1. The Senses
Chapter 35

2. 5 senses --- touch , taste, smell, sight & hearing
The skin is the organ of touch
Touch is a combination of pain, pressure, hot & cold
TASTE
The tongue is the organ of taste
Receptors for taste are located in the taste buds
Sweet--- tip of tongue
Salt--- sides of tongue near front
Sour--- sides of tongue near back
Bitter--- across back of tongue

3. SMELL
The nose is the organ of smell
The Olfactory neurons in the nose detect smell
SIGHT
The eye is the organ for sight

5. The Eye PART FUNCTION conjunctiva protection sclera
Lets no light through
Holds the eye in shape
cornea
Lets light into the eye
choroid
Nourishes eye & prevents reflection of light with in eye

6. Fovea (yellow spot)
Contains cones only– region of sharpest vision
Blind spot
Where optic nerve leaves the eye
Optic nerve
Carries impulses from the eye to the brain
Lens
Changes shape to focus light on the retina
Ciliary muscle
Cause the lens to change shape

7. Iris (coloured part)
Controls the amount of light entering the eye
Pupil
Lets light into the eye
Aqueous Humour
Holds the front of the eye in shape
Retina
Contains rods & cones (the light receptors)
Rods for black & white vision & work in dim light
Cones for colour vision & work in bright light
Vitreous Humour
Holds the back of the eye in shape

8. Long Sightedness--Hypermetropia
Person with long sight can see distant objects clearly, but cannot see near objects
Cause: eyeball is too short
To Fix: use CONVEX lens

10. Short sightedness--- Myopia
Person can see near objects clearly, but cannot see distant objects
Cause: the eyeball is too long
To Fix: use CONCAVE lens

12. Accommodation
Is the ability of the eye to focus light from objects at different distances by altering the focal length of the retina

14. Response of Iris to light
BRIGHT LIGHT
the circular muscles contract
the size of the pupil decreases
Less light enters the eye

15. DIM LIGHT
The circular muscles relax
The size of the pupil increases
More light enters the eye

16. Hearing The function of the ear is hearing and balance
There are 3 sections to the ear
Outer ear
Middle ear
Inner ear

18. The Ear PART FUNCTION Auditory canal
Collects vibrations & carries vibration to eardrum
Eardrum
Carries vibration to the middle ear
Ossicles– hammer, anvil, stirrup
Increases the vibrations & passes them to the oval window
Eustachian tube
Connects the middle ear & pharynx
Equalises pressure between the middle & outer ear

19. Cochlea
Hearing– contain receptors which are stimulated by pressure waves in lymph. Receptors cause electrical impulses to be sent to the brain along the auditory nerve which interprets them as sound
Organ of Corti
Contains receptors for hearing
Pinna
Collect and channel vibration into the auditory canal
Vestibular apparatus
Balance

20. How we hear Sound waves enter the ear Eardrum vibrates
Three bones amplify the sound
Oval window vibrates
Liquid in cochlea moves
hair cells stimulated
Auditory nerve carries impulses to the brain
Brain interprets the sound

22. Glue Ear Is a hearing disorder
Caused: by too much sticky fluid in the middle ear
Corrected: by decongestants or grommets( small tubes inserted into the eardrum)