neurones

Question 1

describe the cell body

Answer 1

• contains organelles
• site of protein / NT synthesis

Question 2

describe the dendrons

Answer 2

carries axon potential from receptor cell to cell body

Question 3

describe the axon

Answer 3

conductive long fibre which carries nerve impulse from cell body to adjacent neurone

Question 4

describe the myelin sheath

Answer 4

• made of Schwann cells
• lipid
• prevents ions passing through

Question 5

describe the nodes of ranvier

Answer 5

• gaps between myelin sheath
• action potential jumps here (saltatory conduction)

Question 6

what is the role of sensory neurones?

Answer 6

transmit electrical impulses from sensory receptors to relay neurones

Question 7

what is the central nervous system made up of?

Answer 7

brain & spinal cord

Question 8

what is the peripheral nervous system made up of?

Answer 8

receptors & nerves

Question 9

what is the role of motor neurones?

Answer 9

transmit electrical impulses from central nervous system to effectors

Question 10

summarise the pathway of electrical impulses

Answer 10

• stimulus
• detected by receptors
• carried to CNS by sensory neurone
• carried to effectors by motor neurone
• response

Question 11

what is the role of the CNS?

Answer 11

processes sensory information and coordinate a response

Question 12

what is the role of receptors?

Answer 12

converts stimulus energy to nervous energy

Question 13

what is the role of effectors?

Answer 13

brings about a response

Question 14

what are dendrites & what is their role?

Answer 14

• extensions from the cell body
• gives a large surface area to receive nerve impulses

Question 15

describe schwann cells

Answer 15

• wrap around axon
• many layers of the plasma membrane create fatty protection
• to create the myelin sheath

Question 16

why is the speed of transmission faster in a myelinated nerve cell?

Answer 16

• impulses are only exchanged at nodes of ranvier
• saltatory conduction occurs
• action potential reaches end of neurone more quickly

Question 17

why do impulses only occur at nodes of ranvier?

Answer 17

• myelin sheath is tightly wrapped
• so prevents movement of ions across the membranes
• so impulses jump between nodes
• conduction is more rapid

Question 18

state 2 factors which affect the speed of transmission

Answer 18

• myelination
• diameter of axons

Question 19

how does axon diameter affect transmission speed?

Answer 19

• wider = faster
• smaller SA:V
• so lose fewer ions to leakage