Digestive System Flashcards
saliva contains
salivary amylase
lingual lipase
antimicrobial agents
lysozyme
bicarbonate ions
mucin
salivary amylase function
begins chemical breakdown of polysaccharides into simple sugars
lingual lipase function
begins the breakdown of fats
lysozyme function
enzyme that works together with immunoglobulin A to break down cell walls of many bacteria
bicarbonate ion function
help saliva maintain pH that is optimal for salivary enzymes as well as other ions
mucin function
protein that helps to form gel-like coating that lubricates the bolus of food
esophagus is
25 cm tube extending from the pharynx to the stomach
esophagus function
passageway for food
esophagus secretes
mucus to aid in the transport of food
esophagus walls
4
mucosa
submucosa
muscular externa
adventitia
esophagus upper third composed of
skeletal muscle and is under voluntary control
esophagus lower third is
entirely smooth muscle
esophageal sphincters
one at superior end of esophagus and one at lower end of esophagus
what is the stomach
a muscular organ that can stretch to accommodate a high volume of food
what is the primary role of the stomach
the storage and mechanical break down of food
inner surface of the stomach
Mucosa- is folded into a series of ridges called rugae
rugae
series of ridges in the stomach. allow the stomach to expand as it fills with food
food in stomach
turns into chyme
pyloric sphincter
regulates passage of chyme into the small intestine
mucosa of stomach contains
gastric glands which open into numerous gastric pits
what are the 4 types of cells in gastric glands
mucous cells
parietal cells
chief cells
endocrine cells
endocrine cell function
also known as G-cellls. release hormones such as gastrin into the blood and do not contribute to gastric juices
parietal cell function
exocrine gland. secrete intrinsic factor and release hydrochloric acid
intrinsic factor
exocrine gland. required for absorption of vitamin B12 in small intestine
hydrochloric acid (HCl) function in stomach
lowers the pH of gastric juice to 1-3
why is an acidic environment required
for the activation of pepsinogen
chief cells function
secrete pepsinogen and gastric lipase
pepsin function
digestive enzyme that breaks down proteins into smaller peptide chains
mucous cell function
secrete bicarbonate-containing mucous to protect the stomach from the acidity and digestive enzymes
where does most fat and protein digestion occur
in small intestine
where are g cells located
(endocrine cells) at the lowest end of the rugae (tip)
where are mucous cells located
lien most of the mucosa
chief and parietal cell location
along the mucosa
layer of muscularis externa
longitudinal layer
circular layer
oblique layer- not seen in the rest of the alimentary canal
stomach location
left superior region of the abdomen
gastroesophageal sphincter
found at the junction between the esophagus and the stomach.
helps to prevent acid reflux of acidic contents
4 main parts of stomach
cardiac region
fundus
body
pylorus
cardiac region function
area where foo dis emptied into the stomach
fundus function
most superior region of the stomach
body function
largest, most centrakregion of the stomach. curves towards the right to form a “J” with the lesser curvature and the greater curvature.
pylorus function
funnel shaped region in the stomach.
wider end- pyloric antrum
narrow end- pyloric canal
pyloric sphincter
value that regulates the release of small amounts of chyme into the small intestine.
liver function
*acts as accessory organ by performing many functions such as the production of bile, nutrient metabolism, and detoxification.
*regulates blood glucose concentration.
*breaks down exogenous compounds such as drugs and alcohol.
how many lobes does the liver have
4
what is the primary digestive function of the liver
synthesis of bile
bile description
yellow-green solution that includes:
bile salts
pigments (mainly BILIRUBIN from the breakdown hemoglobin)
cholesterol
electrolytes
bile function in digestive system
bile salts are what plays a role in digestion.
Bile salts mechanically by emulsifying fats into smaller globules called micelles.
Enhances the absorption of fat-soluble vitamins A, D, E, and K
micelles function
can be acted in by lipases in the small intestine
where is bile stored
stored and concentrated in the gallbladder
liver cell function
synthesize bile salts from cholesterol
what causes bile to be squeezed out of the bile duct
hormone called CCK (chloecystokinin) signals gallbladder to contract and bile to be squeezed into common bile duct when food enters the small intestine
where does the bile duct join with the pancreatic duct
at the hepatopancreatic ampulla or ampula of vater.
how does bile spill into the the duodenum
via duodenal papilla.
it can also flow directly from the liver to dueodenum
what is ammonia converted into in the liver
urea and excreted by the kidneys
what happens in cases of prolonged fasting
the liver can produce glucose from non-carbohydrate sources like proteins and fats.
where does blood from digestive tract enter the liver
through the hepatic portal vein
what happens if blood sugar is too high
liver polymerizes glucose to form glycogen in process called glycogenisis
what happens in liver if blood sugar is too low
liver cells break down stored glycogen and release glucose monomers in the process called glycogenolysis
what is glysogenisis
when liver polymerizes glucose to form glycogen
what is glycogenolysis
when liver cells breakdown stored glycogen and release glucose monomers
what is gluconeogenesis
the process of the liver producing glucose from non-carbohydrate sources like proteins and fats
pepsin function
begins the breakdown of proteins
cholinesterase function
begins the breakdown of acetylcholine
what would happen if the parietal cells were unable to secrete substances into the gastric gland
parietal cells would not secrete corrosive HCl, pepsinogen could not be converted to pepsin, pepsin would not form, dietary proteins would remain undigested.
enteroendocrine cells produce
gastrin
what is gastrin
a local hormone that is vital for regulating digestive activities in the stomach
what does gastrin do
stimulates the release of gastric juices and emptying of the stomach
chief cell function
responsible for producing inactive protein-digusting enzymes called pepsinogens
structural components of lipids
glycerol and fatty acids
how does pepsin aid in the digestion of proteins
by severing the peptide bonds that join amino acids into long chains
