Physiology Practice Exam Review

Vocabulary practice flashcards based on physiology lecture notes covering cell transport, muscle anatomy, action potentials, blood components, immunity, and gastrointestinal function.

Phospholipid Bilayer Structure

The cell membrane structure where the phosphate end is hydrophilic (water-soluble) and the fatty acid portion is hydrophobic (fat-soluble).

Nernst Equation (univalent ions at 37°C)

$EMF = \pm 61 \log(C1/C2)$ in millivolts.

Normal Osmolality

The osmolality of extracellular and intracellular fluids, which is approximately $300\,\text{milliosmoles}$ per kilogram of water.

Primary Active Transport

Transport where energy is derived directly from the breakdown of adenosine triphosphate (ATP) or other high-energy phosphate compounds.

Sodium-Potassium Pump

An ion pump that moves three sodium ions outward and two potassium ions inward, establishing a negative electrical voltage inside the cell.

Secondary Active Counter-Transport

A mechanism where the energy released by sodium moving into the cell causes a different substance to move to the exterior.

Goldman Equation Ions

The most important ions involved in developing membrane potentials in nerve and muscle fibers: sodium, potassium, and chloride.

Depolarization Stage

The phase of the action potential where the membrane becomes highly permeable to sodium ions, neutralizing the polarized state as potential rises rapidly toward zero.

Absolute Refractory Period

The interval during which a new action potential cannot be initiated because sodium channels have become inactivated; lasts about $1/2500\,\text{second}$ in large myelinated fibers.

Saltatory Conduction

The process in myelinated fibers where action potentials jump from node to node at the nodes of Ranvier, increasing velocity up to 5- to 50-fold.

Intracellular Ion Concentrations

$Na^+ \approx 10\,\text{mEq/L}$, $K^+ \approx 140\,\text{mEq/L}$, and $Ca^{++} \approx 0.0001\,\text{mEq/L}$.

Sarcomere

The functional unit of the myofibril located between two successive Z discs.

Sarcoplasm

The intracellular fluid between myofibrils containing large quantities of potassium, magnesium, phosphate, and protein enzymes.

Acetylcholine (ACh)

The neurotransmitter secreted at nerve endings that opens gated channels in the muscle fiber membrane to initiate an action potential.

Myosin Molecule

A contractile protein composed of six polypeptide chains: two heavy chains (approx. $200,000\,\text{MW}$) and four light chains (approx. $20,000\,\text{MW}$).

Oxidative Metabolism

The source of more than 95% of all energy used by muscles for sustained long-term contraction.

Calmodulin

The regulatory protein in smooth muscle that binds with calcium to activate myosin kinase, performing the role troponin has in skeletal muscle.

Synaptic Space (Synaptic Cleft)

The 20 to 30 nanometer wide gap between the nerve terminal and the muscle fiber membrane.

Erythropoietin

The primary glycoprotein stimulus for red blood cell production, with 90% formed in the kidneys.

Ferritin

The intracellular storage form of iron created when iron combines with the protein apoferritin.

Neutrophils

Mobile white blood cells that represent 62% of the total WBC count and provide the first line of defense against infection.

Chemotaxis

The process by which chemical substances in inflamed tissues cause neutrophils and macrophages to move toward the source of the injury.

Humoral Immunity

Also called B-cell immunity; the development of circulating antibodies that attack specific invading agents.

O-A-B Blood Types

The classification system determined by the presence or absence of two antigens (agglutinogens) called Type A and Type B on the surface of RBCs.

Agglutinins

Gamma globulin antibodies (anti-A or anti-B) that develop in the plasma when the corresponding agglutinogen is absent from the RBCs.

Thromboxane A2

A vasoconstrictor substance released by platelets that helps seal small vascular ruptures by stimulating local vascular spasm.

Clotting Factor II

Prothrombin; a b2-globulin plasma protein continually formed by the liver that requires vitamin K for normal activation.

Myenteric Plexus (Auerbach's Plexus)

An outer network of neurons in the enteric nervous system that primarily controls gastrointestinal movements.

Cholecystokinin (CCK)

A hormone produced by I cells in the duodenum and jejunum that stimulates gallbladder contraction and inhibits gastric emptying.

Parietal Cells

Acid-secreting cells in the oxyntic glands that produce hydrochloric acid and intrinsic factor.