1. The Importance of Excreting Wastes

2. Why Pee? The body runs chemical reactions necessary for life. The products of these reactions tend to be useful to the body but some are not – like carbon dioxide in cellular respiration. The body runs chemical reactions necessary for life. The products of these reactions tend to be useful to the body but some are not – like carbon dioxide in cellular respiration. These byproducts that are not used must be removed from the cells/body through excretion. These byproducts that are not used must be removed from the cells/body through excretion.

3. Protein Problems Proteins are the working molecules and they are an absolute necessity for the body. Proteins are the working molecules and they are an absolute necessity for the body. When proteins are broken down the amine group (NH 2 ) is removed in a process called deamination. These must be excreted as they will form ammonia which is toxic to the body. When proteins are broken down the amine group (NH 2 ) is removed in a process called deamination. These must be excreted as they will form ammonia which is toxic to the body. The ammonia is combined with carbon dioxide by the liver to form urea. The ammonia is combined with carbon dioxide by the liver to form urea. Nucleic acids breakdown to give a similar product – uric acid. Nucleic acids breakdown to give a similar product – uric acid.

4. What Else is Excreted? See Table 1 on page 342. This table shows what gets excreted and who gets rid of it. See Table 1 on page 342. This table shows what gets excreted and who gets rid of it. Ammonia, Urea and Uric Acid  Kidneys Ammonia, Urea and Uric Acid  Kidneys Carbon dioxide  Lungs Carbon dioxide  Lungs Lactic Acid  Liver Lactic Acid  Liver Solid Waste (Feces)  Large Intestine Solid Waste (Feces)  Large Intestine

5. The Urinary System

6. How to Get Urine Out Cells dump their waste into the blood – kind of like a sewer system. The blood travels through the renal arteries to the kidneys. (Renal = Kidneys) Cells dump their waste into the blood – kind of like a sewer system. The blood travels through the renal arteries to the kidneys. (Renal = Kidneys) The kidneys are the major filtration organ of the body. They filter the blood and remove waste products. The kidneys are the major filtration organ of the body. They filter the blood and remove waste products. The kidneys have three parts: The kidneys have three parts: –The renal cortex – the outer layer of the kidney. –The renal medulla – the middle area of the kidney which houses the nephrons. –The renal pelvis – the collecting area for urine.

7. Nephrons The nephrons are the actual filtration units of the kidneys. They are microscopic and each kidney has over a million of them. The nephrons are the actual filtration units of the kidneys. They are microscopic and each kidney has over a million of them. The nephrons are housed in the renal medulla. The nephrons are housed in the renal medulla. Nephrons are composed of several parts – glomerulus, Bowman’s capsule, proximal tubule, loop of Henle, distal tubule and the collecting duct. Nephrons are composed of several parts – glomerulus, Bowman’s capsule, proximal tubule, loop of Henle, distal tubule and the collecting duct.

8. What Happens in the Nephron? Blood with waste in it is carried by the afferent arteriole to the glomerulus. Blood with waste in it is carried by the afferent arteriole to the glomerulus. Dissolved matter – both useful and waste products are sent from the glomerulus to the Bowman’s capsule. Blood stays in circulation. Dissolved matter – both useful and waste products are sent from the glomerulus to the Bowman’s capsule. Blood stays in circulation. The good and bad stuff absorbed by the Bowman’s capsule is separated as it travels through the proximal tubule and the loop of Henle – the good stuff is reabsorbed into the blood while the bad stuff stays in the nephron. The good and bad stuff absorbed by the Bowman’s capsule is separated as it travels through the proximal tubule and the loop of Henle – the good stuff is reabsorbed into the blood while the bad stuff stays in the nephron.

9. After the Nephron? The bad stuff leaves the nephron through the distal tubule and enters the collecting duct. The bad stuff leaves the nephron through the distal tubule and enters the collecting duct. The collecting duct leads to the renal pelvis where it collects and is ready to leave the kidney. The collecting duct leads to the renal pelvis where it collects and is ready to leave the kidney. Ureters extend down from the kidney to the urinary bladder and the urine travels down these tubes. Ureters extend down from the kidney to the urinary bladder and the urine travels down these tubes. Urine collects in the urinary bladder that has cells that are capable of stretching. When stretched far enough a nervous impulse is sent to the brain that says “ya gotta go!”. Urine collects in the urinary bladder that has cells that are capable of stretching. When stretched far enough a nervous impulse is sent to the brain that says “ya gotta go!”. Urine exits the urinary bladder and the body through a tube called the urethra. Urine exits the urinary bladder and the body through a tube called the urethra.

10. Formation of Urine

11. The Process of Peeing Urination is the result of three steps or processes…Filtration, Reabsorption & Secretion. Urination is the result of three steps or processes…Filtration, Reabsorption & Secretion. 1. Filtration – Stuff is removed from blood to see what we will get rid of – it is the glomerulus and Bowman’s capsule part. 2. Reabsorption – The good stuff we need is brought back into the blood from the nephron and into the capillaries. 3. Secretion – Taking the bad stuff from the nephron, mixing it with water and expelling it from the body.

12. Interesting Information Once you get to 600ml – you go – like it or not! Once you get to 600ml – you go – like it or not! Only 1ml of every 120ml that is filtered by nephron is turned into urine. The other 119ml is reabsorbed into the blood. Only 1ml of every 120ml that is filtered by nephron is turned into urine. The other 119ml is reabsorbed into the blood. The body will reabsorb all the good stuff until it hits a threshold level for that substance – after that, good or not, it is going to go out in the urine. The body will reabsorb all the good stuff until it hits a threshold level for that substance – after that, good or not, it is going to go out in the urine. A dialysis machine does the same job as the kidneys and nephrons only it takes several hours a day to do so. This is a time consuming, and emotionally draining, daily activity for people with kidney disease/failure A dialysis machine does the same job as the kidneys and nephrons only it takes several hours a day to do so. This is a time consuming, and emotionally draining, daily activity for people with kidney disease/failure

13. FIN