B6 - Brain & Mind

responding to a stimulus
1. a stimulus is a change in environment
  1. animals respond to a stimulus in order to keep themselves in favourable conditions
    1. the stimulus is co-ordinated by the central nervous system
      1. CNS = brain and spinal cord
2. receptors respond to the stimulus and send impulses along the sensory neuron to the CNS
  1. the CNS co-ordinates the information and sends impulses along motor neurons to the effectors, which bring about a response
    1. the peripheral nervous system consists of motor and sensory neurons that take information from the receptor to the CNS, as well as the instructions from the CNS to the effectors
neurons
1. neurons carry signals from one place to another
  1. when neurons are stimulated they transmit an electrical impulse
    1. two neurons do not make direct contact, when they meet there is a small gap between them called a synapse
      1. the signal needs to cross this gap, so it's turned into a chemical which diffuses across the synapse
        the receptor molecules on the second neuron only bind to specific chemicals released from the first neuron
        this stimulates the second neuron to transmit the electrical impulse
reflexes
1. a reflex is an automatic response to a stimulus
  1. simple reflexes
    1. produce rapid, involuntary responses
      1. this ensures that an animal responds in the way most likely to result in its survival
        examples include - moving towards and finding food, moving away from predators and finding a mate
  2. reflex arc
    1. reflex reactions in humans are controlled by the reflex arc
      1. a reflex arc is the nerve pathway which makes rapid automatic responses possible
2. newborn reflexes
  1. grasping reflex
  2. startle reflex
  3. step reflex
learning
1. human brain consists of millions of neurons, these neurons are connected to form billions of pathways
  1. whenever we experience something new, a new pathway in the brain is used
    1. each new experience changes out behaviour, this is learning
      1. if the experience is repeated, or the stimulus is strong, more nerve impulses are sent along the new pathway
        this reinforces the learning process, and shows us how repetition aids the learning process
        learning is an important part of human survival
2. some skills can only be learnt at a certain age
  1. if a child has no human contact from birth, they become feral
    1. feral children can't talk or walk like a human because they didn't learn the skill when they needed to
the brain and memory
1. the cerebral cortex is the part of the brain that is responsible for intelligence, language, memory and conscienceness
  1. scientists use different methods to find out which part of the cerebral cortex do what job
    1. brain damage patients
    2. electrical stimulation
    3. MRI scans
  2. two types of memory
    1. long-term and short-term
drugs
1. drugs affect the impulses that pass from one neuron to another across the synapse
  1. some drugs stop the impulse from passing across the synapse
    1. others stimulate the synapse so once one impulse has crossed the gap, its repeated
      1. serotonin is a chemical that is released in our brains, an increase in serotonin levels makes us feel happier
        serotonin is usually absorbed by the receptor molecules on the other side
        the drug ecstasy blocks the receptor sites in the synapses in the brain, this means serotonin levels increase and the user gets a prolonged feeling of wellbeing

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B6 - Brain & Mind

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