NERVOUS COORDINATION

Question 1

What is a neurone

Answer 1

Specialised cells which carry electrical impulses from 1part of the bond to another

Question 2

Synaptic transmission

Answer 2

1. Depolarisation of presynaptic membrane
2. Ca2+ channel open & ca2+ enter synaptic knob
   3.ca2+ causes synaptic besidles fuse with presynaptic membrane and releases neurotransmitter
   4.neurotransmitter diffuses across synaptic cleft
3. Bund to receptor on postsynaptic membrane
4. Na+ ions enetr postsynaptic neurone leading to depolarisation

Question 3

Advanatges of postsynaptic membrane

Answer 3

Lots of fold tpcorm cleft increases surface area allows more acetlhcholinestrass enzyme hydrolyse acetylchholi e

Question 4

Factors affecting speen of conduction of impulses

Answer 4

1. Temperature:
   High kinetic energy
   Rate of diffusion increases
   Rate lf conduction increases
2. Axon diameter
   Larger axon diameter
   Increases number of channel proteins
   Greater speen of conduction as large membrane so incrase surface area
   3.mylein sheat
   Saltatory conduction
   Probides electrical insulation so depolarisation can only occur at rod of ranvier
   Increases rate of transmission as less axon memebrane need to be depolarised

Question 5

What is an action potential

Answer 5

Acts as stimulus to adjected polarised areas of membrane causing action potential to be passed along

Question 6

Rasting potential

Answer 6

Higher concentration of Na+ ions outside neurone
Higher conventration of K+ inside neurone
Diffusion maintained by Na+/K+ pump
Na+ channel closed so cant diffuse in
K+ channel open so some k+ diffuse in neurone is more permeable to K+ions

Question 7

Depolarisation

Answer 7

Threshold reached
Na+ channel open neurone becomes permeable to na+ ions
Higher concentration of Na+ ions in cell via fcilitated diffusion
K+ channel closed

Question 8

Repolarisation

Answer 8

Na+ channel closes
K+ channel open
K+ diffuse out of cell down concentration gradient

Question 9

Hyperpolarisation

Answer 9

K+ ions channel remain open longer than needed to reach resting potential
Na+/k+ pump restores the resting potential back to -70mv

Question 10

Spatial summation

Answer 10

Action potential arrives from several different neurone at synapse
Relase enough neruotransmiterr to reach threshold & causes action potential in post synaptic nuerone

Question 11

Temporal summation

Answer 11

Rapid succession giving a cumulative effect which is sufficient to depolarise post synatic neurine