Homeostasis [4] - Kidneys - A level biology

A Level Biology: Homeostasis 4 – Kidneys Hi! Welcome to today’s video. Today, we are going to be looking at Osmoregulation, but we are going to split it up into two parts. The first part that we are going to focus on is the kidneys. If you are wondering where your kidneys are, if you were to place both your hands on your hips, the location of where your fingers are should be roughly where your kidneys are found. Most people are actually born with two kidneys, but you can survive with just one. Those who have only one kidney need to have dialysis. Your kidneys do three very important jobs. The first job being removal of urea from the blood; production of urine, as I have already stated; and Osmoregulation. The kidneys are involved in excretion, primarily of urea. What urea actually is it’s a poisonous waste product and it is made within the liver. What happens is when we eat proteins, proteins are made up of amino acids, if we got an excess of proteins, they need to be broken down and gotten rid of. The excess proteins are broken down into their individual monomers which are amino acids. These are then converted to ammonia through a process known as deamination. That’s then converted to urea and then urea is released into the blood where it travels around the body until it is removed by the kidneys. Now, let’s take a look at the structure of the kidneys. As you can see, each kidney is connected to two blood vessels. You got the renal vein which carries blood away from the kidney and you have the renal artery which carries blood towards the kidney. You also got the urethra there as well. That is where the waste or the urine is transported out towards the bladder. If we then look at a cross-section of the kidney, you can see, here you got one individual kidney and you can see that it is basically split up into two parts. You got the outer part which is known as the cortex which is this bit here and an inner part which is known as the medulla which is this bit here. If we take an even closer look, you got a single kidney tubule here. A kidney tubule, one tubule is actually known as a nephron. Here you got the structure of a nephron here. This is the collecting duct and this leads towards the urethra and the bladder. Here, you got the distal convoluted tubule. This bit here is known as the Loop of Henle. Here you got the proximal convoluted tubule and here, you got the Bowman’s capsule. These massive capillaries here are known as the glomerulus. So as you can see here, you also got the renal artery. What happens is the blood containing urea and other waste substances passes through these massive capillaries here. What happens is the water, glucose, urea, salts and everything comes out minus the red blood cells. As it passes through the proximal tubule, some useful substances get reabsorbed. So they passed back into the blood. Those are things like water, glucose and some salts as well. Down here in the Loop of Henle, some of the water also passes back into the blood and we will focus on this when we look at Osmoregulation. Blood which has had the urea and other waste substances removed then heads back towards the renal vein while the products which are left within the tubule forms urine. It dissolved into water and forms urine. That goes towards the collecting duct and out towards the urethra and bladder. There you have it. That’s the structure of the kidney. That concludes the short presentation. I hoped you enjoyed it. Don’t forget to keep a lookout for some more videos coming out soon. [end of audio – 04:47] A Level Biology: Homeostasis 4 - Kidneys Page…1