Bio psychology 1

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  • Bio psychology
    • Nervous system
      • Central NS= brain and spinal cord
        • Brains outer layer (cerebral cortex) highly developed in humans, distinguishes higher mental functioning from animals- divided into 2 hemispheres
        • Spinal cord- extension on the brain, passes messages to and from brain, connects nerves to PNS
      • Peripheral NS= somatic and autonomic NS
        • Transmits messages via millions of neurons to and from CNS
        • Subdivided into: autonomic NS- governs virtual body functions e.g.heart rate and somatic NS- controls muscle movement, receives info from sensory receptors
      • Carries messages across body using individual nerve cells (neurons)
        • Neurons- transmit nerve impulses in electrical signals
    • Endocrine system- glands and hormones
      • Works alongside NS, controls vital body functions. Slower than NS. Glands e.g. thyroid gland, produce hormones
      • Hormones secreted via bloodstream- affect any cell in the body that has a receptor for that hormone e.g. thyroxine produced by thyroid gland, affects various cells e.g. heart cells and can influence metabolic rate
      • Major endocrine gland is pituitary gland , “master gland”, controls release of hormones from all other endocrine glands in the body
    • Fight or flight
      • ANS part of NS, located at brain stem, runs different organs e.g. glands. Makes sure all systems function normally with extra demands on the body e.g. stress. Makes sure more oxygen supplied to muscles when we run, heart rate and blood pressure increase
      • ANS has 2 divisions:1) sympathetic division- prepares for fight or flight, hypothalamus controls body’s response to stress, triggers activity in adrenal gland by releasing ACTH, adrenal releases adrenaline to act of organs and tissue- short lived stress
        • 2)parasympathetic division- threat passes, PSNS return body to resting state, acts as a ‘brake’ to reduce activity increased by SNS- rest and digest response
    • Structure and function of neurons
      • 100 billions neurons in human NS,80% in brain, transmits signals electrically and chemically, provide NS with primary means of communication
      • Motor neuron- connects CNS to muscle and glands, short dendrites and long axons, primarily generate movement e.g. bend knee
      • Sensory neuron- carry message like sight, sound and feeling from PNS to CNS. Long dendrite and short axons
      • Relay neuron- connect sensory and motor neurons. Short dendrites and short axons
      • Structure- vary from less than a millimetre to a metre long, share basic structure. Cell body includes nucleus (DNA), dendrites protrude from them,carry nerve impulses from neighbouring neurons to cell body
        • Axon- carries impulses away form cell body down length of neuron, covered in fatter layer of myelin sheath(protectaxon, speeds up electrical transmission of impulse), gaps in myelin sheath (nodes of Ranvier) encourage signal to speed up, forces them to jump across gaps
    • Electrical transmission
      • Neuron in resting state inside cell is negatively charged vs outside. Neuron activated by stimulus, inside becomes positively charged for split second causing action potential-creates electrical impulse  that travels down axon to end of neuron
      • Synaptic transmission- neurons communicate with each other in groups (neural networks). Each separated by tiny gap (synapse)
        • Signals in neurons transmitted electrically vs between neurons transmitted chemically across synapse
      • When electrical impulse reaches end of neuron (presynaptic terminal) triggers release of neurotransmitter from tiny sacs (synaptic vesicles). Chemicals travel across synapse and stimulate postsynaptic neuron to generate its own electrical impulse
    • Neurotransmitters-
      • Brain chemicals, communicate info throughout brain and body
      • Relay signals between neurons. Brain uses neurotransmitters to tell heart to beat, lungs to breath and stomach to digest
      • Can affect mood- bio psychologists consider imbalance to be appropriate explanation for mental disorders (low serotonin=depression)
      • Chemicals that cross synaptic gap, stimulate receptors on postsynaptic neuron
      • Several dozen types identified- each has own specific molecular structure, sits perfectly in postsynaptic receptor. Have specials functions e.g. ACH found at each point where motor neuron meets receptor , on release muscle contracts

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