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19 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Divisions of the Nervous System CNS: -comprises of brain& spinal cord. -brain divided into separate areas, each with different functions (controlling thought & speech to balance). -Function of spinal cord = relay info between brain & rest of the body. PNS: -comprises of nerves outside the CNS. - Function = relay impulses between the CNS & rest of body - Divided into 2... |
Somatic NS: -comprises of nerves which receive input & output to control voluntary muscles. Autonomic NS: -controls involuntary actions - connects to internal organs & glands. - has 2 divisions. 1. Sympathetic NS: - arousing effect, prepares body for 'Fight or Flight' 2. Parasympathetic NS: - has calming effect - helps body return to homeostasis after excitation - involved in 'rest and digest' response. |
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A neuron is
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a cell that carries electrical impulses throughout the body
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Components of a neuron & their functions
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1. Dendrite - extensions @ beginning of a neuron - increases surface area of cell body -receives info from other neurons (via its receptors) & transmits electrical stimulation to cell body. 2. Cell Body (Soma) - produces proteins for dendrites, axons & synaptic terminals -contains specialisation to provide energy & make parts of neuron. 3. Nucleus - contains genes, consisting DNA which contains cell history & info to manufacture all protein characteristic of a nerve cell. 4. Axon -Main conducting unit of neuron (capable of carrying electrical signals long distance) -many are split into several branches - conveying info to different targets. -wrapped in protective myelin sheath 5. Axon Terminal -Located @ end of neuron - final part to receive an electrical impulse -area where impulse is converted to chemical signal |
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Different Types of Neuron, structure & function
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1. Sensory neuron -long dendrites, short axons, unipolar (only transmits info) - afferent nerve cell that carries sensory impulses to CNS 2. Relay Neuron -short dendrites, short axon terminals, multipolar ( sends & receives info) - found entirely in CNS -can communicate with both sensory & motor neurons. 3. Motor Neurons -short dendrites, long axons, multipolar ( sends & receives info) -efferent nerve cell - transmits nerve impulse from CNS |
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Synapse
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Junction between axon of one neuron and dendrite of another.
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Features of the Synapse
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1. Vesicle - sacs filled with neurotransmitters (chemical messengers). 2. Synaptic Gap - tiny gap between 2 neurons 3. Receptors - on the dendrites of post synaptic neuron receive neurotransmitters |
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Process of Synaptic Transmission: 1. Synthesis 2. Release 3. Receptor Activation 4. Inactivation |
1. Chemicals transported to axon terminal & NT are produced & packaged into vesicles/ 2. In response to electrical impulse, NT are released into synaptic gap 3. NT crosses synaptic gap & binds to specific receptor 4. NT either taken back into terminal (reuptake) or broken down in synapse by enzyme |
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Excitation & Inhibition
NT released from pre-synaptic neuron to receptors on dendrites of post-synaptic neuron.
Excitatory Synapse: - increases chance neuron fires an action potential - receptor is activated by excitatory NTs -generate excitatory post-synaptic potential (EPSP)
E.G Glutamate -arousing effect -increases activity of other NTs -High levels can over-excite neurons until they die - occurs in neurodegenerative brain disorders (Alzheimer's disease)
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Inhibitory Synapse: - decreases chance neuron fires an action potential - receptors activated by inhibitory NTs - generate inhibitory post-synaptic potential (IPSP)
E.G GABA -calming effect -prevents excessive levels of other NTs from influencing neural activity -Regulates cortical functions (vision) -Low levels lead to neurons firing too often, linked to anxiety & epilepsy.
Summation: -Firing of action potentials depend on summation of al EPSPs & IPSPs. -If net result is positive neuron fires. -If negative neuron doesn't
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Difference between hormone & NT
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NT produced within neuron & transmit message quickly whereas hormones are secreted by glands & travel slowly in bloodstream to target organs. |
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Main glands in endocrine system
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-pituitary gland - thyroid gland - parathyroid gland - adrenal gland - pancreas - ovaries (women) -testes (men)
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Hormones have regulatory functions, such as
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- metabolism - development - tissue function - sleep -mood -sexual function - reproduction |
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Pituitary Gland's location & function
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- base of mid-brain & is connected to the hypothalamus -considered 'master gland' - produces hormones that control many functions of other glands. E.G ACTH travels from this gland to adrenal cortex, via bloodstream. - in turn stimulates release of corticosteroids during biological stress encourages body release stored energy ALSO releases LH for testes |
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Function of the Testes
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- receives luteinising hormone from pituitary gland - in turn produces testosterone - acts to support sperm production & linked to higher levels of aggression |
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Adrenal Glands
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- located on top of each kidney - secretes a variety of hormones E.G -adrenal cortex releases cortisol - adrenal medulla releases adrenaline - both involved in body's response to stress |
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Fight or Flight Response Sympathomedullary Pathway: 1. Stressor is perceived & threat is assessed. 2. Hypothalamus activates sympathetic branch of ANS. 3. Sympathetic nerves transmit signal from CNS to PNS, which consists of nerves connected to the adrenal glands. 4. Adrenal medulla releases adrenaline & noradrenaline into bloodstream. 5. Adrenalin constricts blood vessels in skin & divert blood to muscles. |
Role of Adrenaline: -increase in heart rate - speed up blood flow -increase blood pressure - "" -increase lung function - provide oxygen to fuel muscles -increase pupil size - let in more light to improve perception of stressor -increase blood flow to muscle - increase physical mobility -decreases salivation- digestion not needed -decreases digestion - blood directed to muscles. Parasympathetic Response: -once threat has gone, ANS switches from sympathetic to parasympathetic branch. -decrease in amount of hormones -calming effect - rest and digest response - decrease in heart rate - return of digestive processes -returns body to homeostasis |
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Limitation of Fight or Flight Response: May apply to males more than females (androcentric)
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- When males are confronted by stressful situations fight or flight response is triggered. - However, for females = 'tend or befriend' response. - 'Tend' = protective & nurturing b'viours & 'Befriend' = formation of social alliances to cope w/ stressor. - Suggests there are limitations to applying fight or flight to females. |
- What response do males have? - What response do females have? - What does each aspect mean? |
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Limitation of Fight or Flight Response: May not be the 1st Reaction to Threat
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- Overly simplistic to assume fight or flight is the initial response to threat. - Suggested that most animals initially adopt a 'freeze' response in order to be more alert to signs of danger. - Enables animal to focus attention & more effectively assess the most appropriate response to specific threat. - Although animal may proceed to fight or flight response, this is only part of a more elaborate process. |
- Overly simplistic - 'Freeze' response - why? |
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Limitation of Fight or Flight Response: May have -ve Consequences
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- Despite functioning as an adaptive trait helping early humans to survive in dangerous situations, fight or flight response may no longer be adaptive & may have disadvantages. - Stressors in modern life e.g. consistent workplace stress don't require instant physical reaction afforded by fight or flight. - Consequence = continued physiological strain is placed on body such as increased blood pressure = damage of blood vessels & eventually heart disease. - Despite being benefit for early ancestors, fight or flight response may be an evolutionary hangover & actually detrimental to many modern humans as way of living has changed. - Therefore idea of fight or flight response lacks temporal validity. |
- Advantageous for early human but not now - E.g. of modern life stress - What would be the effect of fight or flight response for this stressor? - evolutionary hangover |
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Strength of Fight or Flight Response: Scientific
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- Researchers are able to scientifically investigate physical reactions. - Experimental methods can be used which involve pps being presented w/ stimuli of varying degrees of threat under controlled conditions. - Subsequent biological responses can be objectively measures using ECG, which measures heart rate. - Researchers don't need to use self-report methods to assess bodily response = less subjective, thereby increasing validity of research. |
- Scientifically able to investigate... - What would happen in experiments? - Biological responses can be measured using what equipment? |
