Biological level of analysis Nervous system: structure and function By Ms Lindstrom

How much does a brain weigh?

Answer An avarage 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 to and fro between the CNS and various regions of the body, are called peripheral neurons.

Nervous system The nervous system is made up of the central nervous system, comprising 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

A typical motor neuron nucleus: contains genetic information cell body: houses the nucleus and other structures common to all living cells axon: a thin cylinder of protoplasm which projects away from the cell body and carries signals from the dendrites to other neurones dendrites: branch out from the cell body, and receive signals from neighbouring neurones myelin sheath: a white fatty substance, which insulates the axon and speeds up the rate of transmission Nodes of Ranvier: points along the axon which are not covered by the myelin sheath presynaptic terminal: the small buttons at the end of the branches of the axon

Neurons

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)

Outgoing 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: Acetlcholine – muscle contraction, memory Dopamine – voluntary movement, learning, feelings of pleasure Noradrenaline – arousal, alertness, stimulating the sympathetic nervous system Serotonin – sleep, arousal levels, emotion In total there are over fifty identified transmitter substances

Neurotransmitters “brain's language and acts as the volume buttons” When we feel, think, feel 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=DF04XPBj5uc&feature=related 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?

Brain Group work: present in the following order and make a power point presentation 3 persons mapping the brain: include localization and function of the areas and layers. What happens if it becomes damaged? The history of the area. How do we know about these areas today (link it to studies)? Do not include Broca’s and Wernickes area! 2:Brocas area: mapping, description of the area, history (why it is called Brocas’s area, study + method) 2: Wernicke’s area mapping, description of the area, history (why it is called Wernicke’s area, study + method) 2: Split brain surgery: what is split brain surgery (method)? Why is it used? Examples of studies and findings, history Neurotransmitters: 2: serotonin: describe its use and function and what happens if one has too much or too little of it (link it to a psychological illness that you find) 2: noradrenaline: describe its use and function and what happens if one has too much or too little of it (link it to a psychological illness that you find) 2:Dopamine: describe its use and function and what happens if one has too much or too little of it (link it to a psychological illness that you find) Assessment details: see handout ”Rubric for the Brain Group Work”