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3/30/2017
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THE DIGESTIVE SYSTEM
7-3.3 Recall the major organs of the human body and their functions within their particular body system.
Functions of the Digestive System:
Breakdown food into nutrients that the body can use
Absorb nutrients necessary for energy, growth and
maintenance
Rid the body of solid wastes
Why am I Hungry?
You need food to provide energy for your body.
Food contains Nutrients that are important
substances that enable you to move, grow, and
maintain homeostasis.
Examples of Nutrients: Proteins, Carbohydrates, fats,
and water.
What Jobs do Nutrients Have in My
Body?
Proteins: Growth & Repair
Makes your muscles, bones, and skin
Carbohydrates: Energy for Cells
and contain cellulose which helps in
digestion.
Fat: Energy Storage
Water: Necessary for all living
things. More than ½ your body is
made up of water.
Digestion: What happens to My Lunch?
Before you can use nutrients, food most be broken
down into smaller substances.
Digestion is the process of breaking down food into
usable materials.
Types of Digestion:
Mechanical:
Physical changes
Break food into smaller pieces
Occurs in Mouth when Chewing
Chemical:
Actually change food into different substances
Ex. Saliva in mouth changes starch to sugars
The change in taste is a chemical reaction
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The Digestive System:
Performs the complex jobs of moving and breaking down food.
Includes:
Mouth- Mechanical Digestion
Salivary Glands
Stomach
Small Intestine
Large Intestine
Liver
Gallbladder
Pancreas
Movement of Food Through Digestive
System
Food is moved in wavelike contractions called Peristalsis
Mucous Glands can be found throughout the entire system
to keep food moist.
Mouth and Esophagus
Mouth
Teeth break food down via mechanical digestion
Saliva softens food and begins chemical digestion
Esophagus
Muscle contractions of peristalsis move solid food from
the throat to the stomach in about eight seconds. Liquids
take about two seconds!
Digestive System
Liver
Largest Internal Organ
Filters blood
Produces Bile which breaks down fat
Gallbladder
Stores bile to be sent to the small intestine.
Pancreas
Produces digestive juices that help break down food in
small intestine.
Digestive System Continued
Strong muscles in the stomach mix and mash food.
Stomach acid breaks down food.
Small Intestine
Partially digested food moves from stomach
Uses digestive juices from pancreas, liver, and gallbladder to breakdown nutrients.
Tiny folds called villi that absorb nutrients.
Large Intestine
Water and other nutrients are absorbed.
Tightly packs waste and sends it to the rectum for disposal.
Digestion Guided NotesDigestion: process of breaking down food into
smaller, usable materials
1. The body needs energy and materials
a. Need food for energy
b. Need materials from food
• Those materials are called nutrients
2. Nutrients include:
a. Water- no nutritional value but needed for
bodily functions
b. Proteins: building blocks, used for cell growth
and repair (muscles, bones, skins)
c. Carbohydrates: provide cells with energy (this
is the glucose we use in respiration)
d. Fat: stores energy
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Digestion3. The digestive system moves and breaks
down food
a. Peristalsis: moves food through the digestive
system (contractions to push through)
• Why we can swallow while on our heads
Mechanical digestion
a. teeth breaking food into smaller pieces
b. stomach breaks food by mashing and pounding
Chemical digestion
c. changes the chemical composition of food
DigestionMaterials are broken down as they move
through the digestive tract
a. Mouth: both chemical and mechanical
digestion (teeth, saliva)
b. Esophagus: muscle contractions of peristalsis
move food from throat to stomach
c. Stomach: both mechanical and chemical
• strong muscles here mix and mash food into
smaller parts
• hydrochloric acid (HCL) breaks down food
chemically
– acid could eat through stomach but we
have a lining that is replaced every 3 days
• also have some absorption of nutrients here
Digestiond. Small intestine: partially digested food moves
from stomach to SI
• most of the nutrients made available during
digestion are absorbed in the small intestine
• structures called villi found here, they contain
folds that absorb the nutrients.
– Once absorbed by the villi, nutrients are absorbed
by the circulatory system (talk about that later in
year)
d. Large Intestine: water and some other nutrients
are absorbed here
• Most of the materiel left after water removed is
waste and moves to the rectum
The digestive system breaks down food.2.2
SECTION
OUTLINE
FunctionStructure
Mouth
Esophagus
Stomach
Small
intestine
Large
intestine
chemical and mechanical
digestion
movement of food by
peristalsis from mouth to
stomach
chemical and mechanical
digestion; absorption of
broken-down nutrients
chemical digestion;
absorption of broken-down
nutrients
absorption of water and
broken-down nutrients,
elimination of wastes
mouth
esophagus
stomach
small
intestine large
intestine
Introduction to the Human Body:
How are our bodies organized?
? ?
Review
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All living things are made of CELLS! Cells
have specialized jobs, and are organized in
your body. For example, blood cells.
CELLS
TISSUES
ORGANS
ORGAN SYSTEM
ORGANISM (BODY)
A TISSUE is a group of similar cells that all
do the same thing (they have the same
function). For example, Muscle Tissue
An ORGAN is a structure made of different
tissues. The organ does a specific, complex
job. For example, Heart
An ORGAN SYSTEM is a group of organs
that work together to perform a major job.
For example, Digestive System
An ORGANISM is a living thing, with organ
systems that work together to keep a body
alive. For example, Human Beings
The Digestive System
The Digestive System
The digestive system has 3 main functions:
1. It breaks down foodinto particles that the body can use.
2. It absorbs nutrientsinto the blood.
3. It eliminates wastefrom the body.
Mouth
Esophagus
The Digestive System
Digestion can happen in two ways:
1. Mechanical digestion: foods are physically broken down into smaller parts (like by teeth).
2. Chemical digestion: Chemicals called ENZYMES break foods into their smaller “building blocks” (for example, starch gets broken down into sugar).
Mouth
Esophagus
Fill this chart The Digestive System
• MOUTH: your teeth break down food into smaller pieces (mechanical digestion). Saliva has enzymes that start chemical digestion.
• ESOPHAGUS: smooth muscles push food down to the stomach(peristalsis).
Mouth
Esophagus
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The Digestive System
• Most digestion happens in the Stomach:
• Mechanical digestionoccurs when the stomach muscles churnthe food.
• Chemical digestionhappens when stomach acid breaks down food.
Stomach
Esophagus
Mouth
The Digestive System
• Liver, gallbladder and pancreas: produces & stores chemicals (enzymes) that help digest food in the small intestine.
Stomach
Esophagus
Mouth
Liver
Gallbladder Pancreas
The Digestive System
• Small intestine:completes chemical digestion and absorbs nutrients for the body. The nutrients pass through the villi into blood vessels.
• Large intestine: water is reabsorbed by the body.
• Rectum: compresses waste into a solid form.
Stomach
Esophagus
Mouth
Liver
Gallbladder Pancreas
Small
intestine
Large
intestine Rectum
Acting Out the Digestive System
Teeth
Saliv
a
Esop
hag
us
Sto
mach
Pancre
as
Sm
all
Inte
stine
Larg
e
Inte
stine
Blo
od
Rectu
m
The teeth grind
the food
(mechanical
digestion).
The esophagus
uses muscles to
push food down
to the stomach.
The stomach
churns food and
uses stomach
acid to dissolve
it.
The pancreas
excretes
chemicals to
help dissolve
food.
The small
intestines
absorb
nutrients and
send them to
the blood.
The blood
delivers the
nutrients to the
body.
The large
intestines
reabsorb water
for the body.
The rectum
compresses
and removes
waste from the
body.
The saliva uses
chemicals to
break down the
food.
GRAPHIC ORGANIZER
Esophagus pushes food from mouth to stomach.
In the mouth, the teeth break food into smaller pieces and saliva begins to break down starches.
Large intestine absorbs water and eliminates waste.
In the stomach, food is churned and mixed with digestive juices that break down protein.
In the small intestine, almost all chemical digestion and absorption occurs.
Eating Healthy
Reading Food Labels & Using the Food Pyramid
Eat Sparingly
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Humans need to get a combination
of SIX NUTRIENTS to keep their
bodies healthy:
• FATS
• CARBOHYDRATES
• PROTEINS
• VITAMINS
• MINERALS
• WATER
Why are these nutrients important?
• FATS – provide energy, part of cell membrane, acts as insulation & protection for internal organs.
• CARBOHYDRATES – provide energy and raw materials for body.
• PROTEINS – important raw material for body parts (muscles, etc).
• VITAMINS & MINERALS – used in a variety of chemical reactions in the body.
• WATER – body’s vital processes take place in water.
Few foods have all of the nutrients
you need, so you need to eat a
BALANCED, HEALTHY DIET that
has a VARIETY of foods to provide
the proper amount of nutrients to
keep your body healthy.
There are 2 things that can help
you plan a healthy diet:
1) FOOD GUIDE PYRAMID
2) FOOD LABELS
FOOD GUIDE PYRAMID
This pyramid classifies
foods into SIX groups
and indicates how
many SERVINGS of
each group should be
eaten to maintain a
HEALTHY diet.
Eat Sparingly
FOOD LABELS
These labels allow you
to EVALUATE the
NUTRITIONAL VALUE
of a food.
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When reading a food
label, be sure to:
a) Check the MAIN INGREDIENTS. What’s listed first & second?
b) Identify SUGARS and FATS. Look for words that end in –ose (glucose, fructose, sucrose). These are sugars. Oil, butter, and lard are fats.
When reading a food
label, be sure to:
c) Check the SERVING SIZE.
Is there more than 1 serving
in a package?
d) Count the CALORIES. Most
teens should eat about 2,000
– 3,000 calories a day. What
portion of the calories come
from fat? Watch out if more
than ½ the calories come from
fat.
When reading a food
label, be sure to:
e) Look for the 6
ESSENTIAL NUTRIENTS.
f) Watch for SODIUM &
CHOLESTEROL. It’s best
to avoid foods that are
high in these substances.
When reading a food
label, be sure to:
g) Figure out the FAT CONTENT. What kinds of fats are included? Saturated & Trans-fats are “bad” fats, but avoid eating foods that are too high in any fat.
h) Note the VITAMINS & MINERALS. Look for important vitamins (A, C, D, etc) and minerals (calcium, iron).