Module 10: Special Senses Flashcards Preview

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Flashcards in Module 10: Special Senses Deck (313)
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241

Male Reproductive System (Elderly)

• Prostate gland starts to increase at age 40
• Andropause
• Decreased libido
• Sexual dysfunction: Erectile dysfunction and Retrograde ejaculation

242

Female Reproductive System (Elderly)

• Changes associated with menopause
• Atrophy of the uterus and ovaries
• Atrophy of the lining of the vaginal canal
• Decrease in lubrication
• Prolapse – weakening of the pelvic floor

243

WALL OF THE EYE: 3 concentric layers

A. Outer layer - fibrous coat: cornea, conjunctiva, sclera
B. Middle layer - vascular coat: iris and choroid
C. Inner layer - neural layer: retina

244

- connective tissue and covers the posterior 5/6 of the globe
- Connected to the dura mater
- Maintains the shape of the globe

Sclera

245

• Major refractive area; most anterior portion of the eye
• first contact with the light wave

Cornea

246

• Junction of Iris and Sclera

Limbus

247

• Thin, transparent mucus membrane
• Covers posterior surface of the eye lids and anterior surface of the sclera
• Bulbar and palpebral

Conjunctiva

248

• Rich in blood vessels

Choroid

249

• Has papillary dilator and sphincter muscle
• Controls the entry of light through the pupil

Iris

250

• Transparent, contains nerves
• Covers the posterior of the eye except the “blind spot”
• Visual Acuity is highest at central part (Macula Lutea)
• 2 main blood supplies of the retina
*Central retinal artery and the choroidal arteries

Neural Coat: Retina

251

• Biconvex, crystalline structure
• Covered by a capsule
• Suspended from the ciliary body by the Zonule Fiber or Suspensory ligaments.

LENS

252

• Help maintain the shape of the eye
• Maintains sufficient pressure in the eyeball to keep it distended
• Divided into two portions as separated by the lens

FLUID SYSTEM OF THE EYE

253

• Clear fluid
• Composed of water and ions
• Other: protein, glucose, ascorbic
• Osmotic pressure is higher than plasma
• Formed as a secretion by the epithelium of Ciliary Process

Aqueous humor

254

• Posterior surface of the lens and retina
• Gelatinous mass
• Containing collagen and hyaluronic acid
• Slow diffusion and little flow of fluid

Vitreous humor

255

Flow of Aqueous Humor

Ciliary processes -> anterior chamber ->
pupil -> trabecular meshwork -> Canal of Schlemm

256

• Production vs drainage of aqueous humor
• Any abnormality: Increased Ocular pressure
• Normal IOP: 10-20 mmHg (±2mmHg)

INTRAOCULAR PRESSURE

257

• eye condition that lead to damage to the optic nerve
• IOP pathologically high
• Could lead to blindness
• Tunnel vision
• Primary symptoms: headache, nausea, vomiting

GLAUCOMA

258

• VISIBLE light- tiny portion of the electromagnetic spectrum of energy
• Ranges from 380-760 that can stimulate the photoreceptors of the human retina to produce a visual response.
• Light rays travel differently with different substance

Refraction of Light

259

Different media = different refractive indices

• Air > solid/ fluid
• If Beam is PERPENDICULAR = no deviation of course, only a decrease in velocity
• If Beam is ANGULATED = refraction of ray

260

• bending of light rays at an angulated interface

REFRACTION

261

• Ratio of the speed of light in the air to a speed of light to a substance

REFRACTIVE INDEX

262

Two factors that affect the amount of refraction:

• Difference in the R.I. of the 2 media
• Degree of angulation of medium

263

Convex Lens vs Concave Lens

• Convex lens
- converge light
- Thicker at the middle

• Concave lens
- diverge light
- Thinner at the middle

264

Lens system will pass

1. Air and anterior surface of cornea
2. Posterior surface of cornea and Aqueous humor
3. Aqueous humor and anterior surface of lens
4. Posterior surface of lens and vitreous humor

265

Optics of the eye

• The greater the lens bends light rays, the greater the refractive power
• Refractive power is measured in DIOPTERS
• Lens refractive power = 1 meter divided by the focal length of a converging lens
• Total refractive power= 59
• Cornea: greatest refractive power (2/3)
• Aq. Humor/lens/vit humor: minimal refractive power
• Power of the lens = 20 Diopters
However, the LENS addresses errors through ACCOMMODATION

266

• the adjustment power of the lens to maintain clear focus. (Up to 34 Diopters)
• MECHANISM:
1. Parasympathetic Innervation
2. Ciliary Muscle Contraction
3. Zonular suspensory ligaments
4. Increase AP diameter of lens
5. Subject can focus on near objects because of INCREASES IN FOCAL POWER
• Decreases as we age
- 14D up to 40 years
- 2D at 40-50 years
- 0 D at 70 years

Accommodation

267

• lack of accommodation with age which requires + lens to increase

Presbyopia

268

• Defects of focusing = discrepancy between the size of the eye & refractive power of dioptic media
• Emmetropia- normal vision

Errors of Refraction

269

• Far sightedness
- Image is focused behind the retina
- Due to: poor refractive power or short axial length
- Correction: Converging lens

Hyperopia

270

• Shortsightedness
- Far objects focused in front of retina
- Due to: lens with too much refractive power or the eyeball is too long
- Correction: Diverging lens

Myopia