An Overview of Digestion Flashcards
ingestion
refers to taking food into mouth
peristalsis
moves food through the alimentary canal by waves of muscle contraction
digestion describes
the breakdown of food
mechanical digestion
physically breaks down food into small pieces
chemical digestion
splits complex molecules into smaller molecuels
absorption
describes the movement of diegsted food from the gastrointestinal tract into the bloodstream or lymphatic system for distribution of cells
defecatation
refers to the elimation of indigestible substances from the body
the alimentary canal
a muscular tube that extends from the mouth to the anus
the alimentary canal consists of
mouth, pharynx, esophagus, stomach, small intestine, large intestine
accessory structures include
the teeth, tongue, salivary glands, liver, pancreas, and gall bladder
accessory structure functions
either prepare food for digestion or produce and store secretions that aid in digestion
the mucosa is
the inner lining of the alimentary canal and it consists of sublayers
histology of mucosa
simple columnar epithelium exists throughout most of alimentary canal, but stratified squamous epithelium lines alimentary canal from mouth to stomach and alse anal canal where abrasion mostly occurs
lamina propria
areolar connective tissue that contains blood and lymphatic vessels
lamina propria contains lymphoid tissue to
protect the gastrointestinal tract against bacteria
muscularis mucosae
a thin layer of smooth muscle
muscularis mucosae function
folds in wall of stomach and small intestine increase surface area for digestion and absorption
submucosa
a layer of areolar connective tissue that is thicker than the mucosa
submucosa components
contains blood vessels, lymphatic vessles, submucosal nerve plexus (of Meissner) which controls movements of muscularis
muscularis
contains skeletal muscle in mouth, pharynx, and esophagus to assist in voluntary swallowing, and two layers of smooth muscle throughout the remainder of the alimentary canal to break food down, mix it with secretions and move it towards the anus
outer layer of smooth muscle contains
longitudinal fibers
inner layer of smooth muscle contains
circular fibers
myenteric nerve plexus (of Auerbach)
which controls motility through GI tract
serosa
a thin layer of areolar tissue and squamous mesothelium that secretes serous fluid to keep membrane surfaces moist and reduce friction with the abdominal wall
-also known as visceral peritoneum
peritoneum
the largest serous membrane in the body
parietal peritoneum
lines walls of abdominopelvic cavity
visceral peritoneum
covers some of organs in abdominopelvic cavity
cavity between the parietal and visceral peritoneum contains
slippery fluid that lubricates digestive organs for easier movements
peritonitis
can occur as a result of stab wound or perforated ulcer or ruptrured appendix
large peritoneal folds
contain blood vessels, lymphatic vessels, and nerves and they bind to organ to one another and to the walls of the abdominal cavity
mesentery
binds intestines together and suspends them from abdnominal wall
mesocolon
anchors large intestine to posterior abdominal wall
lesser omentum
extends from stomach to liver
greather omentum
covers small intestine like a loose apron
omenta contain
lymph nodes, lymphatic vessels, blood vessels and nerves
