Download Unit 1 Lesson 4 The Digestive and Excretory Systems Essential

Unit 1 Lesson 4 The Digestive and Excretory Systems
Essential Question: How do your body’s digestive and
excretory systems work?
Lesson 4 – Key Terms The Digestive and Excretory Systems
Digestive system Pancreas
Esophagus Excretory system
Small intestine
Nephron
Enzyme
Liver
Stomach
Kidney
large intestine
urine
Copyright © Houghton Mifflin Harcourt Publishing Company
Process Begins
Functions- The
of Digestive
the Digestive
System
The digestive system has
three main functions.
1. breaks down food into
molecules the body can
use.
2. nutrient molecules are
absorbed into the blood and
carried throughout the
body.
3. undigested wastes are
eliminated from the body.
Unit 1 Lesson 4 The Digestive and Excretory Systems
You Are What You Eat!
What is the digestive system?
• Cells use nutrients from food for
energy, growth, maintenance,
and repair.
• The digestive system breaks
down food into nutrients that
can be used as building
materials that provide energy
for cells.
1.Mechanical Digestion
2.Chemical Digestions
p48
Digestion
Two Types of Digestion
p49
1. Mechanical Digestion is the breaking, crushing, and
mashing of food. Increases surface area of food
2. Chemical Digestions uses an enzyme is a chemical
that breaks down large molecules into smaller molecules.
In your mouth, teeth grind food
Salivary glands release a liquid that helps break down food
Muscles contract (stomach) to grind food into pulpy mixture
Nutrients break down with enzymes (small intestine)
Unit 1 Lesson 4 The Digestive and Excretory Systems
Chew on This
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P50-51
What are the parts of the digestive system?
The mouth is where mechanical and chemical
digestion begins. Saliva helps to break down food.
Food moves through the throat into a long tube called
the esophagus.
The stomach is a muscular bag that crushes food and
contains acids and enzymes for killing bacteria and
breaking down proteins.
Pancreas and Liver aide in digestion
The small intestine is a muscular tube where most
chemical digestion takes place and most nutrients are
absorbed.
In the large intestine, water and nutrients are
absorbed, leaving waste.
- The Digestive Process Begins p50
The Mouth
Both mechanical and
chemical digestion begin in
the mouth.
•Saliva: Important in both
types of digestion
•Enzyme Amylase - Breaks
down starches
(carbohydrates) into sugar
National Geographic - Digestive
System
Esophagus
Connects mouth to stomach
is lined with mucus
–
–
Easier to swallow
Helps move food along
When food enters esophagus…
Contraction of smooth muscles
push food toward stomach
Involuntary muscle contractions
(peristalsis)
– Keeps food moving in
one direction
http://science.nationalgeographic.com/
science/health-and-humanbody/human-body/digestivesystem-article.html
p50
- The Digestive Process Begins p48
The Stomach
Most mechanical digestion and some chemical digestion
occur in the stomach.
• The stomach is a muscular bag that crushes food and
contains acids (HCl) and enzymes (pepsin) for killing
bacteria and breaking down proteins into amino acid.
• Chyme is the mushy mix of food that passes from the
stomach to the small intestines.
The Pancreas
•Triangular organ that lies between stomach and first part of
small intestine
•Role - produces enzymes that flow into the small intestine
and help break down carbohydrates, proteins, fats, and
nucleic acids
•Remember = enzymes do not break down all food
substances Ex. Fiber
Fiber thickens material
makes it easier for
peristalsis to occur
The Liver
•Largest organ inside the body (chemical factory)
•Role: produce bile (substance that breaks up fat particles)
–Flows from liver into gallbladder (stores bile).
–Not an enzyme.
–Does not chemically digest food.
–Does break up large fat particles into smaller fat
droplets.
–Fat droplets then can be chemically broken down by
enzymes produced in pancreas
- The Digestive Process Begins p51
Small Intestine
• Chyme is the mushy mix of food that passes from the
stomach to the small intestines.
• The small intestine is a muscular tube Most chemical
digestion and most nutrients are absorbed
- Final Digestion and Absorption
Absorption in The Small Intestine
Nutrients are absorbed into the bloodstream.
Tiny finger-shaped projections called villi line the
inside of the small intestine. Villi absorb nutrient
molecules. The molecules pass from the villi into
blood vessels.
When material reaches the end of the small
intestine most nutrients have been absorbed.
- The Digestive Process Begins p51
Large Intestine
• The large intestine is where water and nutrients are
absorbed. Waste is compacted, stored, and eliminated
from the body
The Large Intestine
The material entering the large intestine contains water and undigested
food.
Bacteria live in the large intestine to help break down foods the body cannot
use or digest.
Job of Large Intestine:
–As material moves through, water and vitamins are absorbed into
the bloodstream
–Remaining material is readied for elimination from the body
•Rectum is where waste (feces) material is compressed into a solid form
•Anus is where waste material is eliminated
Unit 1 Lesson 4 The Digestive and Excretory Systems
Toxic Waste!
What are the functions of the excretory
system?
• Waste in the body would become toxic without a method
to eliminate it.
• The excretory system eliminates cellular wastes from the
body through the lungs, skin, kidneys, and digestive
system.
• To Sweat: Excess salts are released through the skin as
you sweat.
• To Exhale: The lungs release carbon dioxide and water
as you exhale.
• To Produce Urine and Feces: Kidneys remove cellular
waste from the blood; Digestive system eliminates feces
Unit 1 Lesson 4 The Digestive and Excretory Systems
What organs are in the
urinary system?
• A kidney is one of a pair of organs
that remove cellular waste from the
blood.
• Nephrons are structures in the
kidneys where fluid is filtered from
the blood.
• Water and wastes filtered from the
blood form a liquid called urine.
• Urine travels from the kidneys,
through the ureters, to the bladder.
• The bladder is a saclike organ that
stores urine.
• Urine exits the bladder through a
tube called the urethra.
Cleanup Crew
Unit 1 Lesson 4 The Digestive and Excretory Systems
1) Filtered blood
can get recycled
back into the
bloodstream
2) Waste leave the
kidney as urine
Unit 1 Lesson 4 The Digestive and Excretory Systems
Unit 1 Lesson 4 The Digestive and Excretory Systems
How does the urinary system maintain homeostasis?
• Cells need a certain level of salt and water to maintain
homeostasis.
• Chemical messengers called hormones signal the
kidneys to filter more or less water and salt as needed.
Unit 1 Lesson 4 The Digestive and Excretory Systems
How does the urinary system maintain homeostasis?
When you sweat
the water
content of your
blood can drop.
A hormone is
released that
signals the
kidneys to
conserve more
water and make
less urine.
Unit 1 Lesson 4 The Digestive and Excretory Systems
How does the urinary system maintain homeostasis?
When your
blood has too
much water,
less of the
hormone is
released.
The nephrons
conserve less
water, and
more urine is
produced by
the kidneys.
- The Digestive Process Begins
Digestion
Click the Video button to watch a movie
about digestion.
Digestive System
http://science.nationalgeographic.com/science/healthand-human-body/human-body/digestive-systemarticle.html