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Central Nervous System

Central Nervous System. National 4 & 5: Multicellular Organisms. M ulticellular organisms are made up of many different tissues and organs Cells do not work independently, so they communicate with each other Also, different tissues and organs need to communicate with each other

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Central Nervous System

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  1. Central Nervous System National 4 & 5:Multicellular Organisms

  2. Multicellular organisms are made up of many different tissues and organs • Cells do not work independently, so they communicate with each other • Also, different tissues and organs need to communicate with each other • Communication is usually carried out in 2 ways: • - hormones • - nerve signals Internal Communication

  3. Identify the discrete areas of the brain and understand their functions • Identify the different typed of nerves/neurones in the human body • Examine the role of each type of nerve/neurone • Explain how a reflex action works, and identify examples of this • Examine how information is passed from one neurone to another Learning Outcomes

  4. The nervous system is composed of: • - the brain • - the spinal cord • - nerves What is the nervous system composed of?

  5. Cerebrum • - conscious thought, reasoning, imagination • Cerebellum - balance and co-ordination • Medulla (brain stem) - heart rate and breathing rate The Brain

  6. The brain is approximately 75% water • It weighs about 3 pounds, BUT uses between 20%-25% of your energy supplies each day • Your brain can survive without oxygen for 4-6 minutes before it starts to die • There are over 100, 000 miles of blood vessels in your brain • There are over 100 billion neurons in your brain • It’s not true that humans only use 10% of their brains; each part of the brain has a purpose • The slowest speed information passes around your brain is approximately 260 mph • The number of internal thought pathways that your brain is capable of producing is one followed by 10.5 million kilometers of standard typewritten zero’s! Brain facts

  7. Central Nervous System (CNS) Consists of the brain and spinal cord Stimulus (change) picked up by receptor 1) Impulse carried along nerve cell (Sensory neurone) to spinal cord 2) CNS processes info & sends a response 3) Impulse carried along nerve cell (motor neurone) to effector organ 4) Effector organ brings about a response 5)

  8. Receptors are found all over the body, often as part of sense organs • E.g. eyes, ears, skin • They work in response to a stimulus • The more receptors, the more sensitive an area usually is to a stimulus • Effectors are also found all over the body • They act in response to the CNS • The more effector cells are in a body part, the more it can move or the faster it can act • Effectors are often either muscles or glands • - muscles respond rapidly • - glands respond more gradually Receptors and effectors

  9. Sight

  10. Smell

  11. Skin

  12. Hearing/balance

  13. Taste

  14. A reflex is a rapid, unconscious response to a stimulus • e.g. blinking, pulling a hand off a hot surface • Receptor cells send an impulse along the sensory neurone to the CNS Relay neurone • The relay neurone transfers the impulse to the motor nerve sensory neurone • The motor neurone transfers the impulse to the effector cells, to carry out the response The Reflex Arc motor neurone

  15. What happens in a goalie’s body as he tries to save a goal? The greatest goals of all time

  16. What happens in a goalie’s body as he tries to save a goal? Mark each other’s work: 1 point if they have used any of these words: Eye(s) Brain 2 Points: Nerve(s) Muscle(s) 3 Points: Neurone(s) Receptor(s) Spinal cord 4 Points: Motor (neurone) Sensory (neurone) Use your judgement – any other scientific words that they have used correctly that should get points?

  17. You have been given a series of cards for a series of reflex actions • You must arrange them under the following headings Reflex responses

  18. 1.Using a ruler you have to see how quickly you can catch it. 2. Each person will try three times and record their results in a table 3. We will then collect the class data How fast are your reflexes??

  19. Results

  20. Remember Title, label axis, 0 Who is the fastest - Class results Graph Average reflex (cm) Pupil Name

  21. Information is carried through the CNS by a series of neurones • Information is picked up by a neurone through a dendrite • Then it is passed to the cell body • It then gets passed towards the next neurone by an axon fibre Transfer of information along neurones

  22. Between each neurone is a small gap called a synapse • To pass information between neurones, a chemical passes across this synapse • These chemicals are called neurotransmitters Structure of a synapse

  23. What is meant by the term reflex action? • Give an example of a reflex action. • What is the function of the sensory nerve? • What part of the brain controls our breathing rate? • What part of the brain controls our balance? • What part of the brain is responsible for our memory? Re-Cap

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