The digestive system breaks down food, absorbs nutrients, and eliminates waste. It includes the mouth, esophagus, stomach, small intestine, large intestine, and accessory organs like the liver and pancreas. The excretory system includes the lungs, skin, liver, and kidneys, which filter wastes from the blood and produce urine for excretion. Drinking water helps both systems function properly by hydrating the body and diluting wastes.

1. Section 10.1 Your Digestive System
Your digestive system has three main functions
Functions of the Digestive System
• digestion
• absorption
• elimination

2. Section 10.1 Your Digestive System
• The process by which the digestive system breaks
down food into molecules that the body can use is
called digestion.
Digestion
• During mechanical digestion, foods are physically
broken apart into smaller pieces.
• During chemical digestion, chemicals produced
by your body break large molecules into smaller
ones that your body can use.
• Most of the chemicals involved in digestion are
enzymes, substances that speed up reactions.

3. Section 10.1 Your Digestive System
• Absorption is the process by which nutrients pass
through the lining of your digestive system into your
blood.
Absorption and Elimination
• Materials that are not absorbed are eliminated from
the body as wastes.

4. Section 10.1 Your Digestive System
The organs of the digestive system include the
Structures of the Digestive System
• mouth
• pharynx
• esophagus
• stomach
• small intestine
• large intestine
• liver
• gallbladder
• pancreas

5. Section 10.1 Your Digestive System
• Your teeth tear, crush, and grind your food.
Mouth
• An enzyme in saliva begins to break down starches
in your food.
• Saliva moistens the bites of food.
• Your tongue pushes the food around.

6. Section 10.1 Your Digestive System
• The pharynx is the junction between the digestive
tract and the respiratory system.
Pharynx
• A flap of tissue called the epiglottis seals off the
trachea, or windpipe, preventing food and liquid from
entering your lungs.

7. Section 10.1 Your Digestive System
• After passing through the pharynx, the food enters
the esophagus, a muscular tube that connects the
pharynx to the stomach
Esophagus
• Waves of muscle contractions, called peristalsis,
push food through the rest of the digestive system.

8. Section 10.1 Your Digestive System
Pharynx
Epiglottis
Mouth
Salivary gland
Liver
Esophagus
Stomach
Pancreas
Small intestine
Large intestine
Rectum
Gallbladder

9. Section 10.1 Your Digestive System
• From the esophagus, food passes through a valve
and into the stomach, a muscular pouch located in
the abdomen.
Stomach
• Mechanical digestion occurs as three layers of
muscle produce a churning motion.
• Chemical digestion occurs as cells lining the
stomach release gastric juice.
• Peristalsis moves the food, which is now a thick
liquid called chyme (kym), into the small intestine.

10. Section 10.1 Your Digestive System
• The small intestine is where most chemical digestion and
absorption of nutrients takes place.
Small Intestine
• Liver The role of the liver is to produce bile. Bile is a
substance that physically breaks up large fat droplets that
clump together.
• Gallbladder Bile flows from the liver into the gallbladder, the
organ that stores bile.
• Pancreas The pancreas secretes enzymes into the small
intestine that complete the breakdown of carbohydrates,
proteins, and fats.
• The lining of the small intestine is covered with millions of tiny
fingerlike projections called villi (singular, villus).

11. Section 10.1 Your Digestive System
• The large intestine is about 5 feet long and 3 inches
wide.
The Large Intestine
• As the material moves through the large intestine,
most of the remaining water is absorbed into the
blood.

12. Section 10.2 Keeping Your Digestive System Healthy
• Healthy eating habits and regular exercise are
important for keeping your digestive system healthy.
Avoiding Digestive Disorders
• Consume plenty of fiber.
• Avoid fatty foods.
• Eat moderately.
• Plan meals for a time when you can relax.
• Drink water.
• Get regular exercise.

13. Section 10.2 Keeping Your Digestive System Healthy
To avoid foodborne illnesses, it is very important to
prepare and store food properly.
Food Safety

14. Section 10.2 Keeping Your Digestive System Healthy
• Foodborne illnesses result from consuming a food
or drink that contains either a poison or a disease-
causing microorganism.
Foodborne Illness
• Microorganisms are typically spread in one of three
ways.
• food is undercooked
• raw food touches cooked food
• people preparing food transfer the organisms
onto their hands, countertops, or utensils

15. Section 10.2 Keeping Your Digestive System Healthy
• Cook meat, seafood, poultry, and eggs thoroughly.
Food Preparation and Storage
• Quickly refrigerate leftovers.
• Wash your hands with soap.
• Use paper towels, rather than sponges.
• Rinse fruits and vegetables in running water.
• Keep uncooked food separated to prevent cross-
contamination, the spread of microorganisms from
one food to another food.

16. Section 10.3 Your Excretory System
Health Stats This graph compares the amount of water you excrete in
sweat and urine on a normal day and on a hot day.
In a paragraph, discuss how weather affects water loss.

17. Section 10.3 Your Excretory System
• Excretion is the process by which the body collects
and removes wastes.
Organs of Excretion
• Several organs in the body are involved in waste
collection and removal
• liver
• lungs
• skin
• kidneys

18. Section 10.3 Your Excretory System
• The liver converts impurities and poisons in the body to
less harmful substances.
Liver
• The liver forms urea from a harmful waste product of
protein breakdown.

19. Section 10.3 Your Excretory System
• The lungs remove carbon dioxide and some water
from the body.
Lungs and Skin
• Sweat glands in the skin serve an excretory function
because water and urea are excreted in perspiration.

20. Section 10.3 Your Excretory System
• The kidneys, which are the major organs of the
excretory system, filter urea and other wastes from the
blood.
Kidneys
• You have two kidneys, each about the size of a fist.
• Urine is a watery fluid produced by the kidneys that
contains urea and other wastes.

21. Section 10.3 Your Excretory System
Kidney
The kidneys produce urine by
filtering urea and other wastes
from the blood.
Ureter
One ureter extends from each
kidney. The ureters carry urine
from the kidneys to the bladder.
Bladder
The bladder is a saclike
muscular organ that
stores urine.
Urethra
Urine travels through the
urethra as it exits the body.
The Excretory System

22. Section 10.3 Your Excretory System
• Each kidney contains about a million nephrons, tiny
filtering units that remove wastes and produce urine.
Filtration of Wastes
• The nephrons filter wastes in stages.
• Needed materials and wastes are filtered from
the blood.
• Most needed materials are returned to the blood,
and the wastes are eliminated from the body.

23. Section 10.3 Your Excretory System
• Blood enters the kidneys.
Filtering Out Wastes
• Blood flows through smaller blood vessels until it
reaches a cluster of tiny blood vessels in a nephron
called a glomerulus (gloh MUR yoo lus).
• Urea, salts, glucose, and water are filtered from the
glomerulus into a thin-walled capsule.

24. Section 10.3 Your Excretory System
• As the filtered material flows through the tube, the
glucose, most of the water, and other needed materials
pass from the tube back into the blood.
Formation of Urine
• Urea and other wastes, such as excess vitamins and
harmful substances, stay in the tube.

25. Section 10.3 Your Excretory System
A Nephron Blood flows from an artery into a nephron.
In the glomerulus, urea, water, glucose,
and other materials are filtered from the
blood. These materials pass into a capsule
that surrounds the glomerulus.
The materials pass from the capsule
into a long, twisting tube. The tube
is surrounded by blood vessels.
As the filtered material flows
through the tube, most of the
water and glucose are reabsorbed
into the blood. Most of the urea
and other waste stay in the tube.
After the reabsorbing process is
complete, the liquid that remains
in the tube is called urine.

26. Section 10.3 Your Excretory System
To help your kidneys function at their best, it is
important to drink plenty of water and to see a doctor if
you have symptoms of an infection.
Keeping Healthy

27. Section 10.3 Your Excretory System
Because many of the
waste products filtered by
your kidneys are harmful,
it is best if they are
diluted as much as
possible.
Drinking Water

28. Section 10.3 Your Excretory System
• Urinary tract infections, which are bacterial infections of
the urethra or bladder, are common disorders.
Treating Infections
• Symptoms of urinary tract infections include frequent,
painful urination and blood in the urine.

29. Section 10.3 Your Excretory System
• Kidney stones are pebblelike masses of salts, and often
calcium, that form in the kidneys.
Preventing Kidney Stones
• Drinking plenty of fluids and eating a diet that is low in
salt may reduce your risk of developing kidney stones.

30. Section 10.3 Your Excretory System
• Kidneys that are damaged from an injury, diabetes,
uncontrolled high blood pressure, or other diseases
may fail.
Treating Kidney Failure
• Kidney failure can be treated by dialysis.
• During dialysis, a machine is used to filter blood in
place of the kidneys.