Body Fluids and Membrane transport Flashcards
What percent of body mass is water?
60%
if you have 42 litres of water in your body, how many would be intercellular?
25
if you have 42 litres of water in your body, how many would be extracellular?
17
If you have 17 litres of extracellular fluid how many litres are interstitial?
13
If you have 17 litres of extracellular fluid, how many litres are plasma?
3
if you have 17 litres of extracellular fluid, how many are transcellular?
1
what’s intracellular fluid?
fluid within cells
what’s extracellular fluid?
fluid outside cells
How is Interstitial fluid abbreviated?
ISF
What is interstitial fluid?
fluid between tissues
What is transcellular fluid?
fluids which have to pass through epithelial cells
Give 3 examples of transcellular fluids
any 3 from
- cerebrospinal fluid (in brain)
- urine (kidney and bladder)
- gastrointestinal secretions (saliva, gastric fluid, bile, pancreatic juice)
- sweat
- aqueous and vitreous humors (in eye)
- synovial fluid (in joints)
What differs between blood plasma and interstitial fluid?
There’s some protein in plasma but not in interstitial fluid
What differs between intracellular and extracellular fluid?
inside cells- sodium high, potassium low- opposite outside cells
What are the levels of ions in transcellular fluid?
they vary greatly between different transcellular fluids
what are the 3 barriers that fluids pass between?
- plasma membrane
- capillary endothelium
- epithelia
What forms the basis of plasma membrane?
lipids
what’s the permeability of plasma membrane like and why?
highly selective because nothing water soluble can get across without protein transport
what’s the purpose of transport proteins?
allows the uptake of nutrients e.g. glucose and the export of waste products e.g. urea
what does a plasma membrane surround?
cells
what happens if more water is required inside of a cell?
Cl- and K+ will move into the cell leading to osmosis- the opposite occurs when there’s too much water
what maintains a Na+ and K+ concentration gradient in the cell?
K+/Na+ pump
What are the 3 types of membrane proteins?
- channels
- carriers
- pumps
What do channel membrane proteins do generally?
allow the transport of substances via passive transport
what do channel membrane carriers do generally?
allow the passive transport of substances
What do channel membrane pumps do generally?
allow the active transport of substances using energy from the hydrolysis of ATP, without requiring a concentration gradient
What are the 3 types of carriers?
- facilitator (uniport)
- cotransporter (symport)
- exchanger (antiport)
What do facilitator (uniport) carriers do?
move one type of ion e.g. Na+
what do cotransporters (symport) carriers do?
move 2 types of ion, usually oppositely charge ions e.g. Na+ and Cl-
what do exchanger (antiport) carriers do?
move 2 types of ion (usually oppositely charged) in 2 directions (1 in 1 out)
What is the process of a cell maintaining an electrical gradient?
- K+ is pumped into the cell. Gives a higher concentration of K+ making the cell positively charged
- there is a channel which is opened and allows K+ to leave
- this causes the inside of the cell to become negatively charged (because there’s a negative change from anions in the cell which cannot leave- the K+ can leave)
- This makes the resting potential (difference in charge between inside and outside cell due to ion differences) approximately -70mV
What process determines water distribution of cell?
osmosis
What occurs during osmosis? (3)
- water moves passively (no energy) down gradient
- moves to area of high solute concentration
- water distributes itself so that the osmmotic pressures inside and outside the cell are equal
What is the capillary endothelium?
the very thin layer of specialised cells linking blood vessels
how can capillary endothelium vary?
- it can be leaky (highly permeable) e.g. in the kidneys
- it can be non-permeable e.g. the blood-brain barrier
What’s the ionic concentration difference of ions between blood plasma and ISF like?
low (roughly the same)
What’s the ionic concentration difference of proteins between blood plasma and ISF like?
high (high in plasma, low in ISF)
What pushes blood out of the capillary into ISF from plasma?
Hydrostatic pressure
What is Colloid osmotic pressure?
a force that attracts water through endothelial cells from ISF to plasma
What is epithelia?
layers of cells covering internal and external surfaces of organs and tissues
What’s are the roles of epithelia?
- protective/barrier
- important in absorption and secretion e.g. gut nutrients
What is the apical membrane of the gut?
epithelial layer inside the guy
what is the basolateral membrane of the gut?
epithelial layer on the outside of the gut
How does water travel into the small intestine?
- There’s a Na+/K+ pump maintaing a gradient. This means that Na+, K+ and Cl- are transported into the cell (K+ is dragged in with the other iond)
- this means K+ is in high concentration in the internal epithelial cell
- Cl- travels out of the membrane, so water follows by osmosis
