BIOLOGY: EXCRETORY SYSTEM

BIOLOGY: EXCRETORY SYSTEM

from Femosky110 on 06/11/2020 12:04 PM

The excretory system
The excretory system is a reflexive biological system that expels excess, needless materials from an organism, so as to help maintain homeostasis inside the organism and avert damage to the body.

 

It has the responsibility of eliminating the waste products of metabolism in addition to other liquid and gaseous wastes, like the urine and as a constituent of sweat and exhalation.

Since the majority of healthy functioning organs manufacture metabolic and other wastes, the whole organism relies on the function of the system; nevertheless, just the organs specially for the excretion process are taken as part of the excretory system.

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Parts of the excretory system and their function

1. Kidneys
The kidneys are bean shaped organs which are located in every one of the two sides of the Vertebral column in the abdominal cavity. Humans possess two kidneys and every one of them is supplied with blood from the renal artery.

Kidney expels the nitrogenous wastes from the blood like the urea and salts and excess water are as well expelled from the blood and excreted in the form of urine. This is made possible by the help of millions of Nephrons available in the kidney.

The filtrated blood is taken away from the kidneys by the renal vein or kidney vein. The urine from the kidney is gathered by the Ureter or excretory tubes, one among each one of the kidneys, and is taken to the Urinary bladder. Urinary bladder gathers and stores the urine till they are urinated.

The urine gathered in the bladder is excreted into the outside environment from the body via an opening known as the Urethra.

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The kidney's basic role is to remove waste from the bloodstream through urine production. They carry out many homeostatic functions like -

1. Maintaining the volume of extracellular fluid

2. Maintaining ionic balance in extracellular fluid

3. Maintaining the pH and osmotic concentration of the extracellular fluid.

4. Excreting toxic metabolic by-products like urea, ammonia, and uric acid.

The kidney does this through the 1 million nephrons contained in every kidney, these nephrons function as filters within the kidneys. The kidneys filter required materials and waste, the required materials pass back into the bloodstream, and un-required materials turn into urine and is eliminated.

In a few cases, excessive wastes turn into crystals as kidney stones. They grow and can turn into an aching pain that may need surgery or ultrasound treatments. A few stones are minute enough to be expelled via the urethra.

Liver
The liver detoxifies and breaks down chemicals, poisons and other toxins that get into the body. For instance, the liver transforms ammonia which is poisonous into urea which is subsequently filtered by the kidney into urine.

The liver as well manufactures bile, and the body makes use of bile to breakdown fats into utilizable fats and unusable waste.

Bile
After bile is manufactured in the liver, it is stored in the gall bladder. It is afterwards secreted inside the small intestine where it assists to break down ethanol, fats and other acidic wastes that include ammonia, into less harmful substances.

Large intestine
The large intestine gathers waste from all through the body. It extracts all the remaining utilizable water and subsequently eliminates solid waste. At approximately 10 feet long, it moves the wastes via the tubes to be excreted.

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Skin
The Skin excretes sweat via the sweat glands all through the body. This assists to expel additional wastes, like excess urine. Moreover, the sweat assisted by salt, escapes and helps to maintain the coolness of the body when the body gets warm.

Sweat glands in the skin secrete a fluid waste known as sweat or perspiration; although, its fundamental roles are temperature control and pheromone release. Therefore, its function as a component of the excretory system is negligible. Sweating as well regulates the level of salt in the body.

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Eccrine
Like sweat glands, eccrine glands allow excess water to escape from the body. A lot of eccerine glands are situated largely on the forehead, the bottoms of the feet, and the palms, even though the glands are all over the place in the body. They assist the body to retain its temperature control.

Lungs
One of the major roles played by the lungs is to diffuse gaseous wastes, like carbon dioxide, from the bloodstream as a typical part of respiration.

Ureter
The ureters are muscular tubes that thrust urine from the kidneys to the urinary bladder. In the human adult, the ureters are typically 25–30 cm (10–12 in) long. In humans, the ureters come up from the renal pelvis on the medial facet of every kidney prior to sliding towards the bladder on the front of the psoas key muscle.

The ureters pass over the pelvic brim next to the bifurcation of the iliac arteries. This "pelviureteric junction" is a widespread site that usually feels the impact of the kidney stones. Another site that feels the same impact is the uteterovesical valve.

The ureters dash posteriorly on the sideways walls of the pelvis. They after that bend anterior medially to go through the bladder via the back, at the vesicoureteric junction, passing within the wall of the bladder for some centimeters.

The backflow of urine is prohibited by valves referred as ureterovesical valves. In the female, the ureters pass via the mesometrium on the way to the bladder.

Urinary bladder
The urinary bladder is the organ that collects waste excreted by the kidneys prior to when they are eliminated via urination. It is a bare muscular, and distensible or elastic organ, and settles on the pelvic floor. Urine moves into the bladder via the ureters and to the exterior through the urethra.

Embryologically, the bladder is gotten from the urogenital sinus, and it is at first uninterrupted and with the allantois. In human males, the bottom of the bladder lies in between the rectum and the pubic symphysis.

It is superior to the prostate, and estranged from the rectum by the rectovesical dig. In females, the bladder lies inferior to the uterus and in front of the vagina. It is alienated from the uterus by the vesicouterine dig. In infants and young children, the urinary bladder is in the abdomen even when unfilled.

Urethra
In anatomy, the urethra is a tube which connects the urinary bladder to the exterior part of the body. In humans, the urethra has an excretory function both in male and in female.

Urine Formation
Inside the kidney, blood at first moves via the afferent artery to the capillary formation known as glomerulus and is gathered in the Bowman's capsule -located in the liver, which separates the blood from its contents—principally food and wastes.

After the filtration process, the blood subsequently goes back to gather the food nutrients it requires, while the wastes moves into the collecting duct, to the renal pelvis, and to the ureter, and are then after that excreted out of the body through the urinary bladder.

General features of excretory structures and functions
The physiological process by which organisms dispose of its nitrogenous by-products is known as excretion.

The meaning of excretion is for the most part simply understood in the perspective of vertebrate structure. The animal ingests food (ingestion). In the stomach and intestine a few of the food is converted into soluble products (digestion) that are assimilated into the body (assimilation).

In the body these soluble products experience additional chemical change (metabolism); a few are used by the body for growth, but the majority makes available energy for a variety of activities of the body.

Metabolism involves the intake of oxygen and the removal of carbon dioxide in the lungs (respiration).

Above and beyond carbon dioxide, compounds of nitrogen occur from metabolism and are done away with, mainly by the kidney, in the urine (excretion). Food not digested is expelled via the anus (defecation).

Products of excretion
Although every type of organism takes in a few materials and get rid of other, excretion is strictly a process seen in animals alone. For the purposes of this tutorial excretion will be taken to mean the removal of nitrogenous by-products and the regulation of the constituent of the body fluids.

The most important excretory product that occurs naturally in the animal body is ammonia, obtained roughly completely from the proteins of the ingested food. In the process of digestion proteins are converted into their component amino acids.

Some of the amino-acid pool is subsequently utilized by the animal to manufacture its own proteins, but a lot of it is utilized as a source of energy to compel other imperative processes.

The first step in the mobilization of amino acids for energy production is deamination, which means the removal of ammonia from the amino-acid molecule. The remaining is oxidized to carbon dioxide and water, with the associated manufacturing of the energy-rich molecules of adenosine triphosphate ATP.

The fact that excess levels of ammonia are extremely harmful to the majority of animals, they ought to be efficiently expelled. Minute aquatic animals do not have the same problem because ammonia swiftly diffuses, as a result of its high solubility in water into the surrounding water surfaces.

However in terrestrial animals, and in a few outsized aquatic animals, ammonia is transformed into varieties of less harmful compounds through the process known as detoxication.

In mammals, human being inclusive, it is detoxified to urea, which is taken to be produced through the condensation of a molecule of carbon dioxide with two molecules of ammonia.

Excretory mechanisms
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Vital information on the mechanism of Excretory System in Man

The human excretory system is made up of two kidneys that are bean shaped. The presence of two kidneys in human body is of a very big significance. When one kidney fails, the other can still perform the function of excretion.

The left kidney is situated a little higher than the right kidney. The kidneys are solid, reddish-brown, roughly 10 cm long organs which is situated in the abdominal cavity, one on each side of the vertebral column.

Every human kidney weighs about 150 g. The outer surface of the kidney is convex in shape while the interior is concave. There is a concave hollow known as hilus through which the arteries and veins pass into and leave the kidney.

Kidneys play a crucial role important role in regulating the composition of blood through the process known as osmo regulation.

Interesting points about excretion through kidney
• Roughly 130 ml of filtrate are produced every minute in the glomeruli of the two kidneys of man.

• Roughly 99% of the water of the filtrate is reabsorbed as it moves down the nephron.

• Body salts excreted in human urine may be about 2.2% and urea 6% of the volume of urine.

• The yellow colour of urine is as a result of a pigment called urochrome.

• Roughly1600 ml urine is excreted by an adult in 24 hours. A nephron is a 5-cm extended tubule.

• Urination is known as micturition. This is a reflex action (quick action) that is under the control of the spinal cord.