Multicellular Organisms 3

1. Multicellular Organisms 3

2. 1. Functions of the nervous system There are three major functions of the nervous system • Sensory - to receive information about the internal and external environment of the body. • control- to analyse sensory information, store information and make decisions. • motor- to send messages to muscles or gland in response to stimuli.

3. 2. Organisation of the nervous system The nervous system has two main parts. • The central nervous system which consist of the • brain • spinal cord • nerves/neurones which connect the CNS to all parts of the body.

4. 3. Function of the CNS The CNS sorts out stimuli received from the sense organs and sends messages to those muscles which can make the appropriate response. stimulus Motor nerve Sensory nerve Muscle or gland Sense organ CNS response

5. 4. Nerves Nerves are bundles of nerve cells called neurones which are the longest cells of the body. Sensory neurones carry messages from receptors in the sense organs towards the CNS. Motor neurones carry messages from the CNS to the muscles/glands.

6. 4. Nerves In the CNS there are shorter interconnecting nerve cells called inter neurones which connect sensory neurones to motor neurones. The interaction of these neurones can be seen in reflex actions.

7. Synapse • Where two neurones meet, there is a tiny gap called a synapse. Electrical impulses cross this gap using chemicals. One neurone releases the chemical into the gap. The chemical diffuses across the gap and makes the next neurone transmit an electrical signal.

8. Neurone 1 Neurone 2 The human body contains up to 500 trillion synapses.

9. synaptic vesicle chemicals When a nerve impulse arrives at the end of one neurone it triggers the release of chemicals from synaptic vesicles. The chemicals diffuse across the synaptic gap

10. synaptic gap electric impulse receptor Once across the synaptic gap the chemicals bind with receptors on the next neurone, triggering the next electrical impulse.

11. Reflex action • A reflex action is a rapid, involuntary, protective response.Reflex reactions are not under conscious control and take place to keep the body from harm.

12. Reflex action • A potentially dangerous stimulus triggers nerve endings in a sense organ (eye, ear, tongue, skin or nose). An impulse is sent along a sensory neurone then along an inter neurone in the spinal cord. The impulse is then passed along a motor neurone to an effector (a muscle or gland) causing a response e.g. muscle contraction or hormone secretion.

13. The Reflex Arc Inter neurone

14. If the hand touches something very hot the receptors in the skin detect the pain. • An impulse travels from the receptor along the sensory neurone to the spinal cord Inter

15. 3. An inter neurone connects the sensory neurone to the motor neurone – the reflex arc. 4. An impulse leaves the spinal cord in the motor neurone nerve and travels to the muscle.

16. 3. The muscle responds by contracting and the hand is removed from danger.

18. Common reflexes

19. 5. Reflex action

22. The brain • The human brain is an extremely complex organ made up of hundreds of billions of nerve cells. • The brain can be divided into a number of regions. • Side view of the brain seen in mid vertical section (slice down the middle) Albert Einstein’s Brain

23. Why is the brain enclosed by our skull? The cranium consists of 8 bones. Suture

24. The brain Each region has a specific function. Cerebrum Medulla Cerebellum

25. The cerebrum • Makes up 85% of the brain's weight. • Controls conscious thought, thinking, emotions and intelligence. • The cerebrum has two halves, with one on either side of the head. • Involved in both short and long term memory.

26. Left • Analytical • Math • Logic • Speech Right • Music • Colour • Shapes

27. Short term memory • Last no longer than 30 seconds unless rehearsed within that time frame • 7 plus/minus 2 theory

28. Lets test your short term memory

29. Long term memory • Capacity is unknown. • Information is thought to be stored permanently.

30. The cerebellum • The cerebellum is at the back of the brain, below the cerebrum. • Roughly 1/8 of the size of the cerebrum. • Controls balance, movement, and coordination.

31. The Medulla • Site of involuntary responses e.g. heart rate, breathing, reflexes etc.

32. The brain

33. How is your short term memory doing?? How many objects can you remember from earlier?

34. Tasks • Count the F’s FINISHED FILES ARE THE RESULT OF YEARS OF SCIENTIFIC STUDY COMBINED WITHTHE EXPERIENCE OF YEARS... There are 6. The brain does not register the F in OF. To count 3 is normal.

35. Tasks • What is wrong with the following sentence?

41. Closure

42. Ambiguous images

43. Faces are easily recognised

46. Videos • Einstein mask • Dragons

47. Tasks… • Memory game • Try your Sudoku puzzle 3. Brain past paper questions. http://www.bbc.co.uk/scotland/brainsmart/

48. How is your short term memory doing?? How many objects can you remember from yesterday?

49. Tasks… 1. Model brain for display. 2. Brain past paper questions. 3. Test your memory: http://www.bbc.co.uk/scotland/brainsmart/ Extension: Find out about Alzheimer's disease.