The pupil response 1

Question 1

What happens in low light level?

Answer 1

Mydriasis - dilation of the pupil in low light level

Question 2

What is average dilation of pupil?

Answer 2

8mm

Question 3

What happens in bright light level?

Answer 3

Miosis - constriction of the pupil in bright light level

Question 4

What is average constricted pupil size?

Answer 4

2mm

Question 5

How are pupils size determined?

Answer 5

light levels
genetics
age

Question 6

What happens to pupils as we get older?

Answer 6

Constricted pupil so harder at night to read

Question 7

what do you call large and small pupil sizes/

Answer 7

macrocoria -big

microcoria - small

Question 8

What does genetic factors influence?

Answer 8

Resting pupil size

Question 9

What is the resting pupil size of males>/

Answer 9

9mm

Question 10

What is the resting pupil size in females?

Answer 10

3mm

Question 11

What is the resting pupil size in children?

Answer 11

6mm

Question 12

What was used to dilate pupil?

Answer 12

Atropine

Question 13

Why did womens use atropine?

Answer 13

Make eyes look larger and make them look younger

Question 14

What happens to pupil in very bright light for long time?

Answer 14

in 200ms pupil gets smaller
takes 2 half second to constrict fully
as light levels get lower pupil response takes longer and constricts less

Question 15

What is hippus?

Answer 15

The pupil oscillates around average steady state

Question 16

What is the function of pupil?

Answer 16

To regulate the amount of light entering the eye

Question 17

What is the difference between fully constricted and fully dilated pupil?

Answer 17

x16

Question 18

How much does fully dilated and fully constricted pupil alter the light entering the eye bye?

Answer 18

1.2 log units

Question 19

What does constriction do?

Answer 19

Increases image quality by increasing depth of focus

and reduce amount of spherical aberrations

Question 20

How can you reduce spherical aberrations?

Answer 20

By closing the pupil- make smaller and cut out any peripheral rays

Question 21

How does the traid improve image quality? (3)

Answer 21

Accommodation focuses the object
convergence puts the image on fovea
pupil constriction increases depth of field

Question 22

What does human pupil respond to?

Answer 22

Changes in illuminance
viewing near objects
cortical influences - girls

Question 23

What does the iris contain?

Answer 23

Two smooth muscles - dilator and sphincter muscles

Question 24

What is the orientation of the iris muscles?

Answer 24

sphincter- circular muscles

dilator - runs radially

Question 25

Where is dilator muscle?

Answer 25

> Close to ris pigmented double epithelium (myoepithelium)

Question 26

What is the dilator muscle innervated by ?

Answer 26

Sympathetic branch of autonomic nervous system

Question 27

Where is the sphincter muscle?

Answer 27

separated from iris pigmented epithelium

Question 28

What innervates the sphincter muscle?

Answer 28

Innervated by the parasympathetic branch of the autonomic nervous system

Question 29

How do pupils respond to in animals without rods and cones?

Answer 29

Mice can also respond to light even without photoreceptors because they have melanopsin that contain retinal ganglion cells that respond in the same way

Question 30

What is the initial stage of pupil constriction?

Answer 30

light absorbed by retinal photoreceptors
>rods and cones - lower intensity
>melanopsin containing retinal ganglion cells - high light levels
>ganglion cells leave retina and stimulate ganglion cells in optic nerve

Question 31

What happens to pathway after optic nerve?

Answer 31

To the optic chiasm- decussation- project axons into thE LGN - synapse to optic radiation in visual cortex and results to conscious vision

Question 32

Not all output goes to visual cortex where does it go?

Answer 32

not all vision is conscious

retinal projection to the OPN (bilateral ) and comes from both eyes

Question 33

What is OPN?

Answer 33

Olivary Pretactal nuclei

Question 34

What happens after OPN?

Answer 34

Fibres go directly to the ipsilateral Edingher Westphal nucleus and also to contralateral EWN to mediate consensual response vai the posterior commisure

Question 35

Explain sensory limb of reflex ARC?

Answer 35

>Light absorbed by photoreceptors(rods, cones, melanopsin ganglion cells)
>activity in the ON
partial decussation at the chiasm 
>Projection to OPN
Bilateral Projection to EWN

Question 36

what is the motor innervation of the iris muscles?

Answer 36

Autonomic nervous system

Question 37

what is the difference between sympathetic and parasympathetic ganglia?

Answer 37

Sympathetic ganglia are near spinal chord

Parasympathetic ganglia are located by effector

Question 38

What is the sensory pathway of pupil constriction?

Answer 38

> Bilateral projection to OPN olivary pretectal nuclei from the retina
fibres to EWN of both sides

Question 39

What is the motor pathway of pupil constriction?

Answer 39

Preganglionic parasympathetic fibres travel from the EWN within the 3rd nerve to the ciliary ganglion

Postganglionic fibres innervate the iris sphincter muscle within short ciliary nerves

Question 40

How do ciliary ganglion cells synapse ?

Answer 40

Ach as neurontransmittors

Question 41

What does Ach bind to?

Answer 41

Muscarinic receptors

Question 42

Where do parasympathetic fibres arise from?

Answer 42

Parasympathetic fibres mediating pupillary response arise in the EWN

Question 43

Where do ciliary muscles run?

Answer 43

Ciliary muscles run back to the eye, run to the choroid in front iris and innervate the sphincter pupillae muscle for constriction