the eye, the brain, the reflex arc, homeostasis,blood glucose and the hypothalamus.

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  • the eye
    • the brain
      • homeostasis
        • blood glucose levels
          • the reflex arc
            • stimulus for example heat
              • the heat (the stimulus) is detected by receptors cells in the skin, an electrical impulse (neuron) travels along the sensory neuron
                • at the end of the sensory neuron there is a junction known as a synapse.
                  • at the synapse a chemical is released which diffuses across to a relay neurone - in the CNS
                    • at the end of the relay neuron there is another synapse where another chemical is released which diffuses across to a motor nuerone.
                      • an electrical impulse (nuerone) travels to an effector such as a gland or a muscle.
                        • the muscle or gland then resonds to the situation by secreting a hormone (gland) or by contracting (muscle)
                          • in this case the effector is responding to heat so the muscle will comtract, pulling the person away from the heat source.
                            • the reflex arc doesnt interact with the contious part of the brain which reflexes automatic and rapid in order to protect from physical danger
            • the central nervous system
          • if blood glucose levels are too high
            • the pancreas will produce insulin
              • the glucose will be transported from the blood stream into cells
                • once in liver or muscle cells the insulin will convert glucose into glycogen so that it can be stored
          • if blood glucose levels are too low
            • the pancreas will produce glucagon
              • glucagon converts glycogen stored in the liver and muscle cells back into glucose
                • the glucose is then transported back into the blood stream
          • type 1 diabetes
            • is a genetic non-communicable disease which is the result of the bodies  inability to produce sufficient insulin
              • treatments
                • the patient  must regularly test their blood sugar levels and inject themselves with insulin if it is too high.
          • type 2 diabetes
            • is a non- communicable disease which is the result of a poor diet- high carbohydrate intake
              • treatments
                • type 2 diabetes is not permanent and can be corrected by a healthier diet or in sever cases insulin injections and medication.
        • homeostasis is the regulation of internal conditions in order to maintain optimum conditions for the function of enzymes
          • features of automatic control systems
            • stimulus, receptor cells, coordination centre, an effector and a response
              • receptor cells detect a stimulus
                • an electrical impulse is sent to a coordination centre such as the brain, spinal cord or the pancreas.
                  • the coordination centre interprets information from receptor cells and send instructions to the effector
                    • an example of an effector is a muscle or a gland, which carries out a response in order to restore conditions.
        • the central nervous system
      • the hypothalamus
        • the hypothalamus tracks and regulates body temperature
          • nerves relay information about the skins surface temperature from thermoreceptors in the skin  to the hypothalamus.
            • the hypothalamus also contains thermoreceptors which detect change in the temperature of blood,
        • if body temperature falls
          • capillaries will constrict in order to prevent heat loss through gas exchange
          • hairs will stand in order to trap a layer of warm air along the surface of the skin
          • shivering increases body temperature as increased levels of movement require an increased rate of respiration, which is an endothermic reaction meaning it emits heat energy.
        • if body temperature rises
          • hair will lay flat against the skin to allow cool air to reach the surface of the skin
          • sweating allows us to lose heat energy
          • capillaries will expand allowing us to lose heat through gas exchange.
      • the brain structure
    • the eye is a sense organ, which has receptors which detect light intensity and colour.
    • cornea function= to focus light rays.
  • The lens focuses the light onto the back of the eye
    • the lens changes its shape allowing it to focus on distant or closer objects this is known as accommodation
      • Th ciliary muscles and suspensory ligaments work with the lens, allowing us to focus on objects
    • pupil- light rays pass pass through the iris
      • the iris control the size of the pupill which varys based on line intensity ie low light= larger pupil in order to allow the most light rays to enter to eye.
      • cornea function= to focus light rays.
    • retina - contains receptor cells and detect light intensity and colour
    • receptor cells send nuerones down the optic nerve to the brain
  • pupil- light rays pass pass through the iris
    • the iris control the size of the pupill which varys based on line intensity ie low light= larger pupil in order to allow the most light rays to enter to eye.
  • the reflex arc
    • stimulus for example heat
      • the heat (the stimulus) is detected by receptors cells in the skin, an electrical impulse (neuron) travels along the sensory neuron
        • at the end of the sensory neuron there is a junction known as a synapse.
          • at the synapse a chemical is released which diffuses across to a relay neurone - in the CNS
            • at the end of the relay neuron there is another synapse where another chemical is released which diffuses across to a motor nuerone.
              • an electrical impulse (nuerone) travels to an effector such as a gland or a muscle.
                • the muscle or gland then resonds to the situation by secreting a hormone (gland) or by contracting (muscle)
                  • in this case the effector is responding to heat so the muscle will comtract, pulling the person away from the heat source.
                    • the reflex arc doesnt interact with the contious part of the brain which reflexes automatic and rapid in order to protect from physical danger

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