The Gallbladder: 9-06-13 (BIO181) Flashcards
- pear shaped muscular sac
- located in indentation of liver’s right lobe
- stores and concentrates bile prior to excretion into the small intestine
- releases bile into the duodenum
the gallbladder
regions of the gallbladder
fundus
body
neck
extends from gallbladder until it joins with the common hepatic duct and forms the common bile duct
cystic duct
full gallbladder contains ___-___ mL of bile
40-70
- the composition of bile is gradually changed in the gallbladder
- water is absorbed
- bile salts and solutes become concentrated
bile modification
regulatory mechanisms center around ___ where acids are neutralized and enzymes added
duodenum
___ and ___ mechanisms coordinate activities of digestive glands
neural; hormonal
- motor neurons synapse onto the digestive tract and release neurotransmitters
- prepare digestive tract for activity
- inhibit gastrointestinal activity
- coordinate movement of materials along the digestive tract
neural mechanisms
-intestinal tract secrets peptide __ that work at several regions of digestive tract and in the accessory glandular organs
hormones
___ ____ cells produce several hormones that work to coordinate digestive functions
duodenal enteroendocrine
- is released when chyme enters the duodenum
- increases secretion of bile and buffers by the liver ans pancreas
secretin
- secreted in duodenum when chyme contains lipids and partially digested proteins
- accelerates pancreatic production and secretion of digestive enzymes
- relaxes hepatopancreatic sphincter and gallbladder to eject bile and pancreatic juice into duodenum
Cholecystokinin (CCK)
- is secreted when fats and carbohydrates enter small intestine
- slows things down
Gastric inhibitory peptide (GIP)
- stimulates secretion of intestinal glands
- dilates regional capillaries
- inhibits acid production in stomach
vasoactive intestinal peptide (VIP)
- secreted by g cells in duodenum when incompletely digested proteins are exposed
- promotes stomach mobility
- stimulates the production of acids and enzymes
gastrin
- released when chyme enters the small intestine
- stimulates mucin production by submucosal glands of duodenum
enterocrinin
it takes about _ ____ for materials to pass from the duodenum to end of ileum
5 hours
- Movements of the ___ increases absorptive effectiveness
- stir and mix intestinal contents
- constantly change environment around epithelial cells
mucosa
- horseshoe shaped
- extends from end of ileum to anus
- lies inferior to stomach and liver
- frames the small intestine
the large intestine
- pouch like first portion of the large intestine
- receives material arriving from the ileum
- stores material and begins compaction
cecum
- a slender, hollow appendage that is attached to the cecum
- dominated by lymphoid nodules
- immune response
appendix
- has a larger diameter and thinner wall than small intestine
- walls form series of pouches (haustra) that permit expansion and elongation
colon
- forms the last 15cm (6in) of digestive tract
- expandable organ for temporary storage of feces
- movement of fecal material into it triggers urge to defecate
rectum
- the ___ ____ is the last portion of the rectum
- contains small logitudinal folds called anal columns
anal canal
- also called the anal orifice
- exit of anal canal
anus
- circular muscle layer of muscularis externa
- has smooth muscle cells that are INVOLUNTARY
internal anal sphincter
- encircles distal portion of anal canal
- a ring of skeletal muscle fibers that are VOLUNTARY
external anal sphincter
-less than __% of nutrient absorption occurs in the large intestine
10
bile salts are reabsorbed in the ___ and then transported back to the liver for secretion into bile
cecum
- required by liver for synthesizing clotting factors
- fat soluble
vitamin K
- important in glucose metabolism (for energy)
- water soluble
biotin
- required in manufacture of steroid hormones and some neurotransmitters
- water soluble
B5
-reabsorption of water
-compaction of intestinal contents into feces
-storage of fecal material prior to deification
all happen in the __ ___.
large intestine
-bacteria in the ___ ___ convert biliruben to substances that can ultimately be excreted
large intestine
bacteria break down ___ in feces and generate ammonia, nitrogen compounds, and hydrogen sulfide
peptides
bacteria feed on indigestible ____ to produce intestinal gas
carbohydrates
___ and ___ reflexes move material into the cecum while you eat
gastroileal; gastroenteric
movement from the cecum to transverse colon is very ___
slow
waves of muscular contractions move material along length of the entire colon
peristaltic waves
mix contents of adjacent haustra
segmentation
- powerful peristaltic contractions that occur a few times each day
- movement form transverse colon through rest of large intestine
- ultimately force feces into the rectum
mass movement
distension of the rectal wall triggers defecation reflex, which is ____
involuntary
-triggers peristaltic contractions in rectum
short reflex
stimulates mass movements
long reflex
rectal stretch receptors also trigger two reflexes important to __ control of defication
voluntary
- mediated by parasympathetic innervation in pelvic nerves
- causes relaxation of internal anal sphincter
a long reflex
- motor commands carried by puudendal nerves
- stimulates contraction of external anal sphincter (skeletal muscle)
a somatic reflex
___, ___ and ___ are large organic molecules that must be digested before absorption can occur
carbohydrates, protiens, and lipids
__,__, and ___ can be absorbed without digestion or processing
water, electrolytes, and vitamins
salivary glands, tongue, stomach, and the pancreas secrete ___ ___ taht are crucial in digestion
digestive enzymes
break down simple sugars
carbohydrases
break down amino acids
proteases
seperate fatty acids from glycerides
lipases
brush boarder enzymes break nucleotides into
sugars, phosphates, nitrogenous bases
only ___ can be absorbed into the bloodstream
monosaccharides
____ and ___ have to be broken down into _____ so they can be absorbed
disaccharides and trisaccharides; monosaccharides
carbohydrate digestion states in the ___ via salivary amylase
mouth
carb digestion continues in the ___ ___ via pancreatic amylase and continues the digestion of polysaccharides into disaccharides
small intestine
digestion of carbs into ____ is completed by brush border enzymes in the small intestine
monosacchardies
once carbs have been digested to monosaccharides, they can be absorbed by ___ cells lining intestinal villi
epithelial
amino acids, dipeptides, and tripeptides are all products of ___ ___.
protein digestion
protiens are digested by
proteases
protein digestion begins in the
stomach
enzyme that digests protein
pepsin
pepsinogen is converted to the active pepsin by the acid in the ___
stomach
___ cells secrete inactive pepsinogen
chief
__ cells secrete HCl
parietal
the enzymes ___, ___, and ___ are all involved in protein digestion in the small intestine along with brush border enzymes
trypsin; chymotrypsin; carbozypeptidase
___ secretes typsinogen, chymotrypsinogen and procatboxypeptidase
pancreas
___ ___ enzymes convert trypsinogen to trypsin
brush border
trypsin then activates ___ and ___
chymotrypsin; carboxypepidase
__ and __ break up amino acids
trypsin; chymotrypsin
___ and __ __ ___ complete protein digestion
carboxypepidase; brush border enzymes
once protiens are digested, __ ___ are actively transported into intestinal cells, where they are diffused into the blood
amino acids
lipids are not __ soluble
water
lipid form huge __ __ on the surface of chyme
fat droplets
enzymes of digestion
lipases
lipases can only act on molecules near __ of fat droplet
edge
____ ____ increase surface area of droplets by breaking large fat droplets into smaller ones that is called ____.
bile salts; emulsificaiton
lipid digestion stats in the mouth with ___ ___
lingual lipase
lipid digestion continues in the stomach with lingual lipase and ____ ____
gastric lipase
___ ___ takes over in the small intestine, but cannot complete digestion
pancreatic lipase
bile salts act on these droplets in the ___
duodenum
bile salts are ___ molecules
amphipathic
bile salts have one ___ side and one ___ side
polar; non-polar
when bile salts come into contact with a fat globule, their _____ side faces toward the fat droplet
hydrophobic
monoglycerides and fatty acids are then secreted into the interstitial fluid via ___. then enters the lymphatic system via ___. and then carried to the blood stream
exocytosis; lacteals
2 liters of water are taken into the GI tract and another __ from digestive organ secretions to be reabsorbed
7
___ cannot actively absorb or secrete water
cells
- vitamin A,D,E,K
- absorbed by epithelial cells in parallel with lipids
fat soluble vitamins
- especially B12
- absorbed via active transport or facilitated diffusion
water soluble vitamins
