Biopsychology

Physiological Psychology

The Genetic Basis of Behaviour

Physiological Psychology

• Physiology is the scientific study of living organisms and is concerned with functions and processes that sustain life. In contrast, anatomy is the study of the structures of living organisms. Psychologists are interested in the physiology of animals especially human beings.

• This is because of the importance of our nervous system particularly the brain, and because of its role in how we behave, think and sense the world around us. Physiological psychologists are also interested in the interaction of the physical body and the mind. The body can affect the mind, as shown by the effects of alcohol. In turn the mind can affect the body, for example, extreme stress may cause tiredness and lethargy.

• Bio psychologists generally regard the brain and the mind to be the same thing.

• Others regard mental life as not physical, and hence different to brain functions. This is known as the mind body problem and was first raised by the French philosopher Rene Descartes (1596-1650)

http://www.youtube.com/watch?v=7GzBeS8KDcY

What do Bio psychologists think?

Neurons and Synaptic Transmission

• It is estimated that there are about 100 billion neurons or nerve cells in the average human nervous system.

• Neurons vary in size and shape.

• The neuron is specialised for communication, whether between other neurons, whether between other neurons, to and from muscles, or with other organs in the body, such as the heart or stomach.

How Neurons Work

• http://www.youtube.com/watch?v=ysDGX6bOgAw&feature=related

The structure of a neuron

Neurons explained

• Although no two neurons are exactly alike, their cellular structure is basically the same. Each neuron has a cell body, axon, terminal buttons and dendrites. The cell body, or soma, includes a nucleus which contains the genetic material (chromosomes) of the cell. Surrounding the nucleus are other components that are essential for the functioning of the whole neuron.

• The axon is a long extension from the cell body, which may be nearly a metre in length in some neurons. The axon usually has two or more branches, called collateral branches.

• Nearly all axons in the human nervous system are covered with a myelin sheath. The myelin sheath insulates or protects the axon from external influences that might affect the transmission of the nerve impulse down the axon.

• The myelin sheath gives the is what gives the brain its white appearance, while the cell bodies give a grey colour to the brain. The myelin sheath also helps to increase the speed of transmission of the nerve impulse down the axon.

• At the end of the axon are what are called terminal buttons. Terminal buttons of one axon send signals to an adjacent cell (another neuron, muscle cell, etc). If the adjacent cell is another neuron, it is the dendrites (and cell bodies) that receive the nerve impulse or signal from the adjacent neuron. In this way information is passed between neurons through electrical signals.

• When a neuron is at rest there is a negative electrical charge inside the cell and a positive charge outside the cell. An electrical impulse moves down the neuron and along the axon. This is called action potential.

Action potential

• Action potential occurs as a result of a chemical process that affects the electric charge both inside and outside the neuron. The electrical charge inside and outside the cell reverses when the cell ‘fires’, or when a nerve impulse (action potential) passes down the cell to the synapse.

Functions of the synapse

• The connection between neurons is at the synapse. Neurons do not exactly touch at the synapse; the electrical impulse ‘jumps’ between the cells at what is called the synaptic cleft.

• The terminal buttons, sometimes called synaptic knobs, at the end of the axon contain small structures called synaptic vesicles. These contain certain chemicals called neurotransmitters.

• Neurotransmitters can either increase or decrease the firing (signal transmission between neurons) of the neuron and the transmission of the electrical impulse from one cell to another. Where a neurotransmitter increases the firing of a cell it is called an excitatory synapse, and where it decreases the firing of the cell it is called an inhibitory synapse.

• The function of the neuron is to pass and receive electrical information, or nerve impulses, either from other neurons or from other cells (such as muscle cells or heart cells).