Anatomy, Physiology, Homeostasis & Cell Biology Flashcards

Comprehensive key term and definition flashcards covering fundamental human anatomy, physiology, chemistry, cellular metabolism, transport mechanisms, membrane potential, neurophysiology, and histology.

Anatomy

The study of body structure.

Physiology

The study of body function.

Pathophysiology

The study of the mechanisms of disease, specifically how normal physiological function is disrupted by disorder or injury.

Homeostasis

The body's tendency to maintain a stable internal environment despite external changes.

Negative Feedback

A homeostatic control loop that opposes or reverses a change, returning a physiological variable back toward its set point.

Positive Feedback

A control loop that amplifies a change, driving a variable further away from its starting point until a definite endpoint is reached.

Receptor

A sensor that detects or monitors a physiological variable (the stimulus) and sends information to the integrator.

Integrator

The control center that compares receptor input to a set point and determines the appropriate physiological response.

Effector

An organ, cell, or gland that carries out the physiological response to correct a deviation from the set point.

Covalent Bond

A strong chemical bond formed by the sharing of electron pairs between atoms.

Ionic Bond

A chemical bond formed by electrostatic attraction between a cation and an anion following complete electron transfer; easily broken in water.

Hydrogen Bond

A weak attraction between a \text{̢̡}\text{H} atom carrying a partial positive charge (̢̡+) on one polar molecule and an $\text{O}$ or $\text{N}$ atom carrying a partial negative charge (̢̡-) on another molecule.

Enzyme

A protein or RNA catalyst that speeds up a specific biochemical reaction without being consumed.

Glycogenesis

The process of storing excess glucose as glycogen, occurring primarily in the liver ($\sim 25\%$) and skeletal muscle ($\sim 75\%$).

Triglyceride

The body's primary energy-storage lipid, composed of $1$ glycerol molecule and $3$ fatty acid chains linked by ester bonds.

High-Density Lipoprotein (HDL)

A lipoprotein with a high protein-to-lipid ratio that transports excess cholesterol away from tissues and arteries to the liver for disposal.

Low-Density Lipoprotein (LDL)

A lipoprotein with a high lipid-to-protein ratio that delivers cholesterol to body tissues and can contribute to arterial plaque buildup.

Adenosine Triphosphate (ATP)

The primary energy-transfer molecule in cells, composed of adenine, ribose, and three phosphate groups.

Dehydration Synthesis

An anabolic reaction that joins two smaller molecules into a larger one by removing a water molecule.

Hydrolysis

A catabolic reaction that breaks down a larger molecule into smaller components by adding a water molecule across a bond.

Buffer

A chemical substance that resists changes in $\text{pH}$ by absorbing or releasing $\text{H}^+$ ions as needed.

Glycolysis

An anaerobic metabolic pathway in the cytosol that converts glucose into $2$ pyruvate, producing a net yield of $2\text{ ATP}$ and $2\text{ NADH}$.

Citric Acid Cycle

A series of reactions in the mitochondrial matrix that processes pyruvate-derived acetyl-CoA to produce $\text{CO}_2$, $\text{NADH}$, $\text{FADH}_2$, and a small amount of $\text{ATP}$.

Electron Transport Chain

Reactions in the inner mitochondrial membrane that oxidize $\text{NADH}$ and $\text{FADH}_2$ to create an $\text{H}^+$ gradient that powers the majority of cellular $\text{ATP}$ synthesis.

Aerobic Respiration

Mitochondrial metabolic pathway requiring oxygen that breaks down glucose into $\text{CO}_2$ and $\text{H}_2\text{O}$, producing up to $32\text{ ATP}$ per glucose.

Anaerobic Fermentation

A cytosolic pathway requiring no oxygen that converts pyruvate to lactate, yielding $2\text{ ATP}$ per glucose from glycolysis alone.

ATP Synthase

A channel protein in the inner mitochondrial membrane that uses the movement of $\text{H}^+$ down its electrochemical gradient to synthesize $\text{ATP}$ from $\text{ADP}$.

Intracellular Fluid (ICF)

Fluid inside cells (cytosol), representing approximately $\sim 2/3$ of total body water, where $\text{K}^+$ is the dominant cation.

Extracellular Fluid (ECF)

Fluid outside cells (interstitial fluid, plasma, lymph, CSF), representing $\sim 1/3$ of body water, where $\text{Na}^+$ is the dominant cation.

Simple Diffusion

The passive movement of small, nonpolar molecules directly through the lipid bilayer down their concentration gradient without energy consumption.

Facilitated Diffusion

Passive transport of molecules down a concentration gradient across a cell membrane via channel or carrier proteins.

Active Transport

Movement of substances against (up) their concentration gradient requiring a membrane pump protein and cellular energy ($\text{ATP}$).

Isotonic Solution

A solution with a solute concentration equal to that of intracellular fluid, resulting in no net movement of water.

Hypotonic Solution

A solution with a lower solute concentration than intracellular fluid, causing water to enter the cell, leading to swelling or lysis.

Hypertonic Solution

A solution with a higher solute concentration than intracellular fluid, causing water to exit the cell, leading to cell shrinkage (crenation).

Denaturation

The loss of a protein's functional 3-D shape due to exposure to extreme heat, altered $\text{pH}$, or harsh conditions.

Phagocytosis

A form of endocytosis ("cell eating") in which a cell engulfs large particles, debris, or whole foreign organisms.

Resting Membrane Potential

The electrical potential across the plasma membrane of a resting neuron ($\sim -70\,\text{mV}$), established primarily by potassium leak channels and the $\text{Na}^+/\text{K}^+$ pump.

Sodium-Potassium Pump

An active transport pump protein that consumes $\text{ATP}$ to move $3\text{ Na}^+$ out of the cell and $2\text{ K}^+$ into the cell against their concentration gradients.

Depolarization

The action potential phase where stimulus opens voltage-gated $\text{Na}^+$ channels, allowing $\text{Na}^+$ inflow and shifting membrane potential from negative toward positive.

Repolarization

The action potential phase where $\text{Na}^+$ channels inactivate, voltage-gated $\text{K}^+$ channels open, and $\text{K}^+$ rushes out, driving membrane potential back toward negative.

Hyperpolarization

The brief period where voltage-gated $\text{K}^+$ channels stay open past rest, causing membrane potential to become more negative than resting potential.

Saltatory Conduction

The rapid propagation of an action potential along a myelinated axon as it leaps from one node of Ranvier to the next.

Absolute Refractory Period

The duration during and immediately following an action potential when another action potential cannot be generated regardless of stimulus strength.

Relative Refractory Period

The period following the absolute refractory period when an action potential can only be triggered by a stronger-than-normal stimulus.

Epithelial Tissue

Tissue composed of closely packed cells with little matrix and no blood vessels (avascular), featuring a free apical surface; functions in protection, lining, absorption, and secretion.

Connective Tissue

Tissue characterized by cells scattered within an abundant extracellular matrix (fibers and ground substance); functions in binding, support, protection, and transport.

Pseudostratified Columnar Epithelium

An epithelium that appears multi-layered due to varying nuclear positions, but in which every cell contacts the basement membrane; typically lines the respiratory tract.

Transitional Epithelium

A specialized stratified tissue capable of stretching as cells shift from cuboidal to flattened shapes; lines the urinary bladder.

Fibroblast

The main resident cell type of most connective tissues that produces collagen and other extracellular matrix fibers and ground substance.

Eccrine Gland

An exocrine gland (also known as merocrine) that releases its secretory product via exocytosis while keeping the secretory cell completely intact.

Apocrine Gland

An exocrine gland that releases its product by pinching off the apical portion of the secretory cell.

Holocrine Gland

An exocrine gland whose cells accumulate secretory products and completely rupture to release them, being replaced by underlying cells.