Nervous System

Question 1

what does the central nervous system contain?

Answer 1

brain and spinal cord

Question 2

what does the peripheral nervous system contain?

Answer 2

cranial nerves, spinal nerves and sense organs

Question 3

what do sensory neurones do?

Answer 3

transmit nerve impulses from receptors to the central nervous system

Question 4

what do relay neurones do?

Answer 4

transmit nerve impulses from the sensory neurones to motor neurones in the central nervous system

Question 5

what do motor neurones do?

Answer 5

transmit nerve impulses from the central nervous system to the effectors

Question 6

what is the structure of a neurone?

Answer 6

• cell body containing a nucleus and organelles
• dendrons that transmit impulses towards the cell
• axons that transmit impulses away from the cell
• myelin sheath consisting of Schwann cells that wrap around the axon
• node of Ranvier between Schwann cells

Question 7

what do Schwann cells do?

Answer 7

wrap around the axon and dendrons at fixed intervals, their membranes forming the myelin sheath for protection and insulation

Question 7

how does the myelin sheath protect and insulate the axon and dendrons?

Answer 7

• prevents the loss of current from the axon
• increases the speed of transmission of nerve impulses

Question 8

what are synaptic knobs?

Answer 8

• bulbous structures found at the end of axons
• relay nerve impulses from one another by releasing neurotransmitters that are contained in vesicles called synaptic vesicles

Question 8

what is the node of Ranvier?

Answer 8

gaps in myelinated neurones where the myelin sheath is absent

Question 9

what is grey matter?

Answer 9

• consists of cell bodies of neurones
• outer layer of the brain
• central part of the spinal cord

Question 10

what is a voluntary action?

Answer 10

an action under the control of a will

Question 10

what is white matter

Answer 10

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

Question 13

what is a reflex action?

Answer 13

immediate response to a specific stimulus without conscious control

Question 14

what is a spinal reflex?

Answer 14

reflex action controlled by the spinal cord

Question 15

what is a cranial reflex?

Answer 15

reflex action controlled by the brain in the head region, but unconsciously

Question 16

what is a reflex arc?

Answer 16

shortest pathway for nerve impulses to travel from the receptor to effector in a reflex action

Question 17

reflex action vs. voluntary action?

Answer 17

reflex action / voluntary action
1. unconscious control / conscious
2. stimulus involved / no stimulus
3. occurs faster / occurs slower
4. same response / not always same response

Question 18

nervous system vs. endocrine system?

Answer 18

nervous system / endocrine system
1. nerve impulses & chemicals / hormones
2. transmit by neurones / blood
3. quick response / slow response
4. short-lived response / short & long-lived
5. voluntary & involuntary / involuntary
6. localized / affects one or more target organs

Question 19

steps to a spinal reflex?

Answer 19

1. stimulus stimulates the receptor
2. receptor generates nerve impulses that travel along sensory neurone to spinal cord
3. in the spinal cord, impulses are transmitted across a synapse to the relay neurone and another synapse to the motor neurone through neurotransmitters
4. nerve impulses travel along the motor neurone to the effector
5. meanwhile, relay neurone transmits nerve impulses to the brain to make aware of it