nervous system

Question 1

what is a stimulus?

Answer 1

change in the environment that causes a reaction

Question 2

what is a response?

Answer 2

an organism’s reaction

Question 3

what is the role of the nervous system?

Answer 3

• allows us to detect change and respond to it

- enables coordination of diff body parts

Question 4

define involuntary action?

Answer 4

• automatic, not controlled

Question 5

define voluntary action?

Answer 5

controlled conconsciously

Question 6

what are the components of the nervous system?

Answer 6

1. Central Nervous system (brain, spinal cord)

2. Peripheral nervous system (cranial nerve, spinal nerve)

Question 7

what does nervous tissue consists of?

Answer 7

nerve cells called neurones

Question 8

what is the function of the cell body?

Answer 8

• nucleus, cytoplasm, cell surface membrane and organelles

Question 9

what is the function of the dendron?

Answer 9

• nerve fibre that trasnmits nerve impulses towards cell body
• end branches, dendrites, receive nerve impulses

Question 10

what is the function of the axon?

Answer 10

• nerve fibres that transmit nerve impulses away from cell body

Question 11

what is the function of the myeline sheath?

Answer 11

• layer of fatty substances enclosing many nerve fibres

- insulates axon

Question 12

what is the function of node of ranvier?

Answer 12

• regions where myelin sheath are absent

- speeds up transmissions of impulses by allowing them to jump from node to node

Question 13

what is the function of the axon terminal?

Answer 13

• transmit nerve impulses to effector

Question 14

what is the function of the motor end plate

Answer 14

• junction between axon terminal and dendrite

Question 15

what is the function of the motor neurone?

Answer 15

transmit nerve impulses from CNS to nerve effectors

Question 16

what is the function of the sensory neurone?

Answer 16

transmit nerve impulses from the sense organs to CNS

Question 17

what is a synapse?

Answer 17

• junction between 2 neurones, or a junction between a neurone and an effector
• impulses transmitted from axon to dendron of another neurone
• transmission of nerve impulses across a synapse by chemical means (neurotransmitters)

Question 18

what are nerves?

Answer 18

• a bundle of nerve fibres enclosed in a sheath of connectivity tissue
• from brain : cranial nerve
• from spine : spinal nerve
• they may contain :
• sensory nerve fibres only, conduct nerve impulses from sense organs
• motor nerve fibres only, conduct to effector
• mixed fibres (spinal nerves)

Question 19

what is the function of grey matter?

Answer 19

• mainly consists of cell body of neurones
• outer layer of brain
• central part of spinal cord

Question 20

what is the function of white matter?

Answer 20

• mainly consists of nerve fibres of neurones
• central part of brain
• outer layer of spinal cord

Question 21

what is the function of the dorsal root ganglion?

Answer 21

• contains cell bodies of sensory neurones

Question 22

what is the function of the dorsal root?

Answer 22

• only contains sensory neurones

Question 23

what is the function of ventral root?

Answer 23

• only contains motor neurones

Question 24

what is the function of the spinal nerve?

Answer 24

• nerve fibres from dorsal root and ventral root

- both sensory and motor neurones

Question 25

what is the nervous system pathway of touching ice?

Answer 25

receptor in skin --> sensory neurone --> relay neurone in spinal cord --> forebrain - impulses produced in forebrain and transmitted by a relay neurone from forebrain, down white matter of spinal cord, to grey matter. Impulses transmitted to motor neurone then to effector muscles. Muscle contracts forebrain --> relay neurone in spinal cord --> motor neurone --> effector

Question 26

what is a reflex action?

Answer 26

immediate response to a specific stimulus without conscious control

Question 27

what is cranial reflex?

Answer 27

controlled by brain, usually in head region (pupil reflex)

Question 28

what is spinal reflex?

Answer 28

controlled by spinal cord (knee jerk)

Question 29

what are the similarities of reflexes?

Answer 29

1. both involve transmission of nerve impulses 2. both involve motor neurone 3. both involve effectors to carry out desired response

Question 30

what are the differences between the reflexes?

Answer 30

1. boluntary involves conscious control but reflex does not involve conscious control 2. voluntary may not have an immediate response but reflex has immediate response 3. voluntary does not heed stimulus but reflex occurs in response to stimulus 4. voluntary is intiated by brain but reflex is not initiated by brain

Question 31

what happens when your hand touches an hot object?

Answer 31

1. receptors in skin - heat on object stimulates nerve endings (receptors) in your skin and impulses are produced 2. sensory neurone - neurone impulses are transmitted along sensory neurone to spinal cord 3. spinal cord - in spinal cord, the nerve impulses are transmitted first across a synapse to relay neurone, and then across another synapse to motor neurone - at the same time, another set of nerve impulses are transmitted along relay neurone parallel to spinal cord, to brain 4. motor neurone - transmits the impulses from the spinal cord to effector 5. effector muscle contracts - muscle (effector) contracts then causes your hand to withdraw suddenly