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

What is nagel''s anomaloscope, What is Nagel's Anomaloscope The patient...

What is Nagel's Anomaloscope The patient is asked to match a yellow with a mixture of red and green wave lengths. A defect can be detected based on the amount of red and green

Effects on aquatic organisms - water pollution, Effects on Aquatic Organism...

Effects on Aquatic Organisms - Water Pollution Toxic water pollutants such as metals, pesticides, insecticides and chemicals affect aquatic species directly whereas the non-t

Explain about the acesulfame k - artificial sweeteners, Explain about the A...

Explain about the Acesulfame K - Artificial Sweeteners? Acesulfame-K (potassium salt of 6-methyl-1, 2, 3-oxathazin-4(3H)-one 2, 2 dioxide) is a sweetener which is commonly used

Tissue culture, Note on production of haploid by tissue culture.

Note on production of haploid by tissue culture.

What is single ventricle physiology, What is Single Ventricle Physiology ? ...

What is Single Ventricle Physiology ? In complete correction of a congenital cardiac condition, it is ideal to have two ventricle correction (Pulmonary and systemic ventricles

Explain antioxidants, Antioxidants  Antioxidants are the substances tha...

Antioxidants  Antioxidants are the substances that can delay onset, or  slow the rate of oxidation of autoxidizable materials. By virtue of this property,  they provide protect

Explain why the plasmid is described as a vector, Humans produce insulin fr...

Humans produce insulin from certain cells in the pancreas.The insulin gene is isolated from a human pancreas cell and then inserted into a plasmid.The DNA responsible for the synth

Phototropism, wich variables are controlled when conducting a phototropism ...

wich variables are controlled when conducting a phototropism experiment

Analysis of developmental potency of nuclei, Analysis of Developmental Pote...

Analysis of Developmental Potency of Nuclei The instances given above and many other observations and experimental results of this nature provide tough support to the hypothes

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