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Function: | it allows us to experience the outside world |
5 sensory receptors | Chemorecptors - stimulated by changes in the chemicalâ taste & smell*
Pain Receptors - tissue damage - pain*
Thermoreceptors - temp.- heat & cold*
Mechanoreceptors â movements of body fluids - hearing & equilibrium*
Photoreceptors â light - sig |
2 groups of senses are: | General (Somatic) and Special |
General senses are | – pain, touch, pressure, temperature and proprioception |
General senses are found in | skin, muscle, joints and viscera |
Special senses are | – taste, smell, sight, hearing, balance |
Eyes include organs such as - | – eyebrows, eyelids, conjuctiva, eyelashes, lacrimal apparatus, extrinsic eye muscle |
Function of eyelids | – protect eyes from foreign substances * wash tears over the surface of the eyes |
Function of eyebrows | – keeps perspiration out * shade the eyes from glaring sunlight |
What is conjunctiva? | It is a thin mucous membrane that lines the inner surface of the eyelids * It secretes a thin mucous film that moistens the surface of the eye * It is also caused by allergies and irritation |
Function of Eyelashes | – aka Cilia - helps in traping dust |
Shapeand size of eye balls | - spherical in shape, 3/4 to 1 inch (2 – 3 cm) in diameter |
Lacrimal Apparatus - | secretion, distribution and drainage of tears * tears moisten, lubricate and cleans the surface of the eye. |
What is Retina? | contains – cons and rods *
innermost layer of the eyeball *
sensitive to light thus called photoreceptors |
List the 3 layers of the eye ball | Sclera *
Choroid *
Retina * |
What are the 2 cavities of the eyball? | Anterior and Posterior |
Function of ciliary body? | Separates the Aqueous humor and Vitreous humor |
What is Sclera? | Tough fibrous connective tissue, covering most of the eyeball * Helps contain the contents of the eye * Shapes the eye * Site for attachment of the extrinsic eye muscles |
What Cornea? | Is an extension of the sclera to cover the iris
Avascular
Called window of the eye
Rich supply of sensory nerve fibres thus sensitive to touch |
Window of the eye | - cornea |
What is corneal reflex? | If the surface of the cornea is touched lightly, the eye tears and blinks to remove the source of irritation, thus serving a protective function. |
What is Choroid? | The middle layer of the eye * * Highly vascular |
Functions of Choroid? | Provides retina with a rich supply of blood * Dark pigments located in the choroid absorb any excess light to prevent glare |
Name the anterior extensions of the choroid and sclera | Choroid – cililary body and iris *
Sclera – cornea |
Differentiate Cons and Rods? | Cons -are most abundant, provides with colour vision *
Rods – Sensitive to dim light, black and white vision. |
Function of Ear | Ear is the organ of the sense of hearing. |
Parts of the ear | - outer ear, middle ear, inner ear. |
Parts of the outer ear, which you can see | – auricle. It is a cartilage covered by a loose fitting skin. |
Function of the auricle | – gathering and directing sound waves |
What separates the outer ear from the inner ear? | Tympanic membrane |
What is earwax? | Auditory canal is lined with tiny hairs and glands that secrete cerumen, a yellowish waxy substance called earwax. |
Function of cerumen? | The ear wax or cerumen protect the inner ear from dust and dirt. |
Why should we not any foreign objects in our ear? | This could push the ear wax towards the eardrum thus imparing it from hearing. |
What is the middle ear? | Small air-filled chamber located between the tymphanic membrane and the bony wall. |
Parts of the inner ear | – tymphanic membrane, malleus, incus, stapes, eustachian tube |
Functions of the ossicles | – transmit vibration from the tymphanic membrane to the oval window. |
Proprioception | Sense of the body position and movement. Often uses as a test for nervous system damage. |
Pinna | ear flap, what we see |
Cochlea | snail shell-shaped cavity |
Organ of Corti | receptor organ of hearing; runs the length of the cochlea in the cochlear duct |
Vascular | middle layer of eye. Contains Choroid, Iris, Ciliary body |
Nervous | inner layer of eye; retina. Contains sensory receptors; rods and cones |
Anterior chamber | in front of the iris |
Posterior Chamber | behind the iris |
Lens | soft transparent, elastic, biconvex |
Iris | changes pupil size. colored portion of eye |
Rods | Greys |
Cones | Color |