EXCRETORY SYSTEM

1. EXCRETORY SYSTEM

2. Intended Learning Outcomes

3. VOCABULARY _____ Afferent arteriole _____ Aldosterone _____ Antidiuretic hormone _____ Blood pressure _____ Bowman’s capsule _____ Collecting duct _____ Constriction _____ Cortex _____ Dehydration _____ Distal convoluted tubule _____ Efferent arteriole _____ Excretion _____ Filtrate _____ Glomerulus _____ Hypertonic _____ Hypothalamus _____ Juxtoglomerular apparatus _____ Kidney _____ Loop of Henle _____ Medulla _____ Nephron _____ Osmotic pressure _____ Peristalsis _____ Peritubular capillaries _____ Permeable _____ Posterior pituitary _____ Pressure filtration _____ Proximal convoluted tubule _____ Renalarteries _____ Renal pelvis _____ Renalvein _____ Renin _____ Selective re-absorption _____ Tubular secretion _____ Tubule _____ Urea _____ Urinary bladder _____ Urination _____ Water re-absorption

4. WHAT IS EXCRETION? • If you knew there was poison hidden in your house, you would surely do everything possible to find and remove that poison. • If you didn't, you and your family would slowly die. • How would you find and then remove it? • You would probably figure out a system of searching and removing. • That is what the excretory system does!!

5. interesting facts • The Human bladder can stretch to hold about 1.5 cups (400ml) of urine. • All the blood in our body passes through each kidney 400 times every day. • When the bladder is ½ full, our brain tells the bladder to relax and we get the urge to urinate. We can’t control or stop urination until we are 2 years old. • Even if 75% of the nephrons are lost, the kidney will still function. It is possible to live a healthy life with only one kidney. • Normal urine is sterile (germ-free). It is composed of water, salts, and waste products.

6. interesting facts • The kidneys have 1 million little filters which filter 1.3 litres of blood every minute. That is 1,620 litres every day.  • 99.9% of the materials passing through the kidneys are reabsorbed back into the blood. • We made approximately 1.5 litres of urine per day. • A traditional medical practice in India is called urine therapy, and they apply urine to the skin or drink it to cure various health problems. • Urine has a lot of urea (waste), and it is a good source of nitrogen for plants. Gardeners often recommend you add 1 cup of urine to 15 cups of water and apply it to pot plants and flower beds to help them grow.

7. interesting facts • The ancient Romans used to bleach their clothes with urine. • People lost at sea or in the desert for a long time often resort to drinking their urine when no rainwater is available. However, this won't prevent you from dying of dehydration, especially if it causes vomiting. • Urine has also been used as an antiseptic. In times of war, when other antiseptics were unavailable, urine, the darker the better, was used on open wounds to kill bacteria. • The yellow colour of urine was once thought to come from gold. Alchemists in the middle ages spent a lot of time trying to extract gold from urine. They were, of course, unsuccessful.

8. FUNCTIONS OF THE EXCRETORY SYSTEM • Filtersthe blood • Removes wastes from the blood • Keeps the amount of water and salts in the blood constant • Helps to regulate Blood Pressure

9. Dessication Humans will die if they lose about 12% of their body water. The threat of dessication is the most important problem confronting terrestrial life. How do we control our loss of water? Multiple layers of dead, keratinized skin cells Drink and eat moist foods Nervous and hormonal mechanisms control thirst Behaviour: (ie: stay out of intense heat) Kidneys and other excretory organs help conserve water.

10. Dessication Water loss can be considerable: a person in a 38oC temperature will lose 1 Litreof H2O/hour. We acquire most of our water in our food and drink, and obtain a smaller amount by dehydration synthesis and as a by-product of cellular respiration. We lose water by urinating, defecating, sweating, and breathing.

11. EXCRETION • The Excretory System is made up of the kidneys, liver, lungs, and skin. Each plays a role in excretion. • Skin: sweat with water, salts, heat and some urea • Lungs: excretes carbon dioxide, water, and heat • Liver: gluconeogenesis – makes urea as a byproduct • Intestines: excretes certain heavy metals • Kidneys: the main excretory organ. Excrete toxins, drugs, wastes (urea…), and water.

12. PARTS OF THE EXCRETORY SYSTEM

14. #1 KIDNEY • Kidney: • Bean-shaped • 10 cm long • Lower, dorsal part of the abdomen • Blood enters the kidney via therenal artery, is cleaned, and leaves the kidney in the renal vein

15. inside the kidney The kidneys account for less than 1% of the weight of the human body, but they receive about20% of the blood pumped with each heartbeat.

17. Renal cortex

18. Renal cortex renal medulla

19. Renal cortex renal medulla renal pelvis

20. Renal cortex renal medulla renal pelvis Renal pyramid

21. Renal cortex renal medulla renal pelvis Renal pyramid Ureter

22. #2 KIDNEY Ureter: Waste fluid made in the kidney exits through a duct called a ureter. Moves the urine to the bladder via peristalsis URETER

23. #3 KIDNEY Bladder: stores the urine An average bladder can hold a maximum of 1.5 to 2 cups of urine. When full, the sphincter muscles control the release of urine from the bladder URETER BLADDER

25. #4 KIDNEY Urethra: when the sphincter relaxes, the urethra carries the urine outside the body. 20 cm in males 4 cm in females Females are more prone to infections of the urinary system. URETER BLADDER URETHRA

32. Homeostasis • The kidneys perform a number of homeostatic functions, as they are the chief regulators of our internal environment: • Regulates blood volume and osmotic balanceby excreting or conserving water as the situation demands. • Regulates the ionic balanceof the blood by controlling the excretion of inorganic salts (especially sodium). • Regulates Blood pH by excreting excess acids or base • Excretes toxic metabolic by-productssuch as urea, ammonia, uric acid, and creatine (a product of muscle activity).

33. Nitrogen Wastes Nitrogen wastes are a by-product of protein metabolism. When proteins are turned into glucose during gluconeogenesis, ammonia is made. Because ammonia is very toxic and must be diluted as it travels around the body, however, terrestrial animals usually need to conserve water. What do we do? The liver converts the ammonia to urea, which is then transported to the kidneys, where it is concentrated and excreted out of the body as urine. This takes a lot of energy.

34. NEPHRON The functional unit of the kidney is the NEPHRON, which consists of a renal tubule and its associated blood vessels. Each kidney contains approximately 1 million nephrons, which represents approximately 80km of tubules.

35. Water, urea, salts, and other small molecules in the blood flow from the capillaries into the renal tubules, where the fluid is now called FILTRATE. The epithelial cells that line the renal tubule adds and removes things from the filtrate to eventually form URINE. From the 1100 to 2000L of blood that flows through the human kidneys each day, the nephron processes about 180L of filtrate, but excretes only ~1.5L of urine. The rest of the filtrate, including ~99% of the water, is reabsorbed into the blood. NEPHRON

39. NEPHRON STRUCTURE 1 4 2 5 3

40. NEPHRON STRUCTURE • 1. Bowman’s Capsule: this cup shaped receptacle is the blind end of the renal tubule, which receives filtrate from the blood. It encloses a ball of capillaries called the glomerulus. blood filtrate

41. NEPHRON STRUCTURE • 2. Theproximal convoluted tubule (PCT): most of the important things (nutrients, water, salt…) are reabsorbed from the PCT. nutrients water salt

42. NEPHRON STRUCTURE 3. The ascending and descending loop of Henle: a lot of salt and water are reabsorbed from Loop of Henle. salt water salt water

43. NEPHRON STRUCTURE 4. The distal convoluted tubule (DCT): the blood dumps things it wants to get rid of into the DCT so it can be removed in the urine. drugs acids

44. NEPHRON STRUCTURE 5. The collecting duct collects filtrate from many tubules and pass the urine into the renal pelvis. Water and urea are also reabsorbed here. water urea

46. NEPHRON CAPILLARIES 2 3 1 4 5

47. NEPHRON CAPILLARIES 1. Afferent Arteriole: this arteriole enters the bowman’s capsule from the renal artery . Renal artery Renal vein

48. NEPHRON CAPILLARIES 2. Glomerulus: the capillaries of the glomerulus are porous and very twisted up. They sit within the Bowman’s capsule. Renal artery Renal vein

49. Bowman’s Capsule