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38–3 The Excretory System
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38–3 The Excretory System
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Functions of the Excretory System
Functions of the Excretory System
Every cell produces metabolic wastes.
The process by which these wastes are eliminated is called excretion.
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.
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38–3 The Excretory System
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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.
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38–3 The Excretory System
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The Kidneys
The kidneys are located on either side of the spinal column near the lower back.
The functional blood-filtering unit of the kidney is called a nephron.
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38–3 The Excretory System
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The Kidneys
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.
Urine is excreted through the urethra - a tube leading from the bladder to the outside of the body.
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38–3 The Excretory System
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The Kidneys
Structure of the KidneysKidney Nephron
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38–3 The Excretory System
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The Kidneys
“Dirty” blood enters the kidney through the renal artery & it 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.
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38–3 The Excretory System
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The Kidneys
Cortex
Medulla Renal artery
Renal vein
Ureter
To the bladder
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38–3 The Excretory System
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The Kidneys
The functional units of the kidney are called nephrons.
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38–3 The Excretory System
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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.
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38–3 The Excretory System
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Kidney Disorders
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
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38–3 The Excretory System
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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
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38–3
A dialysis machine performs the function of which structure in the excretory system?
a. nephron
b. ureter
c. urethra
d. glomerulus
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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.
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38–3
Urine leaves the body through the
a. loop of Henle.
b. glomerulus.
c. urethra.
d. bladder.