Cillary Body and aqueous humour Flashcards
where is the cillary body located?
check diagram
label the cillary body and become familliar with the different sections
check ss
what are the three parts of the cillary body?
ciliary epthilium
ciliary stroma
ciliary muscle
what is accommodation?
how the lens focuses light onto the retina to get an image
what happens in accommodation?
-contraction of ciliary muscles pulls the ciliary body forward
-the forward movement releases tension in suspensory ligaments making the lens more convex and increasing refractive power
go over muscle contraction sliding filament theory
- calcium ions bind to troponin on the actin
- this displaces the tropomyosin to expose actin’s myosin binding sites
- the head of each myosin is bound to an ADP molecule and a phosphate molecule
- the phosphate is then released and the myosin heads then bind to the myosin binding sites
- the two myofilaments slide past eachother propelled by the head first movement powered by the chemical energy stored in the myosin heads
- as they move, the ADP is released from their heads
- the movement is then stopped when ATP molecules bind to the myosin heads
- the heads detach from the myosin binding sites
- myosin ATPase hydrolyses the ATP to form ADP and Pi releasing energy that gets stored in the myosin head ready for the next muscle contraction
10.
What are the three main functions of the ciliary body?
-produce aqueous humour from blood
-to provide the muscles that change the curvature of the lens
-to produce and maintain the lens zonules
what are the layers of the ciliary epithelium and what are each of their features?
-Inner layer: non pigmented, constitutes the anterior continuation of the nervous part of the retina and covers the vitreous body
-outer layer: pigmented and constitutes the continuation of the retinal pigment epithelium
what is the ciliary stroma?
Bundles of loose connective tissue rich in blood vessels and melanocytes
what happens to the ciliary muscles when they’re parasympathetically stimulated?
muscles contract
what happens to the ciliary muscles when they are sympathetically stimulated?
they relax
What is the anterior and posterior chamber bounded by?
prosteriorly by iris and lens, anteriorly by cornea and limbus
in what ways can the depth of the anterior chamber vary? what do variations affect?
-if its shallow the lens is placed forward making it the pupillary margin
-if its deep the pupil lies behind the plane of the iris root
these affect the angle formed by the intersection of the iris with the limbus
what decides if glaucomas are classified as open or closed?
the angle of the anterior chamber which depends on the depth
how do convection currents work in the aqueous humour?
-aqueous flowing through the posterior chamber is warmer than that in the anterior chamber as its in contact with the cornea which is cooler
-this creates convection currents that carry newly arribved aqueous upward and then down along the corneas prosterior surface
