1. Responding to Stimuli Thyroid Pancreas Adrenal Pituitary O

2. By the end of today’s lesson you should be able to: Know the four structures of response in living things Outline the nervous system components: central nervous system (CNS) and the peripheral nervous system (PNS) Receptor messages are carried through these systems by nerve cells or neurons.

3. The structure and function of a neuron: variation in size and shape. Neuron -- Three part structure:> dendrite(s), the axon the cell body, Outline the structure & function of the neuron including: cell body, dendrites, axon, myelin sheath, schwann cell, and neurotransmitter vesicles & synaptic cleft

4. Response Living things sense and respond to environmental changes in a variety of ways. Response is a form of defence that allows organisms to survive in their environments.

5. 3.5.1 Structures for response Living things respond in various ways: 1.Nerve and organ systems 2.Chemical or hormonal response 3.Muscular and skeletal systems 4.Immune systems

6. Human responses – the nervous system

7. The Nervous System  A nervous system allows an organism to detect and respond to stimuli in its internal or external environment. e.g. a flash of light, a noise, a fly landing on your nose.  A stimulus is any change in your environment

8.  The central nervous system (CNS) is your brain and spinal cord.  The peripheral nervous system (PNS) is the nerves branching from the CNS to all parts of the body. The nervous system in the human is made up of two different parts:

9. Check your learning.. What is a stimulus? How does our nervous system help to protect us? What is the difference between the CNS and the PNS?

10. By the end of today’s lesson you should be able to: Three different types of neuron The structure and function of a neuron: variation in size and shape. Neuron -- Three part structure:> dendrite(s), the axon the cell body, Outline the structure & function of the neuron including: cell body, dendrites, axon, myelin sheath, schwann cell, and neurotransmitter vesicles & synaptic cleft

12.  A neuron is a specialised cell that carries electrical messages (impulses) around the body.  They vary in size and shape depending on their job.

13. There are three types of Neuron :  Motor neuron –carries impulses from the CNS to muscles and glands.  Interneuron –connects sensory and motor neurons and so carries messages within the CNS.  Sensory neuron –carries messages from the sense organ to the central nervous system (CNS).

16. Carrying messages along neurons Messages are carried around the body by the neurons. The conduction of an impulse along a neuron involves the movement of ions.

17.  Dendrites receives information and carry it towards the cell body.

18.  The cell body contains the nucleus and other organelles and produces neurotransmitter chemicals.

19.  The axon conducts impulses away from the cell body.

20.  Many Schwann cells wrap their fatty cell membranes around an axon, forming a myelin sheath.

21.  The myelin sheath insulates the neuron from electrical impulses flowing in other neurons.

22. By the end of today’s lesson you should be able to: Outline the structure & function neurotransmitter vesicles & synaptic cleft Outline impulse movement & synapse. Explain activation & inactivation of neurotransmitter.

24.  Synapse—place where two neurons come into close contact.  Synaptic cleft—the gap between two neurons

25. Carrying messages along neurons When an impulse reaches the end of a neuron it causes chemicals to be released called neurotransmitters. The neurotransmitters are said to be activated  Neurotransmitter—chemical released across a synaptic cleft to carry a signal from one neuron to another.

27. Carrying messages along neurons The neurotransmitters diffuse across the synaptic cleft. They are taken in by the next neuron and cause a new impulse to be started here!

29. Deactivation of neurotransmitters Some neurotransmitters remaining in the synaptic cleft will be broken down by an enzyme – this is called inactivation The remaining chemicals are reabsorbed into the presynaptic neuron and used again to make new neurotransmitters.

31. Nervous System Disorder  Parkinson’s disease is a nervous system disorder in which muscles become rigid and movement is slow and difficult, with persistent tremors [shaking].

32. Causes of the disease  In people with Parkinson’s disease it is found that the brain has reduces the normal amount of dopamine that it makes.  The lack of dopamine neurotransmitter causes signalling problems in the body – some messages can’t be carried properly

33. Treatment  There is at present no means of preventing it, but giving L-dopa (which the body changes into dopamine) can relieve the symptoms in many patients.

35. Think... Depression is known to be caused by a lack of the neurotransmitter serotonin in the brain How could a pharmacologist tackle this problem?

36. Can you… Outline the structure & function of the neuron including: cell body, dendrites, axon, myelin sheath, schwann cell, and neurotransmitter vesicles & synaptic cleft Outline impulse movement & synapse. Explain activation & inactivation of neurotransmitter.  Outline disorders from NS disorders: Parkinson's including:Cause/Treatment

37. By the end of today’s class… Outline the role of CNS, brain & spinal cord.  State location & function of cerebrum / hypothalamus / pituitary gland / cerebellum / medulla oblongata

38. The central nervous system  The central nervous system (CNS) is your brain and spinal cord.

39. The Brain

40.  The cerebrum is our conscious brain, with different parts having different jobs to do.  The pituitary gland secretes hormones that stimulate other glands to release their hormones.  The hypothalmus is the centre for the regulation of the internal organs. cerebrum hypothalamus pituitary

42.  The cerebellum co-ordinates processes that we have learned to do automatically, such as speaking.  The medulla oblongata co-ordinates involuntary, automatic processes — such as breathing, heartbeat. cerebellum Medulla oblongata

43. Conscious actions A conscious action is one where the brain makes a considered response. Here’s what happens: Stimulus Receptor Sensory Neuron Coordinator Motor Neuron Effector Muscle Response 1) Receptors in your skin detect a stimulus 3) Here another sensory neuron carries the signal to the brain 4) The brain decides to move away the hand 5) This impulse is sent by MOTOR NEURONS to the hand muscles (the effectors) via the spinal chord… 2) The impulse is carried by SENSORY NEURONS to the spinal chord 6) Which then moves the hand away

44. Consider this You've got an itchy ear!! What will you do??? Think about how the message will get passed around your body and how your body would respond

45. LEARNING CHECK Name the 3 main parts of the brain and one function of each. How is the brain protected? What is meant by “conscious action”? What does the term “involuntary” mean? Distinguish between the cerebrum and the cerebellum.

46. By the end of today’s class you should be able to: Outline the role of CNS, brain & spinal cord

47.  The spinal cord is protected by the vertebrae, meninges (three membranes) and cerebrospinal fluid.  It sends impulses to and from the brain and controls many reflex actions.

50.  Outside the grey matter, the spinal cord consists of white matter (containing axons only).  Grey matter contains cell bodies and dendrites

51.  spinal nerves branch off from the spinal cord. The ventral root consists of nerve fibres carrying information out from the spinal cord, to the muscles and glands.  The dorsal root consists of nerve fibres carrying information into the spinal cord from the senses

52. Peripheral nervous systems  The peripheral nervous system (PNS) is the nerves branching from the CNS to all parts of the body.

53. PNS The dendrites and axon parts of some neurons are found in the PNS. The cell body part of neurons are found in the CNS or in ganglia

54. Suppose you touch a hot flame.  A message is sent from pain receptors in the skin to the spinal cord by a sensory neuron Interneuron REFLEX ACTION --- The Reflex Arc  A reflex action is a quick, automatic response to a particular stimulus.

55.  In the spinal cord, the message is passed on to an interneuron and then to a motor neuron, and so into muscles that respond by contracting and pulling your hand from the flame. Interneuron

57. By the end of today’s lesson you should be able to: Know that sense organs contain receptors, with the brain as an interpreting centre for received information. Knowledge of the five senses and related organs. Study the eye– recognition and function of the main parts.

58. SENSE ORGANS  Animals collect information about their environment by using receptor cells.  A receptor is a cell that can detect a stimulus (any change in the environment).  Each of our sense organs contain receptor cells.  We have five sense organs – the eye, the ear, the tongue, the nose and the skin.  The five senses are sight, hearing, touch, taste and smell.

59. Our nose

60. Smell Taste Touch Hearing Sight Sense Nose Tongue Skin Ear Eye Organ chemicals [receptors in the nasal cavity detect vapours] chemicals [taste buds detect sweet, sour, salt and bitter]. touch, pressure, temperature and pain [receptors spread throughout body] sound [receptors in cochlea] light [by rods and cones in the retina] Stimulus detected

61. Section through a mammalian eyeball The eye

62.  Eyelids can cover and protect the eyes. The EYE  Conjunctiva — thin transparent lining protecting the cornea. Conjunctiva Eyelid  Cornea—front transparent part of the sclera. It focuses light rays on the retina. Cornea

63.  Sclera—tough fibrous outer layer – the ‘white’ of the eye; it maintains the shape of the eyeball.  Choroid—contains blood vessels supplying food and oxygen to the cells of the eye.  Retina—the innermost layer that contains the receptor cells [rods and cones]. Sclera Choroid Retina

64. Conjunctivitis is an inflammation of the conjunctiva most commonly due to an allergic reaction or an infection (usually bacterial, but sometimes viral).conjunctivaallergic reaction infectionbacterial viral

65.  Iris—controls the amount of light entering the eye [through the pupil]. Iris  The fovea is where our best vision is [mainly cones] Fovea

66.  In bright light, pupil decreases in size  In dim light, the pupil increases in size Pupil

67.  Ciliary body [muscle] —controls the shape of the lens  Lens—it focuses the light rays on the retina.  Suspensory ligaments — hold the lens in place. Ciliary muscle Suspensory ligaments Lens

68. A cataract is a clouding that develops in the lens of the eye which obstructs the passage of light lens

69. Seeing things at different distances For distant objects, the ciliary muscle relaxes and the shape of the lens is thinner– the light doesn’t bend as much. For close objects the ciliary muscle contracts, and the shape of the lens to goes fatter, thus bending the light more.

70.  Aqueous humour— keeps the shape of the cornea and lens.  Vitreous humour—gel that helps maintain the shape of the eye. Aqueous humour Vitreous humour

71.  When light rays focus on the retina, receptor cells are stimulated and impulses are carried along the optic nerve to the brain.  Blind spot—where the optic nerve fibres pass through the retina and there is no room for receptors! Optic nerve Blind Spot

73. Can you… Recognise the main parts of the eye and explain their functions?

74. Section through a mammalian eyeball The eye

83. Section through a mammalian eyeball The eye

84. Objectives Today: You should learn the parts of the ear, and all of their functions. How the ear works One disease of the ear – cause and correction

86.  Pinna—funnels sound into the ear canal. The Outer ear  Ear canal —tube leading to the ear drum. It has hairs and wax glands to trap dirt and germs.  Eardrum—membrane of skin that vibrates when sound waves hit it. Eardrum Pinna Ear Canal

87.  Eustachian tube- keeps air pressure equal on each side of the eardrum.  Ossicles— 3 small bones [hammer, anvil and stirrup], that amplify the sound. Middle Ear Ossicles Eustachian tube

88.  Semi-circular canals—help us keep our balance and posture.  Cochlea—a coiled, fluid- filled tube that convert sound vibrations into electrical impulses. Inner Ear Cochlea Semi-circular canals

89. How does the ear hear?

90. 1.Sound waves are collected by the pinna, 2. The waves travel along the ear canal. 3.The waves make the ear drum vibrate. 4.The ossicles amplify the vibrations. 5.Tiny hairs in the cochlea sense the vibrations and turns them into electrical signals. 6.The auditory nerve takes the signals to the brain. 3 4 5 6 1 2 How does the ear hear?

91. Glue ear A hearing disorder in children which results in some deafness. Cause –Eustachian tube becomes blocked and too much sticky fluid collects in the middle ear. Prevents the bones in the middle ear from vibrating! Correction – nose drops taken to decongest and unblock the Eustachian tubes.

92. Can you…. Name the parts of the ear, and all of their functions? Explain how the ear works Describe one disease of the ear – cause and correction!

93. 160 140 120 100 80 60 40 20 0 permanent ear damage can just be heard aircraft overhead decibels circular saw at 2m quiet countryside pin being dropped loud bell personal stereo How loud is loud?

94. Deafness  Deafness can be caused by long exposure to a high level of noise, drugs, or ear infections.  Damage to the eardrum, ossicles [bones], and cochlea, which can be caused by loud sounds, produces incurable deafness. Ear Defects – additional info  Workers exposed to prolonged sounds of over 90 decibels [dB] are obliged by law to wear ear protection.  Any exposure to 140 dB causes immediate damage to hearing.