5.5.5 mammalian nervous system

Question 1

autonomic nervous system

Answer 1

part of the nervous system responsible for controlling involuntary motor activities of body

Question 2

central nervous system

Answer 2

brain & spinal cord

Question 3

peripheral nervous system

Answer 3

sensory & motor neurones connect sensory receptors & effectors to CNS

Question 4

somatic nervous system

Answer 4

motor neurones under conscious control

Question 5

what must a communication system enable

Answer 5

1. detection of stimuli
2. cell signalling
3. coordination of range of effectors
4. illicit suitable responses

Question 6

outline the divisions of the nervous system

Answer 6

nervous system:
–> CNS = brain & spinal cord
–> PNS

PNS divided into:
–> sensory system
–> motor system

motor system divided into:
–> somatic nervous system
–> autonomic nervous system

Question 7

describe the central nervous system (CNS)

Answer 7

= brain & spinal cord

brain:
- most of brain composed of relay neurones
- mostly non-myelinated = grey matter

spinal cord:
- many non-myelinated relay neurones = grey matter
- many myelinated neurones = outer region of white matter
- myelinated neurones allow rapid communication
- protected by vertebral column
- between each vertebrae: peripheral nerves enter/leave

Question 8

describe the peripheral nervous system (PNS)

Answer 8

• role = ensure rapid communication between sensory receptors, CNS & effectors
• sensory & motor neurones
• usually bundled together in connective tissue heath forming nerves

Question 9

describe the sensory nervous system - division of PNS

Answer 9

• sensory fibres enter CNS = dendrons of sensory neurones
• conduct action potentials from sensory receptors to CNS
• cell body in dorsal root leading into spinal cord
• short axon which connects to other neurones in CNS

Question 10

describe the motor nervous system - division of PNS

Answer 10

= action potentials CNS to effectors

subdivided into:
1. somatic nervous system
- motor neurones from CNS to effectors under voluntary control
- mostly myelinated = rapid
- always 1 motor neurone connecting CNS to effector
2. autonomic nervous system
- motor neurones from CNS to effectors not under voluntary control
- mostly non-myelinated = doesn’t require rapid responses
- at least 2 neurones involved in connection between CNS and effector –> connected at ganglia
- subdivided into sympathetic nervous system & parasympathetic nervous system

Question 11

describe the sympathetic v. parasympathetic nervous systems - subdivisions of autonomic nervous system

Answer 11

(antagonistic systems)

sympathetic:
- prepares body for activity

parasympathetic:
- conserves energy

Question 12

outline the features of the sympathetic nervous system

Answer 12

• consists of many nerves leading out of CNS to separate effectors
• ganglia just outside CNS
• short pre-ganglionic neurones
• long post-ganglionic neurones
• use noradrenaline as neurotransmitter
• increases activity
• most active at times of stress

effects include:
- increase HR
- dilates pupils
- increase ventilation rate
- reduce digestion activity
- orgasm

Question 13

outline the features of the parasympathetic nervous system

Answer 13

• few nerves leading out of CNS, which divide & lead to different effectors
• ganglia in effector tissue
• long pre-ganglionic neurones
• short post-ganglionic neurones
• use acetylcholine as neurotransmitter
• decreases activity = conserves energy
• most active in sleep/relaxation

effects include:
- decreased HR
- constricts pupils
- reduced ventilation rate
- increase digestion activity
- sexual arousal