chapter17 part2 p572-4 Flashcards
what two small pores drain the lacrimal lake?
lacrimal puncta
tears accumulate at the medial canthus in an area known as
lacrimal lake
The tears from lacrimal lake drain in to
lacrimal canaliculi
lacrimal canaliculi leads to
lcarimal sac
which duct delivers tears from lacrimal sac? to where?
nasolacrimal duct, nasal cavity on that side
The nasolacrimal duct empties into
inferior meatus
narrow passageway inferior and lateral to the inferior nasal concha
inferior meatus
tears stream across face when
lacrimal puncta can’t provide neough drainage
what cushions and insulates the eye?
orbital fat
name 3 distinct layers in the wall of the eye
- outer fibrous layer
- intermediate vascular layer/uvea
- deep inner layer/retina
The wall of the eyes was formerly called
tunics
other name for visual receptors
photoreceptors
eyeball is filled with
fluid
eyeball cavities can be divided into what 2 cavities?
anterior and posterior
anterior cavity has which 2 chambers and where are they located
anterior chamber- between cornea and colored iris
posterior chamber - between iris and lens
anterior cavity is filled with
aqueous humor
other name for posterior cavity
vitreous chamber
posterior cavity contains
vitreous body
describe vitreous body
gelatinous substance
describe aqueous humor
clear, watery fluid
fluid part of vitreous body is called
vitreous humor
What is a function of the vitreous body and aqueous humor?
stabilization of shape of the eye
the outermost layer of the eye is called
fibrous layer
2 components of the fibrous layer are
sclera and cornea
what are the 3 functions of the fibrous layer
- support and protect
- serve as attachment site for extrinsic eye muscles
- contains structures that assist in focusing
white of the eye
sclera
The sclera consists of a dense fibrous connective tissue containing what 2 components?
collagen and elastic fibers
The sclera layer is thickest at what part
posterior surface of the eye, near the exit of the optic nerve
which part is the sclera the thinnest?
anterior surface
the 6 extrinsic eye muscles insert on the sclera blending their ________ with those of the __________ layer
collagen fibers, fibrous layer
The surface of the sclera contains __________ and _________ that penetrate the sclera to reach the internal structures
small blood vessels and nerves
The transparent __________ is structurally continuous with the sclera
cornea
What is the corneal limbus
border between transparent cornea and sclera
Deep to the corneal epithelium, cornea consists primarily of dense matrix containing multiple layers of ___________
collagen fibers
deep in corneal epithelium, how are the multiple layers of collagen fibers organized
to not interfere with the passage of light
Cornea has no _________
blood vessels
How does cornea obtain oxygen and nutrients?
diffusion from the tears that flow across the surfaces
What is the most sensitive portion of the eye and why?
cornea - numerous free nerve endings
corneal ability to repair itself is
restricted- injuries must be treated immediately
Most common form of transplant surgery
corneal transplant
why can corneal transplant happen between unrelated individuals?
no blood vessels to carry white blood cells
pigmented region of the eye that includes 3 components = name the region and the 3 components
vascular layer/uvea
contains iris, ciliary body, choroid
Name 3 tissue structures included in the vascular layer/uvea
- blood vessels
- lymphatic vessels
- intrinsic/smooth muscles of the eye
Name 4 functions of the vascular layer/uvea
- provide route for blood vessels and lymphatics that supply tissues of the eye
- regulate the amount of light that enters the eye
- secretes and reabsorbs the aqueous humor that circulates within the chambers of the eye
- controls the shape of the lense- part of focusing
lris contains which types of tissue/cells? (3)
- blood vessels
- pigment cells
- 2 layers of smooth muscle fibers
What are the 2 layers of smooth muscle fibers called in the iris?
pupillary muscles
What do the pupillary muslces control?
contract- change diameter of the pupil.
central opening of the iris is
pupil
What are the 2 types of pupillary muscles?
dilators and constrictors
Which nervous system controls the 2 pupillary muscle groups?
autonomic nervous system
parasympathetic activation causes what in pupils- this is called what
contriction, consensual light reflex
sympathetic activation of the pupils cause what?
dilation of the pupils
body of the iris consists of what type of tissue?
highly vascular, pigmented, loose connective tissue
which part of the iris has no epithelial covering?
anterior surface
The anterior surface of the iris is covered by what?
incomplete layer of fibroblasts and melanocytes
What is scattered within the body of the iris?
melanocytes
What is the posterior surface of iris covered by?
pigmented epithelium that is part of the inner layer and contains melanin granules
disease of the retina
retinopathy
what develops in many people with diabetes mellitus
diabetic retinopathy
leading cause of blindness in US
ldiabetic retinoathy
diabetic retinopathy results from
blockage of small retinal blood vessels, followed by excessive growh of abnormal blood vessels
What do the growth of abnormal blood vessels do in diabetic retinopathy?i
they invade the retina/inner layer and extend into the space between its 2 parts - outer pigmented part and inner neural part, causing loss of visual acuity from the damage to photoreceptors that are deprived of oxygen and nutrients.
the blood leaks into posterior cavity
What is a possible treatment for the vessel growth in diabetic retinopathy?
laser therapy0 seal leaking vessels and block new vessel growth. The posterior cavity can be drained and the cloudy fluid replaced by clear substitute= vitrectomy
Where do photoreceptors get oxygen and nutreints from?
Blood vessels in the choroid- diffusion
What is a detached retina?
neural part of the retina becomes separated from the pigmented part
What are possible causes of detached retina?
sudden hard impact to the eye
What is a possible treatment for detached retina?
welding parts together with laser beams focused through cornea- heat and fuse 2 parts together - produce permanent blind spots
What makes eyes blue?
connective tissue of the iris contains few melanocytes- light passes through it and bounces off the pigmented epithelium
What makes green, brown, black eyes?
increasing numbers of melanocytes in the body and surface of the iris
Genes determining eye color affect which parts of the body?
anterior surface and interior of the iris
density of the pigmented epithelium
