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

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’

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

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

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

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

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

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

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

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

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

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

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