Veins - circulation, Biology

Assignment Help:

Veins - Circulation

The veins bring back the blood from the capillaries to the heart. They form a large volume low pressure system. The vessels have a larger internal diameter. In mammals 50% of the total blood volume is present in the veins and pressure is approximately 10-5 mm Hg. If there is any blood loss, the venous volume is decreased and not the arterial volume. So that arterial blood pressure and capillary blood flow is maintained. Flow of blood in veins is affected by several factors. Pressure exerted by the diaphragm on the gut and activity of the limbs both help to squeeze the veins of those regions.

This squeezing and action of pocket valves (that prevent back flow) help the flow of blood towards the heart. Breathing in mammals also helps in drawing the blood from the veins in the head and abdominal cavity. Smooth muscles in veins also help in regulating blood supply in the venous system. When a person changes his position from sitting to standing the change in the relative position of heart and brain with respect to gravity activates the nerve fibres that are present in the veins of the limb. This causes a contraction of the smooth muscles. The pooled blood is thus, redistributed.


Related Discussions:- Veins - circulation

Simple tips to diarrhoea patient, A few simple tips which should be given t...

A few simple tips which should be given to the patient. • Boiling, steaming, baking, pressure cooking should be encouraged • Consume small and light meals frequently instea

What is bile salts, What is Bile salts Bile salts have a considerable...

What is Bile salts Bile salts have a considerable ability to lower surface tension. By  this property, they prevent  the coming together of the small fat droplets in  the  in

What are the structures that form the external ear, What are the structures...

What are the structures that form the external ear? What is its function? The internal ear comprises the pinna, or auricle, and the auditory canal. Its function is to conduct t

Determine the photographic analysis, Photographic Analysis Documentatio...

Photographic Analysis Documentation is critical in any clinical procedure and more importantly in this field where due to the cost of the treatment involved, there is little ma

How folate is important for pregnant women, How Folate is Important For Pre...

How Folate is Important For Pregnant Women? Folate is also important for pregnant women. Low blood levels of folate during pregnancy can cause neural tube defects-anencephaly (

What capacity does the brain have to repair itself, What capacity does the ...

What capacity does the brain have to repair itself after injury or disease? It has long been accepted dogma that central nervous system doesn't regenerate itself after traumati

Express the term - amnion, Express the term - Amnion One of the extraem...

Express the term - Amnion One of the extraembryonic membranes found in terrestrial vertebrate. The amnion is filled with fluid and the developing embryo of reptiles, birds, and

Can you explain lane and eynon method, Q. Can you explain Lane and Eynon me...

Q. Can you explain Lane and Eynon method? Reducing sugars are those, which have free sugar groups (e.g. glucose, fructose etc.) and hence may be estimated directly by titrat

Hybrid sterility, Hybrid sterility can be regarded as yet another form of i...

Hybrid sterility can be regarded as yet another form of interspecific sterility. The offspring of the interspecific crosses are mainly sterile. Geological studies have shown that t

What is hemoglobin f, What is hemoglobin F? Why does the fetus need a diffe...

What is hemoglobin F? Why does the fetus need a different hemoglobin? Hemoglobin F is the hemoglobin found in the mammalian fetus and hemoglobin A is the normal hemoglobin. Hem

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