ch 23 digestive system p1 Flashcards
the digestive system associated terms
GI tract and alimentary canal
6 functions of digestive system
ingestion, movement, mechanical breakdown, digestion, absorption, defecation
movement in digestive system
food propelled through peristalsis, ensures things don’t move backwards
mechanical breakdown in DS
food broken down to smaller pieces to increase digestion efficiency, inc SA of food
digestion in DS
enzymes breakdown complex foods to building blocks. catabolic process of creating monomers
absorption inDS
building blocks are passed from DS to blood or lymph
membranes of the DS
peritoneum, mesentery
peritoneum
serous membrane covers organs of abdominopelvic cavity. visceral covers organs, parietal clings to body wall, peritoneal cavity is the fluid filled space between visceral and parietal
why do we need the peritoneal cavity
prevents friction from organ to organ or organ to body. ensures no damage
mesentery
double layer peritoneum extends from digestive organs to body wall. holds organs in place provides blood passage as well as nerve n lymph to digestive organs. fat storage too
alimentary canal
portion of digestive system that forms lung tube out of body. mouth, pharynx, esophagus, stomach, small intestine, large intestine. also has associated glands.
alimentary canal layers, from inner to outer
Epithelia, lamina propria, muscularis mucosae, mucosa, submucosa, muscularis externa, serosa
mucosa of alimentary canal
innermost, has epithelia lamina propria and muscularis mucosa.
epithelia of mucosa
simple columnar mostly, secretes mucous and digestive enzymes, hormones, absorptive surface. stratified squamous in anus and mouth and esophagus.
lamina propria of mucosa
loose areolar connective tissue, vascularized to substances can get absorbed here, MALT tonsils and appendix
muscularis mucosae
smooth muslce cells, creates movement to increase digestion and secretion. secretes digestive enzymes and hormones
submucosa
superficial to mucosa, areolar connective tissue with elastic fibers, rich blood supply Nd nerve fibers serving GI tract
muscularis exterrna
generates movement in GI tract like a worm. has circular and longitudinal Layer. they DO NOT contract at the same time.
circular layer of muscukaris external
constricts and fibers of muscle are around circumference constrict, long and small
longitudinal layer of muscularis external
contraction makes tube wider, along whole length widens and shortens
alternating contractions of the circular and longitudinal layers allows for
waves called peristalsis, if they wrnt at same time, tube would do nothing. no movement and as one relaxes other goes
sphincters
thickening in muscularis externa, controls movement of one alimentary organ to another, prevents back movement of ingested food.
serosa
outermost layer, has visceral peritoneum
in organs NOT in abdominopelvic cavity what is serosa
adventitia, which holds the organs in place with dense connective tissue.
splanchnic circulation
bloody supply to digestive organs, arteries branch off aorta and hepatic portal circulation.
what do arteries do in splanchnic circulation
branch off celiac trunk that serve spleen liver and stomach, spleen is not digestive directly.
hepatic portal circulation
collects nutrient rich blood draining from digestive organs and transport to liver. WHY? to be filtered, veins don’t go to heart with portal system so many nutrients absorbed to prevent sensitive organs from bad exposure
innervation of the digestive system consists of the
enteric NS, the nerve supply to alimentary canal. NOT CNS. called our second brain.
enteric nervous system consists of two major intrinsic nerve plexuses
submucosal, found in submucosa to control secretions and absorptions
myenteric, found between circular and longitudinal muslce layers to control muslce tone in GI tract
function of the instrinsic nerve plexus’
both plexuses supply walls of entire GI tract and help regulate motility. intrinsic is built in.
long reflex of enteric NS
initiated by stimuli inside and outside the GI tract. involves CNS and extrinsic autonomic nerve.
sympathetic stimulation- inhibits gastric activity, slows digestion during dight or flight.
parasympathetic stimulation- stimulates enhanced gastric activity during rest
short reflex of enteric NS
mediated entirely by enteric NS in response to GI tract stimuli. ex; peristalsis.
the mouth
part of alimentary canal, composed of several skeletal muscles, for ingestion and movement. has hard and soft palate.
hard palate
rigid and ribbed surface on roof of mouth, hooks break down food when tongue pushes against it
soft palate
soft and mobile surface behind hard palate, has uvula which protects from soft palate and helps close off nasopharynx
what is function of soft palate and uvula
both help close nasopharynx as u swallow
the tongue
accessory organ, bundles of skeletal muscle, has intrinsic and extrinsic muscles
instrinsic tongue muscles
confined within tongue, not bone attached. allows tongue to change space
extrinsic muscle of tongue
origin of muslce is found on bone, allows tongue to change position in the mouth. ex moving side to side or sticking out
salivary glands of the mouth
accessory organ, has saliva which uses IgA to cleanse, dissolves food chemicals for taste, moistens food, and contains digestive enzymes to breakdown stuff
salivary amylase
a digestive enzyme of the salivary glands, begins digestion of STARCHY foods
lingual lipase
another digestive enzyme of the salivary glands, begins lipid breakdown and is not as important
3 major salivary glands
parotid (largest, from roof of mouth), submandibular (opens at floor of mouth under tongue), sublingual (smallest, directly under tongue, really important has 10-20 dif ducts)
teeth
accessory glands of alimentary Canal, tear and grind food to smaller pieces while chewing
deciduous teeth
baby teeth or milk teeth, 20, shed in early childhood 6 mo to 2 yrs
permanent teeth
well eventually replace baby teeth that falll out during adolescence. 32 of them.
3 teeth types
incisors- cutting
canines- tearing
premolars and molars- grinding
primary dentition formula
2I, 1C, 2M divided by 2I,1C, 2M times 1. no premolars
permanent dentition formula
2I, 1C, 2PM, 3M divided by 2I, 1C, 2PM, 3M times
main regions of teeth
crown, exposed portion and enamel tough mineral substance covers exposed tooth surface
root, portion embedded in jawbone anchored to periodontal ligament
hardest substance made by body
enamel, acidic foods eat at it, and cavity destroys it, we don’t produce more once gone.
teeth are composed of what
dentinm softer than enamel and absorbs shock
what cell lays down dentin
odonotblast
dentin surrounds what
the pulp cavity, which has connective tissue blood vessels and nerve supply
pharynx
alimentary canal organ, contractions of muslce propels food to esophagus,.
esophagus joins tummmm
joins stomach at cardiac orifice. collapsed when no food is there. cardiac sphincter can be found at where stomach and esophagus join
function of cardiac sphincter
closes stomach off when no food enters thru esophagus, also prevents food from going back into esophagus
4 stomach regions
cardia, fundus, body, pyloric portion.
