QP1 neurones PMT Flashcards
What are the ways in which sensory and motor neurons are the same
- both have a cell body with a nucleus
-both have an axon
-both have dendrites
-both have a myelin sheath
-both have voltage gated channels/ sodium potassium pump
explain the effect of sweating on the body
-evaporation will have a cooling effect/ reduce body temperature
-heat taken from the body/ blood is used for evaporation
-water has a high latent heat of vaporization/ evaporation
alcohol causes vasodillaiton, someone drinks alcohol when they are cold, what are the effects
-vasodillation of arterioles causes more blood to be nearer the skin surface.
-further heat loss from the body
-organs will not be able to maintain function/ metabolism
why does deformation of the tip of the plasma membrane surrounded by a pacinian corpuscle cause the membrane to be more permeable to Na+
-stretch mediated sodium ion channels open when deformation occurs
-pressure causes temporary gaps/ holes and spaces in the phospholipid bilayer
explain the all or nothing law
if the stimulus is not strong enough then the threshold won’t be reached, depolarization of membrane is insufficient and an action potential is not generated
why are action potentials not generated constantly when someone is wearing clothes
sodium ion channels remain open/ resting potential not reestablished.
Ions in the wrong place for correct ion movement
outline the role of synapses in the nervous system
-allow neurons to communicate/ cell signalling
-ensure transmission between neurons in one direction
-allows convergence/ impulses from more than one neuron to be spread to a single neuron
-allows divergence/ impulses from a single neuron to be passed to more than one neurone
-filters out background/low level stimuli
-ensures that only stimulations strong enough will be passed on
-prevents fatigue/ overstimulation
-allows many low level stimuli to be amplified
-permits memory/learning/ decision making
explain why myelinated neurones have a greater speed of conduction
-depolarisation can only occur where (voltage gated) sodium ions are present
-myelinated neurones have longer sections where no voltage gated sodium ion channels are present
-ion movement can only take place at gaps
-longer local currents/circuits
-saltatory conduction/ action potentials jump from node to node
what are microtubules made from
made from proteins
state one way in which the nervous system decreases the heart rate
-via impulses along the parasympathetic nerve
-impulses along the vagus nerve
-nerve endings releasing acetylcholine
describe and explain how the resting potential is established and how it is maintained in a sensory neurone
active:
the sodium potassium pump is active which uses ATP. it pumps/ actively moves Na+ out of the cell/neuron and potassium ions in
passive:
-K+ diffuse/leak out of the cell
-membrane is less permeable to Na+ so fewer Na+ diffuse/leak in
-voltage gated channels are closed
comment on the relationship between the strength of a stimulus and the resulting action potential
-only stimuli that are greater than threshold value produce an action potential
-due to all or nothing law
-all action potentials will be of the same magnitude/size
-action pot is the same no matter the strength of the stimulus
-a strong stimulus however can produce many action potentials in rapid succession.
