Nerves

Question 1

Function and location of the cell body

Answer 1

COntains the nucleus
Genetic code for neurotransmitter production
Nissl Granules- protein synthesis
SN- Dorsal root ganglio
MN- Brain/ spinal cord

Question 2

Axon function and structure

Answer 2

transmits impulses away from the cell body
rapid transmission
reduces number of synapses reequired
SN- Short (sesnsory receptor to cell body)
MN- long

Question 3

Dendron

Answer 3

Transmits impulses towards cell body
SN- long
MN- no

Question 4

Dendrites

Answer 4

allows communication between neurones

Question 5

Schwann cells

Answer 5

Thin cells wrapped around the neurone

High phosphlipid content- electrical insulation

Question 6

Myelin sheath

Answer 6

Enclosing layer created by shwann cells

Question 7

Synaptic knob

Answer 7

Point where the neurotransmitter is released from one neurone to another neron

Question 8

Motor end plates

Answer 8

Point at which the neurontransmitter is released from one neurone to transfer AP to muscle

Question 9

Describe the response of a reflect arc

Answer 9

Innate
involuntary
immediate
invariable

Question 10

why neurones need mitochondria

Answer 10

Produces ATP during aerobic resp
Maintains resting potential
release neurotransmitters via exocytosis

Question 11

genreator potential

Answer 11

small depolarisation caused by NA+ ions enterin the cell

Question 12

Action potential

Answer 12

Depolarisation of membrane to value of +40 mv inside is > + than outside

Question 13

What happens to the resting potential after applying metabollic poison

Answer 13

Aerobic resp would stop, ATP wouldnt be produced, so NA+/K+ ATPase pumps would stop working Both ions would reach equilibrium

Question 14

Resting potential

Answer 14

The potential difference across the membrane when the neurone is at rest (-60mv) inside the cell compared to outside

Question 15

Voltaage gated channels

Answer 15

Channels in the CM that allow passage of ions through. The gates respond to changes in pD

Question 16

Threshold potential

Answer 16

the pd across CM is -40mv if depolarisation doesnt reach TP then no AP is created

Question 17

Depolarisation

Answer 17

The sodium channels open, and NA+ diffuse down EC gradient in, TP reached and VGC open, more NA diffuse in
= loss of polarisation

Question 18

Repolarisation

Answer 18

The NA+ channels close
K+ channels open
K+ diffuse out
restores RP

Question 19

Refractory period

Answer 19

Time after AP has passed
IMPOSSIBLE TO STIMULATE AP AGAIN- VGC NOT OPEN
ensures AP move in one direction
keeps impusles separate

Question 20

Local current

Answer 20

The movement of ions along the nerone. due to an increased concentration at one point, causing dffusion away from the higher concentration

Question 21

How myelin sheaths causes saltatory conduction

Answer 21

The sheath is a layer of fatty insulation material wrapped around the neurone. It’s impermeable to Na+ and K+. There are gaps called N of R
ions diffuese through the memorane at N of R
AP jumps from one node to another

Question 22

Differences between Myelin and non mylein

Answer 22

Speed:
Myelin- 120 fast
Non Myelin 20 slow

Nodes of R- Yes No

Myeline sheath Yes no

Location:
Myeline- peripheral nervous system carrying impluse from sensory to CNS or CNs to effector

Non Myelin- CNS and nerves, controled organs no conscious control

Question 23

Significance of synapse

Answer 23

Allows AP to travel in 1D–> Neurotransmitter only in pre
receptor molecules only in post

One pre neurone diverge into many post–> same signal transmitted to different parts (reflex arc)

Low level impulses AMPLIFIED BY SUMMATION, generates several succesive AP’s in pre

Acclmitisation- repeated simulation results in running out of vesivles- synapse is fatigued NS doesn’t respond to stimulus….avoids over stimulation of an effector