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Chapter 24
Digestive and Urinary Systems
Section 1: Objectives
•
Compare mechanical digestion with
chemical digestion.
•
Describe the parts and functions of the
digestive system.
The Digestive System
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Your digestive system is a group of organs that
break down food so that it can be used by the
body.
Food passes through the digestive tract.
•
The digestive tract includes your mouth, pharynx,
esophagus, stomach, small intestine, large
intestine, rectum, and anus.
•
The liver, gallbladder, pancreas, and salivary glands
are also part of the digestive system.
The Digestive System
The Digestive System
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The breaking, crushing, and mashing of
food is called mechanical digestion.
•
In chemical digestion, large molecules are
broken down into nutrients with the aid
of enzymes.
The Digestive System
The Digestive System

Teeth With the help of strong jaw
muscles, teeth break and grind food.
The Digestive System
•
Saliva contains an enzyme that begins
the chemical digestion of carbohydrates.
•
Leaving the Mouth Once the food has
been reduced to a soft mush, the tongue
pushes it into the throat, which leads to a
long, straight tube called the esophagus.
The Digestive System
•
The stomach is a muscular, saclike, digestive
organ attached to the lower end of the
esophagus.
•
Tiny glands in the stomach produce
enzymes and acid to break food down into
nutrients.
•
After a few hours of combined mechanical
and chemical digestion, food leaves your
stomach as a soupy mixture called chyme.
The Digestive System
•
The Pancreas is an organ located between the
stomach and small intestine.
•
The pancreas makes fluids that protect the small
intestine from the acid in chyme.
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The Small Intestine is a muscular tube that is
about 2.5 cm in diameter.
•
In the small intestine, nutrients are absorbed into
the bloodstream through fingerlike projections
called villi.
The Digestive System
The Digestive System
•
The liver is a large, reddish brown organ
that helps with digestion by making bile to
break up fat.
•
Bile is stored in a saclike organ called the
gallbladder, which squeezes the bile into
the small intestine.
•
The liver also stores excess nutrients until
the body is ready to absorb them into the
bloodstream.
The Digestive System
The Digestive System
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Material that can’t be absorbed into the
blood is pushed into the large intestine.
•
The large intestine absorbs most of the
water in undigested material and changes
the liquid into semisolid waste material.
The Digestive System

It has taken each of your meals about 24
hours to make this journey through your
digestive system.
Chapter 24 Sec. 1 Recap
1) List all of the parts of the digestive
system.
 2) What is the difference between
mechanical and chemical digestion?
 3) What does the enzyme found in saliva
responsible for?
 4) What is the function of the pancreas?
 5) What is the function of the liver?

Section 2: Objectives
•
•
•
Describe the parts and functions of the
urinary system.
Explain how the kidneys filter blood.
Describe three disorders of the urinary
system.
The Urinary System
•

The urinary system contains the organs that
remove waste products from your blood.
The kidneys act as filters for the blood.
•
The kidneys are a pair of organs in the urinary
system that clean the blood and excrete products
as urine.
•
Inside each kidney are more than 1 million
microscopic filters called nephrons.
The Urinary System
The Urinary System
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The evaporation of water in sweat cools you
down.
As the water content of the blood drops,
the salivary glands produce less saliva,
resulting in thirst.
When you get thirsty, antidiuretic hormone
is released.
ADH hormone signals the kidneys to take
water from the nephrons and return it to
the body.
The Urinary System

Some beverages contain caffeine, which is
a diuretic.

Diuretics cause the kidneys to make
more urine.

Diuretics decrease the amount of water
in blood.
The Urinary System
Three Kidney Injuries/Diseases:
• Bacterial Infections Bacteria can get into the
bladder and ureters through the urethra and
cause painful infections.

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Kidney Stones Salts and other wastes can
collect inside the kidneys and form kidney stones.
•
Kidney Disease Damage to nephrons can
prevent normal kidney functioning and can lead to
kidney disease.
Chapter 24 Sec. 2 Pop Quiz

1) What is the function of the kidneys?

2) What does ADH signal to the body?

3) What is the effect of diuretics to the
body?

4) List 1 common diuretic.

5) List 3 common kidney injuries/diseases.