Digestive Pt 2 Flashcards
Be prepared to label the different regions and anatomical features of the stomach
what is the term for a bolus of food after it is undergoing digestion in the stomach
chyme: liquified slurry of food
modified tunics
- muscularis has an added internal, oblique layer to allow increased mixing and churning
secretory cells
- mucus neck cells
- parietal cells
- chief cells
- enteroendocrine cells
mucus neck cells
produce thin, soluble mucus
parietal cells
produce HCI and secrete intrinsic factor (required to absorb B12)
chief cells
secrete pepsinogen and lipases
enteroendocrine cells
secrete chemical messengers into the lamina propria as well as gastrin
mucosal barrier
produced to protect the stomach
- thick coating of bicarbonate-rich mucus
- tight junction between epithelial cells
- quickly replacement of damaged mucosal cells by stem cells
peptic/gastric ulcers
erosion of the stomach wall - cause gnawing, epigastric pain
- pain appears 1-3 hrs after eating and resolves with eating again
- ulcers are linked to peritonitis and H. pylori
propulsion
peristalsis
mechanical breakdown
churning
digestion
breakdown of proteins by HCI and pepsin (rennin in infants)
absorption
only lipid-soluble substances - alcohol and aspirin
secretion of intrinsic factor
essential for B12 absorption and maturation of RBCs
which branch of the autonomic nervous system increases gastric secretions
- stimulation by vagus nerve
- sympathetic Nervous system decreases secretion
gastrin
- stimulate secretion of HCI by the stomach
3 phases of the gastric secretions
- cephalic/reflex phase
- gastric phase
- Intestinal phase
cephalic/reflex phase
triggered by smell, taste, and sight; act via the vagus nerve
gastric phase
triggered by stretch receptors and/or chemical stimuli - partially digested protein, caffeine, rising pH
- activates G cells to secrete gastrin
- gastrin initiates release of HCI
- low pH or firing of the SNS will inhibit gastrin
Intestinal phase
partially digested food enters the SI and triggers the release of intestinal gastrin
- distention of the SI and/or presence of acidic, fatty, or hypertonic chyme will inhibit gastric secretions - protects the SI from excess acidity and being overwhelmed
enterogastric reflex
short reflexes by the enteric nervous system and long reflexes by the sympathetic and vagus nerves inhibit acid secretion
enterogastrones
duodenal enteroendocrine cells release secretin or cholecystokinin to inhibit gastric secretions
liver
production of bile
bile
fast emulsifier
- produces 900mL a day
- functions: processes Bloodborne nutrients, stores fat-soluble vitamins, and performs detoxification
be prepared to label the lobes of the liver and the two major ligaments
lobes of liver
right, left, caudate, and quadrate
falciform ligaments
seperates the larger right lobe from the smaller left lobe and suspends the liver from the diaphragm and anterior abdominal wall
round ligament/ligamentum teres
remnant of fetal umbilical vein; runs along the free edge of the falciform ligament
what is the liver’s functional unit
liver lobules
hepatocytes
liver cells
portal triad
located in each corner of the lobule
- hepatic artery
- hepatic portal vein
- bile duct
hepatic artery
supplies oxygen to the liver
hepatic portal vein
brings nutrient-rich blood from the intestines
bile duct
receives bile from bile canaliculi
stellate/hepatic macrophages
exist in liver sinusoids to remove debris and old RBCs
bile salts
cholesterol derivatives that function in fat elmusification/absorption
bilirubin
yellow pigment formed from heme during the breakdown of RBCs
- metabolized by bacteria in the SI to stercobilin which gives feces a brown color
what portion of the SI reabsorbs bile salts for recycling
enterohepatic circulation
pathway for bile
- right and left hepatic ducts
- ducts fuse into common hepatic duct
- fuse with cystic duct
- common bile duct it combination of cystic duct and common hepatic duct
hepatitis
inflammation of liver - viral infection, can be caused by alcohol, drug toxicity, or wild mushrooms
- transmitted through food, remainder via blood
cirrhosis
progressive, chronic inflammation from hepatitis or alcoholism
- liver activity is depressed
- liver becomes fatty and fibrous
- portal hypertension
portal hypertension
flow of blood through the liver is obstructed
gall bladder
- thin walled, muscular sac on the inferior surface of the liver
- appears green when filled with bile
- functions to store and concentrate bile
gallstones
obstruct the flow of bile from the gallbladder
obstructive jaundice
blockage causes bile salts and pigments to build up in blood
exocrine function
production of pancreatic juice - contains enzymes needed to break down all categories of foodstuffs
endocrine function
secretion of insulin and glucagon by pancreatic islet cells
pancreatic juice
watery, alkaline solution used to neutralize acidic chyme from the stomach
- contains electrolytes, primarily HCO3
- digestive enzymes
is pancreatic juice acidic or basic
basic
digestive enzymes
- proteases
- amylase
- lipase
- nucleases
proteases
for proteins; secreted in inactive form to prevent self-digestion
amylase
for carbohydrates
lipase
for lipids
nucleases
for nucleic acids
Be prepared to label the main pancreatic duct, the hepatopancreatic ampulla, and the major duodenal papilla. (slide 23)
