Electrolyte Transport and Body Fluid Compartments

Flashcards summarizing key concepts about electrolyte transport, membrane potentials, and fluid balance.

What determines the distribution of major electrolytes across a cell membrane?

Concentration gradients and membrane permeability

What role does the lipid component of plasma membranes play?

It forms a barrier separating intracellular space from extracellular fluids.

How does simple passive diffusion work?

Movement path across membrane lipids does not involve a protein

What are the main categories of membrane transport pathways?

Simple diffusion, facilitated diffusion, primary active transport, and secondary active transport

What are the three main types of membrane transport proteins?

Channels, transporters (carriers), and pumps

What is the direction of passive ion/electrolyte or water movement in channels?

From high concentration towards low concentration

Name three types of ion channels.

Ligand-gated, voltage-gated, and stretch-activated

In primary active transport, what directly powers the movement of molecules?

ATP hydrolysis

What are the functions of primary active transporters (ATPases)?

Pump electrolytes out of one compartment into another, create solute gradients for osmotic stability, create ion gradients for bioelectricity, and facilitates secondary active transport

What is the key difference between primary and secondary active transport?

Primary active transport uses ATP directly, while secondary active transport uses the ion gradients created by primary active transport

What drives the electrochemical equilibrium potential for a single highly permeant ion species?

Concentration gradient

What are the major forces governing electrolyte movement in cells?

Electrical forces (voltage/potential) and chemical concentration gradients

What primarily determines the membrane's resting potential?

K+ electrochemical equilibrium potential

How does metabolic acidosis affect potassium levels?

It can result in hyperkalemia due to electrically "silent" exchange of H+ with K+.

How does Rhabdomyolysis affect Cardiac cell electrical balance?

Release of intracellular K+ pool into plasma from muscle crush

What are the two major fluid compartments in the body, and how much of the body weight do they comprise?

Intracellular fluid (ICF, ~40% BW) and extracellular fluid (ECF, ~20% BW)

Name the two components of the ECF

interstitium and plasma

What principle that measures volumes of body fluids is described here?
Add a quantity of soluble substance to an unknown volume of water, allow distribution, then calculate the volume based on concentration.

Dilution principle

What factors influence passive movement in capillaries?

Chemical concentration gradients and physical pressures (hydrostatic and colloid osmotic = oncotic)

What forces determine fluid movement between the plasma and interstitial fluid?

Starling pressures, hydrostatic and colloid osmotic (oncotic) pressures

What is the main determinant of ECF volume?

NaCl

What is osmolality?

Number of free (dissociated) particles in solution

In Hypertonic Expansion, what happens to the ICF and ECF, and what is the change?

Increase in ECFosm, H2O moves OUT of cells to restore osmotic equilibrium. Decrease in ICFV, increase in ECFV. Increase in osm.

What happens to the concentration of ions in isotonic expansion?

Only ECF expansion and no change in osm. Increase in TB H2O.

In Hypertonic contraction, what happens to the ICF and ECF?

Both ECF and ICF volumes decrease.

What are three types of volume expansion?

Hypotonic, isotonic, and hypertonic

What happens to cell volume during changes of osmolality?

Movement of water across the cell wall causes cell volume to change