Chapter 17: Digestive System Flashcards
components of bile
- water
- bile salts
- bile pigments
- cholesterol
- electrolytes
bile salts
produced from cholesterol, emulsify fats, only bile component with digestive function
gall bladder
- pear shaped
- stores & concentrates bile
- cystic duct from gb joins with common hepatic duct from liver to form common bile duct
- bile duct empties into duodenum
- hematopancreatic sphincter
gall stones
- occurs if bile is too concentrated
- crystals
cck
causes gall bladder to contract, in response to fats entering the duodenum; the bile is then released into the duodenum
what do bile salts do
aid digestive enzymes through emulsification; enhance absorption of fatty acids & cholesterol by forming micelles
duodenum
shortest & most fixed end of SI
jejunum
middle, thicker & more active than ileum
ileum
distal end of SI, Peyer’s patches
mesentary
helps to hold ileum & jejunum in place
greater omentum
attached to inferior aspect of stomach; hangs down covering intestines
intestinal villi
tiny projections of muscles; greatly increase surface area for absorption of digestive end product
what does each intestinal villi contain?
simple columnar epithelium w/ a core of connective tissue, w/ BV, lacteal, and nerve fibers
microvilli
free surfaces of epithelial cells; increase surface area for absorption
Brunner’s glands
specialized mucus secreting cells that secrete a thick, alkaline mucus in response to certain stimuli
what do intestinal glands secrete
a watery fluid, that picks up digestion product & transports them to villi; does not have digestive enzymes
enzymes in microvilli membranes (4)
- peptidase
- lipase
- sucrase
- maltase
carb absorption
- salivary & pancreatic amylase break down starch & glycogen into disaccharides
- intestinal enzymes break down disaccharides to monosaccharides
- monosaccharides absorbed by facilitated diffusion & active transport into BV in villi
protein absorption
- pepsin breaks down proteins into polypeptides
- pancreatic proteases break down proteins & polypeptides into smaller proteins
- intestinal peptidases break peptides into AA
- AA absorbed by active transport into BV of villi
fat absorption
- emulsified by bile salts
- digested mainly by enzymes from pancreas & SI
- ingested into glycerol and fatty acids
- fatty acids & glycerol absorbed by blood or lacteals
peristaltic rush
occurs when small intestine becomes over distended or irritated; sweeps contents into LI, resulting in diarrhea
ileocecal sphincter
joins ileum of SI to cecum of LI & helps regulate flow of chyme
parts of large intestine (4)
- cecum
- colon
- rectum
- anal canal
cecum
- pouch, forms beginning of LI
- appendix is attached here
colon
ascending, transverse, descending, & sigmoid
rectum
extends from sigmoid to anal canal
anal canal
- last 2.5-4 cm of LI; opens to outside as anus
- internal & external sphincter guard anus
internal sphincter
involuntary
external sphincter
voluntary
haustra
“bubbles” on LI; bands that create pouches, help form feces
taeniae coli
longitudinal muscle that runs down entire length of colon
how many layers does the LI wall have?
4
what does the LI wall NOT have?
villi & place circulares
functions of large intestine (5)
- little to no digestive
- contains goblet cells, which secrete mucus
- absorbs water & electrolytes
- houses intestinal flora, which break down contents such as cellulose, vitamin K & B12, thiamine
- forms feces
vitamin K
important in blood clotting
movements of large intestine
- slower & less frequent than SI
- mixing & peristalsis
- peristaltic waves produce mass movements, which usually follow a meal
- defecation reflex relaxes internal anal sphincter & then external
feces composition (4)
- water
- mucus
- bacteria
- bile pigments
odor components of feces (5)
- phenol
- ammonia
- hydrogen sulfide
- indole
- skatole
