Opening Activity
Directions:
After you eat the snack provided, write the
following parts of the digestive system in
the order your snack passes through your
body. Do not include accessory organs
within your list. Not every part will be used.
THE WINNING GROUP GETS 5 EXTRA
CREDIT POINTS ON THEIR QUIZ
• Duodenum
• Pharynx
• Stomach
• Jejunum
• Mouth
• Colon
• Esophagus
• Anus
• Salivary glands
• Ilium
• Pancreas
The Digestive
System
By: Rebecca DePalma, Elisha
Son, & Connor Kuykendall
Function
Turning food into the
energy you need to
survive and packaging
the residue for waste
disposal
Organs of the
Digestive System
Location and Function
Salivary
Glands
Mouth
Pharyx
Esophagus
Liver
Stomach
Gallbladder
Pancreas
Small intestine
Large intestine
Anu
Rectum
Function: Mouth
Mechanical breakdown of food,
chemical digestion of carbs
Function: Pharynx
Connects mouth to esophagus
Function: Esophagus
Peristalsis pushes food to stomach
Function:
Stomach
Mixes food with secretions
to begin protein digestion
Function: Small
Intestine
Mixes food with pancreatic juice and
bile, breakdown of food molecules
Small Intestine Breakdown
•Duodenum - fixed portion of the small intestine,
first portion following the stomach; 25 cm long
•Jejunum - next portion, making up 2/5 of the small
intestine
•Ileum - the remainder of the small intestine
•Mesentery - double-layered fold of peritoneal
membrane; suspends intestines from the posterior
abdominal wall
•Intestinal villi - tiny projections of mucous
membrane, greatly increasing the surface area of the
lining, aiding absorption; numerous in the duodenum
Function: Large
Intestine
AKA Colon; Absorbs water and electrolytes to form
feces (indigestible materials in preparation for
elimination)
Function: Rectum to
Anus
Regulates elimination of feces
Accessory Organs
Function: Salivary Glands
Secretes saliva
Accessory Organs
Function: Liver
Produces bile which
emulsifies fat
Accessory Organs
Function: Gallbladder
Stores bile and introduces it
into the small intestine
Accessory Organs
Function: Pancreas
Produces/secretes pancreatic
juice into small intestine
Structure of Alimentary Canal
•Consists of 4 distinct layers; mucosa, submucosa,
muscular layer, and serosa
1. Mucosa:
• Formed by surface epithelium, underlying
connective tissue, and a small amount of
smooth muscle
• In certain regions, the mucosa is folded with
tiny projections that extend into the
passageway (lumen)
• Lumen increases absorptive surface area
• Mucosa protects the tissues underneath it and
carries on secretion and absorption
• Has glands that are tubular invaginations into
which the lining of the cells secrete mucus and
digestive enzymes
2. Submucosa
•Consists of loose connective tissue,
glands, blood vessels, lymphatic
vessels, and plexus
•Plexus – nerves organized into a
network
•Its vessels nourish surrounding tissues
and carry away absorbed materials
3. Muscular Layer
•Produces movement of the tube
•Consists of 2 layers of smooth muscle tissue
+ some nerves organized into a plexus
•Circular fibers – fibers of the inner layer
that encircle the tube
•Contraction of circular fibers result in a
decrease in diameter of the tube
•Fiber of the outer muscular coat run
lengthwise
•When these longitudinal fibers contract,
the tube shortens
4. Serosa
•AKA serous layer
•Visceral peritoneum has a serous
layer, or outer covering, of the tube
•The cells of the serosa protect
underlying tissues
•Also secretes serous fluid which
moistens and lubricates the tube’s
outer surface so that organs within the
abdominal cavity slide freely against
one another
Movements of the Tube
Two motor functions:
1. Mixing movements
•occurs when smooth muscles in small
segments of the tube contract rhythmically
•ex: muscular contractions to mix food with
digestive juices
2. Propelling movements
•includes peristalsis (wavelike motion)
•ring of contraction appears in the wall of the
tube
•pushes tubular contents ahead of it (think of it
as a propeller)
Digestive Enzymes
• Digestion enzymes are enzymes
that break down polymeric
macromolecules into their smaller
building blocks, in order to
facilitate their absorption by the
body
• Aid in the digestion of food
Digestive Enzymes cont.
•
•
•
•
Where are they found?
Stomach secreted by cells lining the
stomach
Pancreatic juice secreted by
pancreatic exocrine cells
Saliva secreted by the salivary glands
Small and large intestinal secretions
Products of Digestion: Absorption
Locations
Food:
• Stomach enzymatic
digestion of
proteins
• Small Intestine main site of
nutrient
absorption
Water:
• Large Intestine absorbs water
and electrolytes
•Vitamins & Minerals
• Small intestine absorbs these,
organic substrates
and ions
Absorption Mechanisms
• Water:
-Osmosis
• Electrolytes:
-Diffusion, active transport
• Monosaccharides:
-Facilitated diffusion, active transport
• Fatty acids and glycerol:
-Facilitated diffusion
• Amino acids:
-Active Transport
Carbohydrate Digestion To
Cells
• Breaks down glycogen to
glucose
• Converts non-carbohydrates to
glucose
• Polymerizes glucose to
glycogen
Protein Digestion To Cells
• Deaminates amino acids
• Forms urea
• Synthesizes plasma proteins
• Converts certain amino
acids to other amino acids
Lipid Digestion To Cells
• Oxidizes fatty acids
• Synthesizes lipoproteins,
phospholipids, and cholesterol
• Converts portions of
carbohydrate and protein
molecules into fats
Diseases of the System:
• Hiatal hernia:
o portion of the stomach protrudes through a weakened area of the
diaphragm
o results: gastric juices regurgitate into the esophagus, causing
heartburn, difficulty in swallowing, or ulceration, and blood loss
• Ulcers:
o open sore in the skin or mucous membrane resulting from localized
tissue breakdown
o caused by the bacteria, helicobacter pylori
o cures: acid reducing drugs and antibiotics
• Tonsillitis:
o infected tonsils tend to swell
o may swell to the point where they block the passageways of the
pharynx and interfere with breathing and swallowing
o may have to get them removed if patient is non responsive to
antibiotics
Diseases of the System:
•
•
•
Jaundice:
o turns the skin and whites of the eyes yellow
o reflects buildup of bile pigments
o obstructive jaundice: bile ducts are blocked
o hepatocellular jaundice: liver is diseased
o hemolytic jaundice – red blood cells are destroyed too
rapidly
Cystic fibrosis:
o abnormal chloride channels in cells in various tissues draw water
inward from interstitial spaces
o dies out secretions in the lungs and pancreas, leaving a sticky
mucus behind
Acute pancreatis:
o extremely painful condition
o results from a blockage in the release of pancreatic juices
o Alcoholism, gallstones, certain infections, traumatic injuries, or the
side effects of some drugs can cause pancreatis
Nutrition
• Adequate diets provide sufficient energy, essential
fatty acids, amino acids, vitamins, and minerals
• Food pyramid: carbs, fruits, vegetables, protein, dairy,
fats/oils/sweets
Nutrition
•Individual requirements vary based
on age, sex, growth rate, levels of
stress, etc...
•Malnutrition – lacking essential
nutrients
Ex: anorexia, bulimia
•Normally active people (3x per week)
would need more calories than a
person who doesn’t exercise at all
•Your body needs to replace burned