[15.1] neurones and nervous coordination

Question 1

what are the 2 main forms of coordination in animals?

Answer 1

• the nervous system
• the hormonal system

Question 2

describe features of the hormonal system

Answer 2

• communication is by chemicals called hormones
• transmission is by blood system
• transmission is usually relatively slow
• hormones travel to all parts of the body, but only target cells respond
• response is widespread
• response is slow
• response is often long-lasting
• effect may be permanent and irreversible

Question 3

describe features of the nervous system

Answer 3

• communication is by nerve impulses
• transmission is by neurones
• transmission is ery rapid
• nerve impulses travel to specific parts of the body
• response is localised
• response is rapid
• response is short-lived
• effect is usually temporary and reversible

Question 4

what are neurones adapted to do?

Answer 4

rapidly carry electrochemical changes (nerve impulses) from one part of the body to another

Question 5

what is a mammalian motor neurone made up of?

Answer 5

• cell body
• dendrites
• axon
• schwann cells
• myelin sheath
• nodes of ranvier
• neuromuscular junction

Question 6

motor neurone: cell body

Answer 6

• contains all usual cell organelles
• has nucleus and large amounts of RER, which is associated with production of proteins and neurotransmitters

Question 7

motor neurone: dendrites

Answer 7

• enable connections to multiple different relay neurones
• carry nerve impulses towards the cell body

Question 8

motor neurone: axon

Answer 8

• single long fibre that carries nerve impulses away from the cell bod
• elongated section of DN, enabling nerve impulses to be carried long distances quickly

Question 9

motor neurone: schwann cells

Answer 9

• produces myelin sheath
• carry out phagocytosis (removal of cell debris) and play a part in nerve regeneration

Question 10

motor neurone: myelin sheath

Answer 10

• layers of lipid surrounding the axon
• provides electrical insulation

Question 11

motor neurone: nodes of ranvier

Answer 11

gaps between sections of myelin sheath where axon membrane is exposed

Question 12

motor neurone: neuromuscular junction

Answer 12

point at which MN connects to a muscle (ie. effector)

Question 13

what is the function of a motor neurone?

Answer 13

transmit nerves from relay neurone to effector (eg. gland or muscle)

Question 14

what is the function of a sensory neurone?

Answer 14

• transmit nerve impulses from receptor to motor neurone
• carries impulse towards cell body and axon carries it away from cell body

Question 15

what is the function of a relay neurone?

Answer 15

transmit impulses between neurones eg. from sensory to motor