Ch. 22 AA Flashcards
alimentary canal
continuous muscular tube that runs from the mouth to anus
organs of the alimentary canal
mouth, pharynx, esophagus, stomach, small intestine, large intestine, anus
accessory digestive organs
teeth, tongue, gallbladder
Digestive process
ingestion, propulsion, mechanical breakdown, digestion, absorption, defecation
ingestion
eating
propulsion
movement of food through alimentary canal
peristalisis
major means of propulsion of food that involves alternating waves of contraction and relaxation
mechanical breakdown
includes chewing, mixing food with saliva, churning food in stomach, and segmentation
segmentation
local constriction of intestine that mixes food with digestive juices
digestion
series of catabolic steps that involves enzymes that break down complex food molecules into chemical building blocks
absorption
passage of digested fragments from lumen of GI tract into blood or lymph
defecation
elimination of indigestible substances via anus in form of feces
peritoneum
serous membranes of abdominal cavity that consists of: visceral and parietal peritoneum
visceral peritoneum
membrane on external surface of most digestive organs
parietal peritoneum
membrane that lines body wall
peritoneal cavity
fluid-filled space between two peritoneums
mesentary
double layer of peritoneum; layers are fused back to back
Four basic layers (tunics) of digestive organs
mucosa, submucosa, muscularis externa, serosa
mucosa
tunic layer that lines lumen
mucosa secretes
mucus, digestive enzymes, and hormones
mucosa absorbs
end products of digestion
mucosa protects
against infectious disease
three sublayers of mucosa
epithelium, lamina propria, muscularis mucosae
epithelium
simple columnar epithelium and mucus-secreting cells in most of tract; secretes mucus
mouth, esophagus, and anus are made up of
stratified squamous epithelium
lamina propria
made of loose areolar connective tissue; many capillaries needed for nourishment and absorption located here
muscularis mucosae
smooth muscle that produces local movements of mucosa
submucosa
consists of areolar connective tissue; has elastic tissues that help organs to regain shape after storing large meal
muscularis externa
muscle layer responsible for segmentation and peristalisis
serosa
outermost, layer, which is made up of the visceral peritonium; connective tissue covered with mestothelium (single layer of squamous epithelium)
the serosa is replaced with ___ in esophagus
adventitia (holds it to surrounding structures)
splanchnic circulation
arteries that branch off aorta to serve digestive organs; hepatic, splenic, and left gastric arteries; inferior and superior mesenteric arteries
hepatic portal circulation
drains nutrient-rich blood from digestive organs; delivers blood to liver for processing
enteric nervous system
nervous system of GI tract; also called gut brain; contains more neurons than spinal cord
submucosal nerve plexus
regulates glands and smooth muscle in mucosa
myenteric nerve plexus
controls GI tract motility
short reflexes
mediated by enteric nerve plexuses; respond to stimuli in GI tract
long reflexes
respond to stimuli arising inside or outside of gut
