The human excretory system consists of kidneys and urinary tracts. In the excretory system, urine formed in the kidneys is transported through the urinary tract, in one sense, to the outside of the body. The urinary tract is partly inside the kidneys (intrarenal pathways), partly outside them (extrarenal pathways).
THE FORMATION OF URINE
The formation of urine occurs at the level of nephrons and is carried out in 3 stages:
- glomerular ultrafiltration
- tubular reabsorption
- tubular secretion
1.Glomerular ultrafiltration is carried out at the level of the Malpighi renal corpuscle; it consists in the passage of a large amount of water, ions and toxic substances from the capillaries of the vascular glomeruli into the space between the walls of the Bowman capsule.
2.Tubular reabsorption is carried out at the level of the urinary tube; it consists in the passage of useful substances from the primary urine into the peritubular capillaries surrounding the urinal tube.
3.Tubular secretion is carried out at the level of the urinary tube and is the reverse process of tubular reabsorption.It consists in the passage of toxic substances from peritubular capillaries into the urinary tube.
DISEASE
I.CYSTITIS is an inflammation of the lining of the bladder. It is caused by microbial infections from the kidneys or ureters. It is manifested by pain in the bladder, frequent and painful urination, hematuria (blood in the urine), cloudy urine. Compliance with the rules of intimate hygiene, avoiding exposure to cold, especially the kidney area.
II. NEPHRITIS is acute or chronic inflammation of interstitial renal tissue (nephron supporting tissue). It is caused by microbial or viral infections. It is manifested by intense low back pain, urinary disorders, fever and chills. Compliance with the rules of intimate hygiene, avoidance of drug abuse.
III.GLOMERULONEPHRITIS is bilateral inflammation of the renal glomeruli. It is caused by microbial infections. It is manifested by low back pain, headache, asthenia (rapid muscle fatigue). Compliance with the rules of intimate hygiene and avoidance of drug abuse.
Extrarenal urinary tracts are the ureters, bladder and urethra. Each renal pelvis continues with a ureter, longer tube with smooth muscle walls; the ureters descend through the abdomen, to the pelvis (pelvis), where they open into the bladder. The bladder is a hollow organ for storing urine; the smooth-muscle walls have a role in removing urine; the lower, the bladder has circular (sphincter) muscles, both smooth and striated, plays a role in controlling urination. The bladder continues with the urethra, unpaired tube.
THE KIDNEYS
The kidneys are paired organs, located in the abdominal cavity. The dimensions of the kidneys of an adult are 10-12 cm long, 5-6 cm wide and 3-5 cm thick. The kidneys are bean-shaped, with the hollow part (concave) oriented towards the large blood vessels; at its level, the renal artery, the renal vein and the ureter are visible.
The kidneys form urine from substances in the blood and therefore they contain numerous blood vessels, which give the kidneys the reddish-brown color. The small components of urine-forming rhinicha are nephrons, about one million in each kidney.
Excretion is the process by which water, non-useful substances and excess substances are removed from the body in the form of urine. Urine is formed and eliminated by the structures of the excretory system. The excretory system consists of: kidneys (formed from structural and functional units called nephrons) and extrarenal urinary tracts (urinary bladder, urethra).
