Children>adults, men>women (more fat); male body fluids account for 60% of body weight, women 50%.

body fluid

The cations are mainly Na, followed by K, Ca, and Mg (extracellular fluid)

The anions are mainly Cl-, followed by hco3, hpo4, so4 and organic acids and proteins (extracellular fluid)

intracellular fluid

90%-95% of the extracellular fluid osmotic pressure comes from Na, Cl-, HCO3-

Plasma osmotic pressure is between 290-310mmol/L

The intracellular fluid osmotic pressure is mainly K and HPO4-especially potassium ions

Physiological functions of water

water balance

The normal range of sodium ions is 135-150mmol/L

The relative stability of extracellular fluid volume and osmotic pressure is achieved through the regulation of the neuro-endocrine system

OsmoreceptorsHypothalamic supraoptic nucleus and paraventricular nucleus

Increased extracellular fluid osmotic pressure → hypothalamic supraoptic nucleus receptors → thirst center excitement → drinking water

Increased ADH secretion → Binds to V2 receptors in the distal convoluted tubule and collecting duct → Enhances water reabsorption in the distal convoluted tubule and collecting duct

Inhibit the secretion of aldosterone → weaken the reabsorption of sodium ions → increase the excretion of sodium ions → reduce the concentration of sodium ions in the extracellular fluid → return the osmotic pressure of the extracellular fluid to normal

Renal urination can regulate water balance. Only when renal function is severely impaired will it have a greater impact on the total water balance.

Atrial natriuretic peptide ANP affects water and sodium metabolism: reduces renin secretion; inhibits aldosterone secretion; antagonizes the vasoconstrictor effect of angiotensin; antagonizes the sodium ion retention effect of aldosterone

Aquaporin AQP

ADH receptor V2R and AQP2 are closely related

hypotonic dehydration

hypertonic dehydration

isotonic dehydration

Causes and Mechanisms

Effect on the body

Prevention and control

Causes and Mechanisms

Effects on the body

Prevention and control

Water and sodium are lost in proportion but the concentration remains normal

It can be seen in vomiting and diarrhea, large area burns, and large amounts of pleural effusion and ascites.

Too much water intake

Reduced water excretion: more common in acute renal failure and excessive secretion of ADH

Increased extracellular fluid volume, blood dilution

Intracellular edema, transfer of external fluid into cells

Central nervous system symptoms, cell swelling, and central nervous system compression symptoms caused by increased intracranial pressure

Prevention and treatment of primary diseases: acute renal failure, postoperative heart failure patients, limiting water intake

Mild patients, limit fluid intake

Severely ill patients should be given strict fluid intake and hypertonic saline or diuretics

systemic, local

Cardiac edema (congestive heart failure)

Renal edema (nephrotic syndrome and nephritis)

Hepatic edema (liver disease)

dystrophic edema

inflammatory edema

Lymphedema

Imbalance of fluid exchange inside and outside blood vessels (effective hydrostatic pressure, effective colloid osmotic pressure and lymphatic reflux)

Imbalance of fluid exchange inside and outside the body - sodium and water retention, bulbar balance

Characteristics of edema

The impact of edema on the body

cell membrane sodium potassium pump

Extracellular hydrogen and potassium exchange

Changes in the transmembrane potential inside and outside the renal tubular epithelial cells affect their potassium excretion

Aldosterone and distal tubule fluid flow rate

Colon excretion of potassium and sweating

Causes and Mechanisms

Effects on the body