Question 1. Regulation of water metabolism.
Answer.
Water is the commonest liquid with the most uncommon properties. Water content of the body changes with age. It is almost 75% in the newborn and decreases to less than 50% in older individuals. Water content is maximum in brain tissue and least in adipose tissue.
Regulation of Water Metabolism
- Antidiuretic hormone or Vasopressin which has got the property to enhance water reabsorption
- Hypothalamus known as a thirst centre. Besides this, osmoconcentration of plasma also stimulates supraoptic and paraventricular nuclei
- Adrenal Cortex. Aldosterone has controll excretion of sodium and potassium by the kidneys
- Rennin-Angiotensin system. Angiotensin II stimulates the synthesis and secretion of aldosterone and the release of vasopressin, and thereby increases renal absorption of Na+ and H2O.
- Prostaglandins. They may also increase urinary loss of water by inhibiting the antidiuretic effect of vasopressin and by increasing the urinary sodium.
- Solutes. Osmotic effect of Na+ helps to retain water in extracellular fluids. Elevation in plasma Na+ raises the ECF volume in primary aldosteronism while an increase in urinary Na+ raises the urinary water output in Addisons disease. K+ helps to retain water in the cells, whereas, plasma proteins do help to retain water in the body by their osmotic effects. Increase in urinary urea or excretion of glucose in urine increases osmotically the urinary loss of water (osmotic diuresis).
Question 2.Composition of body fluids.
Answer.
Total water in the body is about 40 L. It is distributed into two major compartments:
- Intracellular fluid (ICF): Its volume is 22 L and it forms 55% of the total body water.
- Extracellular fluid (ECF): Its volume is 18 L and it forms 45% of the total body water.
ECF is divided into 5 subunits:- Interstitial fluid and lymph (20%)
- Plasma (7.5%)
- Fluid in bones (7.5%)
- Fluid in dense connective tissues like cartilage (7.5%)
- Transcellular fluid (2.5%) that includes:
- Cerebrospinal fluid
- Intraocular fluid
- Digestive juices
- Serous fluid – intrapleural fluid, pericardial fluid and peritoneal fluid
- Synovial fluid in joints
- Fluid in urinary tract.
Volume of interstitial fluid is about 12 L. Volume of plasma is about 2.75 L. Volume of other subunits of ECF is about 3.25 L. Water moves between different Compartments.
Question 3. Functions and requirement of water.
Answer.
Importance (Functions) of Water
- It acts as a carrier of nutritive elements to tissues and removes waste materials from tissues.
- It provides the media in which chemical reactions of the body take place.
- The fluidity of blood is because of water.
- It is the solvent for electrolytes and regulates the electrolytic balance of the body. It maintains the equilibrium of osmotic pressure extended by the solutes dissolved in water.
- It is a regulator of body temperature, because of its high specific heat, it can absorb or give off heat without any appreciable change in temperature. Also, because of its high latent heat, it provides the mechanism for the regulation of heat loss by sensible (sweating) and insensible (through the respiratory tract) perspiration.
Question 4. Overhydration.
Answer.
Definition
Overhydration, also called water excess or water intoxication, is a condition in which the body contains too much water.
Description
- Overhydration occurs when the body takes in more water than it excretes and its normal sodium level is diluted. This can result in digestive problems, behavioral changes, brain damage, seizures, or coma.
- Overhydration is an imbalance of fluids. It happens when your body takes in or holds on to more fluid than your kidneys can remove.
- Drinking too much water or not having a way to remove it can cause water levels to build up. This dilutes important substances in your blood. Endurance athletes, such as those who run marathons and triathlons, sometimes drink too much water before and during an event.
- Overhydration is an imbalance of fluids. It happens when your body takes in or holds on to more fluid than your kidneys can remove.
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- Drinking too much water or not having a way to remove it can cause water levels to build up. This dilutes important substances in your blood. Endurance athletes, such as those who run marathons and triathlons, sometimes drink too much water before and during an event.
- Treatement for overhydration depends on how severe your symptoms are and what caused the condition.
Treatments may include:
- cutting back on your fluid intake
- taking diuretics to increase the amount of urine you produce
- treating the condition that caused the overhydration
- stopping any medications causing the problem
- replacing sodium in severe cases
Question 5. Dehydration.
Answer.
In physiology, dehydration is a deficit of total body water,[1] with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mild dehydration can also be caused by immersion diuresis, which may increase risk of decompression sickness in divers.
Dehydration Signs and symptoms
The hallmarks of dehydration include thirst and neurological changes such as headaches, general discomfort, loss of appetite, decreased urine volume (unless polyuria is the cause of dehydration), confusion, unexplained tiredness, purple fingernails and seizures.
Dehydration Cause
Risk factors for dehydration include but are not limited to: exerting oneself in hot and humid weather, habitation at high altitudes, endurance athletics, elderly adults, infants, children and people living with chronic illnesses.
Dehydration can also come as a side effect from many different types of drugs and medications.
Dehydration Treatment: Management of dehydration
The treatment for minor dehydration that is often considered the most effective is drinking water and stopping fluid loss. Plain water restores only the volume of the blood plasma, inhibiting the thirst mechanism before solute levels can be replenished . Solid foods can contribute to fluid loss from vomiting and diarrhea. Urine concentration and frequency will customarily return to normal as dehydration resolves .
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