How Do Nerves Work 1 Flashcards
what is selective permeability?
allows the cell to control which molecules pass through the cell membrane either into or out of the cell through passive transport, active transport and transport using vesicles
describe the structure of the plasma membrane?
dynamic structure in which proteins float in a sea of lipids
what are the 3 major groups of lipids in a membrane?
phospholipid
glycolipid
cholesterol
what is the structure of a phospholipid?
hydrophilic polar head -> phosphate group - usually attached to an alcohol e.g. choline
glycerol
non-polar hydrophobic tails -> fatty acid chains
ester bonds
what are fatty acids?
Long hydrocarbon chain of various lengths and degrees of unsaturation terminated by a carboxylic acid group.
why do we need differing chain length and saturation of fatty acids?
control fluidity of membrane, shorter chain length and saturated -> more fluid
what is the structure of a glycolipid?
galactose
sphingosine
1 fatty acid chain
what is the purpose of cholesterol in the membrane?
gives membrane rigidity
Cholesterol groups are orientated in a specific way within the membrane which enables them to reduce fluidity of the membrane
in the lipid bilayer the hydrophobic tails are held together by what?
van der waals forces
in the lipid bilayer the hydrophilic head are held together by what?
ionic bonding
how is fluidity of the membrane controlled?
by lipids
saturation and chain length of fatty acids
amount of cholesterol
what carry out most of membrane processes?
proteins
what kind of transport allows nerve impulses?
active transport -> sodium potassium pump
when a neurone is at rest (no AP) where is K+ and Na+?
lots of K+ inside the cell
Na+ outside.
what are the 4 steps in the transmission of an action potential?
action potential -> depolarisation
repolarisation
refractory period
hyperpolarisation
what happens during depolarisation?
Na+ moves inside the cell
what happens during repolarisation?
K+ move outside, Na+ stay inside
what happens during the refractory period?
back to normal -> K+ returns inside, Na+ returns outside
what happens during hyperpolarisation?
more K+ outside than Na+ inside
