Physiological fluids

Why does th PM have cholesterol

Embedded in phospholipid tails for fluidity and stability

Why does the PM have carbs

At outer surface for cell recognition and interactions

What susbstances can move through the plasma membrane

Non-polar

small

Lipid soluble

How do lipid-soluble substances cross the PM

Passive diffusion down a conc gradient

What is the rate of diffusion determined by

Conc gradient

Membrane permeability

SA

Thickness

Substance size

How do ions move

Through faster conduction along an electrical gradient

How are electrochemical gradients formed

Electrical gradient with a conc gradient for an ion

Important for mainting excitability of certain cells

What is a hyper-osmotic solution

Higher solute conc

What is a hypo-osmotic solution

Lower solute conc

How is hydrostatic pressure created

CHnage in volume creates difference in hydrostatic pressure across PM

What is osmotic pressure

Needed to stop osmosis is determined by solute conc

What is osmolality

Osmotic pressure

Osomoles / kg of water

What is osmolarity

Appromimated osmotic pressure

Osmoles / litre of water

What does osmolarity depend on

Number of particles in solution

What is tonicity

Effect of concentration of solutes

What is an isotonic solution

Same solute concentration as cell

What is hyper-tonic solution

Higher solute conc than cell

What is hypo-tonic solution

Lower solute conc

What are gated channels

Open or close by chanding shape in response to a control mechanism

What are leak channels

Open and ions leak across PM

What are aquaporins

Protein channels in PM

Aloow water to move quickly

What is passive carrier transport determined by

Specificity

Saturation

Competition

What is the balance conecpt

Substances in ECF are maintained at appropriate levels by balancing substance input and output

What is the difference betwwen ECF nad ICF

ICF has higher levels of proteins, carbs, amino acids etc

Levels of certain ions differ

Most ions are elcetically balanced

What does an NA+/K+ ATPase pump do

Acts as antiport

Pumps Na+ out of cell so more Na+ in ECF

Pumps K+ into cell so more K+ in ICF