of cellular respiration that is expelled from the body through the lungs.
Pulmonary Ventilation – The process of moving air in and out of the lungs, commonly known as breathing.
Inhalation – The process of taking air into the lungs.
Exhalation – The process of expelling air from the lungs.
Tidal Volume – The amount of air inhaled or exhaled during normal breathing.
Vital Capacity – The total amount of air that can be exhaled after a maximal inhalation.
Residual Volume – The amount of air remaining in the lungs after a maximal exhalation.
Larynx – The voice box, which houses the vocal cords and is involved in sound production.
Pharynx – The throat, a passage that serves both the respiratory and digestive systems.
Nasal Cavity – The hollow space behind the nose that is involved in air passage and filtering.
Sinuses – Air-filled cavities in the skull that are connected to the nasal passages.
Epiglottis – A flap of tissue that prevents food from entering the trachea during swallowing.
Ventilation – The mechanical process of moving air into and out of the lungs.
Diffusion – The movement of gases (oxygen and carbon dioxide) across the alveolar membrane.
Hemoglobin – A protein in red blood cells that binds to oxygen and carries it to tissues.
Respiratory Rate – The number of breaths taken per minute.
Pleura – The membranes surrounding the lungs and lining the thoracic cavity.
Pulmonary Gas Exchange – The process of oxygen entering the blood and carbon dioxide leaving the blood in the lungs.
Hypoxia – A condition in which there is a deficiency of oxygen in the tissues.
Hyperventilation – Rapid or deep breathing that can lead to a decrease in carbon dioxide levels in the blood.
Asthma – A chronic respiratory disease characterized by airway inflammation and constriction.
Pneumonia – An infection of the lungs that causes inflammation and fluid accumulation.

Unit 9: Digestive System

Digestion – The process of breaking down food into smaller molecules for absorption by the body.
Mouth – The entry point for food, where digestion begins with mechanical and chemical breakdown.
Salivary Glands – Glands that produce saliva to begin the breakdown of food and aid in swallowing.
Esophagus – The tube that connects the mouth to the stomach and transports food through peristalsis.
Stomach – The muscular organ that stores food and secretes digestive juices to break down food.
Small Intestine – The part of the digestive system where most nutrient absorption occurs.
Large Intestine – The part of the digestive system where water and electrolytes are absorbed and waste is formed.
Pancreas – An organ that produces digestive enzymes and bicarbonate to aid digestion in the small intestine.
Liver – An organ that produces bile, detoxifies substances, and stores nutrients.
Gallbladder – An organ that stores bile produced by the liver and releases it into the small intestine.
Bile – A digestive fluid produced by the liver that emulsifies fats for digestion.
Enzyme – A protein that accelerates chemical reactions, including the breakdown of food molecules.
Amylase – An enzyme in saliva and pancreatic juice that breaks down starches into sugars.
Lipase – An enzyme that breaks down fats into fatty acids and glycerol.
Protease – An enzyme that breaks down proteins into amino acids.
Pepsin – An enzyme in the stomach that breaks down proteins into smaller peptides.
Villi – Finger-like projections in the small intestine that increase surface area for nutrient absorption.
Absorption – The process of taking in nutrients from the digestive tract into the bloodstream.
Peristalsis – The wave-like muscle contractions that move food along the digestive tract.
Chyme – The partially digested food that is released from the stomach into the small intestine.
Bolus – A ball-like mixture of food and saliva that is swallowed.
Sphincter – A ring of muscle that controls the flow of substances in the digestive system.
Gastric Juices – A mixture of hydrochloric acid, enzymes, and mucus that aid in digestion in the stomach.
Duodenum – The first part of the small intestine where most chemical digestion occurs.
Jejunum – The middle part of the small intestine, where most nutrient absorption takes place.
Ileum – The final portion of the small intestine, where bile salts and vitamin B12 are absorbed.
Appendix – A small, tube-like structure attached to the large intestine that may play a role in immunity.
Cecum – The first part of the large intestine, where the small intestine connects.
Rectum – The final section of the digestive tract where waste is stored before being expelled.
Anus – The opening at the end of the digestive tract through which waste is expelled.

Unit 10: Urinary System

Kidney – Organs that filter waste products from the blood and produce urine.
Ureter – A tube that carries urine from the kidneys to the bladder.
Bladder – A muscular sac that stores urine before it is excreted.
Urethra – The tube that carries urine from the bladder to the outside of the body.
Nephron – The functional unit of the kidney that filters blood and produces urine.
Glomerulus – A cluster of capillaries in the nephron where filtration of blood occurs.
Bowman’s Capsule – A structure in the nephron that encases the glomerulus and collects filtrate.
Proximal Convoluted Tubule (PCT) – The first part of the renal tubule where reabsorption of water and solutes occurs.
Loop of Henle – A portion of the nephron that concentrates urine by reabsorbing water and salts.
Distal Convoluted Tubule (DCT) – The part of the nephron where additional reabsorption and secretion occur.
Collecting Duct – A tube that collects urine from several nephrons and leads to the renal pelvis.
Renal Pelvis – The central cavity in the kidney that collects urine from the collecting ducts.
Glomerular Filtration Rate (GFR) – The rate at which blood is filtered through the glomeruli of the kidneys.
Renin – An enzyme released by the kidneys that helps regulate blood pressure and fluid balance.
Antidiuretic Hormone (ADH) – A hormone that regulates water balance by increasing water reabsorption in the kidneys.
Aldosterone – A hormone that increases sodium reabsorption in the kidneys, raising blood pressure.
Diuresis – The process of excreting urine, especially in increased amounts.
Filtrate – The fluid that is filtered from the blood in the glomerulus before it becomes urine.
Urine – The waste product produced by the kidneys containing water, urea, and other waste products.
Hemodialysis – A medical procedure that filters waste from the blood for patients with kidney failure.
Peritoneal Dialysis – A method of dialysis where the peritoneal membrane is used to filter waste from the blood.
Kidney Stones – Hard deposits of minerals and salts that form in the kidneys and can cause pain and obstruction.
Urinary Tract Infection (UTI) – An infection in any part of the urinary system, often caused by bacteria.
Polycystic Kidney Disease – A genetic disorder characterized by the growth of numerous cysts in the kidneys.
Nephritis – Inflammation of the kidneys, often due to infection or autoimmune disease.
Proteinuria – The presence of excess protein in the urine, often indicating kidney damage.
Hematuria – The presence of blood in the urine, which may indicate a urinary tract issue or kidney problem.
Osmoregulation – The process of regulating the balance of water and electrolytes in the body.
Excretion – The process of eliminating waste products from the body.
Micturition – The process of urination or the act of expelling urine from the bladder.

Unit 11: Endocrine System

Endocrine Glands – Glands that secrete hormones directly into the bloodstream to regulate body functions.
Hormones – Chemical messengers produced by endocrine glands that regulate physiological processes.
Pituitary Gland – A small gland at the base of the brain that controls other endocrine glands and produces growth hormone.
Hypothalamus – A part of the brain that controls the pituitary gland and regulates homeostasis.
Thyroid Gland – A gland located in the neck that produces hormones regulating metabolism.
Parathyroid Glands – Small glands located on the thyroid gland that regulate calcium levels in the blood.
Adrenal Glands – Glands located on top of the kidneys that produce hormones such as adrenaline and cortisol.
Insulin – A hormone produced by the pancreas that regulates glucose levels in the blood.
Glucagon – A hormone produced by the pancreas that raises blood glucose levels by promoting the release of glucose from the liver.
Estrogen – A group of hormones responsible for the development of female reproductive traits and the regulation of the menstrual cycle.
Testosterone – The primary male sex hormone responsible for the development of male reproductive traits.
Cortisol – A hormone produced by the adrenal glands that helps the body respond to stress.
Thyroxine (T4) – A hormone produced by the thyroid gland that regulates metabolism.
Triiodothyronine (T3) – A hormone similar to thyroxine but more potent, produced by the thyroid.
Prolactin – A hormone produced by the pituitary gland that stimulates milk production after childbirth.
Oxytocin – A hormone produced by the hypothalamus and stored in the pituitary gland that stimulates uterine contractions during labor and milk ejection.
Growth Hormone (GH) – A hormone produced by the pituitary gland that stimulates growth and cell reproduction.
Adrenocorticotropic Hormone (ACTH) – A hormone produced by the pituitary gland that stimulates the adrenal glands to produce cortisol.
Aldosterone – A hormone that regulates sodium and water balance, affecting blood pressure.
Leptin – A hormone that helps regulate energy balance by inhibiting hunger.
Melatonin – A hormone produced by the pineal gland that regulates sleep-wake cycles.
Thymosin – A hormone produced by the thymus that stimulates the production of T-cells in the immune system.
Renin – An enzyme and hormone produced by the kidneys that helps regulate blood pressure.
Pineal Gland – A small gland in the brain that produces melatonin.
Endorphins – Neurotransmitters that act as natural painkillers and are produced by the pituitary gland.
Thyroid-Stimulating Hormone (TSH) – A hormone produced by the pituitary gland that stimulates the thyroid to produce thyroxine.
Follicle-Stimulating Hormone (FSH) – A hormone produced by the pituitary gland that stimulates the growth of eggs in ovaries and sperm production in testes.
Luteinizing Hormone (LH) – A hormone that triggers ovulation in females and the production of testosterone in males.
Cushing’s Syndrome – A condition caused by excessive cortisol production, often from the adrenal glands.
Diabetes Mellitus – A condition characterized by abnormal insulin production or function, leading to elevated blood sugar levels.

Unit 12: Immune System

Immune System – The body's defense system against harmful pathogens, including bacteria, viruses, and other invaders.
Antibodies – Proteins produced by B cells that recognize and neutralize foreign antigens.
Antigens – Substances that provoke an immune response, typically found on the surface of pathogens.
White Blood Cells (WBCs) – Cells involved in the immune response, including lymphocytes and phagocytes.
Macrophages – Large white blood cells that engulf and digest pathogens and debris.
Lymphocytes – White blood cells that include T cells and B cells, which are crucial to adaptive immunity.
B Cells – Lymphocytes that produce antibodies and are involved in the humoral immune response.
T Cells – Lymphocytes that directly attack infected cells and help regulate other immune responses.
Helper T Cells – A type of T cell that assists other immune cells by secreting cytokines.
Cytotoxic T Cells – T cells that directly destroy infected or cancerous cells.
Memory Cells – Long-lived lymphocytes that remember past infections and enable faster responses upon re-exposure.
Phagocytosis – The process by which cells, such as macrophages, engulf and digest foreign particles.
Inflammation – A protective response of the body to injury or infection, characterized by redness, swelling, heat, and pain.
Complement System – A group of proteins that work with antibodies to destroy pathogens.
Interferons – Proteins produced by cells in response to viral infection that inhibit viral replication.
Immunization – The process of introducing antigens into the body to stimulate an immune response and confer immunity.
Vaccination – The administration of a vaccine to provoke an immune response without causing disease.
Allergy – An exaggerated immune response to harmless substances, such as pollen or food.
Autoimmune Disease – A condition in which the immune system mistakenly attacks the body’s own cells, such as in rheumatoid arthritis.
Influenza – A viral infection that attacks the respiratory system.
HIV – The human immunodeficiency virus, which attacks helper T cells and leads to acquired immunodeficiency syndrome (AIDS).
Lymphatic System – The network of vessels and organs (such as lymph nodes and the spleen) that help defend the body against infection.
Spleen – An organ involved in filtering blood and recycling iron, as well as storing white blood cells.
Lymph Nodes – Small, bean-shaped structures that filter lymph fluid and house immune cells.
Tonsils – Lymphoid organs that help protect the respiratory system from pathogens.
Immunodeficiency – A condition where the immune system’s ability to fight infections is impaired.
Sepsis – A life-threatening condition that occurs when the body’s response to infection damages its tissues.
Transplant Rejection – The immune system’s attack on a transplanted organ or tissue, recognizing it as foreign.
Active Immunity – Immunity acquired through exposure to pathogens or through vaccination.
Passive Immunity – Immunity acquired by receiving antibodies from another individual, such as through breast milk or a blood transfusion.

Unit 13: Muscular System

Muscle Tissue – Tissue responsible for producing force and causing motion in the body.
Skeletal Muscle – Voluntary muscles attached to bones that facilitate movement.
Smooth Muscle – Involuntary muscles found in the walls of organs, such as the intestines and blood vessels.
Cardiac Muscle – Involuntary muscle found in the heart that contracts to pump blood.
Myofibrils – Thread-like structures in muscle cells that contain the contractile proteins actin and myosin.
Sarcomere – The functional unit of muscle contraction, made up of actin and myosin filaments.
Actin – A thin protein filament in muscle fibers involved in muscle contraction.
Myosin – A thick protein filament in muscle fibers that interacts with actin to produce contraction.
Tendon – A fibrous connective tissue that attaches muscle to bone.
Ligament – A fibrous connective tissue that attaches bone to bone.
Motor Unit – A motor neuron and all the muscle fibers it controls.
Neuromuscular Junction – The synapse where a motor neuron communicates with a muscle fiber.
Acetylcholine – A neurotransmitter released at the neuromuscular junction to stimulate muscle contraction.
Excitation-Contraction Coupling – The process by which electrical impulses trigger muscle contraction.
Calcium Ions – Ions that play a key role in muscle contraction by interacting with the protein troponin.
Troponin – A protein that binds to calcium and regulates muscle contraction.
Tropomyosin – A protein that blocks the binding sites on actin, preventing contraction when calcium is absent.
ATP (Adenosine Triphosphate) – The energy molecule required for muscle contraction.
Creatine Phosphate – A molecule that stores energy in muscles and replenishes ATP during short bursts of activity.
Aerobic Respiration – The process of producing ATP using oxygen, occurring in mitochondria.
Anaerobic Respiration – The process of producing ATP without oxygen, often leading to lactic acid buildup.
Lactic Acid – A byproduct of