AQUEOUS HUMOR LECTURE NOTES
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Transcript AQUEOUS HUMOR LECTURE NOTES
AQUEOUS
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AQUEOUS HUMOR
LECTURE
Reading
Assignment: Chapter 8, Adler's
Physiology of the Eye.
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I.
DEFINITION
FUNCTION
AND
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.
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II. PRODUCTION
A.
Ciliary Body
– 1. extends from the iris to the ora serrata.
– 2. Principally unstriated muscle
• a. longitudinal, radial and circular
– 3. Two divisions
• a. pars plicata - anterior third consisting of
ciliary processes
• b. pars plana - posterior 2/3rds
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II. PRODUCTION
– 4. Ciliary processes approximately 70
ridges projecting
inward from the pars
plicata
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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 system
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II. PRODUCTION
– 7. Nervous supply - long posterior and
short ciliary nerves, parasympathetic and
sympathetic innervation
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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.
• b. Basement membrane for the nonpigmented
layer is the internal limiting membrane.
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II. PRODUCTION
– 3. Many connections between the two
layers
• a. desmosomes, gap junctions, tight junctions
• b. 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 barrier
– i. clinical consequences
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II. PRODUCTION
C.
Mechanism of Aqueous Formation
– 1. Three possible
• diffusion
• ultrafiltration
• active transport
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II. PRODUCTION
– 2. Active transport
• a. produces the bulk of the aqueous, requires
energy
• b. Na/K ATPase located along lateral cellular
interdigitations of NPE
• c. aqueous production decreases when use
ouabain
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II. PRODUCTION
• d. Na+ transported out with Cl-, HCO3- and
H2O following
• e. positive charge in aqueous near NPE wall
• f. solute concentrated at region near the tight
junction and decreases as you approach the
posterior chamber
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II. PRODUCTION
– 3. Ultrafiltration
• a. a substance is forced across a membrane
with the help of a hydrostatic driving force
• b. produces a small amount of aqueous
• c. hydrostatic pressure probably greater in
opposite direction (out of eye)
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II. PRODUCTION
– 4. Diffusion
• a. movement of a substance down its
concentration gradient
• b. small amount of aqueous made this way
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III.
AQUEOUS
COMPOSITION
HUMOR
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)
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III. AQUEOUS HUMOR
COMPOSITION
– 1. Osmolarity
• a. slightly hyperosmotic to plasma
– 2. Electrolytes
• a. Na+ and K+ concentrations similar to plasma
• b. Cl- higher and HCO3- lower than plasma
level
• c. Oxygen diffuses into aqueous from blood so
lower concentration in aqueous
• d. Glucose lower and lactate higher than
plasma concentrations
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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
aqueous
– i. thus, secreted actively by a specific carrier
mechanism that can be saturated
• f. 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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III. AQUEOUS HUMOR
COMPOSITION
• 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. 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
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III. AQUEOUS HUMOR
COMPOSITION
• i. Other compounds found include hyaluronic
acid, corticosteroids, lipids, vitamin B12 and
lens proteins.
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III. AQUEOUS HUMOR
COMPOSITION
Clinical
Significance
– may aid in Dx
• diabetes mellitus
• glaucoma
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