Unit 1

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  • Created by: cova
  • Created on: 18-05-11 18:53

Parts of nervous system

  • The nervous system consist of the brain, spinal cord, spinal nerves and receptors.
  • Its allows organisms to react to their surroundings and to coordinate their behavior.
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Types of neurones

  • Motor neurone: Impulse travels away from cell body.
  • Sensory neurone: Impulse travels towards cell body.
  • Relay neurone: Impulse travels firts towards and then away from cell body.

Neurons are elongated to make connections between parts of the body.

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Connections between neurons

Neurons do not touch each other; there is a gap between them called a synapse.

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Types of receptor

Receptors detect stimuli.

  • Light- receptors in the eyes.
  • Sound- receptors in the ears.
  • Change in position- receptors in the ears.
  • Taste- receptor in the tonge.
  • Smell- receptors in the nose.
  • Touch, pressure, pain and temperature- receptors in the skin.
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Reflex action

  • Reflex action speeds up theresponse time by missing out the brain completly.
  • The spinal cord acts as the coordinator and passes impulses directly from a sensory neurone to a motor neurone via a relay neurone.
  • Reflex actions are automatic and quick.
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Internal conditions

Humans need to keep their internal environment relatively constant.

  • Temperature: Increased by shivering and narrowing skin capillaries; Decreased by sweating and expanding skin capillaries.
  • Water content: Gained by drinking; Lost by breathing via the lungs and sweating; Any excess is lost via the kidneys in urine.
  • Ion content: Gained by eating and drinking; Lost by eating and drinking; Lost via sweating; Excess is lostvia the kidneys in urine.
  • Blood sugar (glucose) levels: Glucose provides the cells with a constant supply of energy; Gained by eating and drinking.
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How conditions are controlled?

  • Many processes within the body are coordinated by hormones.
  • Hormones are chemical substances.
  • Hormones are produced by glands.
  • Hormones are transported by the bloodstream.
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Hormones and fertility

  • Hormones regulate the functions of many organs and cells.
  • A woman naturally produces hormones that cause the release of an egg from her ovaries.
  • These hormones are produces by the pituitary gland and the ovaries.
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Natural control of fertility

  • Follicle stimulating hormone (FSH): Produced in the pituitary gland; Causes the ovaries to produce oestrogen and an egg to mature.
  • Oestrogen: Produces in the ovaries; Inhibits the production of FSH and causes the production of luteinising hormone (LH).
  • LH: From th epituitary gland; Stimulates the release of an egg in the middel of the menstrual cycle.
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Artificial control of fertility

FSH and oestrogen can be given to women in order to achieve opposing results.

  • Increasing fertility: FSH is given as a fertility drug to women who don't produce enought naturally, to stimulate eggs.
  • Reducing fertility: Oestrogen is given as an oral contraceptive to inhibit FSH production. This means that eggs don't mature in the ovary.
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Comments

Pete Langley - Get Revising founder

are these finished?

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