Composition of capillaries, Biology

Assignment Help:

Composition of Capillaries

Capillaries are made up of a single layer of endothelial cells surrounded by a basal membrane. The walls ale thin and fragile but because of their small diameter resist stretching in response to capillary blood pressure. Water and dissolved substances of small molecular weight (gases, salts, sugars, amino acids etc.) can diffuse easily.

2056_Composition of Capillaries.png

Figure:  Fluid exchange across a capillary wall

In addition, fluid is forced out through the walls. Substances of molecular weight more than 70,000 (mostly proteins) do not pass out of the capillary walls. These proteins exert an osmotic effect called the colloidal osmotic pressure, which tends to draw water back into the capillary from the surrounding tissue fluid. Another force, the hydrostatic pressure of blood tends to push the water across the endothelial cell layer out of the capillaries. When the hydrostatic pressure within the capillary exceeds colloidal osmotic pressure, fluid is passed out through the capillary wall; when the hydrostatic pressure in the capillary falls below the colloidal osmotic pressure the 'fluid is drawn in. The hydrostatic pressure in the arterial end of the capillary is higher than the colloidal arterial pressure while at the venous end it is often lower. Therefore, fluid is filtered out at the arterial end and redrawn in at the venous end. This amount of fluid forced out and the amount re-entering varies greatly. Usually outflow exceeds inflow and excess fluid remains in the interstitial spaces. This as you already know forms the lymph.


Related Discussions:- Composition of capillaries

Vaccine against tuberculosis, Q. Is there vaccine against tuberculosis? ...

Q. Is there vaccine against tuberculosis? The vaccine against the tuberculosis is called as BCG (bacillus Calmette-Guérin). BCG is not used in a few countries where tuberculosi

Determine the carbon based materials, Carbon Based Materials These incl...

Carbon Based Materials These include Pyrolytic carbon, polycrystalline (Vitreous Carbon), and carbon/silicon interstitial combination. Vitreous Carbon -Solid or porous vitre

What is the histological nature of the glands, What is the histological nat...

What is the histological nature of the glands? How are they formed? The glands are epithelial tissues. They are made of epithelium that throughout the embryonic development inv

Oxidation reduction potential, what exactly is oxidation and reduction pote...

what exactly is oxidation and reduction potential and how its an imp. factor in spoiling meat

Mollusca, General characters of mollusca

General characters of mollusca

Cell Coat, What role would a cell coat play if it was a part of a city?

What role would a cell coat play if it was a part of a city?

What is the vector of malaria, Q. What is the vector of malaria? How differ...

Q. What is the vector of malaria? How different is its behavior from the behavior of the vector of dengue fever? The vector of malaria is the mosquito of the genus Anopheles, a

What is the use of uncoated polyvinyl chloride, Q. What is the use of Uncoa...

Q. What is the use of Uncoated polyvinyl chloride? Uncoated polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC): PVC and PVDC are closely related plastics that are a

In how many categories nutrients are divided, In how many categories nutrie...

In how many categories nutrients are divided? The nutrients are grouped into three categories: 1) Energy Yielding: Carbohydrates and fats produce energy in the body. 2) B

Determine the parts consists in our urinary system, Determine the parts con...

Determine the parts consists in Our urinary system Our urinary system consists of following:  Two kidneys  Two ureters  One urinary bladder  One urethra Apart fr

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd