Sense Organs (Eye and Nose)

Question 1

Layers of Cornea (outer fibrous layer)

Answer 1

1. Stratified squamous non-keratinized epithelium (5-6 layers)
2. Anterior basement (Bowman’s) membrane
3. Stroma (90% of cornea - Collagen and Keratocytes)
4. Dua’s Layer (Collagen Layer)
5. Posterior basement (Descemet’s) layer
6. Endothelium (simple squamous epithelium)

Question 2

Limbus

Answer 2

• between cornea and sclera
• contains stem cells for Regeneration of corneal epithelium

Question 3

Layers of Iris (vascular layer)

Answer 3

1. Layer of fibroblasts and melanocytes
2. Stroma (vascularized and pigmented loose CT + muscle cells near the pupil)
3. Epithelium (on the posterior surface)
   a) anterior pigment myoepithelium
   b) posterior Pigment epithelium

Question 4

General structure of the eye - layers

Answer 4

1. Outer fibrous layer (cornea and sclera)
2. Middle vascular layer (choroid, ciliary Body and iris)
3. Inner Sensory layer (retina + optic nerve)

• Lens behind the Iris

Question 5

Chambers of the eye

Answer 5

1. Anterior Chamber
   - between cornea and Iris
   - aqueous humor
2. Posterior chamber
   - between posterior surface of iris and the lens
   - aqueous humor
3. Vitreous Chamber
   - between post. Surface of Lens and the retina
   - vitreous humor

Question 6

Layers of sclera (outer fibrous layer)

Answer 6

1. Episclera (loose CT with blood vessels)
2. Substantia propria (dense network of thick Collagen fibers and fibroblasts)
3. Suprachoroid lamina (LCT with thinner Collagen fibers, elastic fibers, fibroblasts, melanocytes, macrophages)

Question 7

Layers of ciliary Body (middle vascular layer)

Answer 7

1. Stroma
   a) ciliary muscle (outer layer, smooth muscle fibers
   b) inner vascular region (thickening form ciliary processes, in anterior part)
2. Epithelium
   - Double layer of low columnar cells, contains melanin

Question 8

Layers of choroid (middle vascular layer)

Answer 8

1. Choroidocapillary lamina (thicker layer)
   - LCT with blood vessels and melanocytes
2. Bruch’s membrane (thinner layer)
   - Collagen and elastic fibers

Question 9

Lens structure

Answer 9

-Transparent, avascular, biconvex
1. Lens capsule (Type IV collagen)
2. Subcapsular epithelium (only in anterior Lens Surface)
- Single layer of cuboidal cells
3. Lens fibers

Question 10

Lens function

Answer 10

1. Accomodation
2. Refraction

Question 11

Layers of retina (inner sensory layer)

Answer 11

1. Retinal Pigment epithelium (RPE)
   
   • outer layer
2. Neural retina
   
   • inner layer
   • contains neurons and neuroglia

Question 12

Regions of retina (inner sensory layer)

Answer 12

1. Non-photosensitive region
   - anterior to ora serrata
2. Photosensitive region
   - posterior to ora serrata

Question 13

Layers of RPE and neural Retina (inner sensory layer)

Answer 13

1. RPE (Not Part of neural retina)
2. Layer of Rods and cones (RCL)
3. Outer limiting membrane (OLM)
   - apical boundary of Müller’s cells
4. Outer nuclear layer (ONL)
   - bodies of photoreceptors
5. Outer Plexiform layer (OPL)
   - processes of cells
6. Inner nuclear layer (INL)
   - bodies of cells
7. Inner Plexiform layer (IPL)
8. Ganglion cell layer (GCL)
9. Nerve Fiber layer (NFL)
10. Inner limitating membrane (ILM)

Question 14

Photoreceptor cells

Answer 14

1. Rods
   - more sensitive to light
   - allow Vision with low light levels
   - Rhodopsin in them
   - Image in grey tones
2. Cones
   - Produce Color vision
   - Iodopsin in them

Question 15

Phototransduction

Answer 15

1. Rhodopsin absorbs a photon
2. 11-cis retinal converted to all-trans retinal and detaches from opsin (Bleaching)
3. Reaction cascade leading to photoreceptor hyperpolarization
4. Reduced synaptic Release of neurotransmitters
5. Depolarization of bipolar neurons
6. Action Potential Send to ganglion cells of optic nerve

Question 16

Müller’s cells (General Information)

Answer 16

• bodies located in INL
• processes surround all neuronal processes, cell bodies and blood vessels
• ends of apical processes form the OLM
• ends of basal processes Form the ILM

Question 17

Functions of Müller’s cells

Answer 17

1. Maintain blood-inner retina Barrier
2. Remove waste products
3. Regulate Water and ion homeostasis
4. Provide structural Support to neurons

Question 18

Optic Disc

Answer 18

• region where axons in the NFL converge and leave the eye as optic nerve
• called blind spot

Question 19

Fovea centralis

Answer 19

• shallow Depression in the retina
• only RCL
• only Cones
• ensures maximal Visual acuity

Question 20

Macula lutea

Answer 20

• area surrounding the fovea centralis
• high concentration of cones

Question 21

Layers of olfactory mucosa

Answer 21

1. Olfactory epithelium
   - pseudostratified columnar cells
   a) olfactory neurons
   b) supporting cells
   c) basal cells
2. Lamina propria
   - loose CT with
   a) blood and lymphatic vessels
   b) bundles of axons
   c) olfactory (Bowman’s) glands

Question 22

Basal cells (olfactory epithelium)

Answer 22

• small, spherical
• close to basal lamina
• stem cells for supporting and olfactory cells
• replace olfactory neurons every 2-3 months

Question 23

Supporting cells (olfactory epithelium)

Answer 23

• columnar
• nuclei located more apically
• apical end - microvilli
• metabolical and physical Support to olfactory neurons
• secrete odorant-binding proteins

Question 24

Olfactory (Bowman’s) glands (lamina propria of olfactory mucosa)

Answer 24

• branched tubuloalveolar serous glands
• their secretions serve as a trap and solvent odoriferous substances