The Digestive System
Homework
• Chapter 6.3 – Practice Problems 1-3
• Section 6.4 – Practice Problems 1-5
• Section 6.5 – Practice Problems 1-6
• Copy Figure 2 (p. 217) into your notes in
your own words
• Copy Figure 3 (p. 217) into your notes.
This week
• Today – Powerpoint Digestive System
• Tuesday – Quiz (Label the Dig. System)
– Villi, Absorption, Proteins, Carbs and Lipids
– Extra Help After School
• Wednesday – Review
• Thursday – Worm Overview/ Test Review
Sheets
• Friday – Worm Lab
• Sunday – Extra online help
• Monday – Unit Test
4 Functions of the
digestive system
• INGESTION
• DIGESTION
• ABSORPTION
• EGESTION
Digestion
• Starts in the mouth
• Ends in the anus
• Food can be broken down mechanically
(chewing) and chemically (with enzymes)
to be digested (broken down).
Absorption
• Digested food into the bloodstream
through the walls of the small intestine.
• Cells burn the energy (sugar, fatty acids,
and amino acids) in the presence of
oxygen to release stored energy within
the food.
Absorption
• Cells also use larger proteins to help build
larger protein molecules needed for
growth and development.
Elimination
• The digestive system eliminates materials
that cannot be used in the body via
elimination.
• The large intestine concentrates these
solid wastes, called FECES, and finally the
waste passes out of the body through the
anus.
Inside the Oral Cavity
• The gastrointestinal tract (GI tract) begins
with the oral cavity.
• Oral (or/o = pertaining to the mouth)
• The cheeks form the walls of the oval
shaped oral cavity, and the lips surround
the opening of the cavity.
• The hard palate form the anterior portion
of the roof of the mouth.
• The soft palate consists of the muscular
membrane that lies posterior to it.
The Oral Cavity
The Oral Cavity
•Ruage are the bumps on the top of
the hard palate.
• The uvula is the small tissue projection that
hangs from the soft palate (hangy ball)
• The uvula helps with the production of the
sounds of speech.
• The tongue covers the floor of the oral cavity,
aids in moving the food during mastication
(chewing) and deglutition (swallowing).
The Oral Cavity
The Oral Cavity
• Papillae, small raised bumps on the tongue,
contains taste buds.
• Sensitive to food chemicals and allow
discrimination of different tastes as the food
moves across the tongue.
Papillae
• Some people think that every bump on their
tongue is, itself, a taste bud, but that is NOT
true.
– Each papillae has many taste buds within it.
– In addition, we have taste buds that are not
even on our tongues.
– Some taste buds are found in our throats,
cheeks, and in the roof of our mouths.
Papillae
Taste Regions
Tonsillitis
The Oral Cavity
• The gums are fleshy tissue that surrounds
the sockets of the teeth.
• The adult human has 32 teeth (16
permanent teeth top/16 bottom arch).
Central incisor
Lateral incisor
Canine
First premolar
Second premolar
First molar
Third Molar (wisdom tooth)
Salivary Glands
• 3 pairs in the oral cavity
• Produce Saliva, that
contain digestive
enzymes.
• Saliva is released from the
parotid gland,
submandibular gland and
sublingual gland on EACH
side of the mouth.
• Narrow ducts carry saliva
into the oral cavity.
The Oral Cavity
• Together the teeth and saliva breakdown
food in the oral cavity.
Components of the
Digestive System
•
•
•
•
•
•
•
Esophagus
Stomach
Small Intestine
Large Intestine
Gall bladder
Liver
Pancreas
Esophagus
• the tube that connects your
mouth and your stomach
Esophagus
• Muscular tube
• 9-10 inches from the pharynx to the
stomach
• Peristalsis is the involuntary, progressive,
rhythmic contraction of muscles in the
walls of the esophagus (and other
gastrointestinal organs) propelling a bolus
(mass of food) toward the stomach.
Food Passage thus far
1.
2.
3.
4.
Oral cavity (teeth, tongue, saliva)
Pharynx
Esophagus
Stomach
Stomach
• A stretchy bag that holds your food
after you eat
• Helps to break food into smaller
pieces so your body can use it for
energy and nutrition
Esophagus
Stomach
The Stomach
• From the esophagus into the stomach
• 3 parts: Fundus (upper portion)
Body (middle section)
Antrum (lower portion)
FUNDUS
ANTRUM
BODY
Inside the Stomach
• Folds in the lining of the
stomach are called rugae.
• The rugae contain
digestive glands that
produce the enzyme
pepsin (to begin digestion
of proteins) and
hydrochloric acid.
• Food leaves the stomach
in 1 to 4 hrs or longer,
depending on the
type/amount of food
eaten.
Sphincters
• Rings of muscles
• Control the opening and
closing of the stomach
• Lower esophageal
sphincter (cardiac
sphincter) relaxes and
contracts to move food
from the esophagus to the
stomach.
• Pyloric sphincter allows
food to move from the
stomach to the intestine.
Small Intestine
• Tube that is 20 feet long.
• Continues to digest food
• Food stays in your small intestine for
4 to 8 hours
Small
Intestine
Small Intestine
• 20 feet from the pyloric sphincter to the
first part of the large intestine.
3 parts of the
small intestine:
1. DUODENUM
2. JEJENUM
3. ILEUM
The Small Intestine
• Lined with VILLI
• Tiny microscopic
projections
• Microscopic blood
vessels in the villi
absorb the digested
nutrients into the
bloodstream and
lymph vessels.
Duodenum
•
•
•
•
•
1 foot long
Receives food from the stomach
Bile from the liver
Bile from the gallbladder
Pancreatic juice from the pancreas
• Enzymes and bile help digest food before it
passes to the second part of the small intestine.
Large Intestine
• Tube that is 5 feet long
• Gets waste from small intestine
• Waste stays for 10 to 12 hours
The Large Intestine
• Receives the fluid waste from digestion
(the material that is unable to pass into the
bloodstream).
• It stores the waste until they can be
released from the body.
Large Intestine
Large Intestine
• From the small intestine to the anus
• 6 sections
– The APPENDIX hangs from the large
intestine.
• The appendix has no clear function but can
become inflammed and infected when clogged or
blocked.
• Thought to be involved with breakdown of plants
during primitive life.
Large Intestine Sections
The Large Intestine
• Absorbs water within the waste material
allowing the body to expel solid feces
(stools).
• Defecation is the expulsion or passage of
feces from the body through the anus.
• Diarrhea, or watery stools, results from
reduced water absorption into the
bloodstream through the walls of the large
intestine.
Gall Bladder
• Storage tank for bile (a greenish-yellow
liquid) that helps your body break down
and use fats
• Located under your liver
• Shaped like a pear
Gall
Bladder
Gallbladder
• Pear-shaped sac
• Stores and concentrates bile for a later
use.
• After you eat the gallbladder contracts,
forcing the bile into the cystic duct into the
common bile duct.
Liver
• Factory for antibodies and bile
• Stores vitamins and sugars until your body
needs them
The Liver
• Produces BILE (a thick,
orange-black, sometimes
greenish fluid).
• Bile contains cholesterol
(a fatty substance), bile
acid, and bile pigments.
• Bilirubin – produced from
the breakdown of RBCs
in normal RBC destruction.
• Bilirubin travels to the liver
through the bloodstream,
where it is conjugated with
another substance and
added to bile.
• Bilirubin enters the intestine
with bile.
• Bacteria in the colon
breakdown bilirubin into
pigments that gives feces its
brown color.
• Bilirubin and bile leave the
body in feces.
Liver
Other Functions of the Liver
1. Maintain proper sugar levels (glucose)
2. Manufacture blood proteins (blood
clotting)
3. Releasing Bilirubin, a pigment in bile
4. Remove Poisons (toxins) from the
blood.
Jaundice
• Occurs when bilirubin can’t leave the
body.
• Causes a yellowish discoloration of the
skin, whites of the eyes, and mucous
membranes.
Pancreas
• Helps you digest
food by breaking
down sugars
Functions
• Digest the food we eat
• Take the nutrients out of your food so
your body can use it
Food Passage thus far
1.
2.
3.
4.
5.
Oral cavity (teeth, tongue, saliva)
Pharynx
Esophagus
Stomach
Small Intestine (duodenum, jejunum,
ileum)
6. Large Intestine (6 sections)
7. Liver
Recap..
can you
remember
the food
path?
Food Pathway
LIVER
BILE
GALLBLADDER
Food Enters the …
•
Oral Cavity
•
Pharynx
PANCREAS
•
Esophagus
•
Stomach ENZYMES
•
Duodenum
SMALL
•
Jejunum
INTESTINE
•
Ileum
•
Cecum
•
Ascending Colon
•
Transverse Colon
LARGE
INTESTINE
•
Descending Colon
•
Sigmoid Colon
•
Rectum
•
Anus
Feces Leaves the body
Hernia
• A hiatal hernia occurs when the upper
part of the stomach protrudes upward
through the diaphragm. This condition
can lead to GERD (gastroesophageal
reflux disease).
Heartburn
• Has nothing to do with the heart - it is a
digestive problem
• Heartburn is a pain behind the breast bone,
often described as ‘burning’ in quality.
• Acid is present in the stomach to digest food.
Heartburn occurs when small amounts of this
acid rise up into the esophagus - the tube
which carries food from the mouth to the
stomach. This is called reflux.
• The gullet, unlike the stomach, does not have
a protective lining. So when it is exposed to
the acid, it can become inflamed and painful.
Anorexia
• Lack of appetite (-orexia = appetite)
• A sign of malignancy or liver disease.
• It is a loss of appetite caused by emotional problems such as
anger, anxiety, and fear.
• It is an eating disorder classified as a refusal to maintain a
minimally normal body weight.
• The individual is intensely afraid of gaining weight and has a
disturbance in the perception of the shape or size of his/her
body.
• Predominantly affects adolescent females, and its principal
symptom is a conscious, relentless attempt to diet along with
excessive, compulsive over activity, such as exercise, running,
or gymnastics.
• Most postmenarchal females with this disorder are
amenorrheic.
Bulimia
• Bulimia Nervosa (bulimia means abnormal
increase in hunger) is characterized by
binge eating (uncontrolled indulgence in
food) followed by purging (eliminating food
from the body).
• Individuals maintain normal or nearly
normal weight because after binging they
engage in inappropriate purging.
– E.g. self-induced vomiting and the misuse of
laxatives or enemas.