Excretory System Of Human
Excretory system

The excretory system is a passive biological system that removes excess, unnecessary materials from an organism, so as to help maintain homeostasis within the organism and prevent damage to the body.

The excretory system is a passive biological system that removes excess, unnecessary materials from an organism, so as to help maintain homeostasis within the organism and prevent damage to the body.

As most healthy functioning organs produce metabolic and other wastes, the entire organism depends on the function of the system; however, only the organs specifically for the excretion process are considered a part of the excretory system.

There are several parts of the body that are involved in this process, such as sweat glands, the kidney, the ureter, the urinary bladder and the urethra.

Excretory system

 
Essential components of the human excretory system
Kidney

Kidneys are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and regulation of blood pressure via maintaining salt and water balance.

Kidneys serve the body as a natural filter of the blood, and remove wastes which are diverted to the urinary bladder. In producing urine, the kidneys excrete wastes such as urea and ammonium, and they are also responsible for the reabsorption of water, glucose, and amino acids.
Kidney

The kidneys secrete a variety of hormones, including erythropoietin, and the enzyme renin. Erythropoietin stimulates erythropoiesis(production of red blood cells) in the bone marrow.

The kidneys receive blood from the renal arteries, left and right, which branch directly from the abdominal aorta. Despite their relatively small size, the kidneys receive approximately 20% of the cardiac output.

After filtration occurs the blood moves through a small network of venules that converge into interlobular veins. As with the arteriole distribution the veins follow the same pattern, the interlobular provide blood to the arcuate veins then back to the interlobar veins which come to form the renal vein exiting the kidney for transfusion for blood.

Many of the kidney's functions are accomplished by relatively simple mechanisms of filtration, reabsorption, and secretion, which take place in the nephron.

Filtration, which takes place at the renal corpuscle, is the process by which cells and large proteins are filtered from the blood to make an ultrafiltrate that eventually becomes urine. The kidney generates 180 liters of filtrate a day, while reabsorbing a large percentage, allowing for the generation of only approximately 2 liters of urine.

Reabsorption is the transport of molecules from this ultrafiltrate and into the blood.

Secretion is the reverse process, in which molecules are transported in the opposite direction, from the blood into the urine.

The kidneys excrete a variety of waste products produced by metabolism. These include the nitrogenous wastes called "urea", from protein catabolism, as well as uric acid, from nucleic acid metabolism. Formation of urine is also the function of the kidney.

Each adult kidney weighs between 125 and 170 grams in males and between 115 and 155 grams in females. The left kidney is typically slightly larger than the right kidney.The kidney is approximately 11–14 cm in length, 6 cm wide and 4 cm thick.

 
Ureters
In human anatomy, the ureters are tubes made of smooth muscle fibers that propel urine from the kidneys to the urinary bladder. In the adult, the ureters are usually 25–30 cm (10–12 in) long and ~3-4 mm in diameter.
 
Urinary bladder

The urinary bladder is the organ that collects urine excreted by the kidneys before disposal by urination. A hollow muscular, and distensible (or elastic) organ, the bladder sits on the pelvic floor. Urine enters the bladder via the ureters and exits via the urethra.

The detrusor muscle is a layer of the urinary bladder wall made of smooth muscle fibers arranged in spiral, longitudinal, and circular bundles. When the bladder is stretched, this signals the parasympathetic nervous system to contract the detrusor muscle. This encourages the bladder to expel urine through the urethra.

The urinary bladder usually holds 300-350 ml of urine. As urine accumulates, the rugae flatten and the wall of the bladder thins as it stretches, allowing the bladder to store larger amounts of urine without a significant rise in internal pressure.

 
Urethra
The urethra is a tube that connects the urinary bladder to the genitals for the removal of fluids from the body. In males, the urethra travels through the penis, and carries semen as well as urine. In female placental mammals, the urethra is shorter and emerges above the vaginal opening.

In the human female, the urethra is about 1.5 inches (3.8 cm) to 2 inches (5.1 cm) long and exits the body between the clitoris and the vagina

In the human male, the urethra is about 8 inches (20 cm) long and opens at the end of the penis.
 
 
 
Science

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Water and it's states
Spheres of the earth
Nutrients & Deficiency Of Nutrients & It's Effect
Interesting Facts About Human Organs
Circulatory system
Digestive system
Endocannabinoids system
Endocrine system
Excretory system
Integumentary system
Immune system
Lymphatic system
Nervous system
Respiratory system
Musculoskeletal system
Vestibular system

 
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