B6 Brain and Mind Summary

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  • Created by: Farhana
  • Created on: 04-01-13 15:21
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  • Neurones
    • Sensory neurones
      • They carry impulses from the receptors to the CNS
        • Receptors are cells that detect stimuli e.g. taste receptors on the tongue
    • Motor neurones
      • They carry impulses from the CNS to the effectors
        • Effectors are all muscles and hormones excreting cells found in glands
        • CNS is the processing centre that coordinates a response. It is the brain and the spinal cord
          • They carry impulses from the receptors to the CNS
            • Receptors are cells that detect stimuli e.g. taste receptors on the tongue
          • A reflex arc goes through the CNS- the spinal cord or the unconscious part of the brain
            • Reflexes are involuntary responses
              • A stimulus detected by receptors, impulse sent alond sensory neurones to CNS. In CNS, sens. neurones pass onto relay neurone. Relay neurone pass impulse to motor neurone. Motor neurone to effector
              • Simple reflexes improve the chance of survival e.g. sea anemones- tentacles, molluscs- close shells
                • Humans have simple reflexes e.g. contract eye allowing in less light. Dropping a hot object. Knee jerk. Newborn baby reflexes, suckling, grasping, stepping
              • Reflex responses can be modified by the brain- response overridden by a neurone btween brain & motor neurone of reflex arc
              • Reflex responses can be learned- conditioned reflex
                • Animals learn to produce a sam reflex response to a sceondary stimulus
                  • Pavlov's dog learnt to respond to sound of bell(sec stim)- salivating, expecting food, conditioned
                • Conditioned reflex can increase chances of survival, e.g. birds eating bright coloured insects-poisonous
          • The environment can affect brain development and learning
            • The brain of a newborn baby is partly deveopled & most neurone connections are not yet formed
              • Connections form when child experiences new things, neurone connects to other neurones, creating new pathways
                • More exp.s repeated- strengthens pathways- more likely to transmit impulse than others
                • There are definate stages in development of child's brain- some pathways need to be strengthened at partic. age or too late e.g. feral children
            • Complex animals adaptable cos of variety of potential pathways
              • Simpler animals less flexible nervous systems- behav. more predictable, less adaptable
          • Cerebral cortex outer part of brain controls intelligence, memory, language and consciousness
          • To study the brain methods:
            • 1. Studying patients with brain damage, back part damaged, blind= vision
            • 2. Electrically stimulating the brain- tiny electrode into tissue w/ electricity. Observ what stim-ing diff parts do
            • 3. MRI scans- machiene gioces detailed pic of brain's tructure- fibnd out what parts active when doing things
    • Transmit information around the body as electrical impulses
      • Electrical impulses pass along the axon of the nerve cells
        • Axons are made of the nerve cell's cytoplasm into a long fibre, surrounded by cell membrane
          • Axons are surrounded by fatty sheath- acts as insulator, shield neurones from nearby neurones, speeds up electrical impulse
    • The gap between 2 neurones- a synapse
      • When electrical impulse reaches end of neurone, triggers release of transmitter chems. in the synapse
        • The transmitter chems. diffuse across gap & bind to receptor molecules
          • Only specific chems. can bind to receptor molecules on neurone- trigger new electr. impulse in next nuerone
      • Some drugs e.g. ecstasy, blocks sites in brain's synapses
        • Serotonin removed- concentration increases = mood-enhancing effects
          • Serotonin though to affect things like pain, agression & appetite- determine's person's mood


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