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The Senses Chapter 35.

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Presentation on theme: "The Senses Chapter 35."— Presentation transcript:

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)

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