Introduction to Physiology & General Principles

Vocabulary practice flashcards defining key principles of medical physiology, body solutions, fluid compartments, cellular structures, tissue types, and homeostatic control mechanisms.

Physiology

The sub-discipline of biology focused on how living organisms, organ systems, organs, cells, and biomolecules carry out their functional processes in a living system.

Solution

A homogeneous mixture consisting of a solute dissolved in a solvent.

Solute

The substance that is dissolved within a solvent to form a solution.

Solvent

The dissolving medium in a solution, with water serving as the primary solvent in biological systems.

Extracellular Fluid (ECF)

The fluid environment surrounding cells (also called the 'internal sea') that makes up one-third of total body water and accounts for $20\%$ of total body weight.

Intracellular Fluid (ICF)

The fluid contained within body cells that makes up two-thirds of total body water and accounts for $40\%$ of total body weight.

Electrolytes

Molecules (such as $\text{NaCl}$) that dissociate in water into their respective cation (e.g., $\text{Na}^+$) and anion (e.g., $\text{Cl}^-$) equivalents.

Mole

The standard SI unit for expressing the amount of a substance, defined as its gram-molecular weight.

Equivalent (Eq)

A unit of electrical equivalence defined as $1\,\text{mol}$ of an ionized substance divided by its valence.

Buffer

A substance that maintains a relatively constant pH in solution by binding or releasing $\text{H}^+$ ions.

Serum Physiologic (Physiological Saline)

A sterile, isotonic solution containing $0.9\%$ $\text{NaCl}$ ($9\,\text{g}$ of $\text{NaCl}$ dissolved in $1000\,\text{ml}$ of water).

Dextrose 5% in Water (D5W)

An intravenous fluid containing a form of glucose, administered to replace lost fluids, provide carbohydrates, treat hypoglycemia or insulin shock, and provide parenteral nutrition.

Ringer's Lactate

An isotonic intravenous fluid containing water, essential electrolytes ($\text{NaCl}$, sodium lactate, $\text{KCl}$, and $\text{CaCl}_2 \cdot 2\text{H}_2\text{O}$), and a buffer, commonly used for fluid resuscitation after blood loss.

Cell Differentiation

The developmental process by which an unspecialized cell transforms into a specialized cell type adapted for specific functional roles.

Tissue

An aggregation of differentiated, closely related cells specialized to perform a common function.

Endocrine Glands

Ductless glands that produce hormones and release them into the surrounding interstitial fluid or directly into the bloodstream.

Exocrine Glands

Glands containing ducts or channels that convey their secretions to a specific target area or external body surface.

Collagen

The most abundant protein in the human body, providing high durability and strength to connective tissue fibers.

Fibroblasts

Connective tissue cells that secrete matrix proteins and drive tissue repair and regeneration during healing.

Plasma

The intravascular ECF subcompartment circulating within blood vessels, accounting for $5\%$ of body weight.

Interstitial Fluid

The ECF subcompartment occupying the spaces between and around tissue cells, accounting for $15\%$ of body weight.

Edema

The accumulation of excess fluid within tissues, caused by increased fluid leakage from blood plasma or decreased removal by the lymphatic system.

Homeostasis

The process through which the body maintains stable internal conditions despite ongoing changes in the external environment.

Receptor (Sensor)

A component of a feedback loop that detects changes in a monitored physiological variable.

Control Center

A component of a feedback loop that defines the set point range, processes input from receptors, and directs output to effectors when corrections are required.

Effector

A component of a feedback loop that carries out a physiological response in direction of output signals from the control center.

Negative Feedback Loop

A self-terminating regulatory process in which the body's response opposes or reverses the initial stimulus to restore homeostatic balance.

Positive Feedback Loop

A regulatory mechanism in which the body's response magnifies the initial stimulus, driving the system further away from equilibrium until shut off by an external factor.