Visual, Vestibular, and Auditory Histology (Dr. Olinger) TEST 2

Question 1

Gross Anatomy of the Eye

Answer 1

ANTERIOR CHAMBER:
- Everything Anterior t the Iris

POSTERIOR CHAMBER:
- Everything between the Iris and Lens

VITREOUS CAVITY:
- Located behind the Lens

Question 2

Tunica

Answer 2

1) OUTER TUNICA (Sclera and Corena):
- CORNEA: is Transparent

• SCLERA: Opaque and LINED inside the Middle or Vascular Pigmented Layer that ABSORBS Light

2) MIDDLE TUNICA (Uvea):
- UVEA: Contains the Iris, the Ciliary Process, and the Choroid. All of the Blood Vessels run INTO the Choroid

3) INNER TUNICA (Retina):
- The RETINA contains Photoreceptor Neurons (Cones and Rods), Conducting Neurons (Bipolar and Ganglion), Association Neurons (Horizontal and Amacrine Cells), and a Supporting Neuroglia Cell (Müller Cell)

• Only CONE Cells are present in the FOVEA!!!
• Axons from the Retinal Ganglion Cells pass across the surface of the Retina, converge on the PAPILLA or OPTIC DISC, and leave the eye through many openings of the Sclera

Question 3

Outer Tunica

Answer 3

• The LIMBUS is the Zone of transition of the Epithelium of the CONJUCTIVA with that of the Cornea
• The LUMBUS is also the boundary of the Transparent CORNEA with the Opaque SCLERA

Question 4

Cornea

Answer 4

• BASAL Cells of the Corneal Epithelium are ANCHORED to BOWMAN’S LAYER by HEMIDESMOSOMES!!!
• CORNEAL ENDOTHELIUM Participates in the ACTIVE TRANSPORT of Materials from the AQUEOUS HUMOR into DESCENT’S MEMBRANE and part of the Corneal STROMA!!!
• Corneal Endothelial Cells contain ABUNDANT MITOCHONDRIA!!!

Question 5

Cornea Layers

Answer 5

1) Corneal Epithelium
2) Hemidesmosomes
3) Bowman’s Layer
4) Stroma
5) Descent’s Membrane
6) Corneal Endothelium
7) Aqueous Humor

• The STROMA is formed by COLLAGEN LAMELLAE oriented at an angle to one another. FIBROBLASTS, surrounded by Extracellular Matrix, are present between Lameliae
• The transparency of the Cornea depends on the arrangement of the Collagen Lamellae and the affinity for Water of the Extracellular Matrix. BLOOD VESSELS ARE NOT PRESENT IN THE STROMA!!!!!!!!
• CORNEAL ENDOTHELIUM is PERMEABLE to AIR Oxygen used for Various Oxidative reactions, in particular Glutathione Reduction and Oxidation.
• The GLutahtione Pathway NEUTRALIZES Excess Active Oxygen in the Cornea. About 30% of Glucose is Metabolized in the Cornea by GLYCOLYSIS

Question 6

Clinical Considerations: Corneal Transplants

Answer 6

• The MOST COMMON form os Tissue Allotransplantation with a SUCCESS RATE of over 90%!!!

Question 7

Tunica

Answer 7

• CILIARY PROCESSES extend INWARD from the Ciliary Body. The Vascular Layer continues as the IRIS, whose free edge outline the PUPIL!!!!
• The ANTERIOR Portion of the CILIARY BODY contains Smooth Muscle:
  1) MUSCLE of the CILIARY BODY
  2) Dilator Muscle of the Iris
  3) Constrictor Muscle of the Iris

**The Smooth Muscle of the Ciliary Body regulates the TENSION of the ZONULE or SUSPENSORY LIGAMENT of the Lends and therefore, is an IMPORTANT element in the mechanisms of ACCOMMODATION!!!!!!

Question 8

Aqueous and Vitreous Humor

Answer 8

• AQUEOUS HUMOR: FLUID like, needs to be Circulated, and Regenerated!!!!!
• VITREOUS HUMOR: Gel like!!!!

Question 9

Ciliary Body

Answer 9

1) DILATOR PUPILLAE:
- Consisting of MYOEPITHELIAL CELLS, contains Alpha Adrenergic Receptors and is Innervated by SYMPATHETIC NERVE FIBERS
- Contraction of the Dilator causes PUPIL DILATION or MYDRIASIS

2) SPHINCTER PUPILAE:
- Consisting of Smooth Muscle Cells, has ACETYLCHOLINE Receptors and is Innervated by PARASYMPATHETIC NERVE FIBERS
- Sphincter Contraction REDUCES the Diameter of the Pupil or MIOSIS!!!!

Question 10

Inner Tunic

Answer 10

• RETINA runs all the way around the CHOROID!!!!
• FOVEA: Only CONES are present in the Fovea where FINE DETAIL VISION is BEST!!! It is hard to see light with the Fovea but it can see a LOT of COLOR!!!
• PAPILLA (Optic Disc): Axons from the Retinal Ganglion Celsl pass across the Surface of the Retina, CONVERGE on the Papilla (Optic Disc), and leave the Eye through many openings of the SCLERA (The Lamina Cribrosa) to from the OPTIC NERVE!!!!

Question 11

Retina

Answer 11

Layers:
1) Inner Limiting Region

2) NERVE FIBER LAYER (Axons of Ganglion Cells):
- Layer that comes together to make the OPTIC NERVE

3) GANGLION CELL LAYER
- Cell Axons make the OPTIC NERVE

4) INNER PLEXIFORM LAYER
- Bipolar Cell Axons are Synapsing on Ganglion Cell Dendrites

5) INNER NUCLEAR LAYER
- Take info from Rods and Cones and send it up to the Ganglions (Bipolar Cells and Body Cell Layer)

6) OUTER PELXIFORM LAYER
- Photoreceptor Cell Axons are SYNAPSING on BIPOLAR Dendrites

7) OUTER NUCLEAR LAYER
- Contains cell bodies of Photoreceptor Cells

8) OUTER LIMITING MEMBRANE

9) INNER and OUTER SEGMENTS of RODS and CONES
- Actual SEEING!!!!!!
- Contains the Rods and Cones

10) PIGMENTED REPITHELIUM

Photoreceptors:

1) CONES: Color
2) RODS: Light

Question 12

Fovea Centralis

Answer 12

• At the FOVEA CENTRALIS, tightly packed Cones are arranged at an ANGLE to the Pigmented Layer. Consequently, the OUTERN NUCLEAR Layer and the other layers of the Sensory Retina DO NOT OBSTRUCT the Light PATHWAY
• The Outer Segment of the Photoreceptor Cells receives Light that has NOT passed FIRST through the Other Layers of the Retina!!!

Question 13

Optic Disc and Fovea

Answer 13

OPTIC DISC:
- The axons of the GANGLION CELLS turn into the OPTIC NERVE at the OPTIC DISC, which LACKS Photoreceptors and corresponds to the BLIND SPOT of the Retina

• When Intraocular Pressure INCREASE, the Disk of the Optic Nerve appears CONCAVE. The Disc becomes Swollen (Papilledema) and the Veins are DILATED when Intracranial Pressure INCREASES!!!

FOVEA:
- Previous Cell Layers are SLATED OUTWARD so that the most light is hitting the Cone Cells

• In its Center, the Fovea is for HIGH QUALITY VISION
• The rest of the Retina is for PERIPHERAL VISION.

Cones: Color Distinction
Rods: Movement Detection

Question 14

Clinical Consideration: Detachment of the Retina

Answer 14

• Separationg of TWO Layers of the Retina

- Caused by Trauma, Vascular Disease, Metabolic Disorders, and Aging!!!!!

Question 15

Rod Cells

Answer 15

INNER Segment of Rod Cells:
- MITOCHONDRIA Synthesize ATP required for the assembly of the Visual Pigment RHODOPSIN!!!!!

OUTER Segment of Rod Cells:

• Contains the PLASMA MEMBRANE that folds in on itself a Bunch of times. This INCREASES the changes of the Cell becoming excited in LOWER LIGHT by INCREASING the SURFAC AREA!!!
• Do all the SEEING in the OUTER SEGMENT!!!!**

Question 16

Cone Cells

Answer 16

• There are THREE TUPES of Cones, each with a Different Photopigment Sensitive to:
  a) Blue
  b) Green
  c) Red

Clinical Significance: Color Blindness

• When a Single Group of Color- Receptive Cones is missing, the Individual cannot Distinguish some color from others
• Green/ Red Color Blindness can be due to missing part of the X Chromosome!!!

Question 17

Chambers of the Eye

Answer 17

• If the TRABECULAR MESHWORK becomes PLUGGED
  (Accepts the Fluid)

2) Canal of Schlemm —->
( Fluid Empties into the Canal)

3) Episcleral Veins —->
( Fluid taken away by Episcleral Veins)

Question 18

Clinical Considerations: Glaucoma

Answer 18

• Obstruction of AQUEOUS HUMOR that causes an INCREASE in INTRAOCULAR Pressure
• Produces PAIN and NAUSEA
• Either by BLOCKAGE of CANAL of SCHLEMM (Most Common) or INFLAMMATION preventing Aqueous Humor from reaching the Trabecular Meshwork!!!!!

**Do the PUFF TEST!!!!!!

Question 19

Lens

Answer 19

** DENSE Irregular Connective Tissue!!!!!!

1) The ANTERIOR LENS EPITHELIUM is formed by FLATTENED CELLS
2) When Epithelial Cells reach the EQUATORIAL REGION of the Lens, the begin to DIVIDE by MITOSIS and ELONGATE!!!!!!!
3) CORTICAL LENS FIBERS contacts the Ciliary Body and allows the Lens to CHANGE SHAPE and FOCUS!!

Question 20

Clinical Considerations: Cataracts

Answer 20

• OPACITY of the Lens caused by Change in the SOLUBILITY of LENS PROTEINS
• IMPAIRS Vision
• Result of AGING and DIABETES!!!

Question 21

Tarsal Glands and Conjuctiva

Answer 21

TARSAL GLANDS:

• Exists INDISE the Eyelid Itself
• Produces a SECRETION that allows the Eyelid to Float EFFORTLESSLY on the Bulb itself
• **Secrete LIPID-Containg products that retards Evaporation of the Tear Film

CONJUNCTIVA:

• Convers the INNER EYELID and FOLDS OVER onto the SCLERA
• Keeps the Eye MOISTENED!!!!
• ** Lines the Anterior Surface of the Eyeball up to the LIMBUS and the Inner Surface of the Eyelid
• MOLL’S GLAND*
• Modified APOCRINE Sweat Glands that are found in the MARGIN of the Eyelid

Question 22

Clinical Consideration: Pink Eye

Answer 22

• SUBJUNCTIVAL HEMORRHAGE and CONJUNCTIVITIS

Question 23

Gross Anatomy of the Ear

Answer 23

1) External Ear
- Sound capture and CONDUCTION
* ** Conveys sound to the TYMPANIC MEMBRANE

2) Middle Ear
- Conversion of Sound Waves into Fluid Waves
* ** Contains the OSSICLES (Bones)
* ** Communicates with the PHARYNX

3) Internal Ear
- Fluid movements displaces the Basilar Membrane and stimulates the Hair Cells
* ** Where we do all of out actual HEARING with Neurons
* ** Also where we are determine our Balance

Question 24

External Ear

Answer 24

• Helix
• Scapha
• Antihelix, stem
• CONCHA
• Tragus
• Antitragus
• Lobe

Question 25

Middle Ear

Answer 25

- Sound Vibrations hit the Tympanic Membrane and Vibrate it - That Vibration is TRANSMITTED from the MALLEUS to the INCUS to the STAPES!!! - The Vibrations move the FOOTPLATE of the STAPES in the OVAL WINDOW and causes for the FLUID to VIBRATE * ** Tensor Tympani Muscle * ** Stapedius Muscle - Tensor Tympani and Stapedius Muscles can TENSE UP and make it so that LOUD Noises DON'T Damage our ears!!! - Eventually these Muscle can become TIRED (When your older) and thats when you cant so well

Question 26

Components of the Membranous Labyrinth

Answer 26

1) Utricle 2) Saccule 3) COCHLEA - Superior Semicircular Duct - Posterior Semicircular Duct - Horizontal Semicircular Duct ****Each AMPULLA contains the CRISTA AMPULLARIS. Sensory RECEPTORS in the Crista Ampullaris respond to the position of the Head, generating Nerve Impulses necessary for correcting the Position of the Body

Question 27

Endolymphatic Duct and Perilymphatic Duct

Answer 27

PERILYMPHATIC Duct: - Circulates inside the UTRICLE and SACCULE, and communicates with the SUBARACHNOID SPACE that contains CSF. It DUMPS into the Subarachnoid Space ENDOLYMPHATIC Duct: - The Endolymphatic Duct communicates to the ENDOLYMPHATIC SAC in the SUBDURAL SPACE!!!!!!

Question 28

Saccule and Utricle

Answer 28

- The MACULAE are SENSORY RECEPTOR areas located in the Wall of the SACCULE and UTRICLE - There are HAIR CELLS (Types I and II) attaches to the BASE of the MACULA!!!!!!

Question 29

Saccule and Utricle Parts of the Hair Cells

Answer 29

1) KINOCILLIUM (One Big Fiber): - Most responsible for the production of DEPOLARIZATION of HYPERPOLARIZATION - Either OPENS or INHIBITS the Ion Channel 2) STEROCILIA (Bunch of Small Fibers): - INWARD movement DEFORMS the Plasma Membrane and Triggers DEPOLARIZATION! DEPOLARIZATION: Excitation HYPERPOLRIZATION: Inhibition

Question 30

Ampulla o the Semicircular Canal

Answer 30

*** Widened area of the Semicircular Canal that communicates with the UTRICLE!!!! CUPULA: A Glycoprotein containing GELATINOUS Structure surrounded by ENDOLYMPH - Type I Hair Cells on the TIP of the CUPULA!!! - Type II Hair Cells on the BASE of the CUPULA!!!

Question 31

Cochlea

Answer 31

1) Sound from the External Ear hits the Tympanic Membrane, and transmits the sound via Vibrations, through the Ossicles which causes the STAPES to act on the OVAL WINDOW and through the Perilymphatic Channels. 2) SOUND WAVES traveling across the PERILYMPHATIC CHANNELS produce Oscillatory movements of the COCHLEAR Partition, including the Basilar Membrane 3) Oscillatory Movements against the OVAL WINDOW result in Equal but OPPOSITE movements of the ROUND WINDOW (End)!!!!

Question 32

Parts of the Cochlear Duct

Answer 32

1) Scala Vestibuli * **REISSNER'S MEMBRANE (Vestibular Membrane)!!!!!!!! - Separates Scala Vestiboli and Scala Media 2) Scala Media * **ORGAN OF CORTI!!!!!!!! - Separates Scala Tympani and Scala Media 3) Scala Tympani

Question 33

Cochlea Cont 1

Answer 33

* ** TECTORIAL MEMBRANE is ANCHORED to the OUTER Hair Cells - Fluid Vibrates around the Outer Hair Cells and causes the Tectorial Membrane to move from the VIBRATIONS - When the Scala Vestibule and Tympani VIBRATE, they will CHANGE SHAPE and VIBRATE the HIAR CELLS that will cause the TECTORIAL MEMBRANE TO MOVE!!!!!

Question 34

Cochlea Cont 2

Answer 34

1) HELICOTREMA: - Top of the Cochlea - FLUID SPIRALS up tot he Helicotrema and then COMES BACK DOWN!!! - SCALA TYMPANI is whats connected to the OVAL WINDOW - Vibration technically NEVER hits the Fluid of the Scala Media (Where the Organ of Corti is)

Question 35

Organ of Corti

Answer 35

- The ORGAN OF CORTI is located in the SCALA MEDIA and extends the FULL LENGTH of the Basilar Membrane - Hair Cells are the SENSORY RECEPTORS of the Organ of Corti There are two types of Hair Cells 1) INNER Hair Cells 2) OUTER Hair Cells - In DIRECT Contact with the TECTORIAL MEMBRANE

Question 36

What compartments contain which fluid?

Answer 36

SCALA MEDIA (Cochlear Duct): Contains ENDOLYMPH which has a HIGH K+ Content SCALA TYMPANI and VESTIBULI: Contain PERILYMPH which has a HIGH Na+ Content