ITEC Anatomy & Physiology flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Plasma membrane

A phospholipid bilayer studded with proteins that encloses the cell and controls which substances enter and leave, providing selective permeability and a boundary between intracellular and extracellular fluid.

Osmosis

The net movement of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration, requiring no ATP and continuing until concentrations equalize.

Mitochondria

Organelles with folded inner membranes (cristae) where oxidative phosphorylation produces most cellular ATP, making them the principal site of aerobic energy production in the cell.

Epithelial tissue

A covering and lining tissue composed of closely packed cells with little matrix, avascular but innervated, resting on a basement membrane and regenerating rapidly.

Osteoblasts versus osteoclasts

Osteoblasts are bone-forming cells that secrete matrix and become osteocytes; osteoclasts are large multinucleate cells that resorb bone, releasing calcium into the blood.

Compact versus spongy bone

Compact bone is dense with osteons and provides strength; spongy bone is a lattice of trabeculae with marrow spaces that reduces weight and absorbs stress.

Endochondral ossification

The process in which a hyaline cartilage model is gradually replaced by bone, producing long bones; it involves a primary ossification center in the diaphysis and secondary centers in the epiphyses.

Parathyroid hormone

A hormone released when blood calcium falls; it raises calcium by stimulating osteoclast activity, increasing renal calcium reabsorption, and activating vitamin D for intestinal absorption.

Sarcomere

The functional contractile unit of muscle, bounded by two Z discs and containing overlapping actin and myosin filaments whose sliding shortens the muscle fiber.

Sliding filament theory

Muscle contraction occurs when myosin heads bind actin and pivot, pulling thin filaments toward the sarcomere center, shortening the sarcomere while filament lengths stay unchanged.

Neuromuscular junction

The synapse between a motor neuron terminal and a muscle fiber, where acetylcholine is released, binds sarcolemma receptors, and triggers depolarization that leads to contraction.

Antagonist muscle

A muscle that opposes the action of a prime mover, relaxing while the agonist contracts and often reversing the movement at the same joint.

Cardiac output

The volume of blood pumped by one ventricle per minute, calculated as heart rate multiplied by stroke volume; typical resting value is about five liters per minute.

SA node

The sinoatrial node in the right atrial wall is the heart's natural pacemaker, generating impulses that set the resting heart rhythm before conduction reaches the AV node.

Hemostasis

The stoppage of bleeding through three steps: vascular spasm constricts the vessel, platelets form a plug, and coagulation converts fibrinogen to fibrin to seal the break.

Lymphatic system function

Returns excess interstitial fluid to the blood, transports absorbed fats from the intestine, and houses lymphocytes and lymph nodes that filter pathogens and support immunity.

Alveoli

Microscopic air sacs at the end of respiratory bronchioles with walls one cell thick and surrounding capillaries, providing the surface for diffusion of oxygen and carbon dioxide.

Tidal volume

The volume of air moved into or out of the lungs during one normal quiet breath, approximately 500 mL in a resting adult.

Boyle's law in breathing

At constant temperature, gas pressure is inversely proportional to volume; increasing thoracic volume lowers intrapulmonary pressure below atmospheric, so air flows inward during inspiration.

Central chemoreceptors

Receptors in the medulla that detect rising carbon dioxide and falling pH in cerebrospinal fluid and stimulate the respiratory centers to increase ventilation.

Bile

A fluid produced by the liver and stored in the gallbladder that emulsifies fats into small droplets, increasing the surface area for pancreatic lipase; it contains no digestive enzymes.

Villi and microvilli

Fingerlike projections of the small intestine lining and their surface folds that greatly increase absorptive surface area and contain capillaries and lacteals for nutrient uptake.

Cholecystokinin

A hormone released by the duodenum in response to fat and protein, stimulating gallbladder contraction and pancreatic enzyme secretion while slowing gastric emptying.

Action potential

A rapid reversal of membrane potential caused by sodium influx and potassium efflux; it propagates along the axon and is followed by a refractory period.

Sympathetic division

The fight-or-flight branch of the autonomic nervous system that raises heart rate, dilates airways and pupils, and mobilizes glucose using mainly norepinephrine.

Negative feedback

A control mechanism in which a change from the set point triggers a response that reverses the change, restoring stability; it regulates temperature, glucose, and hormone levels.

Epidermis

The outer avascular layer of skin made of keratinized stratified squamous epithelium, whose deepest layer contains dividing keratinocytes and melanocytes.

Melanin

A pigment produced by melanocytes and transferred to keratinocytes that absorbs ultraviolet radiation, protecting DNA and contributing to skin and hair color.

Thermoregulation by skin

The skin regulates temperature through sweating and dermal vasodilation to lose heat, and through vasoconstriction and shivering to conserve heat under hypothalamic control.

Nephron

The functional unit of the kidney, consisting of a glomerulus and renal tubule, which filters plasma, reabsorbs useful substances, and secretes wastes to form urine.

Antidiuretic hormone

A hormone from the posterior pituitary that increases water reabsorption in the collecting ducts, producing concentrated urine and conserving body water.

Homeostasis

The maintenance of a relatively stable internal environment around a set point, achieved by receptors detecting change, a control center integrating it, and effectors responding.