body fluid compartments Flashcards
1
Q
what are the different fluid compartements
A
- intracellular
- extracellular
- plasma
- interstitial
- transcellular
2
Q
how much of your blood volume is haematocrit
A
40% (volume of red blood cells in blood)
3
Q
what is transcellular fluid
A
fluid found trapped within the spaces completely surrounded by epithelial cells - taking fluid from blood stream - move fluid into epithelial space
4
Q
what are the different types of fluid?
A
- transcellular fluid
- Synovial fluid
- Cerebrospinal fluid: creates ionic environment for ionic environment, in CNS
- Aqueous humour: Eye - maintaining tissues, Providing part of optical pathway
- Pericardial fluid
- Pleural fluid: Lungs and chest cavity - lubricant and cellular functions
5
Q
how to measure compartment volume
A
- use a tracer substance that is: non-toxic, easy to assay, doesn’t alter normal fluid distribution, not metabolised or taken up by cells, rapidly and evenly distributed through compartment, not significantly excreted during equilibration period
1. inject a known volume of a tracer substance at a known substance into compartment
2. allow to equilibrate through the compartment and then measure concentration in that compartment
6
Q
how does filtration between plasma and interstitial fluid space work
A
through bulk flow
7
Q
how is water lossed
A
- regulated: urine, sweat, faeces
- insensible: skin, lungs
8
Q
how do we get net filtration into the cells
A
- Net filtration
- Lymphatic system returns filtrate back into the plasma
- Drains the interstitial fluid
- Net gain in
- Net gain loss
9
Q
how is there an exchange between intracellular and extracellular fluid
A
- Osmosis
- Water shifts between intracellular and extracellular compartments along the osmotic pressure gradient
- Low solute to high solute
- Moves via aquaporins
- Solutes can only exert an osmotic force if they are differentially distributed across the plasma membrane
- Difference in composition of intracellular and extracellular fluids
- Osmoregulatory system helps to keel the osmotic pressure of your extracellular fluid constant
10
Q
what is starling forces
A
- looks at the filtration rate, the capillary hydrostatic pressure
- calculation that determines the force of filtration
- ## at a high capillary hydrostatic pressure, it forces out into interstitial space
11
Q
what is starling forces
A
- looks at the filtration rate, the capillary hydrostatic pressure
- calculation that determines the force of filtration
- at a high capillary hydrostatic pressure, it forces out into interstitial space
12
Q
how does the endothelial structure affect the capillary
A
- continuous - most capillary beds, low filtration coefficient
- fenestrated - kidneys, water to go directly between the inside and the outside. greater permeability for water, high filtration rate, remove taxic waste products
- sinusoid - liver and spleen, allow proteins and cells to translocate as well as water
- protein stays trapped - creates a protein gradient across the infiltration barrier (osmotic pressure forcing water back into capillaries)
