Excretion and Waste Management. Biology 30S - Miss Paslawski

Transcription

1 Excretion and Waste Management Biology 30S - Miss Paslawski

2 Lesson 1 Waste Products and Organs 2

3 3 Excretion Excretion: Process by which dissolved metabolic wastes are separated from body fluids and removed from the body. If these metabolic wastes were not removed, the organism would die. Since unabsorbed and undigested food never enter the body cells they are not metabolic wastes. Elimination is the removal of unabsorbed and undigested food from the digestive tract in the form of feces.

4 4 Functions of the Excretory System Functions of the Excretory System 1. Removal of metabolic waste from an organism Eliminate the excretory products from the body Removing foreign substances (such as drugs) 2. Maintain a constant body temperature by removing excess heat 3. Maintaining the water concentration, salt concentration and ph balance.

5 5 Excretory Organs 1. Kidneys remove urine (urea, salt, and excess water) through urination 2. Lungs remove carbon dioxide and water vapor from the body through respiration 3. Skin removes urea, salt, and excess water through sweat Excretory organs work with the respiratory system integumentary system, endocrine system (hormones) to keep the body s internal environment constant, and maintain homeostasis.

6 6 Body s Main Metabolic Wastes Carbon Dioxide (CO2) Carbon dioxide from cellular respiration is excreted by the lungs across the body s respiratory surfaces. Glucose + Oxygen Carbon Dioxide + Water + Energy Water (H2O) Also a waste product of cellular respiration Glucose + Oxygen Carbon Dioxide + Water + Energy Water is excreted by the skin, lungs and kidneys

7 7 Body s Main Metabolic Wastes Nitrogenous Waste Protein metabolism is the breakdown of proteins into amino acids Ammonia (NH3) is a waste product of protein metabolism and is toxic to humans. Urea (CO(NH2)2 is a product of the reaction between ammonia and carbon dioxide in the liver Urea must be excreted with some water by the kidneys and the skin Uric Acid C5H4N4O3, not soluble in water, is excreted in small amounts in the urine Kidney stones is caused by too much uric acid

8 8 Body s Main Metabolic Wastes Mineral Salts Mineral salts are compounds containing metals such as iron, sodium, potassium, copper, magnesium etc. The human body requires these minerals to function properly, however a proper homeostatic balance is necessary Excreted by the skin (perspiration) and kidneys (urine)

9 9 Role of Excretory Structures Role of the Lungs The lungs are considered part of the excretory system because they rid the body of carbon dioxide and water (water vapor) created during cellular respiration Glucose + oxygen carbon dioxide + water + energy Function: Carbon dioxide diffuses out of the body cells into the bloodstream Carried by the blood to the lungs, where it is released and expelled from the body.

10 10 Role of Excretory Structures Role of the Skin Made up of many different kinds of tissues, and performs a number of functions. One of these functions is excretion of wastes. Function: Keep microorganisms and other foreign materials from entering the body Since the outmost layer of skin is waterproof, the skin also keeps the body from drying out. Excretes a small amount of ammonia and urea in sweat, which is 99% water The skin also removes excess body heat

11 11 Role of Excretory Structures Role of the Liver The liver plays a significant role in excretion as well as digestion as seen in previous units 1. Detoxification: Converting toxic substances into forms that are safe and not harmful to the body Removes harmful substance such as drugs, alcohol and chemicals from the blood. Toxic forms of the substances are returned to the kidney and excreted from the body by the urine Therefore the liver purifies or detoxifies the blood

12 12 Role of Excretory Structures 2. Deamination: Removal of Nitrogenous Wastes Excess proteins are stored in the body and must be converted into amino acids Amino group (NH2) must be removed. This process is referred to as deamination By-product is ammonia (NH3) Ammonia is toxic in concentrated solutions In the liver, ammonia is converted to a less toxic form called urea that can be excreted by the kidneys.

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14 Lesson 2 The Urinary System 14

15 15 The Urinary System The urinary system is a group of organs that function to filter out excess fluid, waste and other substances from the bloodstream. Consists of two kidneys, two ureters, the urinary bladder, and the urethra.

16 16 The Kidneys Two bean-shaped organs in the human body (although one is enough to accomplished purification and elimination functions) About the size of a fist (11 cm) Located on either side of the spinal column, high in the lumbar (lower back) region. Fat surrounds the kidney for protection along with some protection from the bottom two ribs The adrenal gland sits on top of each kidney

17 17 The Kidneys Did you know? Each kidney contains about 100,000 to 1,500,000 nephrons If all nephrons in 2 kidneys were stretched end to end, they would cover nearly 120 km Your blood supply circulates through the kidneys about 12 times every hour. Each day your kidneys process around 200 litres of blood. Produces 1.5 liters of urine

18 18 1,000,000 Nephrons in each Kidney 12 Times Every hour 1.5 Liters Of Urine

19 19 Ureters Paired tubes that transport urine from the kidneys to the urinary bladder Urine (composed of urea, salt, and water) is pushed along by peristalsis (wave like muscle contractions) Composed of smooth muscle fibers

20 20 Urinary Bladder Smooth, muscular bag that temporarily stores urine until it is ready to be excreted. Allows urination to be infrequent and voluntary When the bladder is full, it becomes distended, nerve receptors sense this distension and tell the brain that it's time to empty the bladder The normal capacity is ml Empties into the urethra in a process called urination

21 21 Urinary Sphincters Muscle that controls the retention and release of urine Internal urinary sphincter is involuntary and controls the movement of urine into the urethra External urinary sphincter is voluntary and controls that movement of urine out of the body

22 22 Urethra Tube leading from the bladder to outside the body. Shorter in females (4 cm)than in males - makes females more susceptible to urinary tract infections. Longer in males (20 cm) and connected to reproductive system.

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24 24 Role of the Kidneys Removes metabolic wastes and forms urine Removes waste and toxins from the blood Regulates the body s blood pressure, ph, and water content (maintain homeostasis of body fluids) If the blood is too dilute (too much water) the water is removed and put into the urine If the blood is too concentrated (not enough water), little water will be removed

25 25 Structure of the Kidneys The kidney has three main parts: 1. Renal Cortex: Reddish brown, outer region made up of tubes called nephron tubules, where the filtrate (filtered substances) is carried to the renal pelvis Covered by the renal capsule 2. Renal Medulla: Inner region where blood is filtered in the nephrons 3. Renal Pelvis: cavity that collects urine and connects into the ureter

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27 Lesson 3 The Nephron 27

28 28 What Makes Up 1 Million The population of San Jose And Calgary Alberta

29 29 What Makes Up 1 Million 1,000,000 dollar bills measures 4,300 inches = 35 Story Building

30 30 The Nephron Nephrons are the structural and functional units of the kidney Each kidney has about 1 million nephrons Part of each nephron is found in the renal cortex and renal medulla

31 31 Parts of the Nephron- Blood Vessels Each nephron has its own renal corpuscle (glomerulus + Bowman s capsule) and renal tubule Blood enters the kidney through the renal artery The arteriole branches to form the network of capillaries that connects to the venule The Afferent arteriole connects the renal artery to the glomerulus, the Efferent arteriole connects the glomerulus to the tubule. Blood then leaves the kidney through the renal vein

32 32 Glomerulus It is a group of capillaries surrounded by the Bowman s capsule, which blood passes through. Bowman s Capsule Surrounds the glomerulus Thin - walled, cup-shaped structure Substances are filtered out of the blood into the Bowman s capsule

33 33 Loop of Henle Middle section of the nephron tubule forms a long loop called the loop of Henle The fluid enters the nephron loop first through the descending limb, and then through the ascending limb Descending part allows water to leave, ascending part allows salt to leave.

34 34 Proximal Convoluted Tubule Proximal convoluted tubule begins at the glomerular capsule. The fluid in the Bowman s capsule space passes into the proximal convoluted tubule Distal Convoluted Tubule Distal convoluted tubule is located after the loop of Henle The fluid that reaches the end of the distal convoluted tubule enters the collecting duct

35 35 Collecting Duct Distal convoluted tubule empties into the collecting tubule. Then empties into the renal pelvis and then urine travels to the ureter. Peritubular Capillaries Surround the proximal convoluted tubule, loop of Henle, and distal convoluted tubule

36 36 Distal Convoluted Tubule Bowman s Capsule Proximal Convoluted Tubule Glomerulus Renal Artery Collecting Duct Renal Vein Peritubular Capillaries Loop of Henle

37 Lesson 4 Filtration, Reabsorption and Secretion 37 Read Page 9-11

38 38 Distal Convoluted Tubule Bowman s Capsule Proximal Convoluted Tubule Glomerulus Renal Artery Collecting Duct Renal Vein Peritubular Capillaries Loop of Henle

39 39 Waste and Water Management Many of the substances in the blood and body fluids must be kept at the correct level for the body to function properly.

40 40 Regulating Fluids Keeping the concentrations of various ions and other important substances constant. Keeping the volume of water in your body constant. Removing wastes from your body. Keeping the acid/base concentration of your blood constant.

41 41 Kidney Functions 1. Filtration - the passage of substances through the capillaries of the glomerulus into Bowman s capsule. 2. Reabsorption - the transfer of essential solutes and water from the nephron back into the blood 3. Tubular Secretion - the movement of water (mostly) from the blood back into the nephron.

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44 Reabsorption - Proximal Tubule 44 Label on Page 13 Filtration - Glomerulus Reabsorption - Nephron Tubule Secretion - Distal Tubule

45 45 Filtration, Reabsorption and Secretion Concept Map

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47 47 Game Time!

48 Lesson 5 Water Balance and Blood Pressure 48

49 49 Water?

50 50 Kidneys and Water Balance Maintaining water balance is an important function of the kidneys. The filtration rate of the kidneys is about 125 ml/min which totals to 180 L each day. Humans have 7 to 8 liters of blood in our body which means your blood gets filtered times each day. Without reabsorption of water, you would produce about 190L of urine each day.

51 51 How does the body maintain water balance? Controlled by the presence of anti-diuretic hormone around the collecting duct of the nephron. The Distal Convoluted Tubule is selectively permeable depending on the presence of the Antidiuretic Hormone (ADH) If the body is properly hydrated there is a low concentration of ADH. The body does not need additional water and the Distal Convoluted Tubule becomes permeable to water allowing water to move into DCT by osmosis If the body is dehydrated there is a high concentration of ADH. The body needs more water so the Distal Convoluted Tubule becomes impermeable to water which prevents water from moving into the Distal Convoluted Tubule ADH is produced by the hypothalamus and is secreted from the pituitary gland The secretion of AHD is stimulated when osmoreceptors in the hypothalamus respond to an increase in blood osmotic pressure

52 52 Drugs Affect ADH Caffeine and alcohol blocks the release of ADH and increase the volume of urine output. Ecstasy increases the release of ADH causing your kidneys to produce a smaller volume of less dilute urine. This can result in the body having too much water

53 53 Negative Feedback of ADH Control Centre: Pituitary Gland Effector: Release ADH Receptor: Osmoreceptors in the hypothalamus Change: Water concentration in blood lowered Cause: Intense physical activity without fluid intake Change: Water is reabsorbed in the blood Feeling of thirst Normal Condition: Water concentration in the bloodstream

54 54 Kidneys and Blood Pressure The kidneys and the circulatory system depend on each other for good health. High blood pressure can damage renal arteries and reduce their ability to work properly. Our kidneys and body work together to monitor and control blood pressure.

55 55 How does the body maintain Blood Pressure? Controlled by a hormone called aldosterone that is secreted by the adrenal gland that controls reabsorption and excretion of sodium and potassium Aldosterone Production Aldosterone is linked with two other hormones: renin and angiotensin. When the body experiences decrease blood flow to the kidneys (drop in blood pressure/blood volume) renin is released which triggers production of angiotensin and then production of aldosterone. When blood levels return renin production drops followed by angiotensin and aldosterone

56 56 How does the body maintain Blood Pressure? Aldosterone Present When aldosterone is present the body will increase reabsorption of Na+ and water into the bloodstream to increase blood volume and stimulate secretion of K+ Aldosterone Absent When aldosterone is absent the body will reabsorb normal levels of Na+ and 100% of K+ is reabsorbed (zero grams of K+ excreted in the urine) Approximately 90% of filtered NA+ and K+ is reabsorbed in the proximal convoluted tubule. Final concentration of Na+ and K+ in the urine is determined in the distal convoluted tubule

57 57 Ted-Ed