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Human Biology - Unit 3 - Key Definitions
Terms in this set (27)
the cerebral cortex is the centre of concious thought. It can recall memories or alter behaviour in the logh of past experiences.
Memory involves the encoding, storage and retrieval of information. It includes past experiences, thoughts and knowledge.
Sensory memory recalls all of the visual and auditory input received for a few seconds.
Why, in the Serial Position Effect, are items listed first and last recalled better than those in the middle?
- Items at the start are likely to be rehearsed over and over again, allowing for their transfer into the LTM
- Items at the end are likely to still be in the STM and so retrieval of them is very accurate
- Items in the middle are likely to therefore have been lost, either through displacement or decay.
Working memory model
Proposes that there are several parts to the STM, such as problem solving or decision making, which work independently from each other. This allows the STM to perform simple cognitive tasks.
Relate to the conditions/circumstances that were first present when the information was encoded.
The process of a myelin sheath developing around an axon. This takes time, and is why an older child or adult will have much quicker responses to stimuli than a baby.
Cells which produce the myelin sheath for an axon, and help to physically support the neuron.
Cause an increase in action e.g muscles contracting. It is the type of receptor which determines whether a signal is excitatory
Cause a decrease in action e.g slow heart rate. It is the type of receptor which determines whether a signal is inhibitory.
When a series of weak stimuli causes the release of enough neurotransmitters for a signal to be passed on. Possible since a neuron can have many synapses with other neurons.
Neurotransmitters, such as acetylcholine, are broken down by enzymes and the products are reabsorbed.
Reuptake of neurotransmitters
Neurotransmitters, such as noradrenaline, are taken back up directly to the presynaptic membrane.
Neurotransmitters that act as natural painkillers, by binding with receptors and blocking pain signals. Endorphins are produced in response to severe injury, lengthy periods of physical exercise and eating certain foods. Increased levels of endorphins are also linked to feelings of pleasure such as eating, sex and prolonged exercise.
Neurotransmitter which activates the reward pathway of the brain. This leads to feelings of pleasure and reinforces the behaviours which led to its secretion.
Substances which act as agonists/antagonists affecting the reward pathway of the brain. This can lead to altering in mood, cognition and behaviour.
Proteins on the surface of cells which trigger a specific immune response.
How is a clonal population formed?
When a lymphocyte binds onto an antigen it becomes activated. This causes it to rapidly divide, creating a clonal population.
How do B lymphocytes destroy pathogens?
B lymphocytes destroy pathogens by producing antibodies which are specific to antigens on invading pathogens. When these antibodies bind to antigens they create an antigen-antibody complex which makes the pathogen more susceptible to phagocytosis.
How do T lymphocytes destroy infected cells?
After a T lymphocyte has been activated and a clonal population has been produced, T lymphocytes will once again recognise the foreign antigens on the pathogen and will induce apoptosis.
When T lymphocytes bind to infected cells and release proteins which cause the production of self-destructive enzymes leading to cell death. The remains of the cell are then removed via phagocytosis.
What does the herd immunity threshold depend on?
The type of disease, the effectiveness of the vaccine and the density of the population.
How do vaccinations work?
Vaccinations involve the use of antigens from infectious pathogens. These antigens help the body to create memory cells, and can be in the form of inactivated pathogen toxins, dead pathogens, weakened pathogens, or parts of a pathogen.
Why would a clinical trial be randomised?
Reduces bias in the distribution of characteristics such as age and gender.
Why would a double-blind technique in a clinical trial be used?
Prevents biased interpretations of the results
Why would a placebo drug be used in a clinical trial?
Ensure valid comparaisons can be made between groups.
Why must clinical trials be of a suitable size?
Reduces the magnitude of experimental error
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