Drugs in the eye Flashcards
How does the brain receive information?
Light comes through the pupil
Through the lens & is focussed on the retina
This sends elec impulses down the optic nerve
To the brain
Which muscle controls accommodation?
The ciliary body
How is the lens suspended?
By suspensory ligaments which are attached to the ciliary body
What is the purpose of accommodation?
To change the size & thickness of the lens to focus on various objects
Uses the mechanisms of the suspensory ligaments & ciliary body
What allows light through the pupil?
The iris - it contains different muscles that allow us to control pupil diameter
What are the two types of muscles that control pupil diameter?
- Circular (constrictor)
- Radial (dilator)
What happens to the pupil during parasympathetic stimulation?
It activates circular (constrictor muscles) in iris
Causes the pupil to become smaller (Miosis)
What happens during mitosis of the pupil?
The circular sphincter muscles contract, causes pupil to become smaller
Parasympathetic stimulation
What happens to the pupil during sympathetic stimulation?
Activates radial (dilator) muscles in iris
Causes the pupil to become bigger
What happens during mydriasis of the pupil?
Activates radial (dilator) muscles in iris - pupil becomes bigger
Sympathetic stimulation
What is reciprocal innervation?
Pupil diameter is controlled by a tonic level of innervation by both para and sympathetic activation
One is always active - lots of action in PNS then less in SNS
What is accommodation?
Ability to adjust our focus based on how far away an object is
What is the muscle used in accommodation?
The ciliary body - it determines the shape of the lens (convex to flat)
What is the ciliary bod mainly innervated by?
The PNS
What happens when the ciliary body contracts in accommodation?
- Ciliary body contracts
- Suspensory ligaments have less tension
- Allows lens to get fatter
- Can focus on things that are closer
- Uses PS innervation
