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

Botany, economic importance of viruses and bacteria ?

economic importance of viruses and bacteria ?

What is radioactivity , What is Radioactivity ? Radioactivity :  Som...

What is Radioactivity ? Radioactivity :  Some isotopes, called radioisotopes, have unstable nuclei that release high energy particles or radiant energy, or both. An example

Fat cow syndrome, F a t cow syndrome Fat cow syndrome, also known as ...

F a t cow syndrome Fat cow syndrome, also known as fatty infiltration of liver, is a highly fatal disease in high yielding dairy animals that occurs a few days before or afte

Evolution of dental implants, The first evidence of implants dates back to ...

The first evidence of implants dates back to 600 A.D. in the Mayan population. There are reports that the ancient Egyptians attempted intra-osseous implantation of animal teeth or

What is the difference between taeniasis and cysticercosis, Q. What is the ...

Q. What is the difference between taeniasis and cysticercosis? The Taeniasis is the parasitic disease caused by the adult tapeworm installed within the human intestine. The

Intervention strategy, Intervention Strategy There are five basic ways...

Intervention Strategy There are five basic ways in which government can correct market failures and ensure equity: inform, regulate, mandate, finance and deliver health care s

M - mode echocardiography, M-Mode was the earliest form of cardiac ultrasou...

M-Mode was the earliest form of cardiac ultrasound used clinically. It displays the amplitude signals of various structures along the length of ultrasound beam with distance or

Effect on water bodies - dissolved oxygen (do), Effect on Water Bodies - Di...

Effect on Water Bodies - Dissolved Oxygen (DO) Most aquatic, organisms respire with oxygen dissolved in water. The quantity of dissolved oxygen in a unit volume of aerated wa

Define energy requirements of infants, Define Energy requirements of infant...

Define Energy requirements of infants? Energy: Energy requirements of infants are based on the energy intake through breast milk by infants of well-nourished mothers. Based on

Role of endarterectomy, Role of Endarterectomy :  Endarterectomy is done a...

Role of Endarterectomy :  Endarterectomy is done as a semi open technique. 5-10mm long incision is made on the outer layers of the coronary artery and plain developed in 11ic thic

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