Download Digestive system

Digestive System Structures
2.07
Digestive system
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AKA:
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Alimentary Canal
Digestive Tract
Gastrointestinal Tract
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Upper GI
Lower GI
Approximately 30’
in length from
mouth to anus
2.07 Remember the structures of the
digestive system
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Physical breakdown of food.
Chemical digestion of food into the end
products of fat, carbohydrates, and
protein.
Absorb nutrients into blood capillaries of
the small intestines.
Eliminate waste products of digestion.
Definitions
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Digestion- the process
of changing complex
solid foods into simpler
soluble forms which
can be absorbed by
body cells
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Enzymes- chemical
substances that
promote chemical
reactions in living
things
Digestion Terminology
Bolus:
soft, pliable ball
created from chewing and addition of salivaslides down esophagus.
Peristalsis:
wavelike motions, moves food along esophagus, stomach
and intestines.
Definitions
Feces:
 undigested semi-solid consisting of bacteria, waste
products, mucous and
 Cellulose
Defecation:
 large intestine fills, defecation reflex triggered colon and rectal muscles contract while internal
sphincter relaxes
 external anal sphincter under conscious control
Digestive System Structures
Primary structures
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Mouth
Esophagus
Stomach
Small intestines
Large intestines
Accessory structures
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Tongue
Teeth
Salivary glands
Pancreas
Liver
Gall bladder
2.07 Remember the structures of the
digestive system
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In the mouth…
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Saliva softens food to make it
easier to swallow
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Ptyalin in saliva converts
starches into simple sugar
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Under nervous control- just
thinking of food can cause your
mouth to water.
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Food enters digestive system
through mouth (buccal cavity)
covered with mucous
membrane
Roof of mouth is HARD
PALATE (bone) and soft
palate
UVULA- flap that hangs off soft
palate-prevents food from
going up the nose when you
swallow.
Buccal cavity
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Tongue
Teeth
Salivary Glands
Palate
Uvula
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digestive system
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Tongue
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Attached to floor of
mouth
Helps in chewing and
swallowing
Made of skeletal
muscle attached to four
bones
Papillae (taste buds) on
the surface
Tongue
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Taste buds on the
surface
 Sweet
 Sour
 Bitter
 Salty
2.07 Remember the structures of the
digestive system
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Three pairs of glands
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Parotid gland
Submandibular gland
Sublingual gland
PAROTID – largest
salivary glands,
become inflamed
during mumps
Secrete saliva
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Gingiva – gums, support
and protect teeth
Mastication – chewing,
teeth helps in mechanical
digestion
Deciduous teeth- baby teeth
(#20)
Adult mouth has 32 teeth
(Permanent).
Palate
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Hard
Soft
Uvula
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Flap of skin
hanging in the
back of the throat
2.07 Remember the structures of the
digestive system
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Pharynx (throat)
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Nasopharynx
Oropharynx
Hypopharynx
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digestive system
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Esophagus
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Muscular tube 10” long
Connects pharynx and
stomach
Esophageal wall layers
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Mucosa
Submucosa
Muscular
External serous
In the Stomach…
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Gastric (digestive) juices
are released
Stomach walls churn and
mix (This mixture is chyme)
Small amount of chyme
enters duodenum at a time
controlled by pyloric
sphincter
Takes 2-4 hours for
stomach to empty.
When will Meagan’s stomach be
empty if she last ate at 9a.m.?
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Upper left quadrant of the
of the abdominal cavity
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Fundus
Body
Pylorus
Stomach has muscular coat
that allows it to contract
(peristalsis) and push food
into the small intestine
Stomach
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CARDIAC SPHINCTERcircular layer of muscle,
controls passage of food into
stomach
PYLORIC SPHINCTERvalve, regulates the entrance
of food into duodenum
RUGAE- mucous coat lining
of stomach in folds when the
stomach is empty
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digestive system
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Small Intestines
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Where digestion is
completed and
absorption occurs
Addition of enzymes
from the pancreas and
bile from
liver/gallbladder
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DUODENUM- first segment,
curves around pancreas, 12”
long
JEJUNUM- Second segment ,
8 ft. long
ILEUM- Third segment, 10-12
ft long
ABSORPTION- in small
intestine, digested food passes
into bloodstream and on to
body cells, indigestible passes
on to large intestine
Acessory organs
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Pancreas
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Liver
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Secretes digestive enzymes
Located behind stomach
Next slide
Gall Bladder
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Stores and concentrates bile
until needed by body
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digestive system
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Liver
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Largest organ in the body
Located below the
diaphragm, upper right
quadrant
Manufactures bile
Connected to gallbladder
and small intestine by ducts
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Functions: produce and
store glucose in the form of
GYCOGENDetoxify alcohol, drugs and
other harmful substances
Manufacture blood proteins
Prepare urea from the
breakdown of amino acids
Store Vitamins A, D, and B
complex
Gallbladder
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Small green muscular sac
secretes bile
located inferior surface of
the liver
Stores and concentrates
bile until needed by body.
When fatty foods digested,
bile released by
gallbladder.
In the Large intestine…
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Regulation of H2O balance by
absorbing large quantities back into
bloodstream
absorbs Vitamin B complex and K
Bacterial action on digested fooddecomposed products excreted
through colon-bacteria form
moderate amounts of B complex
and Vitamin K
Gas formation 1-3 pints/day, pass it
through the rectum (flatulence) 14
times a day, bacteria produce gas
Large Intestine
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Chyme - semi-liquid
food
Approx 2” in diameter
5’ Long
AKA: colon
Cecum-lower right
portion of large intestine
Appendix: blind sac
attached to the cecum,
no known function,
finger like projection
Rectum- last portion of
large intestine
Anus- external opening
Sigmoid colon
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S shaped part of
colon, which extends
7 to 8 inches as the
rectum
Structures of the digestive system
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