Ch 16 Coordination in humans

Question 1

Myelin sheath

Answer 1

1. Insulate nerve fibres, preventing the transmission of nerve impulses to the surroundings
2. Speed up the transmission of nerve impulses

Question 2

Synaptic transmission of nerve impulses

Answer 2

1. A nerve impulse arrives at the synaptic knob
2. Neurotransmitter contained in the synaptic vesicles is released
3. The neurotransmitter diffuses across the synaptic cleft
4. The neurotransmitter binds to the specific protein receptors on the membrane of the next neurone
5. The binding of the neurotransmitter to the receptors stimulates the dendron or the cell body of the next neurone to generate a nerve impulse

Question 3

Cerebrospinal fluid

Answer 3

1. Acts as a shock absorber
2. Provides mechanical support to the spinal cord
3. Provides nutrients and oxygen to the neurones and removes wastes from them

Question 4

Grey matter / White matter

Answer 4

Outer part / Inner part
Cerebrum: Grey matter / White matter
Cerebellum: Grey matter / White matter
Medulla oblongata: White matter / Grey matter
Spinal cord: White matter / Grey matter

Question 5

Reflex action

Answer 5

• inborn
• rapid
• automatic
• involuntary
• does not involve the cerebrum
• stereotyped

Question 6

Withdrawal reflex

Answer 6

1. Pain receptors in the skin are stimulated. They generate nerve impulses
2. Sensory neurone transmits nerve impulses to the spinal cord
3. Interneurone relays nerve impulses to the motor neurone
4. Motor neurone transmits nerve impulses to the effector, arm muscle
5. Arm muscle contracts to withdraw the hand

Question 7

Knee jerk reflex

Answer 7

1. Stretch receptors in the upper leg muscle are stimulated. They generate nerve impulses
2. Sensory neurone transmits nerve impulses to the spinal cord
3. Motor neurone transmits nerve impulses to the effector, leg muscle
4. Leg muscle contracts and the leg kicks

Question 8

Functions of cerebrum

Answer 8

• site for intelligence
• think, make decisions, have memories
• controls voluntary actions

Question 9

Functions of cerebellum

Answer 9

• coordinates muscular actions
• maintain body posture and balance

Question 10

Medulla oblongata

Answer 10

• controls involuntary actions (breathing / heartbeat)
• reflex centre

Question 11

Voluntary action

Answer 11

1. Receptors detect a stimulus and generate nerve impulses
2. The nerve impulses are transmitted to the sensory areas of the cerebrum along sensory neurones
3. The information is processed and integrated in the association areas of the cerebrum. When a decision is made, the motor areas of the cerebrum generate nerve impulses
4. The nerve impulses are transmitted to the effector along motor neurones
5. The effector gives a response