OD - Review Lecture - Week 12

Question 1

(CT): What type of connective tissue is mostly found in the eye: proper, specialised or supporting?

Answer 1

Proper

Question 2

(CT): Name a function of connective tissue

Answer 2

• support
• protection
• storage
• metabolic exchange
• specialised (e.g. Cornea [refractory])

Question 3

(CT):?What is the composition of connective tissue?

Answer 3

• cells

- ECM (fibres: collagen, elastic, reticular,, ground substance: GAGs, proteoglycans, glycoproteins)

Question 4

(CT): What is a glycosaminoglycan and a proteoglycan?

Answer 4

GAG = Repeating disaccharide amino sugar + uronic acid

PG = Core protein + GAG

Question 5

(CT): What cells can be found in the ECM?

Answer 5

Fixed – fibroblast, pericytes, adipose, macrophages, mast cells

Transient – plasma cells, leukocytes

Question 6

(CT): What are the layers associated with the sclera?

Answer 6

• tenons
• conjunctiva (anteriorly)
• episclera
• sclera
• Lamina fusca

Question 7

(CT): What is the composition of the sclera?

Answer 7

Type I, III, V collagen (with associated type VI/XII)

Large Aggrecan

Linked by hyaluronan

Small biglycan

Decorin

Fibroblast

Question 8

(CT): Compare the difference in collagen between the sclera and cornea?

Answer 8

Size, uniformity, organisation, type, spacing

Question 9

(Cornea): what are the layers of the cornea?

Answer 9

Epithelium
Bowman's layer
Stroma 
Descement's membrane 
Endothelium

Question 10

(C): How many cell layers in the epithelium and endothelium?

Answer 10

Epi: 6 layers, ~50um thick

Endo: 1 layer, ~10um thick

Question 11

(C): How are epithelial cells held together?

Answer 11

• tight junctions, desmosomes, gap junctions

Question 12

(C): What collagen type is found in the cornea?

Answer 12

Mostly type I (core), surrounded by III and V

Question 13

(C): what cells are found in the corneal stroma?

Answer 13

• keratocytes: flattened, quiescent, higher number anterior

- —- transform to myocibroblasts after injury/infection

Question 14

(C): What happens when the cornea swells?

Answer 14

• corneal oedema

- loss of clarity

Question 15

(C): what are the factors in the cornea that give it clarity?

Answer 15

• nerves, avascular, few cells, no pigment, ion pumps, collagen arrangement (uniform)

Question 16

(C): why does water want to enter the stroma?

Answer 16

Slightly leaky endothelium, hypertonicity of stroma, Donnan swelling

Question 17

(C): What pumps the water out?

Answer 17

• epithelium and endothelium

Note: that evaporation also counters/opposes swelling

Question 18

(C): What can modify corneal thickness?

Answer 18

• genes
• sleep
• contact lens wear
• trauma
• disease (seminar)

Question 19

(C): Why does the epithelium pump Na+ into the stroma?

Answer 19

Na/K ATPase pumped it into the stroma dlso that it can be used for Chloride co-transport

Question 20

(C): Where does the chloride go and why?

Answer 20

Into the tears, gradient draws water across

Question 21

(C): What neurotransmitter, receptor and second messenger control?

Answer 21

Noradrenaline, b-adronergic, adenyl cyclase, cAMP