GIT 🍫ℹ️ Flashcards
The organs of the digestive system fall into two main groups ..
1) the alimentary canal
2) accessory digestive organs
The alimentary canal, also called ..
gastrointestinal (GI) tract or gut.
The alimentary canal ..
Continuous muscular tube span through the body from the mouth to the anus.
The alimentary canal function ?
Digestion & absorption
The organs of the alimentary canal
Mouth —> pharynx —> esophagus —> stomach —> small intestine —> large intestines
The accessory digestive organs are ..
Teeth, tongue, gall bladder
& secretory large glands —-> liver, pancreas, salivary glands
The accessory digestive organs are functions ..
Secrete digestion substances ..
The processing of food by the digestive system involves six essential activities ..
- Ingestion
- Propeulsion
- Mechanical breakdown
- Digestion
- Absorption
- Defecation
Ingestion ..
taking food into the digestive tract (eating).
Propulsion ..
moves food through the alimentary canal.
includes swallowing, voluntarily, and peristalsis an involuntary process.
Mechanical breakdown ..
increases the surface area of ingested food, physically preparing it for digestion by enzymes.
Mechanical processes include ..
chewing
mixing food with saliva
churning food in the stomach
segmentation (rhythmic local constrictions of the small intestine)
Segmentation function?
mixes food with digestive juices and makes absorption more efficient
Digestion ..
catabolic steps in which enzymes secreted to break down complex food.
Absorption ..
the passage of digested end products from the GI tract through the mucosal cells by active or passive transport into the blood or lymph.
Defecation ..
eliminates indigestible substances from the body via the anus in the form of feces.
The peritoneum of the abdominopelvic cavity is the most extensive serous membrane.
T/F
True
The visceral peritoneum
covers the external surfaces of most digestive organs and is continuous with the parietal peritoneum that lines the body wall.
parietal peritoneum ..
Lines body wall
Between the two peritoneums is the ..
peritoneal cavity, a slitlike potential space containing a slippery fluid secreted by the serous membranes.
The serous fluid allows ..
the mobile digestive organs to glide easily
mesentery ..
double layer of peritoneum— a sheet of two serous membranes fused back to back—that extends to the digestive organs from the body wall.
Mesenteries provide ..
routes for ..
blood vessels
lymphatics
nerves
hold organs in place
store fat
retroperitoneal
organs that lose their mesentery and come to lie posterior to the peritoneum.
include most of the pancreas and duodenum and parts of the large intestine,
intraperitoneal or peritoneal organs.
digestive organs (like the stomach) that keep their mesentery and remain in the peritoneal cavity
From the esophagus to the anal canal, the walls of the alimen- tary canal have the same four basic layers
mucosa
submucosa
muscularis externa
serosa
The Mucosa ..
innermost layer which is moist epithelial membrane that lines the alimentary canal lumen from mouth to anus.
The Mucosa functions are ..
Secrete mucus, digestive enzymes, and hormones
Absorb the end products of digestion into the blood
Protect against infectious disease
typical digestive mucosa consists of three sublayers ..
(1) a lining epithelium
(2) a lamina propria
(3) a muscularis mucosae.
mouth, esophagus, and anus where the epithelium is ..
stratified squamous
the epithelium of the mucosa is ..
simple columnar epithelium, rich in mucus-secreting cells.
The slippery mucus it produces protects digestive organs from being digested
stomach and small intestine, the mucosa also contains both enzyme-synthesizing and hormone-secreting cells.
T/F
True
The lamina propria ..
(proprius = one’s own)
underlies the epithelium
is loose areolar connective tissue.
Its capillaries nourish the epithelium and absorb digested nutrients.
External to the lamina propria is the
muscularis mucosae ..
a scant layer of smooth muscle cells that produces movements for the mucosa that can enhance absorption and secretion.
submucosa ..
just external to the mucosa ..
areolar connective tissue
containing a rich supply of blood and lymphatic vessels, lymphoid follicles, and nerve fibers which supply the surrounding tissues of the GI tract wall
Submucosal is abundant of elastic fibers enabling the stomach to ..
regain its normal shape after temporarily storing a large meal.
The Muscularis Externa
Surrounding the submucosa is the muscularis externa, or muscularis.
It is responsible for segmentation and peristalsis.
It typically has an inner circular layer and an outer longitudinal layer of smooth muscle cells
In several places along the tract, the circular layer thickens, forming sphincters that act as valves to ..
control food passage from one organ to the next and prevent backflow.
The serosa ..
the outermost layer of the intraperitoneal organs, is the visceral peritoneum.
The serosa formed of ..
areolar connective tissue covered with mesothelium, a single layer of squamous epithelial cells.
esophagus, the serosa is replaced by an ..
adventitia, ordinary dense connective tissue that binds the esophagus to surrounding structures.
Retroperitoneal organs have both an adventitia (on the side facing the dorsal body wall) and a serosa (on the side facing the peritoneal cavity).
T/F
True
The splanchnic circulation includes ..
the arteries that branch off the abdominal aorta to serve the digestive organs
the hepatic portal circulation.
arterial supply of the splanchnic circulation are ?
the branches of the celiac trunk that serve
🥩 the spleen
🍕 liver
🌭 stomach
🍦 and the mesenteric arteries that serve the small and large intestines
hepatic portal circulation ..
collects nutrient-rich venous blood draining from the digestive viscera and delivers it to the liver.
enteric nervous system or the gut brain ..
The great regulator of the GI tract which consists of over 100 million neurons.
The enteric nervous system ..
is the in-house nerve supply of the alimentary canal.
It is staffed by enteric neurons
The enteric nervous system is staffed by ..
enteric neurons that communicate widely with one another to regulate diges- tive system activity
intrinsic nerve plexuses are composed of ..
ganglia interconnected by unmyelinated fiber tracts
two major intrinsic nerve plexuses found in the walls of the alimentary canal are ..
the submucosal
the myenteric nerve
The submucosal nerve plexus occupies the ..
submucosa
the large myenteric nerve plexus lies ..
between the circular and longitudinal muscle layers of the muscularis externa ..
submucosal nerve plexus and the large myenteric nerve plexus of the Enteric neurons provide ..
major nerve supply to the GI tract wall.
control GI tract motility (motion).
Short reflexes ..
mediated entirely by enteric nervous sys- tem plexuses in response to stimuli within the GI tract.
Control of the patterns of segmentation and peristalsis is largely ___________, involving ..
Automatic, involving pacemaker cells and reflex arcs between enteric neurons in the same or different organs.
Long reflexes ..
involve CNS integration centers and extrinsic autonomic nerves.
The enteric nervous system sends information to the central nervous system via ..
afferent visceral fibers.
ENS receives sympathetic and parasympathetic branches (motor fibers) of the autonomic nervous system that enter ..
the intestinal wall to synapse with neurons in the intrinsic plexuses
Long reflexes can be initiated by stimuli arising inside or outside of the GI tract.
T/F
True
parasympathetic inputs enhance _________ and sympathetic inpulses __________ .
Digestive activities, inhibit them respectively.
The mouth is also called ..
the oral cavity, or buccal cavity.
Mouth boundaries are ..
🦷 anterior opening is the oral orifice
🦷 the lips anteriorly
🦷 cheeks laterally
🦷 palate superiorly
🦷 tongue inferiorly
🦷 Posteriorly is continuous with the oropharynx.
The walls of the mouth are lined with ..
a thick stratified squamous epithelium ..
thick stratified squamous epithelium function in the mouth ..
withstands considerable friction.
The epithelium is slightly keratinized in ? And why ?
on the gums, hard palate, and dorsum of the tongue.
for extra protection against abrasion during eating.
The lips (labia) and the cheeks function?
help keep food between the teeth when we chew
The lips (labia) and the cheeks, are composed of ..
a core of skeletal muscle covered externally by skin.
the fleshy lips are formed by which muscle ?
The orbicularis oris muscle
the cheeks are formed largely by which muscle?
the buccinators.
oral vestibule is ..
The recess bounded externally by the lips and cheeks and internally by the gums and teeth.
The oral cavity proper ..
area that lies within the teeth and gums ..
The labial frenulum ..
is a median fold that joins the internal aspect of each lip to the gum.
The palate forming ..
the roof of the mouth.
The palate has two distinct parts:
hard palate anteriorly and the soft palate posteriorly
The hard palate is underlain by ..
the palatine bones and the palatine processes of the maxillae.
The hard palate forms ..
a rigid surface against which the tongue forces food during chewing.
The raphe ..
a midline ridge
The mucosa on either side of its raphe ..
is slightly corrugated, which helps create friction.
The soft palate ..
is a mobile fold formed mostly of skeletal muscle that rises reflexively to close off the nasopharynx when we swallow.
the soft palate is anchored to the tongue by the ..
palatoglossal arches
the soft palate is anchored to the wall of the oropharynx by ..
the more posterior palatopharyngeal arches.
fauces ( fauc = throat ) ..
palatoglossal arches and palatopharyngeal arches. This pair of folds form the boundaries of the fauces
the arched area of the oropharynx that contains the palatine tonsils.
uvula ..
Projecting downward from the free edge of the soft palate which looks a fingerlike ..
The tongue occupies ..
the floor of the mouth.
The tongue is composed of ..
interlacing bundles of skeletal muscle fibers.
Tongue functions ..
during chewing, it grips the food and constantly repositions it between the teeth.
mixes food with saliva, forming it into a compact mass called a bolus
initiates swallowing by pushing the bolus posteriorly into the pharynx.
helps us form consonants (k, d, t, and so on) when we speak.