Physiological characteristics of prostatic fluid production and excretion in urine

**1.6//What is the composition of prostatic fluid?**

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Prostatic fluid is an important component of semen, accounting for 30% of its volume. It is a thin, milky-white liquid containing a large amount of lecithin bodies, zinc, protein, acid phosphatase, and citrate.

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Prostatic fluid has a distinctive odor, which comes from the oxidation of spermine within the fluid, resulting in a volatile alkaline smell.

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Clinically, prostatitis is mainly diagnosed based on the number of white blood cells in prostatic fluid. Normal prostatic fluid contains no white blood cells or contains very few (less than 10 per field of view under high magnification). When the number of white blood cells in prostatic fluid increases, the main cause is prostatitis.

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When suffering from chronic prostatitis, prostate function is impaired, the lecithin bodies in prostatic fluid are significantly reduced, and other components also change.

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**Urinary Physiological Characteristics**

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**2.1//How is urine produced?**

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As we all know, urine is produced by the kidneys. With the excretion of urine, many metabolic wastes in the body are eliminated, thereby maintaining the normal internal environment of the human body.

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So how do the kidneys produce urine?

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Urine originates from blood. It is produced by filtering blood through the kidneys, which retains red blood cells, white blood cells, proteins, glucose, amino acids, and most electrolytes such as potassium, sodium, and calcium, while excreting metabolic products such as ammonia, urobilinogen, water, and creatinine.

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The kidney is mainly composed of 1 million nephrons. The nephron is the smallest unit in the kidney that filters blood. It is a glomerulus of capillaries. If capillaries are like yarn, then the nephron is like a ball of yarn, except that the ball of yarn is surrounded by a capsule. After the blood passes through the glomerulus, most of the proteins, red blood cells, and white blood cells are carried away, while other small molecules are filtered out into the capsule of the glomerulus. After reabsorption, many useful electrolytes (such as potassium, sodium, chloride, and calcium), glucose, amino acids, and 98% of the water are absorbed. The remainder is excreted into the renal pelvis and then into the bladder through the peristalsis of the ureter. A normal person produces 1000-2000 ml of urine per day. Less than 800 ml of urine is called oliguria, and less than 400 ml of urine is called anuria.

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Many hormones, such as antidiuretic hormone, renin, angiotensin, and aldosterone, are involved in the regulation of urine production. Their mechanisms of action are very complex. If these hormonal regulatory mechanisms are disrupted, a series of problems such as hypertension, polyuria, and hypocalcemia can occur.

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In addition to producing urine, the kidneys also have endocrine functions.

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The erythropoietin it produces maintains the normal production of red blood cells in the human body.

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There is a condition called renal anemia, which is caused by the kidneys producing too little of this hormone.

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**2.2/1 How is urine excreted?**

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Urine is transported from the kidneys to the bladder via the ureters. When the urine volume increases to 300-400ml, the bladder contracts rhythmically, and the person feels the urge to urinate. When the location and conditions permit, the bladder contracts, the internal and external urethral sphincters open, and the urine is expelled from the body.

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It takes about 20 seconds for a normal person to urinate. The average urine flow rate is greater than 10 ml/second for men and greater than 15 ml/second for women.

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1. Bladder fullness

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Urinating only when it is convenient

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Diagram illustrating how the bladder urinates.

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**2.3//What are the manifestations of abnormal urination?**

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Frequent urination, also known as excessive urination, is often caused by conditions such as cystitis, prostatitis, and diabetes.

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Urinary retention is defined as an excess of urine in the bladder that cannot be expelled.

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There are many causes of urinary retention. In older men, it is often due to benign prostatic hyperplasia (BPH), in women it is often due to bladder neck obstruction, and in younger men it is often due to prostatitis, alcohol consumption, or medication use.

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Urinary incontinence refers to the loss of conscious control over urination, resulting in the unknowing leakage or outflow of urine.

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There are many causes, such as true urinary incontinence caused by sphincter muscle damage in men, stress urinary incontinence caused by relaxation of pelvic floor muscles in women, and cerebral infarction and spinal cord injury are also common causes of urinary incontinence.