Download aqueous humor lecture notes

AQUEOUS
S.C.C.O.
4/29/2017
1
AQUEOUS HUMOR
LECTURE
 Reading
Assignment: Chapter 8, Adler's
Physiology of the Eye.
S.C.C.O.
4/29/2017
2
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.
S.C.C.O.
4/29/2017
3
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
S.C.C.O.
4/29/2017
4
S.C.C.O.
4/29/2017
5
S.C.C.O.
4/29/2017
6
II. PRODUCTION
– 4. Ciliary processes approximately 70
ridges projecting
inward from the pars
plicata
S.C.C.O.
4/29/2017
7
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
S.C.C.O.
4/29/2017
8
S.C.C.O.
4/29/2017
9
II. PRODUCTION
– 7. Nervous supply - long posterior and
short ciliary nerves, parasympathetic and
sympathetic innervation
S.C.C.O.
4/29/2017
10
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.
S.C.C.O.
4/29/2017
11
S.C.C.O.
4/29/2017
12
S.C.C.O.
4/29/2017
13
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
S.C.C.O.
4/29/2017
14
II. PRODUCTION
 C.
Mechanism of Aqueous Formation
– 1. Three possible
• diffusion
• ultrafiltration
• active transport
S.C.C.O.
4/29/2017
15
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
S.C.C.O.
4/29/2017
16
S.C.C.O.
4/29/2017
17
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
S.C.C.O.
4/29/2017
18
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)
S.C.C.O.
4/29/2017
19
S.C.C.O.
4/29/2017
20
II. PRODUCTION
– 4. Diffusion
• a. movement of a substance down its
concentration gradient
• b. small amount of aqueous made this way
S.C.C.O.
4/29/2017
21
S.C.C.O.
4/29/2017
22
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)
S.C.C.O.
4/29/2017
23
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
S.C.C.O.
4/29/2017
24
S.C.C.O.
4/29/2017
25
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
S.C.C.O.
4/29/2017
26
S.C.C.O.
4/29/2017
27
S.C.C.O.
4/29/2017
28
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
S.C.C.O.
4/29/2017
29
III. AQUEOUS HUMOR
COMPOSITION
• i. Other compounds found include hyaluronic
acid, corticosteroids, lipids, vitamin B12 and
lens proteins.
S.C.C.O.
4/29/2017
30
III. AQUEOUS HUMOR
COMPOSITION
 Clinical
Significance
– may aid in Dx
• diabetes mellitus
• glaucoma
S.C.C.O.
4/29/2017
31