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Nervous Control in Multicellular Organisms

Learn about the internal communication required for survival in multicellular organisms, focusing on the nervous control system. Understand the structure and functions of the brain and how neurons transmit messages. Explore sensory input, synapses, and motor responses.

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Nervous Control in Multicellular Organisms

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  1. Unit 2: Multicellular Organisms Chapter 11: Control & communicationPART 1: NERVOUS CONTROL National 5 Biology Mrs Smith - National 5 Biology

  2. By the end of this chapter you should, • Internal communication is required for survival of a multicellular organism. Cells in multicellular organisms do not work independently. • Know the nervous system consists of central nervous system (CNS) and nerves. • You should also be able to explain that the CNS consists of brain and spinal cord. • You must know the structure of the brain and describe the function of each of these brain parts, cerebrum, cerebellum and medulla. • Know that neurons are of three types, sensory, relay and motor. • Describe that receptors detect sensory input/stimuli. Electrical impulses carry messages along neurons. A synapse occurs between neurons. Chemicals transfer these messages across synapses. • Sensory neurons pass the information to the central nervous system. The CNS processes the information from our senses which needs a response. Motor neurons enable a response to occur, which can be a rapid action from a muscle or a slower response from a gland. Learning Intentions: Nervous Control National 5 Biology Mrs Smith - National 5 Biology

  3. Nervous Control Internal communication is required for survival of a multicellular organism Cells in multicellular organisms do not work independently We will be looking at both nervous control and hormonal control of multicellular organisms Mrs Smith - National 5 Biology

  4. Nervous Control The body can only work effectively if all of its parts work in close cooperation with one another The internal communication needed to bring this about is provided by the NERVOUS SYSTEM Mrs Smith - National 5 Biology

  5. Nervous System: 3 parts In humans the nervous system is composed of 3 parts • Brain • Spinal Cord • Nerves Mrs Smith - National 5 Biology

  6. Central Nervous System (CNS) • The CNS is composed of the • The brain • Spinal cord Mrs Smith - National 5 Biology

  7. Mrs Smith - National 5 Biology

  8. CNS • The CNS is connected to all parts of the body by nerves, which lead to and from all organs and systems. • This arrangement ensures that all parts work together as a coordinated whole, with the brain having the overall control Mrs Smith - National 5 Biology

  9. Do you ever feel like a bag of nerves? Just to read this slide, millions of nerve messages are zipping around within your brain! Mrs Smith - National 5 Biology

  10. Sense organs pick up information about the ball Brain sends info to the muscles to enable you to move to hit the ball Sense organs send info to the brain which processes the information Mrs Smith - National 5 Biology

  11. Parts of the Brain Mrs Smith - National 5 Biology

  12. Cerebrum The largest part of the brain Its divides into two connected halves called cerebral hemispheres Its surface is folded to give an area about five times larger than if it were flat Mrs Smith - National 5 Biology

  13. Cerebrum Con’t The cerebrum is the ‘thinking’ part of the brain The cerebrum controls memory, personality, creativity and conscious thought Mrs Smith - National 5 Biology

  14. Cerebellum The cerebellum controls balance and co-ordination We are not aware of it but we use it whenever we walk Mrs Smith - National 5 Biology

  15. Medulla The medulla controls some vital body functions The medulla controls heart rate and breathing rate Mrs Smith - National 5 Biology

  16. Activity Complete ‘Parts of the brain worksheet’ Word bank: Cerebellum Cerebrum Medulla Mrs Smith - National 5 Biology

  17. Did you manage??? Cerebrum Cerebellum Medulla Mrs Smith - National 5 Biology

  18. Summary: Functions of the Brain partsTask... Copy and complete. Cerebrum Cerebellum Medulla Mrs Smith - National 5 Biology

  19. Testing your Knowledge medulla • The ________ speeds up the heart during exercise • The ________ is responsible for memory • A cat has a relatively larger __________ than a human • The _________ controls personality • If the __________ is damaged, gymnastics would be very difficult • Reasoned thought is controlled by the ___________ • The ________ makes us breathe faster during exercise • The _________ sorts out information from the semi-circular canals (control balance) in the ears cerebrum cerebellum cerebrum cerebellum cerebrum medulla cerebellum Mrs Smith - National 5 Biology

  20. Research In 1848, Phineas Gage was working on the construction of a railway Find out what happened to him and how he was affected Prepare a 100 word report with your findings Mrs Smith - National 5 Biology

  21. Your body’s sense organs contain receptors The receptors detect changes in the environment called stimuli Flow of Information: Receptors Sensitive to chemicals in air NOSE Sensitive to chemicals in food TONGUE EARS Sensitive to sound SKIN Sensitive to touch, pressure, temperature & pain EYES Sensitive to light Mrs Smith - National 5 Biology

  22. How does the nervous system work? The central nervous system sorts out information from the senses and sends messages to those muscles which make the appropriate response Stimulus Receptor (sense organ) Message via nerves Effector (muscle or gland) Message via nerves C.N.S Response Mrs Smith - National 5 Biology

  23. Sensory & Motor Nerves Stimulus Receptor (sense organ) Effector (muscle or gland) C.N.S. Sensory Nerves Motor Nerves Response The information which triggers a sensory nerve is a STIMULUS The result of a motor nerve being triggered is a RESPONSE Mrs Smith - National 5 Biology

  24. Flow of Information The flow of information in the nervous system is always in one direction Information always flows from: CNS Sensory nerves Motor nerves Receptors e.g. Sense organs Effectors e.g. Muscles and glands Mrs Smith - National 5 Biology

  25. The ______ and ______ ______ together make up the Central Nervous System (CNS) _________ nerves carry signals to the CNS from receptors ________ nerves carry signals from the CNS to effectors (muscles or _______) Structure of the Central Nervous System brain Spinal cord Sensory Motor glands Spinal cord glands sensory brain motor Mrs Smith - National 5 Biology

  26. Quiz 1: On separate PowerPoint Mrs Smith - National 5 Biology

  27. A bell ringing is a stimulus The stimulus is detected by receptors in the ear Mrs Smith - National 5 Biology

  28. Nerve impulses travel along the sensory nerves to the CNS In the CNS the input information is sorted out If the neurones of the cerebrum are involved in the sorting out then you are conscious of this process and are aware of the responses you choose to make Mrs Smith - National 5 Biology

  29. Message sent from CNS through motor nerves to effector Effector (usually muscles) make the conscious response Mrs Smith - National 5 Biology

  30. Flow of Information WORD BANK Response Sensory nerve Information Motor nerve Receptors Stimulus Sorted Muscle Mrs Smith - National 5 Biology

  31. receptors Sensory nerve stimulus information sorted response Motor nerve Mrs Smith - National 5 Biology muscle

  32. What do you call the slight delay that occurs when reacting to a harmless stimulus? Mrs Smith - National 5 Biology

  33. Reaction Time The brain has to interpret the sensory information Then it must decide on a response All this takes time (reaction time) Stimulus Receptor (sense organ) Sensory nerve Motor nerve Effector (muscle) C.N.S. Response Mrs Smith - National 5 Biology

  34. Reflexes A reflex action is a rapid, automatic response to a stimulus Reflex actions protect the body by allowing it to react quickly when in danger Mrs Smith - National 5 Biology

  35. Examples of reflexes When you touch something hot, you immediately remove your hand Blinking when something flies towards your eyes Raising your arm if a ball is thrown your way Coughing and sneezing Mrs Smith - National 5 Biology

  36. Reflex Investigations 1. 2. 3. Mrs Smith - National 5 Biology

  37. Reflexes work by using relay nerve cells in the spinal cord Mrs Smith - National 5 Biology

  38. Relay Nerve Cells Relay nerve cells connect sensory and motor nerves across the spinal cord Mrs Smith - National 5 Biology

  39. Why is a reflex quicker? Stimulus Receptor (sense organ) Sensory Nerve Motor Nerve Effector (muscle) C.N.S A relay nerve in the spinal cord makes a direct connection between the sensory nerve and the motor nerve This makes the response very fast The brain only ‘finds out’ later Response Mrs Smith - National 5 Biology

  40. Hand Hand Spinal cord Spinal cord Brain Muscle Spinal cord Muscle Mrs Smith - National 5 Biology

  41. Step on sharp pin Step on a stone Mrs Smith - National 5 Biology

  42. The nerve cells that make up nerves are called neurones Mrs Smith - National 5 Biology

  43. Reflex arc Relay neurone CNS (Spinal cord) motor neurone Sensory neurone Effector (muscle) Receptors in skin Protective reflex response Harmful stimulus Mrs Smith - National 5 Biology

  44. Sensory neurone Relay neurone The neurones in a reflex arc are not physically joined They are separated by microscopic gaps called synapses When a nerve impulse reaches a gap it can be carried across the gap by means of a chemical released into the gap Mrs Smith - National 5 Biology

  45. Reflex Arc- Animation Relay neurone CNS (Spinal cord) motor neurone Sensory neurone Effector (muscle) Receptors in skin Protective reflex response Harmful stimulus Mrs Smith - National 5 Biology

  46. Reflexes A reflex response is a very rapid response made by the nervous system without processing information through the brain, e.g sneezing, coughing, blinking and withdrawing limbs from something hot A reflex arc is an arrangement, usually of three neurones, that allows a reflex response to take place A synapse is a microscopically small gap between the end of a neurone fibre and the next neurone. When a nerve impulse reaches a synapse it can be carried across the gap by means of a chemical released into the gap. Mrs Smith - National 5 Biology

  47. Mrs Smith - National 5 Biology

  48. Activity Complete ‘Reflex action at work’ worksheet Mrs Smith - National 5 Biology

  49. Reflex Action at work Cross section of spinal cord Part of spinal cord at shoulder level Mrs Smith - National 5 Biology

  50. Reflex Action at work TASK: Order the following statements Motor neurone carries signal down arm to muscle Hand removed from danger Touch hot element on cooker Relay neurone in spinal cord transfers impulse from sensory nerve to motor nerve Muscle contracts Receptors in skin stimulated which send impulse along sensory neurone Mrs Smith - National 5 Biology

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