Regulation of blood volume:
1. blood pressure diffusion osmosis and capillary permeability are the biophysical factors most concerned in the regulation of blood volume
2. tissue spaces accommodate copious volume of fluid and affect blood volume
3. vitamins in particular vitamin c controls capillary permeability and affects blood volume
4. hormones like antidiuretic hormone of posterior pituitary mineralo corticosteroid of suprarenal cortex (by balancing Na and K ions) parathormone of the parathyroid (by its calcium control in the blood) controls capillary permeability and hence the blood volume
5. thirst and sweat are natural forces affecting blood volume
plasma protenins
these proteins are important constituents of blood plasma there are three types of plasma proteins :(1) serum albumin -4% (2) serum globulin 2.7% and (3) serum fibrinogen- 0.25-0.3% the origin of the serum albumin and fibrinogen is probably from the liver the serum globulin is derived from lymphocytes none of these proteins are obtained from food proteins
properties and functions of plasma proteins:
a. they exert an osmotic pressure amounting from 25 to 30 mmHg this is a factor of importance in the regulation of blood volume
b. they give viscosity to blood and thus aid in the maintenance of blood pressure
c. serum globulin is important for the manufacture of immune substances called antibodies agglutinins precipitin bacteriolysins etc
d. serum fibrinogen plays and essential role in coagulation of blood
e. they help in the transport and storage of certain hormones like thyroxin metals like iron and other substances
f. some of the drugs are reversibly bound to plasma proteins the resultant complexs is pharmacologically inactive and non excretable several type of adverse drug interaction may take place because of plasma protein binding of such drugs
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