Social cells 2 Flashcards
conc of potassium in cell?
high
conc of sodium inside cell?
lower
conc of potassium outside cell?
lower
CONC of sodium outside cell?
higher
conc of chloride and calcium inside cell?
lower
conc of chloride and calcium outside of cell?
HIGHER
What is involved in passive transport?
diffusion through bilayer
diffusion through protein channels
facilitated diffusion
e.g. steroid hormones fatty acids, oxygen, carbon dioxide
facilitated diffusion compared to diffusion?
facilitated transport mechanism is specific
however limited capacity
transport can be affected by competition (number of channels/carriers)
2 mechanisms of active transport?
primary active transport
secondary active transport
secondary sctive transport
TWo being moved at once and the difference in energy is stored
primaru?q
WILL utilise atp
secondaru?
will not utilise ATP
why do we need ion pumpks?
becaise we have a lot of ion leakagfe so we need a process that replenishes them and stops this and creates a gradient for the resting potential
type of ion pumps?
uniporter, symporter, antiporter
what can pumps do?
they can transport ions against their concs gradients e.g. sodium (primary active transport)
sodium-potassium primary active transport?
movement of positive ions out of channel out of the cell against conc gradient
glucose pump example of?
secondary active transport
describe the glucose pump?
coupled to sodium uptake and it uses a co-transporter
describe the calcium ion pumop?
calcium need to be kept in cytosol of cells
cytosolic concentration needs to be kept low
use of ATP
some calcium pumps are coupled to sodium
can be primary and secondary active transport
what are ion channels?
proteins within the cell membrane and transport specific ions
4 types of ion channels?
ligand-gated ion channels
voltage-gated ion channel
leak channels
stretch-activated channels
example of ligand gated ion channel?
ion channel coupled receptor
binding of ligand?
causes the protein change shape
e.g. nicotinicacetylcholine receptor
voltage gated channel?
change in membrane potential of cell
change so the channel is opened
really important for action potentials e.g. ca, cl, na, k
leak channels?
pore within membrane and generally always open and maintain resting potential of the cell - always movement of cells along their conc gradients through these
stretch activated ion channels?
bilayer model, tether model and indirect gating
bilayer model?
swelling due to tension, the channel is essetnially pulled open as the cell gets bigger
tether model?
attached to side skeleton of cell or extracellular matrix protein attached to ion channel, any movement or change causes the channel to open due to tension
indirect gating?
mechanosensitive portien, capable of sensing any mechanical change in th eextracellulkar matrix
compression of cartilage so change in water content of cell - sensed by mechanoreceptors (mechanosensitive protein)
e.g. calium activated potassium channel
importance of ion channels?
muscle paralysis - blocking of voltage gated sodium channels
heart disease - calcium channel blockers
local anaesthetics - lidocane, voltage gated sodium channels - stop feeling by blocking channels
what is the resting membrane potential?
this is not the same as an action potential
IT IS THE POTENTIAL ACROSS THE MEMBRANE WHEN THERE IS NO ACTION POTENTIAL BEING PROPAGATED
all cells can have a resting membrane potetnail but what can all cells not do?
hpwever not all cel,s can proagate action potential
two RMP?
excitable (can propagate action potential) and non-excitavle (cannot)
two equations to work out cell’s resting membrane potentials?
Nernst equation
Goldman-Hodgkin-Katz equation (GHK)
skeletal muscle (myocytes) membrane potential?
-90mV
Synovial fluid (synoviocytes) membrane potentials?
-30mV
very negative?
more of a change in membrane potential to give good prooagation of action potential
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why -90mV resting membrane potwetnial of skeletal m udcle?
Na/K pump –> 3 Na out and 2 K in
positive charges outside of the cell
Leak channels –> more potassium than sodium
flux of Na larger than efflux of K
results in build up of negative ions on OUTSIDE of cells - helps to attritbute for negative resting membrane potetnail –> action potential
pumps?
constantly keeping difference of positive and negative ions either side of membrane
indirect gating?
protein that detects a change in the ewxtracellular matrix which resultsin a conformational change in the ion channel
conformational change?
change in shape
