B9. 2 Nervous System

Question 1

what is the human nervous system made up of

Answer 1

• central nervous system (brain and spinal cord)

* peripheral nervous system (cranial nerves, spinal nerves and sense organs)

Question 2

what does the CNS control

Answer 2

(brain and spinal cord)

Question 3

what does the PNS control

Answer 3

(cranial nerves, spinal nerves and sense organs)

Question 4

what is the function of a sensory neurone

Answer 4

transmit nerve impulses from the sense organs to the central nervous system

Question 5

what is the structure of a sensory neurone

Answer 5

circular cell body
long dendron
short axon

Question 6

what is the function of a relay neurone

Answer 6

• transmits nerve impulses from sensory neurone to motor neurone

Question 7

where are relay neurones located

Answer 7

• located in the central nervous system

Question 8

what is the function of a motor neurone

Answer 8

• transmit nerve impulses from central nervous system to nerve effectors

Question 9

what is the structure of a motor neurone

Answer 9

• short dendron and long axon

Question 10

define synapse

Answer 10

the junction or connection between two neurones

Question 11

how does synapses facilitate nerve transmission between two neurones

Answer 11

Impulses are transmitted from an axon to a dendron across a synapse.

Question 12

how is synapse transmission conducted

Answer 12

Transmission across a synapse is by chemical means (through neurotransmitters).

Question 13

define reflex action

Answer 13

an immediate response to a specific stimulus without conscious control (involuntary)

Question 14

define reflex arc

Answer 14

the shortest pathway by which nerve impulses travel from the

receptor to the effector in a reflex action

Question 15

what are types of reflexes we have

Answer 15

• Cranial reflexes

* Spinal reflexes

Question 16

what does the cranial reflex control

Answer 16

controlled by the brain but not by conscious will

Question 17

what does the spinal reflex control

Answer 17

controlled by spinal cord

Question 18

give examples of cranial reflex actions

Answer 18

pupil reflex, blinking, salivation

Question 19

give examples of spinal reflex actions

Answer 19

knee-jerk reflex, sudden withdrawal of hand on touching hot object

Question 20

what does dendrities do

Answer 20

dendrites of dendron receive nerve impulses from other neurones

Question 21

what is the myelin shealth

Answer 21

layer of fatty substances that shields and insulates nerve fibre

Question 22

what is the axon

Answer 22

nerve fibre that carries nerve impulses away from cell body

Question 23

what is the motor end plates

Answer 23

junction between dendrite and muscle fibre

Question 24

what are nodes of ranvier

Answer 24

regions where myelin sheath is absent to speed up transmission by allowing impulses to jump from node to node

Question 25

what is the dendron

Answer 25

nerve fibre that transmits nerve impulses towards cell body

Question 26

describe how a nerve impulse travels

Answer 26

1. receptors in skin
2. sensory neurone
3. relay neurone
4. motor neurone
5. effector muscle