Quantcast
Wall of the Bulbus Oculi - Pharmacology II

Share on Google+Share on FacebookShare on LinkedInShare on TwitterShare on DiggShare on Stumble Upon
Custom Search
 
  
 
a.  Shape. Normally the bulbus oculi is a spherical bulb-like structure. Its
anterior surface, transparent and more curved, is known as the cornea of the bulbus
oculi.
b.  Wall of the Bulbus Oculi. The bulbus oculi is a hollow structure. Its wall is
made up of three layers known as coats or tunics.
(1)  Sclera. The outermost layer is white and very dense fibrous connective
tissue (FCT). It is known as the sclera, scleral coat, or fibrous tunic. Its anterior portion
is called the cornea. As already mentioned, the cornea is transparent and more curved
than the rest of the sclera. The fixed curvature of the cornea enables it to serve as the
major focusing device for the bulbus oculi.
(2)  Choroid. The middle layer of the wall of the bulbus oculi is known as the
choroid, the choroid coat, or the vascular tunic. This layer is richly supplied with blood
vessels. It is also pigmented with a black material. The black color absorbs the light
rays and prevents them from reflecting at random.
(3)  Retina. The inner layer of the wall of the bulbus oculi is known as the
retina, retinal coat, or internal tunic. The actual photoreceptor elements are located in
the retina at the back and sides of the bulbus oculi. These elements are the rods and
cones. They constitute the nervous portion of the retina. In the anterior part of the
bulbus oculi, the retina continues as a non-nervous portion.
c.
Internal Structures of the Bulbus Oculi.
(1)
The nervous retina.
(a)  The photoreceptors of the nervous portion of the retina (Figure 5-2)
contain chemicals known as visual pigments (rhodopsin). The cones are more
concentrated in the center at the back of the bulbus oculi. The cones can perceive
colors and are used for acute vision. However, cones require more intense light than do
rods. The rods are distributed more toward the sides of the nervous retina. Although
the rods are capable of perceiving less intense light, rods perceive only black and white.
(b)  If you look directly at an object, light from the object will fall in the
small depression of the retina called the fovea centralis. The fovea centralis is at the
posterior end of the bulbus oculi, exactly opposite the centers of the cornea, pupil, and
lens. The fovea centralis is found in a small yellow area of the retina called the macula
lutea. The macula lutea is the area of the retina where vision is the sharpest.
FOVEA
=
small depression
CENTRALIS
=
center
MACULA
=
spot
LUTEA
=
yellow
MD0805
5-3



Medical News
Review: sugar-sweetened drink intake tied to elevated BP
(HealthDay)—Sugar-sweetened beverage (SSB) intake is associated with elevated blood pressure...
medicalxpress.com
Study shows aspirin can reduce colorectal cancer risks for those with specific gene
The humble aspirin may have just added another beneficial effect...
medicalxpress.com
Hearing quality restored with bionic ear technology used for gene therapy
Researchers at UNSW Australia have for the first time used...
medicalxpress.com
A little wine might help kidneys stay healthy
(HealthDay)—An occasional glass of wine might help keep your kidneys...
medicalxpress.com
Statins may reduce risk of progression of renal cancer
(HealthDay)—Use of statins is associated with a reduced risk of...
medicalxpress.com
Protein clusters implicated in neurodegenerative diseases actually serve to protect brain cells
People diagnosed with Huntington's disease, most in their mid-thirties and...
medicalxpress.com
FDA proposes accelerated medical device approval plan
(HealthDay)—The U.S. Food and Drug Administration has proposed a new...
medicalxpress.com
New scale useful for predicting sick leave for back pain
(HealthDay)—A new user-friendly 10-item rating scale is useful for predicting...
medicalxpress.com
New Stanford center aims to promote research excellence
Stanford has a new center, called the Meta-Research Innovation Center...
scopeblog.stanford.edu
FDA Orders New Warning for Epidural Steroids
(MedPage Today) -- Injectable corticosteroids must now carry a new...
medpagetoday.com
Early sign of kidney disease often ignored, study says
(HealthDay)—Too much protein in your urine—an early sign of kidney...
medicalxpress.com
Novel compound halts cocaine addiction and relapse behaviors
A novel compound that targets an important brain receptor has...
medicalxpress.com
Autologous stem cell therapy improves motor function in chronic stroke victims
People who have had a stroke, often suffer motor deficits...
medicalxpress.com
Study finds long-term survival of human neural stem cells transplanted into primate brain
A team of researchers in Korea who transplanted human neural...
medicalxpress.com
Hundreds of genetic mutations found in healthy blood of a supercentenarian
Genetic mutations are commonly studied because of links to diseases...
medicalxpress.com
New target for prostate cancer resistant to anti-hormone therapies
Prostate cancer becomes deadly when anti-hormone treatments stop working. Now...
medicalxpress.com
Classifying sequence variants in human disease
Sequencing an entire human genome is faster and cheaper than...
medicalxpress.com
Talking Tech: Peter Elias, MD
(MedPage Today) -- What was your biggest struggle with health...
medpagetoday.com
ID Briefs: Mumps, MERS, and Money
(MedPage Today) -- A mumps outbreak in Ohio continues to...
medpagetoday.com
Myeloma Drug Meets Phase II Trial Goals
(MedPage Today) -- A novel formulation of a standard myeloma...
medpagetoday.com
   


Privacy Statement - Copyright Information. - Contact Us

comments powered by Disqus

Integrated Publishing, Inc.
9438 US Hwy 19N #311 Port Richey, FL 34668

Phone For Parts Inquiries: (727) 755-3260
Google +