13.6 Organisation Of The Nervous System

Question 1

What two systems is the mammalian nervous systems split into?

Answer 1

• the central nervous system (CNS) — this consists of your brain and spinal cord
• the peripheral nervous system (PNS) - this consists of all the neurones (sensory and motor) that connect the CNS to the rest of the body

Question 2

What two functional systems is the PNS organised into?

Answer 2

• somatic nervous system — controls conscious (voluntary) activities (e.g. running)
  Effector organs: skeletal muscle
• autonomic nervous system — controls unconscious (involuntary) activities. This system works constantly. E.g. digestion and heart rate
  Effector organs: smooth muscle (e.g. in the gut), glands, cardiac muscle

Question 3

What systems is the autonomic nervous system split into?

Answer 3

The autonomic nervous system is split into the sympathetic and the parasympathetic nervous systems, which have opposite effects on the body.

• the sympathetic nervous system is the ‘fight or flight’ system that gets the body ready for action. (E.g. increase in heart rate)
  Sympathetic neurones release the neurotransmitter noradrenaline
• the parasympathetic system is the ‘rest and digest’ system that calms the body down. (E.g. decrease in heart or breathing rate after a period of exercise)
  Parasympathetic neurones release the neurotransmitter acetyl choline

Question 4

Describe sympathetic and parasympathetic stimulation of the following glands:
1) salivary glands
2) lung
3) kidney
4) stomach
5) small intestine

Answer 4

1) sympathetic: saliva production reduced
Parasympathetic: saliva production increased
2) sympathetic: bronchial muscle relaxed
Parasympathetic: bronchial muscle contracted
3) sympathetic: decreased urine production
Parasympathetic: increased urine production
4) sympathetic: peristalsis reduced
Parasympathetic: gastric juice secreted
5) sympathetic: peristalsis reduced
Parasympathetic: digestion increased