B5 - The Kidney Flashcards
What is filtered in the kidney and what is reabsorbed? What is the waste product that is then removed?
Filtered : • glucose • salts • water • urea.
Reabsorbed : • all the glucose • some salts • some water
Removed : The remaining liquid, called urine, passes down the ureter to the bladder.
What are the two main functions of the kidney?
Removes urea
Regulates the amount of salts and water in your body
How many nephrons are there in each kidney? What does each nephron consist of?
There are about a million filtering units, called nephrons, in each kidney. Each nephron consists of
• a knot of capillaries, called a glomerulus, inside a capsule, where high pressure filtration occurs
• a region for selective reabsorption, where useful substances e.g. glucose pass into the blood
• a region for salt and water regulation.
How does blood enter and leave the kidney?
Blood enters your kidney, in the renal artery, under high pressure. Many arterioles branch off from the renal artery and one arteriole goes to each glomerulus. Blood goes from the afferent arteriole into the glomerulus. It then leaves the glomerulus in another arteriole, called the efferent arteriole.
How and why is there high pressure filtration?
The efferent arteriole has a narrower diameter than the afferent arteriole. This produces a bottleneck effect.
The blood cannot leave the glomerulus as fast as it is entering, so it is under high pressure, and the capillaries of the glomerulus are very leaky. The result is high pressure filtration.
Substances with small molecules – water, salts, urea, glucose, amino acids, vitamins, and spent hormones – are filtered out of the blood. They pass along the tubules of the nephron dissolved in liquid that was squeezed out from the glomerulus.
What happens in selective reabsorption?
From the rst part of the nephron, all the useful substances – glucose, amino acids, vitamins, some salts, and some water – are reabsorbed by selective reabsorption.
What is the loop of Henle and what does it do?
The loop of Henle, the rest of the tubule, and the collecting duct regulate the amount of salt and water in the body.
• If your blood is very watery, less water is reabsorbed from the kidney tubules and a lot of dilute urine is produced.
• If your blood is not very watery, more water is reabsorbed from the kidney tubules and a smaller volume of concentrated urine is
produced.
What is ADH? Where is it released from and where does it go?
The hormone ADH is released from a gland in the brain, your pituitary gland, directly into the blood.
Your blood carries it to its target organs, the kidneys.
This hormone makes the walls of the collecting duct more permeable to water, so more water can be reabsorbed into the blood.
Describe the negative feedback mechanism involving ADH.
As your blood passes through your brain, your hypothalamus detects how watery it is.
• If your blood is watery, less ADH is released. Less water is reabsorbed in the kidneys and more water is lost in urine. This adjusts the water content of your blood.
• If your blood is not very watery, more ADH is released. More water is reabsorbed in the kidneys and less water is lost in urine.
How do you remember what ADH does?
Diuresis means making urine.
Anti- means against.
Antidiuretic hormone reduces the volume of urine.
What is renal dialysis ?
Sometimes people’s kidneys stop working properly. When this happens their blood can be filtered by a dialysis machine.
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