iGCSE Biology Section 2 lesson 8

1. iGCSE Biology Section 2 lesson 8

2. Content Section 2 Structures and functions in living organisms a) Levels of organisation b) Cell structure c) Biological molecules d) Movement of substances into and out of cells e) Nutrition f) Respiration g) Gas exchange h) Transport i) Excretion j) Coordination and response

3. Content j) Coordination and response 2.77 understand that organisms are able to respond to changes in their environment 2.78 understand that homeostasis is the maintenance of a constant internal environment and that body water content and body temperature are both examples of homeostasis 2.79 understand that a coordinated response requires a stimulus, a receptor and an effector Flowering plants 2.80 understand that plants respond to stimuli 2.81 describe the geotropic responses of roots and stems 2.82 describe positive phototropism of stems Humans 2.83 describe how responses can be controlled by nervous or by hormonal communication and understand the differences between the two systems 2.84 understand that the central nervous system consists of the brain and spinal cord and is linked to sense organs by nerves 2.85 understand that stimulation of receptors in the sense organs sends electrical impulses along nerves into and out of the central nervous system, resulting in rapid responses 2.86 describe the structure and functioning of a simple reflex arc illustrated by the withdrawal of a finger from a hot object 2.87 describe the structure and function of the eye as a receptor 2.88 understand the function of the eye in focusing near and distant objects, and in responding to changes in light intensity 2.89 describe the role of the skin in temperature regulation, with reference to sweating, vasoconstriction and vasodilation 2.90 understand the sources, roles and effects of the following hormones: ADH, adrenaline, insulin, testosterone, progesterone and oestrogen. Lesson 8 j) Coordination and response

4. Content j) Coordination and response 2.77 understand that organisms are able to respond to changes in their environment 2.78 understand that homeostasis is the maintenance of a constant internal environment and that body water content and body temperature are both examples of homeostasis 2.79 understand that a coordinated response requires a stimulus, a receptor and an effector Flowering plants 2.80 understand that plants respond to stimuli 2.81 describe the geotropic responses of roots and stems 2.82 describe positive phototropism of stems Humans 2.83 describe how responses can be controlled by nervous or by hormonal communication and understand the differences between the two systems 2.84 understand that the central nervous system consists of the brain and spinal cord and is linked to sense organs by nerves 2.85 understand that stimulation of receptors in the sense organs sends electrical impulses along nerves into and out of the central nervous system, resulting in rapid responses 2.86 describe the structure and functioning of a simple reflex arc illustrated by the withdrawal of a finger from a hot object 2.87 describe the structure and function of the eye as a receptor 2.88 understand the function of the eye in focusing near and distant objects, and in responding to changes in light intensity 2.89 describe the role of the skin in temperature regulation, with reference to sweating, vasoconstriction and vasodilation 2.90 understand the sources, roles and effects of the following hormones: ADH, adrenaline, insulin, testosterone, progesterone and oestrogen. Lesson 8 j) Coordination and response

5. Content j) Coordination and response 2.77 understand that organisms are able to respond to changes in their environment 2.78 understand that homeostasis is the maintenance of a constant internal environment and that body water content and body temperature are both examples of homeostasis 2.79 understand that a coordinated response requires a stimulus, a receptor and an effector Flowering plants 2.80 understand that plants respond to stimuli 2.81 describe the geotropic responses of roots and stems 2.82 describe positive phototropism of stems Humans 2.83 describe how responses can be controlled by nervous or by hormonal communication and understand the differences between the two systems 2.84 understand that the central nervous system consists of the brain and spinal cord and is linked to sense organs by nerves 2.85 understand that stimulation of receptors in the sense organs sends electrical impulses along nerves into and out of the central nervous system, resulting in rapid responses 2.86 describe the structure and functioning of a simple reflex arc illustrated by the withdrawal of a finger from a hot object 2.87 describe the structure and function of the eye as a receptor 2.88 understand the function of the eye in focusing near and distant objects, and in responding to changes in light intensity 2.89 describe the role of the skin in temperature regulation, with reference to sweating, vasoconstriction and vasodilation 2.90 understand the sources, roles and effects of the following hormones: ADH, adrenaline, insulin, testosterone, progesterone and oestrogen. Lesson 8 j) Coordination and response

6. The Central Nervous System

7. The Central Nervous System Brain

8. The Central Nervous System Brain Spinal cord

9. The Central Nervous System Brain Spinal cord Spinal nerves

10. The Central Nervous System Brain Spinal cord Spinal nerves Cell body Motor neurone Direction of impulse

11. The Central Nervous System Brain Spinal cord Spinal nerves Sensory neurone Cell body Direction of impulse

12. The Central Nervous System Brain Spinal cord Spinal nerves Relay neurone Cell body

13. Nerve cell (neurone) Neurones are specially adapted cells that can carry impulses (electrical signals)

14. Nerve cell (neurone) Neurones are specially adapted cells that can carry impulses (electrical signals) They are very long (elongated) and connect parts of the body

15. Nerve cell (neurone) Neurones are specially adapted cells that can carry impulses (electrical signals) They are very long (elongated) and connect parts of the body They have branched endings to allow a single neurone to link to may muscle fibres

16. Nerve cell (neurone) Neurones are specially adapted cells that can carry impulses (electrical signals) They are very long (elongated) and connect parts of the body They have branched endings to allow a single neurone to link to may muscle fibres The cell body has many connections, so enabling communication with other neurones

17. Nerve cell (neurone) Dendrites Cell body Myelin (fatty) sheath) Axon endings

18. The Reflex Action A reflex action is a rapid, unlearned response to a stimulus. It has a high survival value. When specific receptors are stimulated they cause a very fast, automatic response to the presence of danger. Co-ordination between the sensory and motor neurones takes place without the need for conscious thought. Eg. removing the hand from a hot object.

19. The Reflex Action

20. The Reflex Action Stimulus, eg. a hot object

21. The Reflex Action Receptor eg. in the skin

22. The Reflex Action Sensory neurone

23. The Reflex Action Relay neurone

24. The Reflex Action Motor neurone

25. The Reflex Action Effector, eg. muscle

26. The Reflex Action 1 1. The receptor is stimulated by the hot object

27. The Reflex Action 2. This causes an impulse to pass along. 2 1 1. The receptor is stimulated by the hot object

28. The Reflex Action 3. The spinal cord (or brain) co-ordinates response without conscious thought. 2. This causes an impulse to pass along. 3 2 1 1. The receptor is stimulated by the hot object

29. The Reflex Action 3. The spinal cord (or brain) co-ordinates response without conscious thought. 2. This causes an impulse to pass along. 4. An impulse is transmitted along a motor neurone 3 2 4 1 1. The receptor is stimulated by the hot object

30. The Reflex Action 3. The spinal cord (or brain) co-ordinates response without conscious thought. 2. This causes an impulse to pass along. 4. An impulse is transmitted along a motor neurone 3 2 4 5 1 1. The receptor is stimulated by the hot object 5. The muscle contracts in response to the stimulus

31. The Conscious Action 1. Receptors in your foot detect a stone in your shoe 1

32. The Conscious Action 2. An impulse is sent along a sensory neurone 1. Receptors in your foot detect a stone in your shoe 2

33. The Conscious Action 3. In the spinal cord another sensory neurone takes the impulse to the brain 2. An impulse is sent along a sensory neurone 3 1. Receptors in your foot detect a stone in your shoe

34. The Conscious Action 4. The brain co-oordinates the input and output 3. In the spinal cord another sensory neurone takes the impulse to the brain 4 2. An impulse is sent along a sensory neurone 1. Receptors in your foot detect a stone in your shoe

35. The Conscious Action 4. The brain co-oordinates the input and output 3. In the spinal cord another sensory neurone takes the impulse to the brain 5. An impulse is sent along a motor neurone in the CNS 5 2. An impulse is sent along a sensory neurone 1. Receptors in your foot detect a stone in your shoe

36. The Conscious Action 4. The brain co-oordinates the input and output 3. In the spinal cord another sensory neurone takes the impulse to the brain 5. An impulse is sent along a motor neurone in the CNS 2. An impulse is sent along a sensory neurone 6. The impulse leaves the CNS via another motor neurone 1. Receptors in your foot detect a stone in your shoe 6

37. The Conscious Action 4. The brain co-oordinates the input and output 3. In the spinal cord another sensory neurone takes the impulse to the brain 5. An impulse is sent along a motor neurone in the CNS 2. An impulse is sent along a sensory neurone 6. The impulse leaves the CNS via another motor neurone 1. Receptors in your foot detect a stone in your shoe 7. Muscles (the effectors) lift the foot out of the shoe 7

38. Responding to our environment LIGHT receptors in the EYES TASTE receptors in the TONGUE SOUND receptors in the EARS SMELL receptors in the NOSE CHANGE OF POSITION receptors in the EARS (balance) TOUCH, PRESSURE and TEMPERATURE receptors in the SKIN

39. Responding to our environment LIGHT receptors in the EYES TASTE receptors in the TONGUE SOUND receptors in the EARS SMELL receptors in the NOSE CHANGE OF POSITION receptors in the EARS (balance) TOUCH, PRESSURE and TEMPERATURE receptors in the SKIN

40. The Eye

41. The Eye

42. The Eye

43. The Eye

44. The Eye

45. The Eye

46. The Eye

47. The Eye

48. The Eye

49. The Eye

50. Focusing on near and distant objects • DISTANT OBJECT • suspensory ligaments pull tight • ciliary muscles relax • lens is pulled thinner and so light isn’t bent as much.