Chapter 15: Anatomy Of The Eye Flashcards Preview

Advanced Anatomy & Physiology > Chapter 15: Anatomy Of The Eye > Flashcards

Flashcards in Chapter 15: Anatomy Of The Eye Deck (28):
1

What are the 5 special senses?

1. Vision
2. Taste
3. Smell
4. Hearing
5. Equilibrium

2

How is the eye protected?

By fat cushion and bony orbit

3

What are the 5 accessory structures of the eye?

1. Eyebrows
2. Eyelids
3. Conjunctiva
4. Lacrimal apparatus
5. Extrinsic eye muscles

4

Describe the Eyebrows

Location: over lie supraorbital margins
Functions: shade, prevents perspiration

5

Describe the Eyelids

Location: separate at palpebral (slit), meet in the corners at medial and lateral commissures

Function: blinks reflexively every 3-7 seconds, offers protection from foreign objects and spreads secretion

Eyelashes

Tarsal (Meibomian) glands

6

Tarsal (Meibomian) glands

Modified sebaceous glands produce oily secretion that lubricates lid and eye

7

Describe the Conjuctivia

Transparent mucous membrane that produces a lubricating mucous secretion

8

Conjunctivitis

Inflammation of the conjunctiva resulting in reddened, irritated eyes

9

Pink Eye

Conjunctival infection caused by bacteria or viruses

10

Lacrimal Apparatus

Consists of lacrimal gland and ducts (that drain into nasal cavity)

Process:
1) lacrimal gland secretes lacrimal secretion (tears)
2) tears drain into lacrimal sac and nasolacrimal duct
3) empties into nasal cavity

11

What causes watery eyes when you have a cold (or nasal inflammation) ?

Lacrimal mucosa are swelled which constricts the ducts and prevents tears from draining--> watery eyes

12

Describe Extrinsic Eye Muscles

6 strap like extrinsic eye muscles
- Origin: bony orbit and insert on eyeball
- Function: enables eye to follow moving objects, maintain shape of eyeball, and hold it in orbit

13

What are the 3 layers of the wall of the eye?

1) Fibrous layer
2) Vascular layer
3) Inner layer

- internal cavity filled w/ liquid (humors)

14

Describe the Fibrous Layer

Has 2 regions

- Sclera: protects and shapes eyeball
- Cornea: lets light enter and bends light

• Numerous pain receptors (blinking and tearing reflexes)

15

Describe the Vascular Layer

Also called uvea

Has 3 regions:

1. Choroid
2. Ciliary Body
3. Iris

16

Choroid region

Posterior portion of uvea

- supplies blood to all layers of eye

17

Ciliary Body

Anteriorly, choroid becomes ciliary body

- Consists of smooth muscle bundles, ciliary muscles--> controls shape of lens

• Capillaries of ciliary processes secrete fluid
• Ciliary zonule (from ciliary processes to lens): holds lens in place

18

Iris

Contains the pupil (controls amount of light entering the eye)

19

Describe the Inner Layer (Retina)

Contains:
• Photoreceptor cells (transduce light energy)
• Neurons
• Glial cells

Has 2-layered membrane
- Outer pigmented
- Inner neural layer

20

Outer pigmented layer

Covers ciliary body and iris

- Function:
1) absorbs light and prevents it from scattering
2) Phagocytizes photoreceptor cell fragments
3) Stores vitamin A

21

Inner Neural Layer

3 types of neurons:
1) Photoreceptors
2) Bipolar cells
3) Ganglion cells

Journey of Light:
Signal--> Photoreceptors --> Bipolar cells --> Ganglion cells ---(exits eye)---> Optic nerve--> brain

Optic disc (blind spot): optic nerve leaves eye

2 types of photoreceptors:
1) Rods
2) Cones

22

Rods

Dim light, peripheral vision
- more numerous and more sensitive to light
- no color vision

23

Cones

Bright light
- color vision
• Macula lutea
• Fovea centralis

24

Macula lutea

Area at posterior pole lateral to blind spot
- contains mostly cones

25

Fovea centralis

Tiny pit in center of macula lutea that contains all cones, so is region with best visual acuity
- eye movement allows to focus on object so fovea can pick it up

26

Internal chambers and fluids

The lens and ciliary zonule separate eye into 2 segments:

1) Posterior segment
2) Anterior segment

27

Posterior segment

Vitreous humor: transmits lights and contributes to intraocular pressure
- forms in embryo and lasts whole lifetime

28

Anterior segment

Aqueous humor: plasma-like fluid continuously formed by capillaries of ciliary processes
- drained by scleral venous sinus
- Function: supplies nutrients and oxygen mainly to lens and cornea and retina, and remove wastes