Tag: urine formation

A completely full urinary bladder is capable of holding approximately 500-600 ml of fluid. The urge to urinate occurs when the bladder contains about 150-200 ml of urine. The urge to urinate is stimulated by expansion of of the bladder. As the bladder walls fill with urine and expand, stretch receptors are stimulated and the micturition reflex is triggered. The micturition reflex centre is located in the spinal cord. 

The distal convoluted tubule (DCT) reacts to the amount of anti-diuretic hormone (ADH) or vasopressin in the blood. The more ADH is present in the blood, the more water is reabsorbed into it. This happens because the presence of ADH in the blood causes the cells in the DCT to become more permeable to water, therefore they allow more water to pass from the tubular fluid back into the blood. This results in more concentrated urine.

Micturition or urination is the process of expelling urine from the bladder. This act is also known as voiding of the bladder. The process of micturition is regulated by the nervous system and the muscles of the bladder and urethra. The urinary bladder can store around 350-400ml of urine before it expels it out.

The shared terminal duct of the reproductive and urinary system in the human male is urethra. In human male urethra is urinogenital duct which carry both urine and sperm. 

Urine reaches the urinary bladder from the kidney to the urinary bladder via the tube-like structure called the' ureter'. While urethra is the channel that conveys the urine from the bladder to the exterior. 

Urine is formed in the kidney. From the kidney through two tubes called ureters the urine descends into the urinary bladder. From the urinary bladder, urine is excreted to outside through urethra. So the correct path taken by urine in our body is kidneys, ureters, urinary bladder, urethra.

Angiotensin is a peptide hormone that causes vasoconstriction and an increase in blood pressure. It is part of the renin–angiotensin system, which regulates blood pressure. Angiotensin also stimulates the release of aldosterone from the adrenal cortex to promote sodium retention by the kidneys.

During micturition, parasympathetic stimulation causes the detrusor muscle to contract and the internal urethral sphincter to relax. The external urethral sphincter (sphincter urethrae) is under somatic control and is consciously relaxed during micturition.