biopsy Flashcards
What are the 2 divisions of the human nervous system?
Peripheral and Central Nervous System.
What is the function of the peripheral nervous system?
Transmits messages to and from the CNS.
Further divided into ANS (governs vital functions) and SNS (controls muscle movement and receives information from senses).
Distinguish between the somatic nervous system and the autonomic nervous system.
Two sub-divisions of the PNS - ANS governs vital functions e.g. heartrate and breathing.
SNS controls muscle movement and receives information from senses.
What is the role of adrenaline in the fight or flight response?
Adrenaline triggers physiological changes in the body (e.g. increased heart rate), which are necessary for for the fight or flight response.
What is meant by the endocrine system?
The Endocrine system works alongside the nervous system to control vital functions in the body.
The endocrine system works much more slowly than the nervous system, but has very widespread effects. It is responsible for instructing various glands to release hormones into the bloodstream.
The endocrine system is made up of a number of different glands which release hormones. Define the term gland. Give one example.
A gland is an organ in the body which synthesizes substances such as hormones.
The thyroid gland, for example, produces thyroxine which affects cells in the heart (increasing heart rate). It also affects cells throughout the body, affecting metabolic rates (growth).
What does the term hormone mean? Give an example.
Chemical substances that circulate in the bloodstream and only affect target organs. They are produced in large quantities, but disappear quickly. Their effects are very powerful.
Outline one difference between the nervous system and the endocrine system.
One difference between the two is the time it takes for the systems to respond to stimuli. The nervous system reacts from electrical and chemical transmission and the response is near instantaneous. The endocrine system reacts much more slowly, but therefore much longer lasting and widespread effects.
Explain the actions of the autonomic nervous system in the fight or flight response.
Hypothalamus triggers the sympathetic nervous system. The adrenal medulla releases adrenaline into the blood. Physiological changes in the body. When the threat has passed the parasympathetic branch activates. This returns the body back to its normal resting state.
What is a neuron?
Neurons are nerve cells that process and transmit messages through electrical and chemical signals in the nervous system.
Outline the function of a motor, relay and sensory neuron.
Motor neurons connect the central nervous system to effectors such as muscles and glands.
Relay neurons connect the sensory neurons to motor neurons and other relay neurons.
Sensory neurons carry messages from the peripheral nervous system to the central nervous system.
Describe the structure of a neuron.
The cell body of a neuron includes the nucleus which contains the genetic material of the cell.
Dendrites are branch-like structures that carry nerve impulses from neighbouring neurons towards the cell body.
The axon carries impulses away from the cell body down the length of the neuron.
The myelin sheath covers the axon to protect and speed up electrical transmission of the impulse.
Nodes of ranvier are the gaps between the myelin sheath these speed up the transmission of impulses by forcing the impulse to jump across the gaps.
Terminal buttons are at the end of the axon, these communicate with the next neuron across the synapse.
Outline the difference between electric and chemical transmission in relation to neurons.
Electric transmission happens within the neuron. This changes the neuron from being negatively charged to positively charged when activated by a stimulus. This then creates the electrical that travels to the end of the neuron.
Explain the function of a neurotransmitter and give an example.
A neurotransmitter is a chemical released from the presynaptic nerve that relays a signal across the synapse. The neurotransmitter diffuses across the synapse and is taken up by the postsynaptic receptor site. The chemical message is then converted back into an electrical impulse.
For example acetylcholine is found where the motor neuron meets a muscle and cause the muscle to contract.
With reference to the process of synaptic transmission, explain what is meant by inhibition and excitation.
Serotonin has an inhibitory effect of the receiving neuron by causing the neuron to become more negatively charged which results in it being less likely to fire the electrical impulse.
However, adrenaline’s an excitatory effect on the neuron by making it more positively charged which results in it being more likely to fire the electrical impulse.
What are the four areas of cortical specialisation in the brain?
Motor Cortex - Voluntary Movement.
Somatosensory Cortex - Information related to the skin.
Visual Cortex - Information from the eye - left visual field to right cortex.
Auditory Cortex - speech based information
Outline the contribution of scientists such as Brocca and Wernicke to our understanding of the brain.
Established the areas of language in the brain.
Broca’s area = left frontal lobe - Speech production.
Wernicke’s area = left temporal lobe - Speech understanding / coherence.
–
Outline 1 study in which localisation of function in the brain has been investigated.
Peterson et al. (1988). Used brain scans to show how Wernicke’s areas was active during a listening task and Broca’s area during a reading task → different functions.
Tulving 1944 - showed that episodic and semantic memory are located in different parts of the prefrontal cortex.
Provide 2 pieces of supporting evidence for localisation of the brain - include research details.
Neurosurgical Evidence. Dougherty (2002). 44 OCD patients underwent a cingulotomy → at a 32 week check up almost half of the patients had made either a partial or successful recovery. Suggests the behaviour and symptoms for mental illness are localised.
Case Study evidence. Phineas Gage - steel rod through the brain removing a lot of the left frontal lobe. Change of personality → turned rude, quick tempered, aggressive. Suggests localisation in the brain.
What is meant by plasticity and why does it challenge the idea of localisation?
When the brain becomes damaged and a particular function has been lost, the brain appears to be able to reorganise itself to recover function. Basically another part of the brain takes over the function. The brain physically adjusts the location of function if damage occurs, which suggests that localisation is not fixed to specific areas. The brain is working as a whole unit rather than specific areas for specific functions.
What is meant by plasticity?
The tendency of the brain to change and adapt as a result of experience. The experiences that we have result in some connection being lost and other being strengthened.
Outline some research into plasticity.
Maquire et al. (2000) - london taxi drivers. More grey matter in their posterior hippocampus → spatial and navigational skills. The “knowledge”. Brain structure is altered.
How has research into brain plasticity helps us in the ‘real world’?
Neurorehabilitation. Physiotherapy following illness or injury e.g. motor therapy and electrical stimulus after stroke. Brain may be able to ‘fix’ itself.
What is meant by functional recovery?
A form of plasticity. After a trauma, the brain’s ability to redistribute functions usually performed by the damaged area to undamaged areas.
What happens in the brain during functional recovery.
Secondary neural pathways are activated to carry out certain functions. Axonal sprouting. Growth of new nerve endings which connect with undamaged nerve cells to create new pathways. New blood vessels. Recruitment of similar areas. E.g. Broca’s area damaged on the left side, the equivalent would be recruited on the right.
Outline one example of animal research into functional recovery and discuss whether what we learn from such studies is worth the permanent damage does to the animals.
Hubel & Wiesel (1963). Cats eyes sewn shut and both visual cortices took over. Generalisability from cats to humans is an issue. We have no insight into thoughts or emotions. Plasticity may be different in animals.
