1. Higher Human Biology Unit 3a
Organisation of the nervous system
Chapter 14a

2. Organisation of the nervous system
Learning Intentions:
What are the central and peripheral nervous systems?
What are the somatic and autonomic nervous systems?
In terms of the nervous system what does antagonistic mean?
Explain using an example what homeostasis is
Explain the terms ‘fight or flight’ and ‘rest and digest’

3. What are the central and peripheral nervous systems?
The peripheral nervous system
- the spinal and cranial nerves that radiate out from the spinal cord and all over the body
The peripheral nervous system consists of a sensory pathway and a motor pathway

4. Flow of information through nervous system
CNS
Nerve impulses carried by sensory neurones in sensory pathways
Nerve impulses carried by motor neurones in motor pathways
receptors
effectors
stimuli
responses

5. What are the somatic and autonomic nervous systems?
These are how the nervous system is divided in relation to function
The somatic nervous system
- voluntary control of the body’s skeletal muscles by the pathway shown in the previous slide
- responsible for certain involuntary reflex actions

6. What are the somatic and autonomic nervous systems?
E.g. looking for fruit in supermarket
- rows of fruit are the visual stimulus
- nerve impulses pass from each retina via sensory nerve cells in the optic nerve to the brain (smell will also be involved)
- association centre processes information and compares it with previous experiences – how to spot fresh or rotten fruit
- decisions are taken and nerve impulses are passed to the motor area of brain which sends impulses via motor neurones to the appropriate skeletal muscles to voluntarily pick up fruit

7. What are the somatic and autonomic nervous systems? Cont’d
The autonomic nervous system
- regulates internal structures and organs (heart, bronchial tubes, alimentary canal, blood vessels, sweat glands)
Works automatically without conscious control
See diagram p204
Within the autonomic nervous system there are sympathetic and parasympathetic nerves which work antagonistically with each other

9. The antagonistic nature of the autonomic nervous system
The autonomic nervous system plays a vital role in homeostasis
The control is very sensitive - effectors are stimulated by both the sympathetic and parasympathetic nerves in order to maintain a very fine balance

10. Homeostatic control of breathing rate
Activity
What is involved in breathing?
Why do we breath?
What is the trigger?
How is breathing stimulated?

11. Fight or Flight
‘Fight or flight’ – sympathetic nervous system sends more impulses than the parasympathetic in order to prepare the body to use energy quickly
Heart rate and blood pressure increase and blood supply diverted to skeletal muscles
Nervous perspiration increases
Epinephrine production stimulated
After the ‘fight or flight’ situation has passed the parasympathetic nervous system takes over briefly to calm you down

12. Rest and digest
After the ‘fight or flight’ situation has passed the parasympathetic nervous system takes over briefly to calm you down
Heart rate and blood pressure drop
Rate of peristaltic contractions increase
Blood re-diverted back to intestines

13. Questions
Testing KU p208
Answer in sentences they can help form notes on the chapter

14. For next lesson Forward preparation is the key to success
Read the rest of the chapter in preparation for tomorrow
Try to come up with 3 questions about things you would like to know or don’t understand