Anat and Physio

Question 1

Name the three layers of the eye ball

Answer 1

1. Fibrous(Sclera n Cornea) 2. Vascular(Choroid, Ciliary Body, Iris) 3. Inner (Retina)

Question 2

Name the two parts of the fibrous layer.

Answer 2

1. Cornea = anterior 1/6 2. Sclera = posterior 5/6

Question 3

What is the external sheet of the cornea made of?

Answer 3

Stratified squamous epithelium

Question 4

What is the corneal endothelium (deep epithelial sheet) composed of?.

Answer 4

Simple squamous endothelium

Question 5

features of the cornea that allow it to keep its transparency

Answer 5

1. No blood vessels 2. Active sodium pumps in corneal endothelium

Question 6

What is the constant pressure in the cornea

Answer 6

There is a constant intraocular pressure pushing aq humour into stroma

Question 7

What is the benefit of the endothelial pump

Answer 7

Maintains clarity of cornea by keeping water content low.

Question 8

What is the function of the sclera?

Answer 8

Provides anchoring site for extrinsic eye muscles

Question 9

Name the three parts of the vascular layer.

Answer 9

1. Choroid 2. Ciliary body 3. Iris

Question 10

What is the function of the choroid?

Answer 10

1. Supplies blood to all 3 layers of the eye. 2. Melanocytes absorb light and prevent it from scattering.

Question 11

What is the function of the iris?

Answer 11

Controls diameter of pupil regulating amount of light admitted to eye.

Question 12

What muscles control the iris functions

Answer 12

1. Dilator pupillae - radial muscle 2. Sphincter pupillae - circular muscle

Question 13

List the two functions of the ciliary body

Answer 13

1. Smooth muscle bundles control shape of lens 2. Produces aqueous humor.

Question 14

Describe the vascularity of the retina.

Answer 14

1. Inner 2/3 supplied by central artery 2. Outer 1/3 - supplied by blood vessels in choroid

Question 15

Describe the histology of the fovea centralis

Answer 15

1. Avascular. 2. Contains only cones. 3. Outer layers of retina displaced - allows light to pass directly to cones.

Question 16

How does the eye focus an image on the retina?

Answer 16

Ciliary muscles and ciliary zonule change shape of lens.

Question 17

What is the anatomical positioning of the lens

Answer 17

Sits behind the pupil suspended from ciliary body by sensory ligaments in a 360 degree fashion

Question 18

Describe the structure of the lens

Answer 18

1. Avascular 2. Biconvex 3. Enclosed in thin, elastic capsule. 4. Flexible 5. Transparent

Question 19

Why is it harder for eye to focus as we get older age?

Answer 19

1. Cuboidal cells in lens ==> new lens fibers continually 2. Lens gets larger, denser, more convex, and less elastic.

Question 20

What structure separates the anterior and posterior segments of the eye?

Answer 20

Lens

Question 21

Describe the structure of the anterior segment?

Answer 21

1. Divided into 2 chambers - anterior and posterior - by iris. 2. Filled with aqueous humor.

Question 22

Name the two muscles of the eyelid and describe their functions.

Answer 22

1. Levator palpebrae superioris - elevates to open 2. Obicularis oculi - contracts to close

Question 23

What is the conjunctiva

Answer 23

Membrane that lines the inside of the eye lid and the sclera infront - doesn’t extend over cornea

Question 24

True or False. The mucous membrane that lines the eyelids and is reflected over the anterior surface of the eyeball is the conjunctiva.

Answer 24

True

Question 25

True or False. Vitamin A needed by the photoreceptor cells is stored by the cells of the retina pigmented layer.

Answer 25

False. Stored by the retinals.

Question 26

True or False. The optic disc is forms a blind spot where the optic nerve leaves the eyeball.

Answer 26

True

Question 27

True or False. Ciliary muscles are considered voluntary, skeletal muscle.

Answer 27

False. Ciliary muscles are controlled by parasympathetic fibers of the oculomotor nerve.

Question 28

True or False. The neural layer of the retina prevents excessive scattering of light within the eye.

Answer 28

False. The pigmented layer prevents excessive scattering of light.

Question 29

True or False. Light passes through the entire thickness of the neural layer of the retina to excite the photoreceptors.

Answer 29

True.