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senses 2: Eyes and ears.
part two revision
23
Anatomy
Undergraduate 1
01/05/2008

Additional Anatomy Flashcards

 


 

Cards

Term

 

 

 

 

Accessory structures of the eyes

Definition

 

 

 

Eyebrows/eyelashes: Protective.

Eyelids: Protective

lacrimal glands:tears wash out dirt

Conjunctivae: lubricate cornea

 

Term

 

 

 

 

Eyeball structure The bulk of the eyeball is made of a jelly (vitreous humour) surrounded by three layers of tissue

 

 

 

Definition

 

 

sclera ……fibrous outer layer – protects and gives shape to eyeball


choroid – rich in blood vessels; nourishes the retina; absorbs light rays

 

retina ……rich in photoreceptors & nerves – image formation

These layers develop into special structures at the front of the eyeball. The sclera becomes the cornea and the choroid becomes the ciliary body (process and muscle) and iris
Term

 

 

 

 

 

cornea

Definition

 

 

 

 

 

bends (refracts) light

Term

 

 

 

 

 

Ciliary process

Definition

 

 

 

 

secretes aqueous humour 

Term

 

 

 

 

ciliary muscle

Definition

 

 

 

 

changes lens shape 

Term

 

 

 

 

 

Iris 

Definition

 

 

 

controls light entry

Term

 

 

 

 

 

lens

Definition

 

 

 

focuses light rays 

 

Term

 

 

 

 

 

Aqueous humour 

Definition

 

 

 

 

 

Bends light; circulates & nourishes front of eye

 

 

 

 

 

Term

 

 

 

 

 

vitreous humour 

Definition

 

 

 

 

bends light, maintains eye shape

Term

 

 

 

 

Formation of an image on the retina involves three processes

Definition

 

 

 

1. refraction  or bending of light rays

      2. formation of an inverted image on the retina (the brain readily reinverts it)

3. adjustments for close vision (accomodation)

 

Term

 

 

 

 

 

common visual problems. 

Definition

conjunctivitis - inflammation of conjunctivae (blood shot eyes)

 

cataract increased opacity of lens/cornea

 

short (near)sightedness eyeball too long; rays focused in front of retina

 

astigmatism uneven surface of lens/cornea; difficult to focus clearly

Term

 

 

 

 

two types of photoreceptor

Definition

 

 

Rods & cones; rods are most numerous

 

The  rod  cells give us black and white vision

 

The  cone  cells can absorb red, blue or green light depending on the type of photo-pigment protein present. Deficiency of pigment leads to colour-blindness

 

 

Term

 

 

 

glaucoma 

Definition

 

 

 

 

Increased pressure inside the eye caused by decreased drainage of aqueous humor compresses the retinal blood vessels 

Term

 

 

 

 

retinopathy

Definition
Term

 

 

 

 

 

 

ears perform two sensory functions:

Definition

 

 

 

 

hearing and balance

Term

 

 

 

 

Gross structure of the ear. 

Definition

 

 

 

·         outer ear - auricle, auditory canal to tympanic membrane

 

·         middle ear- cavity between eardrum and inner ear containing ossicles.

 

·         inner ear - a complex of bony tunnels lined with a membrane

 

Term

 

 

 

 

endolymph.

Definition

 

 

 

Fluid inside the inner ear. 

Term

 

 

 

Receptors for balance

Definition

 

 

Rotational movement of the head will cause endolymph fluid to move within the semicircular canals to varying extents. This is detected by receptor structures called ampullae , located on the membrane at the base of each of the three canals

 

 

 

 

Term

 

 

 

 

receptors for balance.
Definition

 

 

 

 

hair cells.

 

Similar receptor cells are located in two sacs within the vestibule

Both sets of receptors send information via the vestibular  nerve to the cerebellum, a region of the brain important for coordination of movement

 

 

Term

 

 

 

Receptors for Hearing

Definition

 

 

 

  • located in the cochlea of the inner ear.
  • hair cells                                            
This whole sensory structure is known as the organ of corti or spiral organ.

 

 

Term

 

 

  1. Summary of the Mechanism of Hearing
Definition

 

  1. vibration of tympanic membrane (eardrum)
  2. amplified by the ossicles (3 bones in the middle ear)
  3. vibration of the oval window

 

 4. Movement of perilymph  (fluid in the cochlea)

5.  Movement of endolymph (fluid in the cochlear duct)

 6. Hair cells on the organ of corti (spiral organ)

move relative to the membrane above

7.the hairs bend

8. Electrical activity in the hair cells

9.  Nerve impulse (cochlear  nerve)

10.  Translated in the cerebral cortex and perceived as sound.

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