Digestive System Flashcards
what is a GI tract?
gastrointestinal tract (start to finish of digestive tract)
what are accessory structures?
extra parts that help the tract process -ex. appendix, gall bladder
what are the six stages of digestion?
ingestion, secretion, mixing & propulsion, digestion, absorption, defecation
two ways of digestion?
chemical, mechanical
order of digestive tract
mouth to esophagus to stomach to liver to gallbladder to small intestine to cecum to appendix to large intestine to rectum and anus
formed by cheeks, hard and soft palate, lips, and tongue
mouth (oral cavity)
produces saliva
99.5% H2O and 0.5% solutes
salivary glands
what does saliva Do
lubricates and dissolves good (starts carb. digestion)
form floor of Oral cavity
tongue
what is the upper surface of the tongue covered in?
papillae
the dorsum of the tongue contains what producing glands?
lingual lipase (fat breaking enzyme)
food is mixed with saliva into a substance (process)
mastication
what substance is formed by mastication?
bolus
converts starches (polysaccharides) into disaccharides
salivary amylase
continuous movement of bolus from the mouth to the stomach
deglutition
collapsible tube that lies behind the trachea and connects the mouth to the stomach
esophagus
a progression of coordinated contractions and relaxations which pushed the bolus onward
peristalsis
J-shaped enlargement of the GI tract that begins at the bottom of the esophagus and ends at the pyloric sphincter
stomach
what are the functions of the stomach?
- serves as a mixing and holding area for food
- begins digestion of proteins
- continues digesting triglycerides
- converts bolus into chyme
mucosa lies in folds when the stomach is empty
rugae
what 3 gastric gland cells is gastric juice produced from?
chief cells, parietal cells, G cells
secrete pepsinogen and gastric lipase
chief cells
produce HCl and intrinsic factor
parietal cells
secrete the hormone gastrin
G cells
what is pepsinogen
molecule that breaks down protein (it’s in its inactive form) until HCl hits it and turns it active into pepsin
what is gastric lipase?
stomach fat digesting enzyme
what turns on G cells
presence of food causes the g cells to secrete gastrin, then that tells chief and parietal cells to start making their substance
clear colorless liquid consisting most of water salt sodium bicarbonate and enzymes
pancreatic juice
is pancreatic juice basic or acidic?
basic because of the sodium bicarbonate (pH 7.1-8.2)
what 3 things do pancreatic enzymes include?
pancreatic amylase
trypsin and chymotrypsin
pancreatic lipase
what does pancreatic amylase do?
digests carbs
what does trypsin and chymotrypsin do?
digests proteins
what does pancreatic lipase do?
digests fats
what are the protein digesting enzymes called when they are secreted in an inactive form?
trypsinogen and chymotrypsinogen
what enzyme activates trypsinogen and chymotrypsinogen which then activated the other forms?
enterokinase
largest gland in the body and second largest organ
liver
what does the liver do?
produces bile, stores glycogen, detoxifies body of substances, stores vitamins A B 12 D E K
is the bile in the stomach basic or acidic?
basic (pH of 7.6-8.6)
what can the liver do to protect against foreign invaders?
phagocytize aged red and white blood cells and some bacteria
-filters all blood from small intestine
what does the gall bladder do?
stores bile, concentrates bile until needed by small intestine
what is bile?
emulsified fat
what does chyme cause
secretion of CCO which in turn causes secretion of bile
how long is the duodenum?
10 inches long
what does the duodenum do?
receives chyme from the stomach through the pyloric sphincter
-pancreatic juice and bile enter
how long is the jejunum
3 feet long
how long is the ileum
6ft
where does the ileum end?
at the ileocecal valve
what does the ileocecal valve do?
prevents feces from going back into the small intestine
where does absorption in the small intestine occur?
villi and microvilli
what are villi and microvilli
hair like projections that increase surface area
what does mesentary do?
allows for free movement of each coil of the small intestine and helps it from getting tangled
small intestines role in digestion?
chyme is mixed with digestive juices and segmentation brings up the food into contact with the mucosa for absorption
- digestion of each nutrient is completed via enzyme secretions
- about 90% of all nutrient absorption occurs due to the length of time food spends there
what small intestinal hormone increases release of pancreatic juice
secretin
pancreatic juice is rich in?
bicarbonate ions
secretin does what?
raises the pH (decreases gastric secretions) to minimize gastric juice in body
what releases pancreatic juice rich in digestive enzymes and what stimulates this?
CCK
fats stimulate release
CCK inhibits?
stomach emptying
why does the small intestine have so many folds?
increases surface area further for digestion and absorption of nutrients
twisted coiled tube attached to the cecum. found in the lower right quadrant of the abdomen
appendix
what role does the appendix have?
no role at all
about 5ft long and 2.5inches in diameter. no folds or villi.
several vitamins r produced here as well as forming and expulsion of feces.
large intestine
what two types of cells does the large intestine include?
goblet(helps u poop) and absorptive cells (absorbs water)
what are the series of pouches in the large intestine called?
haustra (gives colon puckered appearance)
what three things does the small intestine have to digestive carbs
sucrase, lactase, maltase
what does the small intestine have to digest proteins
peptidases
