Question

HOLII ME AYUDAN PORFIS

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The main excretory system in humans is the urinary system. The skin also acts as an organ of excretion by removing water and small amounts of urea and salts (as sweat).


The urinary system includes a pair of bean-shaped kidneys located in the back of the abdominal cavity. They remove urea, toxins, medications, and excess ions and form urine. The kidneys also balance water and salts as well as acids and bases. At the same time, they return needed substances to the blood.


What is the main excretory system in humans____________________

What is another organ of excretion? ___________________________


Each kidney contains over one million nephrons, each of which consists of a tuft of capillaries surrounded by a capsule on top of a curving tube. The tuft of capillaries is called a glomerulus. Its capsule is cup-shaped and is known as Bowman's capsule. The glomerulus and Bowman's capsule form the top of a tube, the renal tubule. Blood vessels surround the renal tubule, and urine forms in it. The renal tubules of many nephrons join in collecting tubules, which in turn merge into larger tubes and empty their urine into the ureters in the renal sinus.


What is a nephron?
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The job of clearing the blood of wastes in the nephrons occurs in three stages.

They are filtration, reabsorption, and tubular secretion:


The first stage in clearing the blood is filtration, the passage of a liquid through a filter to remove impurities. Filtration occurs in the glomeruli. Blood pressure forces plasma, the liquid portion of the blood, through the capillary walls in the glomerulus. The plasma contains water, glucose, amino acids, and urea. Blood cells and proteins are too large to pass through the wall, so they stay in the blood. The fluid, now called filtrate, collects in the capsule and enters the renal tubule.


Explain the first stage:
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During reabsorption, needed substances in the filtrate travel back into the bloodstream. Reabsorption occurs in the renal tubules. There, glucose and other nutrients, water, and essential ions materials pass out of the renal tubules and enter the surrounding capillaries. Normally 100% of glucose is reabsorbed. (Glucose detected in the urine is a sign of diabetes mellitus, which is characterized by too much sugar in the blood due to a lack of insulin.)


What is reabsorption?
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Tubular secretion is the passage of certain substances out of the capillaries directly into the renal tubules. Tubular secretion is another way of getting waste materials into the urine. For example, drugs such as penicillin and phenobarbital are secreted into the renal tubules from the capillaries. Urea and uric acid that may have been reabsorbed are secreted. Excess potassium ions are also secreted into the urine. Tubular secretions also maintain the pH of the blood.


What is tubular secretion?
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The volume of the urine varies according to need. Antidiuretic hormone (ADH), released by the posterior pituitary gland, controls the volume of urine. The liver also plays an important role in excretion. This organ removes the ammonia and converts it into the less toxic urea.


What does organ control the volume of urine?
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The liver also chemically changes and filters out certain drugs such as penicillin and erythromycin. These substances are then picked up by the blood and transported to the kidneys, where they are put into the excretory system.

What is the function of the liver in the excretory system?
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Answer 1

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