ECF , ICF, Osmosis

What is intra and extracellular fluid

Fluid inside and outside the cell , separated by cell membrane.

Which part of a phospholipid is hydrophobic?

lipid tail

Which part of a phospholipid is hydrophilic?

phosphate head

What is the function of cholesterol in the cell membrane

Structural integrity, more cholesterol = stronger/ridgid

Functions of cell membrane

Selectively Permeable, separates the interior of the cell from the outside environment. regulates the transport of materials entering and exiting the cell.

What pathways allow movement across membranes

pores

channels

carriers (transporters)

pumps

Pore pathways + types

non selective

- porins

-perforins

channel pathways

Allow movement of solutes (ions), simple diffusion. there are non gated and gated pathways.

what are gated channels controlled by

voltage, ligand (something needs to bind), second messenger

examples of gated channels

Na+ channels

K+ Channels

Ca2+ channels

anion channels

what are carrier pathways

facilitate passive transport of smaller molecules.

what are pump pathways

active transport of ions, uses ATP

Exocytosis

Process by which a cell releases large amounts of material

Endocytosis

process by which a cell takes material into the cell by infolding of the cell membrane

difference between transporters and channel proteins

1. Channel proteins transport ions and molecules only down a concentration gradient, no energy. use simple diffusion.

2. Carrier protein (transporters) transport solutes across the membrane both down and up - energy required - the concentration gradient. facilitated diffusion

how do solutes move across membrane

Active transport

Facilitated diffusion

Simple diffusion

endo and exocytosis

how does fluid and solutes balance across a membrane

By diffusion of water or solutes, osmotic balance ensures balance.

Solutes or water move across a semi-permeable membrane

What is an electrochemical gradient

What does it involve

It is the difference in charge and chemical concentration across a membrane.

movement of ions through open channel. in or out of cell

potassium concentration in cells clinical relevance

hypokalaemia - muscle weakness , cardiac arrhythmias

hyperkalemia - bradycardia, reduced reflexes and power

What does cellular fluid consist of?

Sodium - Na+

Potassium - K+

Chlorine - Cl-

Protein-

Components high or low in ICF and ECF
sodium
potassium
chlorine
protein

Sodium - high ECF low ICF

Potassium - low ECF high ICF

Clorine - high ECF low ICF

Protein - low ECF high ICF

what are the main electrolytes

Sodium, potassium, chloride

What do electrolytes do?

regulate nerve and muscle function

hydrate the body,

balance blood acidity and pressure,

help rebuild damaged tissue.

What can dehydration cause?

UTI

Kidney failure / stones

Hypovolemic shock

Seizures

What do the following mean (relate to dehydration).

Hypovolemic shock

Seizures

Hypovolemic shock - dehydration complication. Low blood volume causes drop is BP. Amount of oxygen decreases.

Seizures - electrolytes regulate electrical signals in the body. If electrolytes are unbalanced (caused by dehydration) messages can be messed up.

Why are ICF and ECF concentrations important?

• overall cellular homeostasis.

• nerve signaling

• muscle contraction

• osmotic regulation.

Define osmosis

process by which water moves between body compartments from an area of high to low concentration, no energy is required

osmotic pressure

the pressure needed to stop osmosis, hydrostatic pressure is applied.

Reflection coefficient meaning

how permeable the membrane is the a solute

Reflection coefficient of one

membrane is not permeable to solute

Reflection coefficient of zero

Freely permeable

Reflection coefficient between one and zero

semipermeable to solute

what is tonicity

The effect of a solution on cell volume

how do isotonic solutions effect cell

no net movement

no volume change

pressure is same in ECF and ICF

How do hypotonic solutions effect cell

movement of water inward

volume increases

potential lysis

How do hypertonic solutions effect cell

outward water movement

cell volume decreases

cell shrinkage

What is a osmole?

Depends on number of particles rather than molecules

What is osmolarity

Osmolarity is a measure of osmotic pressure exerted by a solution across a perfectly semi-permeable membrane. measure of activity of solvent. increase in osmolarity means decrease of solvent activity.

how to calculate osmolarity

G X Molar concentration of osmolyte particles

g = osmotic coefficient

What does oncotic mean

pressure exerted by large molecules in solution

Why is osmosis clinically relevant?

ECF is usually isotonic to ICF. Imbalance can lead to oedema (swelling) or cell shrinkage

Gibbs-donan effect

build of ions inside the cell leading to movement into the cell. countered by action of sodium potassium pump. 2 positive potassium in, 3 sodium negative out

ICF and ECF components

what is osmoregulation? why is it important?

• control of solute and water balance within an organism.

• maintain osmotic balance and prevent the cell from losing or gaining too much water.

example of osmotic regulation

sodium-potassium pump

what is the movement of water in and out of capillaries determined by

oncotic pressure and hydrostatic pressure

why is the movement of water clinically relevant

disturbances can lead to issues such as oedema

what is osmotic pressure determined by?

number of dissolved particles in a solution

What is hydrostatic pressure

pressure that any fluid in a confined space exerts.

What is oncotic pressure

type of osmotic pressure induced by the plasma proteins, in a blood vessel's plasma that causes a pull on fluid back into the capillary.