Body fluids and membrane transport Flashcards
Composition of avg human body - 30yr 70kg male
18% fat
22% lean body mass - soft organs, muscle mass etc.
60% water - approx 42litres
Composition of total body water
42L of TBW =
- 25L Intracellular fluid
- 17L Extracellular fluid; 13L Interstitial Fluid (outside blood vessels, not inside cells), 3L Plasma & 1L Transcellular fluid (crossed an epithelial layer)
Examples of trancellular fluid
- Cerebrospinal fluid
- Urine
- Gastrointestinal secretions
- Sweat
- Aqueous and vitreous humours (eye)
- Synovial fluid (joints)
def of osmolality
the number of osmoles of a solute in a kg of solvent - ie attractiveness of a solution to water
effect on osmolality when fluid moves through intracellular and cellular
remains constant
composition of electrolytes from interstitial fluid into intracellular fluid
- Na+ decreases
- thus Cl- decreases
- K+ increases
- proteins increase
- osmolality remains constant
def of transcellular fluid
bodily fluid found in chambers created by linings of epithelial cells
def of interstitial fluid
fluid found in spaces surrounding the cells (stuff between blood vessels and cells)
def of extracellular
fluid outside of the cells (interstitial fluid, plasma, transcellular)
def of intracellular
fluid within the cells
three types of membrane proteins
- channels
- carriers
- pumps
why aren’t there many pumps
- require energy
- typically used to provide a gradient that allows the passive carriers to work
- more energy efficient
what types of molecules do NOT need a transporter
lipid soluble
name of carrier that transports 1 ion species in 1 direction
facilitator/uniport
name of carrier that transports 2 ion species in 1 direction
cotransporter/symport
name of carrier that transports ions of same charge in oppsoite directions (swaps)
exchanger/antiport
function of transport proteins
uptake of nutrients, substrates, cofactors
export of waste products
acid extrusion
- passive process
- H+ moves out and swapped with Na+
- via exchanger
- same charge so are swapped
- increases cell pH
- also makes up for lack of Na+
base extrusion
- passive process
- HCO3- swapped with Cl-
- lowers cellular pH
- via exchanger
regulatory volume decrease
- Cl- and K+ move out via uniports
creates a osmotic gradient
= increases water conc in the cell
= water moves out via osmosis
regulatory volume increase
- Na+ K+ and Cl- move in
- creates osmotic gradient
= water conc. lowers in cell
= water moves in via osmosis
distribution of Na+ K+ ICF vs ECF
ICF ECF
K+ HIGH K+ LOW
Na+ LOW Na+ HIGH
(K+ Na+ gradients achieved via pump)
distribution of Ca+ ICF vs ECF
Ca+ is a signalling molecule, can trigger action
so
ICF = very low
ECF = low
why are Org- and Proteins conc. high in cell and low outside cell
org- cannot leave cell
proteins - produced on inside
neither have transport proteins
why does a high K+ conc. still lead to a -ve internal cell charge
-ve organic molecules that are trapped in cell
potential difference of cell charge
approx -70mV
how thick is the plasma membrane
~5nm
what is colloid osmotic pressure
osmotic pressure induced by proteins in blood vessels plasma
acts across capillary membrane
