Question

Describe how water is distributed in the body (which compartments have the water and what proportion do they have). What is a typical blood volume for a person? What is a typical plasma volume. List the main routes of water gain and loss for the body. Of the ways a person gains or loses water, which are normally the most important (targets of physiological regulation).

Answer 1

ANS: Water distribution in the body:

water consists of 70% of the body weight. In human body, its a largest component.

water is distributed throughout the body: 83% in blood to 10% in adipose tissue.

water is distributed in the body in 2 compartments: 1. intracellular 2. extracellular.

Intracellular water contains 65% of propotion in total body water.

Extracellular water contains 35% of propotion in total body water.

so, the intracellular compartment is largest it consists of 2/3 of body water.

while extracellular compartment consists 1/3 of body water. it contains plasma and interstitial fluid and they have same electrolyte composition. the sodium and chloride ions are the main ions in it.

The other compartment of the body also contain water like lymph, cerebrospinal fluid, eyeball fluid etc. but they consist small volume of water.

Total body water (60-70%)    

Extracellular fluid(35%) and intracelluar fluid(65%)   

Extracelllar fluid (35%) contains plasma fluid(7%) and interstitial fluid (28%).

water is absorbed in the GI tract. then it enters in the vascular system. an then interstitial spaces and transported to every cells.

water is then absorbed in stomach and colon and then small intestine, the duodenum and the jejunum.

water passed from the lumen into plasama by passive transport.

water then transported via blood circulation to the all over the body, to cells and the interstitial fluids.

The distribution of the water is different in different body organs.

water composition of tissues and organ by weight:

brain- 75%, Blood-83%, liver-68%, kidney-83%, adipose tissue-10%, Muscle-76%, skin-72%, heart-79%, lungs-79%, spleen-76%, intestine-75%, bone- 22%.

Blood volume is regulated by the kidneys and The typical blood volume for a person is approx 5 liters.

women have lower blood volume than the women.

Blood volume includes to the total amount of fluid circulating within the arteries, veins, capillaries, venules and the chambers of the heart.

Plasma volume: The typical plasma volume in males is 39ml/kg of the body weight. and in females is about 40 ml/kg.

The typical plasma volume is about 55% of the total blood volume of the body in humans.

List the main routes of water gain and loss for the body:

Kidneys, Skin, Lungs, gastrointestinal tract,

water is gained by the healthy person through eating an drinking.

Fluids provided by the IV route, or feeding tube entering in the stomach.

Kidneys:

water gained by the kidneys and loss by the urine. water loss by kidney is aprrox 1L to 2L.

Skin:

Perspiration( sweating) means loss the water and electrolytes by the skin.

sodium chloride and potassium also loss through skin.

water gained by the skin tissues and loss by the water electrolyte balance by sweating. its depend on environmental temperature also.

water loss by the skin is approx 0 to 1000ml its depends on physcial activity and environmental temp.

Lungs:

The lungs loss water by water vapor at a rate of 400mL.

In dry climate, the loss of water range is much more.

GI tract:

water loss by the GI tract is approx 100 to 200 ml daily.

because most of fluid is reabsorbed by the small intestine. Fistulas losses large water.

in healthy person, the daily water intake and output are almost equal.

water loss from the body by urination, excretion and Perspiration.

water fluid balance also related to osmolality.

A healthy person maintains plasma osmolality within the perticular range and by mechanisms which regulate both water intake and output.

water is great choice to prevent dehydration.

Hormones also play a role in the regulation of physiological processes.

Positive feedback and negative feedback loops plays a role in homeostasis in our body.

Homeostatic regulation: excess water, salts and urea excreted from body.

Hormones involved:- Antidiuretic hormone(ADH) and aldosteron.

sweating, shivering, constriction or dilation of blood vessels at skin surface, insulation by adipose tissue. control of blood pressure.

so, water loss by the body by renal system.