Part 3 of Unit 2: Ch. 5 – Biological influences on behaviour

• This Chapter Presents:• How the Nervous System works• The Role of the Brain in Behaviour• A Discussion of Glands and their influence on Bodily Activity• The Effect of Sleep on Behaviour• Methods used in Hypnosis

• To better understand the focus of this chapter, think of this scenario if you will…• You are about to write the final exam for the toughest course of your entire academic

career, you need this test to not only pass the course, but also pass your program of study… How do you react? What causes you to react this way?

• Nervous, jittery, upset stomach, legs shaky? These are all symptoms caused by your nervous system…

The Nervous System

• Again, while this may be review, it is important to know how and why the nervous system acts the way that it does.• The nervous system regulates the body’s activities and in consequence

regulates the body’s behaviour

• Without the nervous system, you would not be able to hear, smell,use any of your senses, walk, think, laugh, cry, become hungry orthirsty, speak, or even remember things you have done/learned• The Nervous System can be divided into two parts… the Central

and Peripheral nervous systems…

The Nervous Systems

Central Nervous System• This is made up of the brain and

the spinal cord• Nerves in the brain and the

spinal cord are responsible for receiving and sending impulses to your body

Peripheral Nervous System

• This is made up of the fibres that run to and from the central nervous system• It includes the fingers, toes, ears,

heart, lungs, stomach, etc.• It connects and coordinates systems

between the sense organs and the muscles and the glands• Pain happens, message sent to and

from brain via peripheral system

The Neuron

• The way that the impulses travel along the peripheral system is via nerve cells known as neurons – there are billions of neurons in the human body• Neurons can be classified according to their function:

• Sensory neuron = receives and carries sensory information (smells, sounds, tastes)• Motor neuron = involved in motor activities (running, jumping, etc.)

• Impulses go from the brain or spinal cord to muscles/glands

• Neurons are made of four basic parts:• Dendrite = receive nerve impulses• Cell Body = contains the neuron’s chromosomes and genes; provides energy for

activities• Axon = fibre part of the neuron, part that sends messages to other neurons• Synapse = point at which two neurons meet; this is not a physical connection, but

instead a chemical one

The Autonomic Nervous System

• Next on our journey through the biological influences on behaviour, we come to the Autonomic Nervous System• This is part of the central and peripheral systems we have discussed already

• The purpose of this system is to regulate the organs that are necessary for life and reproduction• Generally speaking, it works without us even

knowing it

• Organs under its control include lungs, stomach, heart, liver, and reproductive organs

The most important part is next…

• The Brain:• It basically goes without saying that the brain is “the most important part of the

central nervous system… it plays an essential role in human behaviour”

• But how do scientists determine the role of the brain in our behaviour?• They use 5 methods:

1. Stimulate specific parts of the brain (use of electrodes and minor stimulation, cause things to happen)• Stimulation causes things to happen, i.e. can make a rat drink water

2. Brain lesions (refers to a part of the brain that is missing – do to animals on purpose and/or study humans who have surgically removed)• Study changes in behaviour… so then they can develop theory of what missing part of brain

did

Mr. P. Gage

How we study the brain continued…

3. Another way to study the brain is through use of EEG machines (electroencephalograph) • Records a person’s brain wave patterns on a chart,

recordings change as person changes what they do, changehappens based on scenario (happy, sad, mad, stressed, etc.)

4. Study the nerve connections in a brain (usually after a part of the brain has died)• By tracing the nerve, scientists can determine what that part of the brain did, i.e. move left

arm

5. Biochemical studies (involves chemical analysis of normal brains in healthy people)• Can either be tested on small parts of a human’s brain obtained in surgery, or by testing

chemical substances found in the brain. • Example: certain chemicals found in the brains of rats which have lived in enriched environments, this

substance is also related to learning, so… enrichment allows for learning

The Brain, what does what?

• The highest brain centre in humans (where most things occur) is the cerebral cortex• It is a thick layer of grey-coloured neurons just under the skull

• The cerebral cortex is divided into different area, each with their own function• Some deal with sensory processes (vision, etc.), some deal with motor activities

(walking, etc.)

• Neurons within specific area of the brain have specific functions, i.e. a mild electric stimulus on one part of the brain stimulates the toes to move• Of note, nearly ¾ of the cerebral cortex has no known or specific function

– the process of thinking is thought to be spread out over much of the cortex…

A little Canadianana before we go…