S.C.C.O. 5/17/20151 AQUEOUS

S.C.C.O. 5/17/20152 AQUEOUS HUMOR LECTURE  Reading Assignment: Chapter 8, Adler's Physiology of the Eye.

S.C.C.O. 5/17/20153 I. DEFINITION AND FUNCTION  A. Transparent, colorless liquid in the anterior and posterior chambers of the eye. Provides nutrition for ocular tissues, allows for waste product removal, and maintains eye pressure.

S.C.C.O. 5/17/20154 II. PRODUCTION  A. Ciliary Body –1. extends from the iris to the ora serrata. –2. Principally unstriated muscle a. longitudinal, radial and circulara. longitudinal, radial and circular –3. Two divisions a. pars plicata - anterior third consisting of ciliary processesa. pars plicata - anterior third consisting of ciliary processes b. pars plana - posterior 2/3rdsb. pars plana - posterior 2/3rds

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S.C.C.O. 5/17/20157 II. PRODUCTION –4. Ciliary processes - approximately 70 ridges projecting inward from the pars plicata

S.C.C.O. 5/17/20158 II. PRODUCTION –5. Firmly attached at the scleral spur –6. Blood supply consist of the anterior and long posterior ciliary arteries a. each ciliary process receives an arteriole and is drained by a venule which connects with the vortex systema. each ciliary process receives an arteriole and is drained by a venule which connects with the vortex system

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S.C.C.O. 5/17/ II. PRODUCTION –7. Nervous supply - long posterior and short ciliary nerves, parasympathetic and sympathetic innervation

S.C.C.O. 5/17/ II. PRODUCTION  B. Anatomy –1. Stromal core surrounded by a layer of pigmented epithelium (cuboidal) and nonpigmented epithelium (columnar) –2. Two layers of epithelium face apex to apex. a. Bruchs membrane forms the basement membrane for the pigmented layer.a. Bruchs membrane forms the basement membrane for the pigmented layer. b. Basement membrane for the nonpigmented layer is the internal limiting membrane.b. Basement membrane for the nonpigmented layer is the internal limiting membrane.

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S.C.C.O. 5/17/ II. PRODUCTION –3. Many connections between the two layers a. desmosomes, gap junctions, tight junctionsa. desmosomes, gap junctions, tight junctions b. tight junctions - at apex of nonpigmented cells, form a tight barrierb. tight junctions - at apex of nonpigmented cells, form a tight barrier c. tight junctions and blood vessels with small fenestrations result in a blood-aqueous barrierc. tight junctions and blood vessels with small fenestrations result in a blood-aqueous barrier –i. clinical consequences

S.C.C.O. 5/17/ II. PRODUCTION  C. Mechanism of Aqueous Formation –1. Three possible diffusiondiffusion ultrafiltrationultrafiltration active transportactive transport

S.C.C.O. 5/17/ II. PRODUCTION –2. Active transport a. produces the bulk of the aqueous, requires energya. produces the bulk of the aqueous, requires energy b. Na/K ATPase located along lateral cellular interdigitations of NPEb. Na/K ATPase located along lateral cellular interdigitations of NPE c. aqueous production decreases when use ouabainc. aqueous production decreases when use ouabain

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S.C.C.O. 5/17/ II. PRODUCTION d. Na+ transported out with Cl-, HCO3- and H2O followingd. Na+ transported out with Cl-, HCO3- and H2O following e. positive charge in aqueous near NPE walle. positive charge in aqueous near NPE wall f. solute concentrated at region near the tight junction and decreases as you approach the posterior chamberf. solute concentrated at region near the tight junction and decreases as you approach the posterior chamber

S.C.C.O. 5/17/ II. PRODUCTION –3. Ultrafiltration a. a substance is forced across a membrane with the help of a hydrostatic driving forcea. a substance is forced across a membrane with the help of a hydrostatic driving force b. produces a small amount of aqueousb. produces a small amount of aqueous c. hydrostatic pressure probably greater in opposite direction (out of eye)c. hydrostatic pressure probably greater in opposite direction (out of eye)

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S.C.C.O. 5/17/ II. PRODUCTION –4. Diffusion a. movement of a substance down its concentration gradienta. movement of a substance down its concentration gradient b. small amount of aqueous made this wayb. small amount of aqueous made this way

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S.C.C.O. 5/17/ III. AQUEOUS HUMOR COMPOSITION  A. Initially compared concentration with that of plasma  B. Substances in the aqueous are used by all the surrounding tissues and the aqueous contains all their waste products (cornea, lens, vitreous and iris)

S.C.C.O. 5/17/ III. AQUEOUS HUMOR COMPOSITION –1. Osmolarity a. slightly hyperosmotic to plasmaa. slightly hyperosmotic to plasma –2. Electrolytes a. Na+ and K+ concentrations similar to plasmaa. Na+ and K+ concentrations similar to plasma b. Cl- higher and HCO3- lower than plasma levelb. Cl- higher and HCO3- lower than plasma level c. Oxygen diffuses into aqueous from blood so lower concentration in aqueousc. Oxygen diffuses into aqueous from blood so lower concentration in aqueous d. Glucose lower and lactate higher than plasma concentrationsd. Glucose lower and lactate higher than plasma concentrations

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S.C.C.O. 5/17/ III. AQUEOUS HUMOR COMPOSITION e. Ascorbate - high concentration in aqueous (about 20 X that of plasma) rises with increasing concentration in the blood until a ceiling of about 50 mg/100 ml is reached in the aqueouse. Ascorbate - high concentration in aqueous (about 20 X that of plasma) rises with increasing concentration in the blood until a ceiling of about 50 mg/100 ml is reached in the aqueous –i. thus, secreted actively by a specific carrier mechanism that can be saturated f. Amino acidsf. Amino acids –i. most amino acids in higher concentrations in the aqueous than the plasma which indicates active transport –ii. different amino acids have different concentrations

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S.C.C.O. 5/17/ III. AQUEOUS HUMOR COMPOSITION g. Proteins are limited in the aqueous by the blood aqueous barrier (1/90)g. Proteins are limited in the aqueous by the blood aqueous barrier (1/90) –i. low molecular weight proteins can get into the aqueous (albumin in high conc) h. Immunoglobulinsh. Immunoglobulins –i. IgG concentration of 3 mg/100 ml of aqueous –ii. IgD, IgA and IgM not normally found –iii. small quantities of complement can be found

S.C.C.O. 5/17/ III. AQUEOUS HUMOR COMPOSITION i. Other compounds found include hyaluronic acid, corticosteroids, lipids, vitamin B12 and lens proteins.i. Other compounds found include hyaluronic acid, corticosteroids, lipids, vitamin B12 and lens proteins.

S.C.C.O. 5/17/ III. AQUEOUS HUMOR COMPOSITION F Clinical Significance –may aid in Dx diabetes mellitusdiabetes mellitus glaucomaglaucoma