Chapter 4: Biological Processes And Psychological Explanation

Front 1

What is a genotype?

Back 1

A collection of all of the genes within any cell of an individual, except the sex cells (gametes)
Is a source of information, which together with the environment, determines the development and structure of an individual
Determined at fertilization by combining genes from both parents which remain constant throughout life
The physical structure and behaviour of an individuals results from the genotype interacting with cellular and environment factors which is termed the phenotype
The genotype can be though of as a kind of potential for development into a number of phenotypes
Example = two plants with identical genotype planted in the same environment with develop different phenotypes
Important = demonstrates the influence of nature and nurture - genotype + environment to produce the actual physical structure or behaviour

Front 2

What is an action potential?

Back 2

An action potential is a sudden and dramatic change in the electrical activity of a neuron
It is a change from the resting value to another value and the return back to the resting value
Action potentials travel along the central nervous system from sensory neurons, down the length of one or more neurons and can initiate action potentials in connected neurons or motor neurons to contract a muscle
Sensory neurons send information from the site of a stimuli such as heat/pressure
Motor neurons are connected to muscles and send information to contract
Information in conveyed according to the frequency of action potentials
A synapse is the gap between a neuron and another cell
Action potentials in pre-synaptic neurons can trigger excitation in post-synaptic neurons
Neurotransmitters carry the information across the synapse
Release of neurotransmitter potentials can inhibit action potentials in post-synaptic neurons
Important = action potentials can be measured to determine how information is transmitted in the nervous system

Front 3

What is a neurotransmitter?

Back 3

A neurotransmitter is a chemical released form a neuron which influences a neighbouring cell
The junction between two neurons is called a synapse
Chemical messenger that communicates between the pre-synaptic neuron, across the synapse and the post-synaptic neuron or other cell
Stored in the junction of the pre-synaptic neuron, released when an action potential arrives and and taken up by receptors on the post-synaptic neuron or other cell
Neurotransmitters can trigger excitation in the post-synaptic neuron (an increase in action potentials) or exhibition (a decrease in action potentials)
Neurotransmitters and receptors can be thought of as keys and locks. Only the correct neurotransmitter fits the receptors on the post-synaptic neuron due to its shape
Neurons are characterised by the type of neurotransmitter they store and release eg a 'serotogenic' neurons releases serotonin, 'doperminergic' neurons release dopamine
Important = malfunctions at the synapse are associated with certain mental illnesses eg schizophrenia
Important = disease and drugs can alter the production of neurotransmitters. Prescription drugs can be used to slow reuptake of the neurotransmitters by specific pre-synatic neurons

Front 4

What is a phenotype?

Back 4

The genotype is the collection of all of the genes within the cell of a given individual. It is a source of information from which development takes place
Genes interact with the fluid environment of the cell, cells interact with neighbouring cells and the whole organism interacts with its environment
Phenotype is the physical structure and behaviour of an animal that arises from the interaction of the genotype and the environment
Phenotype features can change as the results of experience eg muscle strength is built, aggression is learnt
The phenotype of can differ between genetically identical individuals. eg identical plant planted in different soil will develop differently
Important = highlights the nature/nurture argument. Although the genes can be identical (nature), nurture (the environment) has an influence on the development of an individial

Front 5

What is a brain lesion?

Back 5

A brain lesion is any sort of brain damage. Examples include gunshot wounds or tumours. Brain lesions can be caused by accident or intent
Other type of brain lesions are blockages of blood vessels within the brain or the breaking of a blood vessel, also known as a stroke
Criticism = lesions made on lab animals inc 'sham lesions' raise ethical problems
Example = Phineas Gage in 1848 who suffered extensive damage to the left prefrontal lobe when a tamping iron passed right through his brain. Left him emotionally uninhibited. Highlights which part of the brain inhibits emotional behaviour. Evidence is problematic. No control group, several brain areas were affected. Other brain areas taking over.
Example = Roger Sperry (1969) severed the brain hemispheres by cutting through the orpus callosum to try to stop epileptic seizures. Each half of the brain could process conflicting bits of information (split brain experiments)