Digestive and Excretory Systems
Study Guide B
Answer Key
SECTION 4. EXCRETORY SYSTEM
1. lungs, skin, kidneys, ureters, urinary
bladder, urethra
2. through sweat, urine, and exhalation
3. carbon dioxide and water vapor
4. the cortex, medulla, nephron, renal artery
and renal vein
5. They remove waste products from the
blood and help to maintain electrolyte,
pH, and fluid balances
6. to filter the blood and remove smaller
molecules, which produces the filtrate
Process Diagram: answer given most
materials in filtrate are reabsorbed into the
capillaries urine moves into loop of
Henle; water is reabsorbed; urine moves
into collecting duct
7. They can damage the capillary walls in
the glomerulus, making them more
porous. As a result, the nephrons lose their
ability to filter the blood.
8. The blood circulates through the dialysis
machinery, which cleans and chemically
balances the blood just as the kidneys do.
9. excrete—excretory; urinate—ureter
10. dialysis “breaks apart” the blood by
separating smaller molecules from the
blood to filter and clean it before returning
the blood to the body.
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide B
Digestive and Excretory Systems
Name ______________________________ Class___________________Date__________________
Section 4: Excretory System
Study Guide B
KEY CONCEPT
The excretory system removes wastes and helps maintain homeostasis.
VOCABULARY
excretory system
urinary bladder
dialysis
kidney
nephron
`
ureter
glomerulus
MAIN IDEA: The excretory system eliminates nonsolid wastes and helps
maintain homeostasis.
1. What are the main organs of the excretory system?
_______________________________________________________________
_______________________________________________________________
2. Name three ways that the excretory system eliminates nonsolid wastes.
_______________________________________________________________
3. What are the waste products removed by the lungs?
_______________________________________________________________
MAIN IDEA: The kidneys help to maintain homeostasis by filtering the blood.
4. What are the main parts of the kidney?
_______________________________________________________________
_______________________________________________________________
5. The kidneys release key hormones to help maintain homeostasis. In what other
ways do the kidneys help to maintain homeostasis?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide B
1
Digestive and Excretory Systems
Section 4: Excretory System
Name ______________________________ Class___________________Date__________________
Study Guide B continued
MAIN IDEA: Nephrons clean the blood and produce urine.
6. What are the main functions of the glomerulus and Bowman’s capsule?
_______________________________________________________________
_______________________________________________________________
Fill in the process diagram to summarize the three steps in which blood is filtered
and urine is formed in the nephron.
Filtration
• Blood enters
glomerulus
• Small molecules
diffuse into
Bowman’s capsule,
forming filtrate
Reabsorption
Excretion
MAIN IDEA: Injury and disease can damage the kidneys.
7. How can diabetes and high blood pressure affect the kidneys?
_______________________________________________________________
_______________________________________________________________
8. How is the process of dialysis similar to the function of the kidneys?
_______________________________________________________________
_______________________________________________________________
Vocabulary Check
9. Which vocabulary words are based on the verbs excrete and urinate?
_______________________________________________________________
10. Dialysis is based on the Greek word dialuein, which means “to break apart.”
What “breaking apart” does a dialysis machine do?
_______________________________________________________________
_______________________________________________________________
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide B
2
Digestive and Excretory Systems
Section 4: Excretory System