exam 2 class 15 Flashcards
stopped at slide 20
Digestive system begins with?
oral cavity (mouth and pharynx), which serves as a receptacle for food
Swallowed food enters
gastrointestinal tract
(GI tract)
gastrointestinal tract
(GI tract) consisting of
esophagus, stomach,
small intestine, and large intestine
Portion of the GI tract running from the
stomach to the anus is also called the
gut
Digestion, chemical and mechanical breakdown of food, takes place primarily in?
lumen of gut
Secretions are added to ingested food by?
secretory epithelial cells and by accessory glandular organs
accessory glandular organs that include?
salivary glands, liver,
gallbladder, and pancreas.
(1) Sublingual glands
under the tongue
(2) Submandibular glands
under the mandible (jawbone)
(3) Parotid glands lying near
the hinge of the jaw
Swallowed food passes into
__________, a narrow tube that travels through the ________ to _________
esophagus
thorax
abdomen
Esophageal walls are _______ initially but transition to
__________ about two-thirds of way down length
skeletal muscle
smooth muscle
Stomach has three
sections:
upper fundus,
central body,
lower antrum
opening between stomach
and small intestine is
guarded by the pyloric
valve
Pylorus {gatekeeper}
Stomach continues digestion that began in the
mouth by mixing food with acid and enzymes to
create?
chyme
Most digestion takes place in
small intestine
what are the three sections of the small intestine
duodenum (the first 25 cm),
jejunum,
ileum
______________is carried out by intestinal enzymes, aided by exocrine secretions from
two accessory glandular organs: pancreas
and liver
Digestion
Digestion finishes in ?
small intestine,
proximal section of large
intestine—watery chyme becomes semisolid
feces, as water and electrolytes are absorbed out of the chyme and into the extracellular fluid
(ECF)
in the colon
(1) inner mucosa facing lumen
(2) submucosa
(3) layers of smooth muscle known collectively as muscularis externa
(4) covering of connective tissue called serosa
4 layers of the GI tract
what does the Mucosa include:
(1) transporting epithelial cells (called enterocytes in the small intestine),
(2) endocrine and exocrine secretory cells,
(3) stem cells
what is done at the mucosal surface
cells secrete ions, enzymes, mucus, and paracrine molecules into lumen
tie GI epithelial cells together
cell to cell junctions
In small intestine,
junctions are ?
leaky
GI tract is prone to?
cancer
is subepithelial
connective tissue: nerve fibers blood
vessels and lymph vessels
Lamina propria
Contraction of muscles
in muscularis mucosae?
moves the
villi back and forth
middle layer of gut
wall
Submucosa:
Submucosa is made of?
Connective tissue with larger blood and lymph vessels running
through it
Submucosa also contains
submucosal or Meissner’s
plexus, one of the major nerve networks of enteric nervous system
Outer wall of GI tract,
muscularis externa, consists
primarily of 2 layers of smooth muscle
inner circular layer and
outer longitudinal layer
Contraction of circular layer
decreases?
Contraction of longitudinal layer?
diameter of lumen.
shortens tube
Outer covering of entire GI
tract, is connective
tissue membrane that is a
continuation of the
peritoneal membrane
(peritoneum) lining the
abdominal cavity
serosa
Four processes of digestive system:
digestion, absorption,
secretion, and motility
If protective mechanisms against autodigestion fail, raw patches known as peptic ulcers develop
autodigestion:
matching fluid input with output, dehydration
Mass balance:
vomiting, diarrhea, loss of blood pressure
Fluid loss:
GI tract is assisted by an array of physiological defense mechanisms, including mucus, digestive enzymes, acid, and the largest collection
of lymphoid tissue in the body, the gut-associated lymphoid tissue (GALT).
Defense:
Gastrointestinal epithelial cells are________, with distinct apical and
basolateral membranes
polarized
