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End Show Slide 1 of 36 Copyright Pearson Prentice Hall Biology.

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Presentation on theme: "End Show Slide 1 of 36 Copyright Pearson Prentice Hall Biology."— Presentation transcript:

1 End Show Slide 1 of 36 Copyright Pearson Prentice Hall Biology

2 End Show Slide 2 of 36 Copyright Pearson Prentice Hall 38–3 The Excretory System

3 End Show 38–3 The Excretory System Slide 3 of 36 Copyright Pearson Prentice Hall Functions of the Excretory System Every cell produces metabolic wastes. The process by which these wastes are eliminated is called excretion.

4 End Show 38–3 The Excretory System Slide 4 of 36 Copyright Pearson Prentice Hall Functions of the Excretory System The skin excretes excess water and salts in the form of sweat. The lungs excrete carbon dioxide. The kidneys also play a major role in excretion.

5 End Show 38–3 The Excretory System Slide 5 of 36 Copyright Pearson Prentice Hall Functions of the Excretory System The kidneys: remove waste products from the blood. maintain blood pH. regulate the water content of the blood and, therefore, blood volume.

6 End Show 38–3 The Excretory System Slide 6 of 36 Copyright Pearson Prentice Hall The Kidneys The kidneys are located on either side of the spinal column near the lower back. A tube, called the ureter, leaves each kidney, carrying urine to the urinary bladder. The urinary bladder is a saclike organ where urine is stored before being excreted.

7 End Show 38–3 The Excretory System Slide 7 of 36 Copyright Pearson Prentice Hall The Kidneys Structure of the Kidneys Kidney Nephron

8 End Show 38–3 The Excretory System Slide 8 of 36 Copyright Pearson Prentice Hall The Kidneys Blood enters the kidney through the renal artery. The kidney removes urea, excess water, and other waste products and passes them to the ureter. The clean, filtered blood leaves the kidney through the renal vein and returns to circulation.

9 End Show 38–3 The Excretory System Slide 9 of 36 Copyright Pearson Prentice Hall The Kidneys Kidney Structure A kidney has two distinct regions: The inner part is called the renal medulla. The outer part is called the renal cortex.

10 End Show 38–3 The Excretory System Slide 10 of 36 Copyright Pearson Prentice Hall The Kidneys Cortex Medulla Renal artery Renal vein Ureter To the bladder

11 End Show 38–3 The Excretory System Slide 11 of 36 Copyright Pearson Prentice Hall The Kidneys The functional units of the kidney are called nephrons. Nephrons are located in the renal cortex, except for their loops of Henle, which descend into the renal medulla.

12 End Show 38–3 The Excretory System Slide 12 of 36 Copyright Pearson Prentice Hall The Kidneys Artery Vein Loop of Henle Bowman’s capsule Glomerulus Capillaries Collecting duct To the ureter

13 End Show 38–3 The Excretory System Slide 13 of 36 Copyright Pearson Prentice Hall The Kidneys Vein Artery Capillaries To the ureter Collecting duct Each nephron has its own blood supply: an arteriole a venule a network of capillaries connecting them

14 End Show 38–3 The Excretory System Slide 14 of 36 Copyright Pearson Prentice Hall The Kidneys Vein Artery Capillaries To the ureter Collecting duct Each nephron releases fluids to a collecting duct, which leads to the ureter.

15 End Show 38–3 The Excretory System Slide 15 of 36 Copyright Pearson Prentice Hall The Kidneys As blood enters a nephron through the arteriole, impurities are filtered out and emptied into the collecting duct. The purified blood exits the nephron through the venule.

16 End Show 38–3 The Excretory System Slide 16 of 36 Copyright Pearson Prentice Hall The Kidneys The mechanism of blood purification involves two distinct processes: filtration and reabsorption.

17 End Show 38–3 The Excretory System Slide 17 of 36 Copyright Pearson Prentice Hall The Kidneys Filtration Passing a liquid or gas through a filter to remove wastes is called filtration. The filtration of blood mainly takes place in the glomerulus. The glomerulus is a small network of capillaries encased in the top of the nephron by a hollow, cup-shaped structure called Bowman's capsule.

18 End Show 38–3 The Excretory System Slide 18 of 36 Copyright Pearson Prentice Hall The Kidneys Fluid from the blood flows into Bowman’s capsule. The materials filtered from the blood include water, urea, glucose, salts, amino acids, and some vitamins. Plasma proteins, cells, and platelets remain in the blood because they are too large to pass through the capillary walls.

19 End Show 38–3 The Excretory System Slide 19 of 36 Copyright Pearson Prentice Hall The Kidneys Reabsorption Most of the material removed from the blood at Bowman's capsule makes its way back into the blood. The process in which liquid is taken back into a vessel is called reabsorption.

20 End Show 38–3 The Excretory System Slide 20 of 36 Copyright Pearson Prentice Hall The Kidneys Almost 99% of the water that enters Bowman’s capsule is reabsorbed into the blood. When the filtrate drains in the collecting ducts, most water and nutrients have been reabsorbed into the blood. Remaining material, called urine, is emptied into a collecting duct. Urine is primarily concentrated in the loop of Henle. The loop of Henle is a section of the nephron tubule in which water is conserved and the volume of urine minimized.

21 End Show 38–3 The Excretory System Slide 21 of 36 Copyright Pearson Prentice Hall The Kidneys As the kidney works, purified blood is returned to circulation while urine is collected in the urinary bladder. Urine is stored here until it is released from the body through a tube called the urethra.

22 End Show 38–3 The Excretory System Slide 22 of 36 Copyright Pearson Prentice Hall Control of Kidney Function The activity of the kidneys is mostly controlled by the composition of the blood. In addition, regulatory hormones are released in response to the composition of blood.

23 End Show 38–3 The Excretory System Slide 23 of 36 Copyright Pearson Prentice Hall Control of Kidney Function When you drink a liquid, it is absorbed into the blood through the digestive system. As a result, the concentration of water in the blood increases. As the amount of water in the blood increases, the rate of water reabsorption in the kidneys decreases. Less water is returned to the blood, and excess water is sent to the urinary bladder to be excreted as urine.

24 End Show 38–3 The Excretory System Slide 24 of 36 Copyright Pearson Prentice Hall Control of Kidney Function When the kidneys detect an increase in salt, they respond by returning less salt to the blood by reabsorption. The excess salt the kidneys retain is excreted in urine, thus maintaining the composition of the blood.

25 End Show 38–3 The Excretory System Slide 25 of 36 Copyright Pearson Prentice Hall Kidney Disorders Humans have two kidneys, but can survive with only one. If both kidneys are damaged by disease or injury, there are two options: a kidney transplant kidney dialysis

26 End Show 38–3 The Excretory System Slide 26 of 36 Copyright Pearson Prentice Hall Kidney Disorders Kidney dialysis works as follows: Blood is removed by a tube and pumped through special tubing that acts like nephrons. Tiny pores in the tubing allow salts and small molecules to pass through. Wastes diffuse out of the blood into the fluid-filled chamber, allowing purified blood to be returned to the body.

27 End Show 38–3 The Excretory System Slide 27 of 36 Copyright Pearson Prentice Hall Kidney Disorders Kidney Dialysis Air detector Dialysis machine Fresh dialysis fluid Compressed air Vein Artery Shunt Blood pump Blood in tubing flows through dialysis fluid Used dialysis fluid

28 End Show - or - Continue to: Click to Launch: Slide 28 of 36 Copyright Pearson Prentice Hall 38–3

29 End Show Slide 29 of 36 Copyright Pearson Prentice Hall 38–3 A dialysis machine performs the function of which structure in the excretory system? a.nephron b.ureter c.urethra d.glomerulus

30 End Show Slide 30 of 36 Copyright Pearson Prentice Hall 38–3 In the human body, the kidneys play an important role in a.producing digestive enzymes. b.circulating the blood. c.destroying old red blood cells. d.maintaining homeostasis.

31 End Show Slide 31 of 36 Copyright Pearson Prentice Hall 38–3 In the nephron, most filtration occurs in the a.renal tubule. b.capillaries. c.glomerulus. d.loop of Henle.

32 End Show Slide 32 of 36 Copyright Pearson Prentice Hall 38–3 Urine leaves the body through the a.loop of Henle. b.glomerulus. c.urethra. d.bladder.

33 End Show Slide 33 of 36 Copyright Pearson Prentice Hall 38–3 Materials filtered out of the blood include all of the following EXCEPT: a.water. b.urea. c.amino acids. d.plasma proteins.

34 END OF SECTION


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