module 5 Flashcards
(20 cards)
how is a constant supply of erythrocytes maintained
haematopoeietic stem cells
define homeostatis
maintaining a relatively constant internal environment
define cell signalling
process by which cells communicate with each other
describe the function of a neurone
transmit electrical impulses rapidly around the body so that the organism can respond to changes in its internal and external environment
each time myelin grows around the axon, what happens
when the schwann cells stop growing, how many layers are there
double layer of bilayer is laid down
20+ layers
why do un-myelinated nerves have slower conduction
impulses have to be transmitted continuously along the nerve fibre
what are sensory receptors:
specific to a type of stimulus
transducers
what do mechanoreceptors detect
movement
what do baroreceptors detect
pressure
what do chemoreceptors detect
chemicals
what do photoreceptors detect
light
where are pacinian corpuscles most abundant
why is this important
fingers and soles of feet + within joints
allows to know what joints are changing direction
describe the pacinian corpuscle
nerve ending has stretch-mediated sodium ion channel
when the channels change (stretched) the permeability to sodium ions change
describe the processes of neural stimulation in the pacinian corpuscle
change shape of corpuscle
changes membrane surrounding the neuron to stretch
sodium ion channels widen
influx of Na channels depolarises the membrane resulting in gen. potential
creates AP
define refractory period
period of time when the axon cannot be excited again
why is the refractory period important
prevents propagation of AP backwards + forwards
prevent overlapping AP
what does repolarisation use
ATP
define all-or-nothing
going past threshold always triggers a response
what does a strong stimuli mean
more frequent AP
what happens in repolarisation
Na+ channel closes
K+ channel opens
