UNIT 4: EXCRETION AND WASTE MANAGEMENT. Introduction

Transcription

1 UNIT 4: EXCRETION AND WASTE MANAGEMENT Introduction

2 List as many waste products of the human body as possible.

3 What are waste products? What would happen if you never threw out your garbage or leftover food?

4 What are waste products? Why do we sweat?

5 What are waste products? Why do we urinate?

6 Excretion and Homeostasis Homeostasis is the process that makes sure everything in the body is kept stable. Excretion helps this process by getting rid of the wastes your body produces.

7 What is excretion? Excretion: removal of metabolic waste from the body to maintain homeostasis. Metabolism: all of the chemical reactions that occur in the cells of an organism. (ex: cellular respiration, photosynthesis, digestion)

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9 Let s imagine We ate a big mac for lunch. What kind of waste products do you think we will produce? Bun = carbohydrates Meat = proteins Vegetables = carbohydrates Others = fat and sodium (salt)

10 In our cells These materials get broken down even further Waste Product Origin of Waste Product Excretory Organ Ammonia NH3 Breakdown of amino acids (from proteins) in the liver Kidneys Urea CO(NH2)2 Conversion of ammonia in the liver Kidneys, skin Carbon Dioxide Water Mineral Salts (NaCl) Cellular respiration (breakdown of glucose in cells) Cellular respiration (breakdown of glucose in cells Food and water Lungs, intestines, skin Kidneys, lungs, intestines, skin Kidneys, skin

11 Ammonia, one of the products of cellular metabolism, is very toxic. This is why it is converted to urea (much less toxic) in the liver before being released into the bloodstream. Ammonia Urea Too much ammonia in your body can cause psychological problems like confusion, tiredness, and possibly coma or death.

12 Ammonia NH3 2 NH3 + CO2 CH4N2O + H2O Ammonia carbon dioxide urea water

13 Organs involved in waste management Liver *not included in excretory system but plays important roles Lungs Skin Intestines Kidneys

14 Liver Largest internal organ in the body 1. Formation of urea Converts toxic ammonia into urea which is then excreted in our urine (yellow) 2. Detoxification Removes toxins, such as alcohol, drugs, and bacteria from the blood

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16 Liver 3. Production of bile Emulsification of fats (easier for absorption) 4. Storage of extra sugar in the form of glycogen. The liver changes glycogen into glucose and secretes it back into the bloodstream when the body needs energy.

17 Bile Bile contains bile salts, cholesterol, part of hemoglobin molecules from old red blood cells. Bile is released by the gall bladder to digest fats in the small intestine. Most bile salts are reabsorbed in the large intestine and returned to the liver to be reused. The remainder are passed in feces. Too much bile salts can cause diarrhea

18 What happens when wastes are not excreted properly and reabsorbed into the blood?

19 Liver Cirrhosis The liver is overgrown with extra tissue which cuts down blood flow and lowers its ability to purify blood. Can lead to death. Caused by overloading the liver with harmful materials, like alcohol.

20 Jaundice Too much bilirubin in the blood. Bilirubin is produced by the normal breakdown of red blood cells. Normally, it passes through the liver, which releases it into the intestines as bile

21 Why is excrement (feces) not included in the list of metabolic wastes? Excrement is not a product of cellular metabolism. It is a leftover after the body absorbs what nutrients it needs from the small intestine

22 Lungs When you inhale and exhale Your lungs exchange CO2 and O2 Toxic CO2 is eliminated while O2 is taken in Also exhale water vapour

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25 Skin Thermoregulation Evaporation of sweat lowers body temperature Contains sweat glands that excrete perspiration through skin pores. Perspiration is made up of nitrogenous wastes (urea), salts, and water.

26 Large Intestines Eliminate solid wastes that remain after the digestion of food.

27 Kidneys Act as filters remove urea and excess water and salts from the blood. the waste becomes urine and is then moved from the kidneys to the bladder More on this later

28 renal arteries renal veins u

29 Review Questions What is metabolism? What is metabolic waste? What waste products do humans excrete? What organs are involved?

30 UNIT 4: EXCRETION AND WASTE MANAGEMENT The Urinary System

31 Questions What is urine? How is it formed?

32 Liquid Wastes from Digestion Waste that leaves the kidneys is called urine. Urine is composed of mostly water, salts, and urea. Urine leaves the kidneys, travels down the ureters and is stored in the bladder. Leaves the body through the urethra.

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34 The Bladder Can hold a maximum of about ml of fluid. When there s about 250 ml of urine in the bladder, we become aware of it. 500 ml, we become very uncomfortable.

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36 Urinary Sphincters 2 rings of muscles that control the drainage of urine from the bladder. One is involuntarily controlled by the brain. The other we learn to voluntarily control.

37 Urethra Urine exits the body through the urethra. Males urethra is ~ 20 cm long Merges with the vas deferens from the testes to form a single urogenital tract. Females urethra is ~4 cm long Reproductive and urinary tracts have separate openings.

38 Urinary Tract Infection (UTI) Bacteria enters the urethra More in common in females due to short urethra

39 Kidneys Humans have 2 fist-sized kidneys, found in the lower back on either side of the spine. Function: to filter the blood in order to remove metabolic waste products from the body. Urea, uric acid, creatinine Filters 180 litres of blood, produces 1 litre of urine

40 Kidneys The human body can function with only 1 kidney. The functioning kidney increases in size to handle the increased workload.

41 Other Functions of the Kidney Control water balance in the blood (affects blood pressure) Control ph levels of the blood Control levels of sodium, potassium, bicarbonate, and calcium ions in the blood Secrete hormones that stimulate red blood cell production and activate vitamin D production in the skin.

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43 Kidney Structure Renal cortex is the outer layer (filtration) Renal medulla consists of pyramid shaped masses of tissue (collects) Renal pelvis is extended into the ureter (transports urine)

44 Kidney Structure When you look at the kidney under high magnification, the kidney is composed of over 1 million nephrons

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46 The Nephron Consists of 5 parts: Bowman s capsule Proximal tubule Loop of Henle Distal tubule Collecting duct Upper portion of the nephron is found in the renal cortex. Loop of Henle is located in the renal medulla.

47 Zac Nephron?

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49 Nephron

50 The Nephron (cont d) Tubules are surrounded by cells and a network of capillaries. Any material that isn t being removed from the body is returned to the capillaries

51 Kidney's Filtration Process 3 Steps Filtration (filters everything out of blood) Reabsorption (returns the good stuff) Secretion (gets rid of the bad stuff)

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53 Step 1: Filtration Blood enters the nephron through a tiny artery that branches to form a network of capillaries called the glomerulus. Blood pressure forces some blood plasma and small particles (water, urea, sugar, etc.) out of the glomerulus and into the Bowman s capsule. Cup-like sac around the glomerulus that acts as a filter Larger blood components (proteins, blood cells), remain in the capillaries.

54 Brian Bowman's Capsule?

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56 Filtered Nitrogenous wastes (urea, ammonia) Water, salts, sugars Not Filtered (too big) Proteins Blood cells, platelets Minerals, vitamins, some drugs

57 Filtration (cont d) The fluid in the Bowman s capsule is called the nephric filtrate. Contains the molecules and ions that have been filtered out of blood (sugars, salts, etc.) The nephric filtrate is pushed out of the capsule into the proximal tubule.

58 Step 2: Reabsorption When the nephric filtrate enters the proximal tubule, reabsorption begins. Materials required by the body are returned to the bloodstream. Osmosis, diffusion, and active transport draw water, glucose, amino acids, and ions from the filtrate. Occurs until the filtrate is isotonic to the surrounding cells.

59 Kidney Threshold Level Different for different substances. If the concentration of a substance in blood is greater than a certain level, excess is not reabsorbed and remains in urine for excretion. Ex: high blood sugar level in a diabetic.

60 180 litres of blood are filtered daily. Do we urinate 180 litres a day? ~179 litres of water are reabsorbed. Only ~1 litre is excreted Reabsorbed Most water Nutrients Required salts Not Reabsorbed Some water Much nitrogenous waste Excess salts

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62 Reabsorption (cont d) Filtrate moves from the proximal tubule to the loop of Henle. Water is removed by osmosis. NaCl is removed by diffusion.

63 Step 3: Secretion Get rid of the waste! Renal tubule collecting duct renal pelvis ureter urinary bladder urethra H2O, salts, urea, uric acid, and drugs are transported from blood to tubule

64 The fluid from a number of nephrons moves from the distal tubules into a common collecting duct. In the collecting duct, the fluid is now called urine which moves into the renal pelvis. At this point: 99% of the water that entered the proximal tubule has been returned to the body in addition to nutrients like glucose and amino acids.

65 Last Stop From the renal pelvis, urine will enter the ureter and be stored in the bladder until it is time to be expelled through the urethra

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67 Kidney Stones Substances can crystallize out of urine in the urinary tract or kidney. If too big to be passed, must be surgically removed or shattered in to small pieces using sound waves or lasers. Diet increases the risk of stone formation. Low fluid intake, salt, refined sugars, grapefruit juice, apple juice, cola drinks, too much animal protein.

68 Assignment Create a chain concept map to illustrate: The main parts of the nephron The direction of water and solute movement in each part

69 Assignment Create a chain concept map to illustrate: The main parts of the nephron The direction of water and solute movement in each part Glomerulus Proximal convoluted tubule; loop of Henle, distal convoluted tubules Collecting duct Urine Blood Blood Blood

70 UNIT 4: EXCRETION AND WASTE MANAGEMENT Water and Salt Balance

71 Why do we sometimes excrete a lot of urine and sometimes hardly any? Why do we sometimes feel so thirsty we can hardly get enough to drink, but sometimes we don t want to drink anything at all?

72 Osmoregulation The ability of the body to maintain a constant internal fluid balance.

73 Water/Salt Balance The amount of water and salt in the body needs to remain constant. Important for neuron and muscle function Fluid taken in by the body must, therefore, balance out fluid excreted by the body. The kidneys work with two hormones to maintain the balance of blood volume and composition through negative feedback mechanisms.

74 Hormones ADH (anti-diuretic hormone): promotes more water absorption back into the bloodstream (blood volume and blood pressure rises) Anti = no Uretic = urine NO URINE HORMONE Aldosterone: regulates sodium levels in the body.

75 Water Balance Dehydration: blood volume is lower than normal. The hypothalamus in the brain detects the narrowing of the blood vessels (vasoconstriction) and instructs the pituitary gland to release ADH. ADH reduces urine volume by causing the collecting tubules to allow more water to be reabsorbed into the bloodstream.

76 Too much fluid in the body Blood volume is higher than normal. The hypothalamus in the brain detects the widening of the blood vessels (vasodilation) and instructs the pituitary gland to stop releasing ADH. Excess water passes out of the body as dilute urine.

77 How does the body regulate blood pressure? Aldosterone increases sodium re-absorption, which increases water re-absorption into the blood from the collecting tubules. Amount of water in urine decreases. Blood volume and blood pressure increases.

78 What do you think would happen from eating salty potato chips? Salt is absorbed into your bloodstream through the wall of the small intestine. This leads to dehydration Receptors in the body alert the brain of the saltiness in the blood aldosterone is released. The kidneys will reabsorb more salt and therefore more water. Blood volume increases.

79 Alcohol prevents the release of ADH, what do you think would result from drinking it? If ADH is inhibited, water would not be re-absorbed in the nephron. More water would be excreted in urine. Repeated trips to the bathroom End result is dehydration. Causes hangovers

80 UNIT 4: EXCRETION AND WASTE MANAGEMENT Kidney Disease

81 What is kidney disease? A gradual loss of kidney function.

82 What could cause kidney failure, malfunction, and disease?

83 Have you signed a donor card? Why would someone sign? Why would someone not sign?

84 Facts

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87 What types of organ donations are there? Living Kidneys, parts of the liver, lung/part of the lung, part of pancreas, part of intestines Bone marrow, umbilical cord blood, blood Deceased

88 What organs can be donated in Canada?

89 Does my age, pre-existing medical condition or sexual orientation prevent me from being a donor? Everyone is a potential donor regardless of age, medical condition or sexual orientation. The oldest Canadian organ donor was 92 and the oldest tissue donor was 104. Even individuals with serious illnesses can sometimes be donors. Your decision to register should not be based on whether you think you would be eligible or not. All potential donors are evaluated on an individual, medical, case-by-case basis.

90 How old do I have to be to register my intent to be an organ donor? If you are under the age of 18 you must have a parent co-sign your donor card or register you on signupforlife.ca.

91 If I have indicated my intent to be an organ and tissue donor, will medical staff still do everything possible to save my life? The first and foremost concern for healthcare professionals caring for critically ill patients is to do everything possible to save lives. The possibility of donation is only considered when all lifesaving efforts have failed.

92 What does it mean to consent to donate organs and/or tissue for medical education or scientific research? Every effort is made for the recovered organs and tissue to be used for transplant. If for any reason this is not possible and you have consented to scientific research and/ or medical education, the recovered organs and tissue may be used for these purposes. Medical education and scientific research is conducted in accordance with the policies and procedures of the establishments involved. These types of donations are important for enhancing medical staff training and evolving technology.

93 Living Donor

94 What is dialysis? 4-hour session 3 times a week

95 Organ Trade

96 UNIT 4: EXCRETION AND WASTE MANAGEMENT Urinalysis

97 Why do we give urine samples when we visit the doctor for a physical examination? What kinds of things can doctors detect with a urine test? Why do athletes get their urine tested?

98 Before you get alarmed Did you eat beets, berries, or rhubarb? Did you eat asparagus?

99 Urinalysis A test of your urine s physical and chemical properties Indicator of overall health Used to detect a wide range of disorders: UTIs Kidney disease Diabetes Involves checking the appearance, concentration, and content of the urine. Abnormal results may point to a disease or illness.

100 What else can they detect? Pregnancy!

101 Research How do home pregnancy tests work?

102 A urinalysis has 3 parts 1. Visual examination Affected by concentration, diet, and hormones Colour, clearness Yellow orange (dehydration) Red/pink = Blood (bladder/kidney infections, stones, kidney disease, cancer) Cloudy = Pus (infection) Bubbles = Protein (kidney disease)

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104 Scent Sweet = high amount of ketone bodies (When fats are broken down for energy, chemicals called ketones appear in the blood and urine.) Seen in diabetics Starvation or low carb diet

105 A urinalysis has 3 parts 2. Dipstick examination Chemically treated strip. Checks for: Protein (kidney disease) Glucose (diabetes) Ketones (diabetes) legal and illegal drugs, ph (UTI, kidney stones, other) Bacteria and white blood cells (UTI) Hormones (pregnancy)

106 A urinalysis has 3 parts 3. Microscopic examination Red blood cells kidney disease, kidney stones, infections, bladder cancer, or blood disorder White blood cells infection Bacteria/Yeast infection Crystals clumps of minerals, may form kidney stones

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108 Barry Bonds Maria Sharapova Lance Armstrong Alex Rodriguez Diego Maradona

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110 Marion Jones

111 Performance Enhancing Drugs Urine is tested for drugs, steroids, and hormones in their system Steroids Body produces large amounts of testosterone Promotes muscle growth Enhances male traits Human Growth Hormones (HGH) Increases muscle mass and burns fat Promotes healing Natural hormone produced by the body to increase height

112 Should urinalysis be mandatory for all pro athletes? Write a well thought out response and hand in to Ms. Maslanka

113 Why can t we drink saltwater?