Biological level of analysis2.1: Physiology and behaviour

The Nervous system:structure and function

By Ms Lindstrom

How much does a brain weigh?

Answer

• An average brain weighs 1,3-1,4 kilos

One way to study biological psychology:

• Physiology: how the nervous system and hormones work, how the brain functions, how changes in structure and/or function can affect behaviour. For example, we could ask how prescribed drugs to treat depression affect behaviour through their interaction with the nervous system.

• Therefore, If we want to understand all aspects of behaviour, perhaps we should start with one of the smallest units, the basic building block of the body, the cell.

The Neuron• The neurons (nerve cells) are one of the

building blocks of behaviour.

• The Neurons send electrochemical messages to the brain so that people can respond to stimuli.

Central Nervous System

Neurons• The human brain is made up of around 10 –

100 billion neurons. The total collection of nerve cells in the body is called the nervous system and the major part of the nervous system, consisting of the brain and the spinal cord, is called the central nervous system (CNS).

• Neurons outside the CNS, which take information between the CNS and various regions of the body, are called peripheral neurons.

The Nervous System The nervous system is made up of the central nervous system, covering of the brain and the spinal cord, and the peripheral nervous system. The latter is further divided into the somatic division and the autonomic division. The somatic division controls voluntary movements and the communication of information to and from the sense organs. The autonomic division controls involuntary functions such as those of the heart, blood vessels and lungs. The autonomic division is further divided into the sympathetic and the parasympathetic divisions. The former prepares the body in

emergency situations and the latter helps the body return to its resting state.

The Spinal Reflex

Neurons handle information in the body, taking messages

from one part of the body to another.

Neurons

Outgoing information p. 39

A typical motor neuron see p. 39 in your booknucleus: contains genetic informationcell body: houses the nucleus and other structures common to all living cellsaxon: a thin cylinder of protoplasm which projects away from the cell body and carries signals from the dendrites to other neuronesdendrites: branch out from the cell body, and receive signals from neighbouring neuronesmyelin sheath: a white fatty substance, which insulates the axon and speeds up the rate of transmissionNodes of Ranvier: points along the axon which are not covered by the myelin sheathpresynaptic terminal: the small buttons at the end of the branches of the axon

Neurons

McGyver Excersise

• In groups of five• Create a model of a “neuron” using whatever

material you can find• You have 5 minutes!

Neurotransmission

• Is the method by which these messages are sent by

With an electrical impulse down the axon of the neuron, it releases neurotransmitters which then cross the gap to another neuron. This gap is called a synapse.

Neurotransmitters are the body’s natural chemical messengers (of information)

Neurotransmission

• Underlies behaviour as mood, memory, sexual arousal and mental illness.

• Drugs as alcohol, marihuana, Ecstasy, Cocaine… affect our neurotransmissions in different ways, producing therefore different outcomes/experiences.

• Psychopharmalogical drugs work in the same way, trying to affect our neurotransmissions to either simulate or to block it, but with the mission of improving the lives

Neurotransmitters

• Examples:• Acetylcholine – muscle contraction, memory• Dopamine – voluntary movement, learning,

feelings of pleasure • Noradrenaline – arousal, alertness,

stimulating the sympathetic nervous system• Serotonin – sleep, arousal levels, emotionIn total there are over fifty identified transmitter

substances

Neurotransmitters

• “brain's language and acts as the volume buttons”

• When we feel, think, and remember the neurotransmitters are involved.

• Depression, neuroses and psychoses can be caused by problems with neurotransmitters.

Videos

NEURONS AND NEURO-TRANSMITTERS http://www.youtube.com/watch?v=FR4S1BqdFG4 Brain of a genius:•http://dsc.discovery.com/videos/understanding-the-brain-genius.html•Teenage brain:•http://dsc.discovery.com/videos/understanding-the-brain-teenagers.html

Questions

•1. What is a neuron?

•2. Explain the meaning of the statement `Neurons are the building blocks of the entire nervous system'.

•3. What is a neurotransmitter?

BrainGroup work: present in the following order and make a power

point presentation (and a poster) about your topic• 2: General mapping of the brain:include localization and function of the areas and layers. What happens if it becomes damaged? (give two

examples) How do we know about these areas today? Do not include Broca’s and Wernicke’s area!• 2: McGuire: taxi drivers: mapping, description of the area, study (aim, procedure and findings)• 2:Broca’s area and Wernice’s area: mapping, description of the area, history (why it is called Brocas’s

area, Wernice’s area, study + method)• 2: split brain surgery: what is split brain surgery (Study by Sperry +method)?

• Neurotransmitters:• 2: Acetylcholine (Ahc): describe its use and function and what happens if one has too much or too

little of it (link it to a study) describe the study (aim, procedure and findings)

• 2:Dopamine: describe its use and function and what happens if one has too much or too little of it (link it to a study and describe the study (aim, procedure and findings)

• 2: Serotonin: describe its use and function and what happens if one has too much or too little of it (link it to a study) describe the study (aim, procedure and findings)

• Assessment details: see handout ”Rubric for the Brain Group Work”• Find info in your textbook, revision guide (handouts) and on the internet