Lesson 3 | The Excretory System

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Name Date Class

LESSON 3

The Excretory System

Directions: Each of the following statements is false. Replace the underlined word(s) to make the statement true

by using a term from the list below. Write your changes on the lines provided. NOTE: You may need to change a

term to its plural form.

area bladder excretory system kidney

nephron ureter urethra urine

1. Urine is stored in a muscular sac called the ureter.

2. A bean-shaped organ called the bladder filters wastes from

the blood.

3. Urine leaves the kidneys through the urethra.

4. Some wastes exit the body in a fluid called area.

5. The organs of the digestive system regulate fluid levels

and eliminate wastes from the body.

6. The actual filtration of blood occurs within the millions of

ureters in the kidneys.

7. Urine leaves the bladder through a duct called the

excretory system.

8. Each nephron of the excretory system has a function.

48 Digestion and Excretion

Name Date Class

LESSON 3

The Excretory System

A. Functions of the Excretory System

1. The collects and eliminates wastes from the body and

regulates the level of fluid in the body.

2. If body is not eliminated, it could become toxic and

damage organs.

3. The excretory system controls how much water leaves the

body through .

4. The organs of the system collect and remove

undigested solids from food.

5. The system processes, transports, collects, and removes

liquid waste from the body.

6. The system, which includes the skin, secretes excess salt

and water through sweat glands.

B. Organs of the Urinary System

1. The is a bean-shaped organ that filters wastes from

blood.

2. are networks of capillaries and tubules in the kidneys,

where filtration of blood occurs.

3. When kidneys filter blood plasma, they produce a fluid

called .

4. Urine leaves each kidney through a tube called the .

5. Both ureters drain into the . It is a muscular sac that

holds urine until the urine is .

6. Urine leaves the bladder through a tube called the .

7. The urethra contains circular muscles called that

control the release of urine.

C. Urinary Disorders

1. A urinary disorder is an illness that affects one or more

of the urinary system.

2. Common urinary disorders include kidney disease, urinary tract infection, kidney

, and bladder control problems.

Digestion and Excretion 49

Name Date Class

Lesson Outline continued

D. The Excretory System and Homeostasis

1. The excretory system helps maintain in two ways. It

filters wastes from the and removes wastes from the

system.

2. A hormone controlled by the causes the tubules

in the kidney to absorb more water from the blood. This helps the body

regulate .

50 Digestion and Excretion

Name Date Class

LESSON 3

The Excretory System

Directions: On each line, write the term from the word bank that correctly completes each sentence. Each term is

used only once.

blood excretory integumentary liquid

nephrons respiratory solids ureter

urethra urinary urine water

1. The system collects and eliminates wastes from the body.

2. The excretory system controls how much is eliminated

from the body.

3. The organs of the digestive system remove undigested ,

whereas the urinary system removes waste.

4. The system removes carbon dioxide and water vapor from

the body.

5. The system secretes excess salt and water through sweat

glands.

6. The system includes two kidneys, two ureters, the bladder,

and the urethra.

7. The kidneys remove wastes from .

8. Networks of capillaries and small tubes in the kidneys are

called .

9. When blood is filtered, is produced.

10. Urine leaves each kidney through a tube called the .

11. The bladder is an organ that holds urine until it is excreted through

the .

52 Digestion and Excretion

Name Date Class

LESSON 3

Refueling with Sports Drinks

Glucose-electrolyte beverages—more

commonly known as sports drinks—were first

used by athletes to replace body fluids lost in

sweat during exercise. The popularity of these

drinks has grown steadily. Now athletes and

nonathletes alike reach for sports drinks to

quench their thirst. Manufacturers have

responded by producing sports drinks in

every shade of the rainbow. The drinks

contain a wide variety of ingredients. Which

ingredients, if any, are beneficial?

What is in a sports drink?

The ideal sports drink contains water,

carbohydrates, and electrolytes, such as

sodium, potassium, and phosphate.

Carbohydrates are complex sugars; they

make the drink taste pleasant and provide

energy. Sports drinks that contain between

4 to 8 percent carbohydrates help the body

absorb fluids in the most efficient manner.

Electrolytes such as sodium replace

salts lost through sweating. They increase

absorption of sugar and water, and help

restore the body’s volume of plasma. They

also help the body retain fluid after it is

consumed.

Water replaces fluids that are lost during

exercise. A loss of body fluid can affect the

heart’s performance and lower blood

pressure. Dehydration can occur if fluids and

salts are lost. Carbohydrates are also lost if

exercise continues for more than one hour.

Signs of dehydration include the

following:

• Thirst

• Loss of appetite

• Lethargy

• Anxiety

• Nausea and dizziness

• Irritability

• Cramps

• Fatigue

• Headache

• Dark urine

Who needs sports drinks?

People who exercise for less than

30 minutes at a time can replace lost

body fluids with an inexpensive, readily

available alternative to sports drinks—

water. At this level of exercise, fluid

replacement is more important than

energy replacement. However, sports

drinks are excellent choices for athletes

and exercisers who need water for

hydration and carbohydrates for energy.

In the end, people make their choices

based on personal tastes. Regardless of

whether you take leisurely walks or run

marathon races, it is important to consume

adequate amounts of fluid to maintain the

proper level of fluids in your body.

Applying Critical-Thinking Skills

Directions: Answer each question or respond to each statement.

1. Infer From a health perspective, why is it important that a sports drink have a pleasant

taste?

2. Relate Which beverage best fits your level of exercise—sports drinks or water? Explain.

Digestion and Excretion 59

Name Date Class

LESSON 3

The Excretory System

Multiple Choice

Directions: On the line before each question, write the letter of the correct answer.

1. Which function is characteristic of the excretory system?

A. provides energy

B. eliminates waste

C. breaks down food

2. Which body system works with the excretory system to regulate fluid levels in

the body?

A. nervous system

B. immune system

C. reproductive system

Matching

Directions: On the line before each definition, write the letter of the term that matches it correctly. Each term is

used only once.

3. organ that removes wastes from the blood

4. capillaries and tubules where blood is filtered

5. tube through which urine leaves the kidneys

6. organ that holds urine until it leaves the body

7. tube through which urine leaves the body

A. bladder

B. kidney

C. nephrons

D. ureter

E. urethra

Digestion and Excretion 61

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Content Vocabulary

Lesson Outline

Content Practice A

Enrichment

Lesson Quiz A

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