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# 23.4: The Excretory System

Difficulty Level: At Grade Created by: CK-12

## Lesson 23.4: True or False

Name___________________ Class______________ Date________

Write true if the statement is true or false if the statement is false.

_____ 1. If you exercise on a hot day, you are likely to lose a lot of sweat in water.

_____ 2. The kidneys filter all the blood in the body many times each day and produce a total of about 1.5 pints of urine.

_____ 3. The amount of water lost in urine is controlled by the kidneys.

_____ 4. The kidney is the structural and functional unit of the nephron.

_____ 5. Excretion is one of the major ways the body maintains homeostasis.

_____ 6. The bladder stores urine.

_____ 7. The kidneys are a pair of bean-shaped organs just below the waist.

_____ 8. The skin is considered an excretory organ.

_____ 9. A single kidney may have more than a million nephrons.

_____ 10. Kidney stones are common. Many people have kidney stones and do not even know it!

_____ 11. The main function of the urinary system is to filter waste products and excess water from the blood and excrete them from the body.

_____ 12. Urine leaves the body through the urethra.

_____ 13. Urine leaves the body through the process of excretion.

_____ 14. The kidneys play very important roles in homeostasis.

_____ 15. Kidney failure is treatable.

Name___________________ Class______________ Date________

Read these passages from the text and answer the questions that follow.

Excretion

Excretion is the process of removing wastes and excess water from the body. It is one of the major ways the body maintains homeostasis. Although the kidneys are the main organs of excretion, several other organs also excrete wastes. They include the large intestine, liver, skin, and lungs. All of these organs of excretion, along with the kidneys, make up the excretory system. This lesson focuses on the role of the kidneys in excretion. The roles of the other excretory organs are summarized below:

• The large intestine eliminates solid wastes that remain after the digestion of food.
• The liver breaks down excess amino acids and toxins in the blood.
• The skin eliminates excess water and salts in sweat.
• The lungs exhale water vapor and carbon dioxide.

Lesson Summary

• The kidneys filter blood and form urine. They are part of the urinary system, which also includes the ureters, bladder, and urethra.
• Each kidney has more than a million nephrons, which are the structural and functional units of the kidney. Each nephron is like a tiny filtering plant.
• The kidneys maintain homeostasis by controlling the amount of water, ions, and other substances in the blood. They also secrete hormones that have other homeostatic functions.
• Kidney diseases include kidney stones, infections, and kidney failure due to diabetes. Kidney failure may be treated with dialysis.

Questions

1. What is excretion?

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2. What are the body's organs of excretion?

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3. Describe the role in excretion of two organs other than the kidney.

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4. What is a nephron? What role do nephrons play in the kidney?

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5. Excretion is one of the major ways the body maintains homeostasis. What role does the kidney play in maintaining homeostasis?

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## Lesson 23.4: Multiple Choice

Name___________________ Class______________ Date________

Circle the letter of the correct choice.

1. Excretion involves which of the following?
1. The large intestine eliminates solid wastes that remain after the digestion of food.
2. The lungs break down excess amino acids and toxins in the blood.
3. The liver eliminates excess water and salts in sweat.
4. The skin exhales water vapor and carbon dioxide.
2. The main function of the urinary system is to
1. form urine.
2. remove excess water from the body.
3. filter waste products and excess water from the blood and excrete them from the body.
4. eliminate solid wastes that remain after the digestion of food.
3. The function of the kidney is to
1. eliminate excess water and salts.
2. filter blood and form urine.
3. excrete water vapor and carbon dioxide.
4. destroy excess amino acids and toxins in the blood.
4. In the nephron, when blood moves diffuses out of the capillaries, it enters the
1. renal artery of the nephron.
2. glomerulus of a nephron.
3. Bowman’s capsule.
4. renal tubule of the nephron.
5. Urine follows which of the following pathways?
1. collecting ducts of the kidneys, ureters, bladder, urethra.
2. collecting ducts of the kidneys, bladder, ureters, urethra.
3. bladder, collecting ducts of the kidneys, ureters, urethra.
4. collecting ducts of the kidneys, urethra, bladder, ureters.
6. The role of the kidneys in homeostasis includes which of the following?
1. The kidneys control the amount of water, ions, and other substances in the blood.
2. The kidneys secrete hormones that regulate other body processes.
3. The kidneys filter all the blood in the body many times each day.
4. all of the above
7. Kidney “stones”
1. are infections of the urinary tract, especially the bladder.
2. are mineral crystals that form in urine inside the kidney.
3. can result in damage to the capillaries of nephrons.
4. are used when blood is filtered through a machine.

## Lesson 23.4: Vocabulary I

Name___________________ Class______________ Date________

Match the vocabulary word with the proper definition.

Definitions

_____ 1. includes the kidneys, large intestine, liver, skin, and lungs

_____ 2. how urine leaves the body

_____ 3. a muscular tube that carries urine out of the body

_____ 4. filters waste products and excess water from the blood and excretes them from the body

_____ 5. the liquid waste product of the body

_____ 6. when the kidneys lose much of their ability to filter blood

_____ 7. the process of removing wastes and excess water from the body

_____ 8. two muscular tubes that move urine by peristalsis to the bladder

_____ 9. the structural and functional units of the kidneys

_____ 10. a hollow, sac-like organ that stores urine

_____ 11. a medical procedure in which blood is filtered through a machine

Terms

b. dialysis

c. excretion

d. excretory system

e. kidney failure

f. nephron

g. ureters

h. urethra

i. urinary system

j. urination

k. urine

## Lesson 23.4: Vocabulary II

Name___________________ Class______________ Date________

Fill in the blank with the appropriate term.

1. The large intestine eliminates solid wastes that remain after the digestion of ____________.

2. The ____________ eliminates excess water and salts in sweat.

3. The lungs exhale water vapor and ____________.

4. The function of the ____________ is to filter blood and form urine.

5. The ____________ is a hollow, sac-like organ that stores urine.

6. ____________ are the structural and functional units of the kidneys.

7. The kidneys filter all the ____________ in the body many times each day.

8. A single ____________ may have more than a million nephrons.

9. If you exercise on a hot day, you are likely to lose a lot of ____________ in sweat.

10. Blood enters the kidney through the ____________ artery.

11. The urethra is a muscular tube that carries ____________ out of the body.

12. Kidney ____________ are mineral crystals that form in urine inside the kidney.

## Lesson 23.4: Critical Writing

Name___________________ Class______________ Date________

Thoroughly answer the question below. Use appropriate academic vocabulary and clear and complete sentences.

Explain how the urinary system filters blood and excretes wastes.

Feb 23, 2012

Oct 07, 2015