nervous system

Question 1

roles of nervous system

Answer 1

-allows organism to detect changes in surrounding and respond to it
-allows organisms to process sensory information
-send nerve impulses to effector cells

Question 2

how does the nervous system process information

Answer 2

-information is first gathered by the receptors
-information converted into nerve impulses
-nerve impulses that transmitted by cranial and spinal nerves to central nervous system
-brain processes information based on pattern of nerve impulses
-brain will send nerve impulses to effectors
-intended action is then carried out

Question 3

function of dendrite and dendron

Answer 3

-dendrites receive nerve impulses from other neurons
-dendrons are nerve fibres that transmit nerve impulses towards cell body

Question 4

what is myelin sheath

Answer 4

-layer of fatty substances that shield the nerve fibre, surrounded by thin membrane, neurilemma

Question 5

what is nodes of ranvier

Answer 5

-regions where myelin sheath are absent, allow impulses to jump from node to node, speed up transmission

Question 6

what is axon

Answer 6

-nerve fibres that carry nerve impulses away from cell body

Question 7

what is motor end plate

Answer 7

-junction between dendrite and muscle fibres
-nerve impulses are transmitted across MEP by chemicals that stimulate the muscle

Question 8

properties of cell body

Answer 8

-irregular in shape in motor neurone
-circular shape in sensory neurone
contains nucleus and cytoplasm

Question 9

structure and function of relay neurone

Answer 9

-cell body with main relay fibre
-transmit nerve signals from sensory neurone to motor neurone

Question 10

what is synapse

Answer 10

-junction between two neurones or between a neurone and effector
-impulses transmitted from axon to dendron
-nerve impulses are transmitted across synapse by chemical, neurotransmitters

Question 11

how do synapse work

Answer 11

-presynaptic cell secretes neurotransmitters that crosses the synaptic cleft
-neurotransmitters crosses over to specific receptors on surface of receiving postsynaptic cell

Question 12

function of sensory nerve fibres and motor nerve fibres

Answer 12

-SNF carry nerve impulses from sense organ
-MNF carry nerve impulses to effectors
-spinal nerves have both SNF and MNF

Question 13

composition and location of grey and white matter

Answer 13

-grey matter consist of cell bodies and neurones, found in out layer of brain and central parts of spinal chord
-white matter consist of nerve fibres, found in central parts of brain, outer layer of spinal chord

Question 14

properties of spinal chord

Answer 14

-31 pairs of nerves emerge at intervals along the length of spinal chord
-narrow central canal containing cerebrospinal fluid runs through middle of spinal chord
-each spinal nerve splits into two roots before it joins the spinal chord

Question 15

properties of dorsal and ventral root

Answer 15

-DR joins the back part of the spinal chord, only contains sensory neurones
-VR joins front part of spinal cord, contains only motor neurones.
-cell bodies and dendrons of the motor neurone lie in the grey matter of the spinal chord
-axons of the motor neurone leaves the spinal chord and enter VR

Question 16

what is dorsal root ganglion

Answer 16

-cell bodies of sensory neurones that are clustered together in a swelling

Question 17

how are nerve fibres supplied to the rest of the body

Answer 17

-spinal nerves that contain nerve fibres from dorsal root and ventral root subdivides into branches

Question 18

what is found in grey matter

Answer 18

-axons and cell bodies from relay neurones, dendrons of sensory neurones are found in dorsal root and spinal nerves

Question 19

transmission of nerve impulses

Answer 19

-relay neurones that lay parallel to spinal chord, form synapse with motor and sensory neurone
-allow transmission of nerve impulses from sensory to motor neurone
-conduct nerve impulses from sensory neurone to brain
-conduct nerve impulses from brain to motor neurone

Question 20

stimulus and response of cat purring on leg

Answer 20

-touch receptors in the leg are stimulated and sends nerve impulses through sensory neurones to the grey matter of spinal chord
-relay neurones conduct nerve impulses to the brain
-feeling of touch occurs when nerve impulses reach brain
-brain transmits nerve impulses through relay neurones of spinal chord to motor neurones
-motor neurones can cause muscle contraction

Question 21

what is voluntary action

Answer 21

-action that involved the brain and the person can decide whether or not to act, since action is under control of will

Question 22

what happens when your hand touches a hot object

Answer 22

-heat stimulates touch receptor in skin
-nerve impulses are produced and they travel along the sensory neurone to spinal chord
-in spinal chord, nerve impulses are transmitted across synapse to relay neurone, across another synapse to motor neurone. At the same time, nerve impulses trasmitted to brain
-upon receiving nerve impulses from relay neurone, motor neurones transmit nerve impulses to effector
-effector muscle contract, resulting in withdrawal of hand from hot object

Question 23

what are reflex centres

Answer 23

-brain and spinal chord

Question 24

recite a simple spinal reflex arc

Answer 24

-receptors in skin in the stimulus
-nerve impulses travel along sensory neurones to relay neurone
-relay neurone back along motor neurone to effector which is muscle