PSC321 Physiology and Pathophysiology I - Unit 1 Flashcards

Vocabulary flashcards focusing on cell structure, membrane proteins, junction types, solute transport mechanisms, resting membrane potential calculations, and clinical pathophysiology.

Microfilament

A cytoskeletal filament with a diameter of $7\,nm$ composed of the protein subunit actin.

Intermediate filament

A cytoskeletal filament with a diameter of $10\,nm$ composed of several protein subunits.

Microtubule

A cytoskeletal filament with a diameter of $25\,nm$ composed of the protein subunit tubulin.

Peripheral proteins

Membrane proteins that are noncovalently bonded with integral proteins and can be removed without disrupting the integrity of the membrane.

Transmembrane proteins

Integral membrane proteins that cross the entire lipid bilayer.

Gap junctions

Pores composed of connexons connecting two neighboring cells that allow the transfer of small, ionized solutes such as $\text{Na}^+$ to rapidly change cellular electrical potential.

Tight junction

A junctional barrier, also known as zonula occludens, formed by strands of transmembrane proteins that blocks the movement of molecules between cells.

Paracrine signaling

Local cell communication where a chemical signal diffuses through interstitial fluid from one cell to act on neighboring cells, such as acetylcholine at the neuromuscular junction.

Fick's Law of Diffusion

An equation stating that the rate of diffusion is $J = \frac{(C_1 - C_2) T S A}{\Delta X}$, where diffusion depends on concentration gradient $(C_1 - C_2)$, temperature ($T$), solubility ($S$), surface area ($A$), and diffusion distance ($\Delta X$).

Donnan effect

The ability of charged, non-diffusible solutes inside or outside a cell to alter the diffusion and equilibrium distribution of water and diffusible ions across a membrane.

Carrier-Mediated Facilitated Diffusion

A passive transport process mediated by membrane conduits gated by two doors that are never open at the same time, moving solutes down their concentration gradient without requiring energy.

Primary Active Transport

A solute movement process that requires direct energy input from ATP to transport solutes against their concentration gradient from low to high concentration.

$$\text{Na}^+/\text{K}^+\text{-ATPase}$$

A primary active transport pump that maintains cellular concentration gradients by hydrolyzing ATP to transport 3 $\text{Na}^+$ ions out of the cell and 2 $\text{K}^+$ ions into the cell.

Secondary Active Transport

A transport process that uses the concentration gradient of one solute (such as $\text{Na}^+$) to transport another solute (such as glucose) against its own concentration gradient.

Resting Membrane Potential (RMP)

The electrical potential across a cell membrane at rest, typically around $-90\,mV$ in mammalian cells, where the chemical diffusive force equals the electrical force for permeable ions (primarily $\text{K}^+$).

Nernst Potential Equation

The mathematical formula $E_x = (\pm) 61 \log\left(\frac{[X]_o}{[X]_i}\right)$ used to calculate the equilibrium electrical potential for a specific ion given its intracellular and extracellular concentrations.

Hypo-polarized

A membrane potential change (also termed de-polarized) where the intracellular voltage becomes less negative and moves closer to $0\,mV$.

Hyper-polarized

A membrane potential change where the intracellular voltage becomes more negative and moves further away from $0\,mV$.

Lisinopril

An ACE inhibitor medication prescribed for primary hypertension.

Hyperkalemia

A medical condition characterized by elevated extracellular potassium levels ($[\text{K}^+]_o > 5.5\,mmol/L$) that depolarizes resting membrane potential and alters cardiac excitability.