1. The Sensory system

2. Lesson 1
OB 28 recall five sense organs in the human (eyes, ears, nose, skin, and tongue) and understand how these enable humans to gather information from their surroundings
Lesson 2
OB 29 describe the role of the central nervous system and the sensory and motor functions of nerves
Lesson 3
OB 30 locate the main parts of the eye on a model or diagram and describe the function of the cornea, iris, lens, pupil, retina, optic nerve and ciliary muscle

3. The Sensory system

4. The Senses What are the senses? Why do we need our senses?
Helps us to avoid danger
Allows us to appreciate nice objects
Tell the class that as animals our senses help us to avoid danger, danger from high voltage or if the principal is in a bad mood!
Show a picture of a Ferrari? Ask the class if they think it is nice?
Engage in a discussion and ask what would happen if they were blind? They will respond that they would not be able to see. The ask what would happen if they were deaf? If they lost the sense of taster, smell, and touch? Try to lead them into finding out what the senses are and how they work. Some will have a good understanding of it before hand and then you can explain everything to them as the lesson go on.

5. The Senses
Animals have 5 senses:
Sight
Hearing
Taste
Smell
Touch

6. The Senses The senses respond to stimuli: Light: sense of sight
Sound: sense of hearing
Pressure and Heat: Senses of touch
Chemical substances: Sense of taste and smell
Each of the senses responds to what is called a stimulus. The stimuli are: Light, Sound, Pressure +heat and chemical substances.

7. Sense Organs Eye: Organ of sight Ear: Organ of hearing
Skin: Organ of touch
Tongue: Organ of taste
Nose: Organ of smell
The human body has 5 sense organs. I have added in three skin cancer types to show the class the importance of taking care of the skin during the summer months. I want them to become aware of the dangers of skin cancer and some of these images may help them.

8. Sense Organs Eyes: Detect light Ears: Detect sound
Skin: Detects pressure + heat
Tongue: Detects taste
Nose: Detects smell
We use our eyes to see things. We can therefore see what dangers are ahead
Our ears help us to hear all around us. This help us to warn us of any dangers. We use our ears to listen to our friends, teachers and to listen to our favourite music.
The skin detects heat and pressure.
The tongue detects taste, this allows us to determine if something is good or bad
The nose detects chemicals in food or perfumes. We use our noses to smell objects, these objects can be pleasant or unpleasant.

9. Nervous system System of communication Two Parts:
Central nervous system: consists of the brain and spinal cord
Peripheral nervous system: consists of the nerves or neurons
The nervous system takes in all the information that comes from our senses. The nervous system also controls the body’s response to this information. The function of the nervous system is a system of communication.

10. Brain Is the centre of our intelligence
Contains 100 billion nerve cells
Electrical signals or impulses pass through these cells
Gives us our ability to think, make decisions
Protected by the skull
The brain communicate with other parts of the body by allowing impulses to pass through the nerve cells. It is in the brain that we actually feel the information that comes from the senses, such as pain and heat.

11. Spinal cord Is an extension of the brain Nerves branch off from it
Most signals pass from the senses and go through the spinal cord
Most signals that pass from the brain go through the spinal cord
Protected by the backbone
Sensory Neurons
Motor Neurons
The branching of nerve cells allows nerve impulses to be carried to and from the parts of the body.

12. Nerves Nerves cell = neuron Two types:
Sensory neurons: carry signals from the senses to the CNS
Motor neurons: carry signals away from the CNS to the muscles
As the class if they have ever put their hand onto a hot cooker. If they have ask them what did they do? They will tell you that they removed their hand very quickly. Explain to them why they did this. Firstly, the skin detected heat coming from the cooker, this message was delivered via sensory neurons in the hand which moved along the arm to the spinal cord. The message was then sent to the brain. Here it was processed and a response to remove the hand was sent through the spinal cord to the muscles in the arm and hand to remove it before it got burned.

13. The Eye Organ of sight Detects light and distinguishes colour
Made up of three parts
Sclera
Choroid
Retina
The eye is the body’s organ of sight. It allows us to detect light and to distinguish colour, let them know that some animals can only see black and white. Having two eyes allows us to judge distances. The basic structure of the eye is a ball shape, of which we can only see a small part. Most of the eyeball is in fact hidden inside the skull.

14. The Eye Sclera Iris Choroid Pupil Aqueous humour Retina Cornea
Think of the eye as a camera. A camera needs a lens and a film to produce an image. In the same way, the eyeball needs a lens to refract, or focus the light and a film (retina) on which to focus the rays.  If any one or more of these components is not functioning correctly, the result is a poor picture.  The retina represents the film in our camera.  It captures the image and sends it to the brain to be developed.
Retina
Cornea
Vitreous humour
Lens

15. Sclera & Cornea The sclera is the outer coating – protects the eye.
The cornea is the transparent bump on the front of the eye; it bends the light, producing an image on the retina. (The lens provides fine adjustment of the focus to match the distance to the object.)
The sclera is commonly known as "the white of the eye." It is the tough, opaque tissue that serves as the eye's protective outer coat. Six tiny muscles connect to it around the eye and control the eye's movements. The optic nerve is attached to the sclera at the very back of the eye. The retina's sensory receptor cells of retina are absent from the optic nerve.  Because of this, everyone has a normal blind spot. This is not normally noticeable because the vision of both eyes overlaps.

16. Choroid Darkly coloured Front part – iris – coloured part of eye
Pupil – centre of the iris
Allows light to enter the eye
Function of the iris is to control the amount of light that enters the eye
The iris has the ability to change in size. This in turn changes the size of the pupil. Pupil can dilate when more light is needed to enter the eye. Conversely the iris can close down the size of the pupil when there is too much light

17. Retina Part of the eye that detects light Cells are light sensitive
Optic nerve carries nerve impulses from the eye to the brain
Blind spot – has no light sensitive cells
Lens – adjusts the focus (depending on the distance to the object) to form a sharp image on the retina.
Ciliary muscles – change the shape of the lens to change the point of focus
When light falls on the light sensitive cells an electrical signal is generated. The signals produced by all of these cells are gathered together and leave the eye through the optic nerve
The lens is just behind the pupil
If you are reading a book you will notice that far away objects are out of focus. As soon as you look up those far away objects come into focus. By changing the shape of the lens, the ciliary muscles change our point of focus.

18. The Eye Sclera Iris Choroid Pupil Aqueous humour Retina Cornea
Think of the eye as a camera. A camera needs a lens and a film to produce an image. In the same way, the eyeball needs a lens to refract, or focus the light and a film (retina) on which to focus the rays.  If any one or more of these components is not functioning correctly, the result is a poor picture.  The retina represents the film in our camera.  It captures the image and sends it to the brain to be developed.
Retina
Cornea
Vitreous humour
Lens

19. Part of The Eye
Function
Cornea
Provides most of the focussing of light.
Iris
Controls the amount of light that enters the eye.
Pupil
The hole in the middle of the iris; allows light to enter the eye
Retina
Detects light and produces nerve impulses.
Lens
Provides fine focus of the image on the retina
Ciliary muscle
Changes the shape of the lens
Optic nerve
Carries nerve signals from the eye to the brain

20. The Eye Sclera Iris Choroid Pupil Aqueous humour Retina Cornea
Think of the eye as a camera. A camera needs a lens and a film to produce an image. In the same way, the eyeball needs a lens to refract, or focus the light and a film (retina) on which to focus the rays.  If any one or more of these components is not functioning correctly, the result is a poor picture.  The retina represents the film in our camera.  It captures the image and sends it to the brain to be developed.
Retina
Cornea
Vitreous humour
Lens