BIOL 202 Human Physiology Unit 1 Exam Review Flashcards

Vocabulary practice flashcards generated from BIOL 202 Unit 1 Exam Review materials.

Homeostasis

The maintenance of relatively stable conditions in the body's internal environment through dynamic regulation.

Emergent Property

A complex property that arises from integrated lower-level components and neural or biological networks, such as cognitive thought and memory arising from neural networks.

Fick's Law of Diffusion

A physiological law stating that the net rate of diffusion across a plasma membrane increases when membrane surface area ($A$) and concentration gradient ($\Delta C$) increase, or when membrane thickness ($X$) decreases.

Selective Permeability

The property of the plasma membrane that permits nonpolar/lipid-soluble molecules to cross easily while restricting large or charged solutes without specific transport proteins.

Crenation

The shrinking of red blood cells due to net water loss when placed in a hypertonic solution.

Transport Maximum ($T_m$)

The maximum rate of solute transport in carrier-mediated transport, achieved when all specific carrier proteins in the plasma membrane are fully saturated.

Primary Active Transport

A transport process that directly hydrolyzes ATP to power the conformational change of transport pumps (such as the $Na^+/K^+$ ATPase pump) and move solutes against their concentration gradient.

Secondary Active Transport

A transport mechanism that uses the potential energy stored in an ionic concentration gradient (such as a $Na^+$ gradient) established by a primary active transport pump, rather than directly consuming ATP.

Transepithelial Transport of Glucose

The process where glucose crosses the apical membrane of intestinal epithelial cells via $Na^+$/glucose symport and leaves the basolateral membrane via facilitated diffusion through GLUT transporters.

Gap Junctions

Intercellular channels composed of connexin proteins that allow rapid ionic diffusion between the cytoplasm of adjacent cells for direct cell-to-cell communication.

Phospholipase C (PLC) Pathway

A $G_q$ protein-coupled receptor pathway that activates Phospholipase C to cleave $PIP_2$ into the second messengers $IP_3$ and DAG.

Signal Amplification

The multiplication of a physiological signal through sequential enzymatic steps in a second-messenger cascade, allowing a single ligand molecule to trigger a massive cellular response.

Competitive Receptor Antagonist

A molecule that binds to the same receptor site as an endogenous messenger, blocking messenger binding without activating the receptor pathway.

Lipid-Soluble Hormones

Hydrophobic hormones (such as cortisol and testosterone) that circulate in the blood bound to transport proteins made by the liver and bind to intracellular receptors to alter gene expression.

Hypothalamic-Hypophyseal Portal System

A specialized vascular arrangement that delivers concentrated hypothalamic releasing and inhibiting neurohormones directly to the anterior pituitary without systemic dilution.

Zona Glomerulosa

The outermost layer of the adrenal cortex that secretes the mineralocorticoid aldosterone to increase renal $Na^+$ and water reabsorption.

Zona Fasciculata

The middle layer of the adrenal cortex that secretes glucocorticoids, primarily cortisol, to promote gluconeogenesis, muscle protein breakdown, and immunosuppression.

Zona Reticularis

The innermost layer of the adrenal cortex that primary secretes adrenal androgens ('sex' hormones).

Thyroglobulin (TGB)

A protein located in thyroid follicle colloid on which iodinated tyrosine residues are coupled to synthesize thyroid hormones ($T_3$ and $T_4$).

General Adaptation Syndrome (GAS) Fight-or-Flight Stage

The immediate acute stress response mediated by sympathetic neural stimulation of the adrenal medulla, causing the release of epinephrine ($80\%$) and norepinephrine ($20\%$) into the blood.

Down-Regulation

The process by which continuous high levels of a hormone cause target cells to decrease their sensitivity by removing and degrading cell surface receptors via endocytosis.

Up-Regulation

The insertion of additional membrane receptors into target cell membranes when a hormone is deficient, making the target cell more sensitive to the hormone.

Osmosis

The net movement of water across a selectively permeable membrane toward a solution with a higher non-penetrating solute concentration.

Posterior Pituitary Gland

A neuroendocrine gland that stores and releases oxytocin and antidiuretic hormone (ADH), which are synthesized in hypothalamic neurosecretory cell bodies.

Adrenal Medulla

A modified sympathetic ganglion containing chromaffin cells that secretes epinephrine ($80\%$) and norepinephrine ($20\%$) directly into the bloodstream during acute stress.

Adenylyl Cyclase

An membrane-bound amplifier enzyme activated by $G_s$ protein-coupled receptors that converts ATP into cyclic AMP (cAMP).

Hypertrophy

An enlargement of an endocrine gland resulting from excessive hormonal or physiological stimulation.

Atrophy

The shrinkage of an endocrine gland or tissue caused by continuous inhibition, lack of stimulation, or negative feedback.

Cortisol

Glucocorticoid secreted by zona fasciculata; promotes gluconeogenesis, breakdown of muscle proteins, and immunosuppression.

Thyroid-Stimulating Hormone (TSH)

Anterior pituitary tropic hormone secreted by thyrotrophs; stimulates synthesis and release of $T_3$ and $T_4$ from thyroid follicles.

Insulin

Peptide hormone secreted by pancreatic beta cells; activates RTKs to insert GLUT4 transporters and lower blood glucose.

Melatonin

Amine hormone secreted by pinealocytes; relies on visual retinal input to regulate $24\text{-hour}$ circadian rhythms.

Aldosterone

Mineralocorticoid secreted by zona glomerulosa; increases renal $Na^+$ and water reabsorption to regulate blood pressure.

Symporter

Membrane transporter that moves two or more different substances in the exact same direction across the plasma membrane.

Receptor Tyrosine Kinase (RTK)

Enzyme-linked plasma membrane receptor that dimerizes and cross-phosphorylates tyrosine residues upon ligand binding (e.g., insulin receptor).

Phagocytosis

Form of endocytosis where white blood cells send out pseudopods using cytoskeleton to engulf large solid particles into a phagosome.

Transcytosis

Integrated transport process combining endocytosis, vesicular transport along microtubules, and exocytosis across an epithelium.

Inositol Trisphosphate ($IP_3$)

Intracellular second messenger produced by Phospholipase C cleavage of $PIP_2$ that binds to ER channels to release $Ca^{2+}$.