2 English reference urine
Normal people excrete about 1 ~ 2L of urine every day and night. Due to the daily intake of water and the amount of water discharged through other channels, the urine volume changes greatly. If the urine volume stays above 2.5L for a long time, it is called polyuria. Continuous in the range of 0. 1 ~ 0.5L is called oliguria; Less than 0. 1L is called anuria, which is an abnormal phenomenon. Polyuria can cause dehydration and other phenomena due to excessive water loss. If the daily urine output is less than 0.5L, the excrement can't be discharged completely, and it will accumulate in the body, which will destroy the internal environment and affect the normal life activities of the body. The consequences of anuria are more serious.
Fresh urine volume is light yellow and transparent. The concentration of solute in urine is usually expressed by specific gravity. The specific gravity of normal urine is inversely proportional to urine volume, usually1.015 ~1.025. If there is an increase in urine volume without a decrease in specific gravity, or a decrease in urine volume without an increase in specific gravity, it is abnormal. The concentration of solute in urine also affects osmotic pressure. Urine osmotic pressure is generally higher than plasma. When drinking a lot of water to increase urine output, it can be temporarily lower than plasma. Checking the specific gravity and osmotic pressure of urine can reflect the function of kidney to concentrate and dilute urine. Normal urine is generally acidic with a pH of 5.0 ~ 7.0. The pH value of urine is mainly influenced by food components. Vegetarian omnivores, due to the decomposition of protein, produce acidic substances such as sulfate and phosphate through the kidneys, so the urine is acidic. Vegetarians, because organic acids such as tartaric acid, malic acid and sodium citrate contained in vegetables or fruits can be oxidized in the body, their acidic products are less and alkali excretion is more, so the urine is alkaline.
The water content of diluted urine accounts for 95% ~ 97%, and the rest is solid matter dissolved in urine. Solids are mainly nitrogen-containing end products and electrolytes produced by protein metabolism. In addition, normal urine also contains trace amounts of sugar, protein, bile pigment, ketone bodies and other components, but it can't be detected by routine clinical testing methods, so it is generally considered that normal urine does not contain the above substances.
Dilution of urine is caused by the reabsorption of solute and water in small tubular fluid. This situation mainly occurs in the thick segment of the ascending branch of the medullary loop. As mentioned above, the thick segment of the ascending branch of the loop can actively reabsorb Na and CI, but it is permeable to water, so the water is not reabsorbed, resulting in hypotonic tubule fluid in the thick segment of the ascending branch of the loop. When there is too much water in the body and the release of antidiuretic hormone is inhibited, the water permeability of the manifold is very low. Therefore, when the tubule fluid of the ascending branch of the medullary loop flows through the distal convoluted tubule and the collecting duct, NaCI continues to be reabsorbed, further reducing the osmotic concentration of the tubule fluid. It can be reduced to 50mO *** /kgH2O, resulting in low urine permeability and urine dilution. If the antidiuretic hormone is completely deficient, such as patients with severe diabetes insipidus, up to 20L of hypotonic urine can be excreted every day, which is equivalent to 10% of glomerular filtration rate.
4 urine concentration