DIGESTIVE SYSTEM Flashcards
consumption of solid or liquid food,
usually through mouth
Ingestion
breakdown of large organic molecules
into smaller molecules that can be absorbed.
(Chemical & Mechanical Digestion)
Digestion
movement of molecules out of the
digestive tract and into the blood.
Absorption
removal of undigested material,
such as fiber from food, plus other waste products
from the body as feces
Elimination
Two main groups of the digestive system
Alimentary canal – continuous coiled
hollow tube (about 30ft long)
Accessory digestive organs
Organs of the Alimentary Canal
Mouth
∙ Pharynx
∙ Esophagus
∙ Stomach
∙ Small intestine
∙ Large intestine
∙ Anus
protect
the anterior opening
Lips (labia)
form the
lateral walls
Cheeks
forms
the anterior roof
Hard palate
forms
the posterior roof
Soft palate
fleshy
projection of the soft
palate
Uvula
space
between lips
externally and teeth
and gums internally
Vestibule
area
contained by the
teeth
Oral cavity
attached
at hyoid and styloid
processes of the
skull, and by the
lingual frenulum
Tongue
2 types of tonsil
Palatins and lingual tonsil
The chewing of food
Mastication
not part of the
digestive system
Nasopharynx
posterior to oral
cavity
Oropharynx
below the oropharynx
and connected to
the esophagus
Laryngopharynx
Serves as a passageway for air and
food
Pharynx
Food is propelled to the esophagus by
two muscle layers
∙Longitudinal inner layer
∙Circular outer layer
Runs from pharynx to stomach
through the diaphragm
Esophagus
∙Innermost layer
∙Moist membrane
∙Surface epithelium
∙Small amount of
connective tissue
(lamina propria)
∙Small smooth muscle
layer Copyright © 2003 Pearson Education, Inc. publishing as
Mucosa
∙Just beneath the mucosa
∙Soft connective tissue with blood
vessels, nerve endings, and lymphatics
Submucosa
smooth
muscle
∙Inner circular layer
∙Outer longitudinal layer
Muscularis externa
∙Outermost layer – visceral peritoneum
∙Layer of serous fluid-producing cells
Serosa
Acts as a storage tank for food
∙ Site of food breakdown
∙ Chemical breakdown of protein begins
∙ Delivers chyme (processed food) to the small intestine
Located on the
left side of the
abdominal
cavity
Stomach
Regions of the stomach
∙Cardiac region – near the heart
∙Fundus
∙Body
∙Pylorus – funnel-shaped terminal end
internal folds of
the mucosa
Rugae
The body’s major digestive
organ
∙ Site of nutrient absorption into
the blood
∙ Muscular tube extending form
the pyloric sphincter to the
ileocecal valve
∙ About 6 meters (20
feet) long
Small intestine
∙Attached to the stomach
∙Curves around the head of the pancreas
Duodenum
∙Attaches anteriorly to the duodenum
Jejunum
∙Extends from jejunum to large intestine
Illeum
Fingerlike
structures formed
by the mucosa
∙ Give the small
intestine more
surface area
Villi of small intestines
Small projections of the
plasma membrane
∙ Found on absorptive cells
Microvilli
Deep folds of the mucosa and
submucosa
∙ Do not disappear when filled with food
∙ The submucosa has Peyer’s
patches (collections of lymphatic
tissue)
Circular folds/Plicae circulares
Larger in
diameter, but
shorter than the
small intestine
∙ Frames the
internal abdomen
Large intestine
saclike first part of the large
intestine
Cecum
∙Accumulation of lymphatic tissue that
sometimes becomes inflamed
(appendicitis)
∙Hangs from the cecum
Appendix
external body
opening
Anus
Accessory Digestive Organs
Salivary glands
∙ Teeth
∙ Pancreas
∙ Liver
∙ Gall bladder
Mixture of mucus and serous fluids
∙ Helps to form a food bolus
∙ Contains salivary amylase to
begin starch digestion
∙ Dissolves chemicals so they can be
tasted
Saliva
The role is to masticate (chew) food
∙ Humans have two sets of teeth
∙Deciduous (baby or milk) teeth
∙20 teeth are fully formed by age two
Teeth
Classification of Teeth
Incisors
∙ Canines
∙ Premolars
∙ Molars
exposed part
∙Outer enamel
∙ Dentin
∙Pulp cavity
Crown
Region in contact
with the gum
∙ Connects crown to
root
Neck
∙Periodontal
membrane
attached to the
bone
∙Root canal
carrying blood
vessels and
nerves
Root
Produces a wide spectrum of digestive
enzymes that break down all categories of
food
Pancreas
Endocrine products of pancreas
Insulin and glucagons
Largest gland in the body
∙ Located on the right side of the body
under the diaphragm
Liver
Produced by cells in the liver
∙ About 600-1000 mL is produced per day
∙ Composition
∙ Bile salts
∙ Bile pigment (mostly bilirubin from the
breakdown of hemoglobin)
∙ Cholesterol
∙ Phospholipids
∙ Electrolytes
Bile
Sac found in hollow fossa of liver
∙ Stores bile from the liver by way of the
cystic duct (45ml)
∙ Bile is introduced into the duodenum in
the presence of fatty food
∙ Gallstones can cause blockages
Gallbladder
moving foods from
one region of the digestive system
to another
Propulsion
alternating waves of
contraction
Peristalsis
moving materials back
and forth to aid in
mixing
Segmentation
∙Mixing of food in the mouth by the tongue
∙Churning of food in the stomach
∙Segmentation in the small intestine
Mechanical digestion
∙Enzymes break down food molecules
into their building blocks
∙Each major food group uses
different enzymes
Chemical digestion
∙End products of digestion are absorbed
in the blood or lymph
∙Food must enter mucosal cells and
then into blood or lymph capillaries
Absorption
∙Elimination of indigestible substances
as feces
Defecation
∙Food is physically broken down by chewing
Mechanical breakdown
∙Food is mixed with saliva
∙Breaking of starch into maltose by salivary
amylase
Chemical breakdown
∙Involuntary transport of the bolus
∙All passageways except to the stomach
are blocked
∙Tongue blocks off the mouth
∙Soft palate (uvula) blocks the
nasopharynx
∙Epiglottis blocks the larynx
Pharyngeal-esophageal
phase
an active protein
digesting enzyme
Pepsin
works on digesting milk
protein
Rennin
2 Local hormones
∙Secretin
∙Cholecystokinin
Chemical reactions necessary to
maintain life
Metabolism
substances are broken
down to simpler substances (Ex.
Glycolysis)
Catabolism
larger molecules are built
from smaller ones (Ex. Bone
Development)
Anabolism
