Outcome 11 - Gastrointestinal System Flashcards
what are the two groups the digestive system is organized into?
1) alimentary canal organs
2) accessory digestive organs
what are considered alimentary canal organs?
- mouth
- pharynx
- esophagus
- stomach
- small intestines
- large intestines
- anus
what are accessory digestive organs?
- teeth
- tongue
- liver
- gallbladder
- pancreas
- salivary glands
what is the definition for “alimentary canals organs”?
continuous tube that extends from mouth to anus
*have direct contact with food and liquids
what is the definition of “accessory digestive organs”?
organs that aid in the physical breakdown or chemical breakdown of food
what are the 6 digestive system processes?
1) ingestion
2) secretion
3) mixing and propulsion
4) digestion
5) absorption
6) defecation
what do GI cells secrete?
- ~7L of water
- acid, buffers
- enzymes
what is “mixing and propulsion”?
alternation between contractions and relaxations of the GI smooth muscles
what is “GI motility”?
mixing food with secretions and propelling them to the anus
what are examples of mechanical digestion?
- use of teeth to breakdown food
- stomach and small intestine churning and mixing it with digestive enzymes
what are examples of chemical digestion?
- digestive enzymes from mouth, stomach, pancreas, small intestine to aid in catabolism
what types of molecules are split by hydrolysis?
- cho, lipid, protein, and nucleic acid
what can be absorbed without chemical digestion?
- vitamins, ions, cholesterol and water
what is absorption?
- ingested and secreted fluids and ions enter the epithelial cells lining the lumen of the GI
- from cells lining gi to passing into the blood or lymph for circulation to the body
what is defecation?
the excretion of indigestible things, waste, bacteria, sloughed cells and materials that aren’t absorbed by feces
what tissues make up the walls of alimentary canals?
- mucosa
- submucosa
- muscular layer
- serosa
what is the mucosa?
it is epithelial tissue that comes into contact with food
- layer will change depending on where we are in the tube (i.e. oropharynx, laryngopharynx)
what are the three components of the mucosa?
- epithelium
- lamina propria
- muscular mucosae
describe the muscular mucosae?
- layer that gives the ridges throughout the whole lining of the mucosa
- layer that creates the contraction
what two types of muscles that make up the muscular layer of the alimentary canal?
- circular muscles
- longitudinal muscles
what is the difference between the circular muscles and longitudinal muscles?
circular = muscles/fibers are running around the circumference of the circle
long - runs parallel with the tube
what is the serosa made of?
areolar connective tissue and epithelium
* continuous of the layer of the peritoneum which lines the abdominal organs
what is the visceral peritoneum?
the serosa layer of the GI tract
what is the parietal peritoneum?
it lines the abdominopelvic cavity
where do you find the peritoneal cavity?
between the visceral and parietal peritoneum
what is found in the peritoneal cavity?
- peritoneal fluid
or - excess fluid called ascites
_____ is the largest serous membrane.
peritoneum
what are some characteristics of the peritoneum?
- have large folds that weaves between organs
- binds organs into abdominal cavity
what is the retroperitoneal?
having organs that lie on the posterior abdominal wall and have only their anterior surfaces covered by the peritoneum
- behind the peritoneal
- outside of the peritoneum protecting them
what are some retroperitoneal organs?
- kidneys, ascending and descending colon, duodenum and pancreas
what are the 5 major folds of the peritoneum?
1) greater omentum
2) falciform ligament
3) lesser omentum
4) mesentery
5) mesocolon
where do you find the greater omentum?
draping over the transverse colon and the coils of the small intestines
which of the 5 folds are the largest?
the greater omentum
where do you find the falciform ligament?
- attaching the LIVER to the ANTERIOR wall of the ABDOMEN and DIAPHRAGM
where do you find the lesser omentum?
it allows for the suspension of the stomach and duodenum from liver
where do you find the mesentery?
it binds the small intestines to the posterior wall of the abdomen
- extension from the posterior abdominal wall
- wraps around the small intestine and then returns to its origin to form a double layered structure
where do you find the mesocolon?
- binding the large intestines to the posterior wall
- carries the blood and lymph vessels to and from the intestine
_______ + _______ hold the intestine loosely in place so muscle contractions to occur.
mesentery and mesocolon
what is peristalsis?
coordinated contraction and relaxation of the circular and longitudinal muscular layers that pushes the bolus onward
what are the different salivary glands?
- parotid gland
- submandibular gland
- sublingual gland
what are the two enzymes we talked about in class that is part of the saliva?
salivary amylase
lingual lipase
what does the salivary amylase do? lingual lipase?
salivary amylase - starts the breakdown of carbohydrates
lingual lipase - breakdown fats
what is important of the lingual lipase?
it isn’t activated till it hits acidic juices of the stomach
what are the salivary glands found in the oral mucosa?
- 2x parotid glands
- 2x submandibular glands
- 2x sublingual glands
what is the composition of saliva?
99.5% water + 0.5% solutes (Na+, K+, Cl-, HCO3-, PO4-, gases, organic substances, urea, uric acid, and lysozymes)
there is no mechanical breakdown or absorption occurring in the esophagus. t/f
true
what is the structure of the esophagus?
it is a collapsible muscular tube
where does the esophagus enter the diaphragm?
- esophageal hiatus
what are the 4 layers of the esophagus?
- mucosa
- submucosa
- muscular layer
- adventitia
what is the adventitia?
the superficial layer of the esophagus that attaches it to its surrounding structures
- replaces the peritoneum as there is no serosa
the first 2/3 of the esophagus is _____ muscle.
last 1/3 of the esophagus is _____ muscle.
2/3 = skeletal muscle (voluntary)
1/3 = smooth muscle (involuntary)
the muscular layer folds into two sphincters called?
- upper esophageal sphincter
- lower esophageal sphincter
what is another word for the upper esophageal sphincter?
pharyngoesophageal sphincter
what is another word for the lower esophageal sphincter?
gastroesophageal sphincter
what part of the digestive system takes place in deglutition?
mouth, esophagus, pharynx
which is the most distensible portion of the GI?
the stomach
what is occurring in the stomach?
- starch digestion continues
- triglyceride and protein digestion starts
- semisolid bolus is converted to liquid
- some substances are absorbed
what is the stomach?
- enlargement of the GI tract that connects the esophagus to duodenum
- is the mixing chamber and storage reservoir
what are the 4 major regions of the stomach?
- cardia
- fundus
- body
- pyloric part
what are the 3 parts that make up the pyloric part of the stomach?
- pyloric antrum
- pyloric canal
- pylorus
what is the cardia?
it is the region that surrounds the superior opening of the stomach
what is the fundus?
rounded portion superior to cardia
what is the pyloric antrum?
part of the pyloric part that connects to the body
what is the pylorus?
the part that connects the stomach to the duodenum
what are rugae?
large folds in the mucosa; gastric folds
where do you find the pyloric sphincter?
between the stomach and duodenum
what is the lesser curvature?
it is the concave medial border of the stomach
what is the greater curvature?
the convex lateral border of the stomach
in the stomach, what are the modifications to the mucosa?
it is the layer of simple columnar epithelial cells (surface mucous cells)
in the stomach, epithelial cells extend down the lamina proprietor to form what?
gastric glands (exo glands)
what do gastric glands open into?
gastric pits which empty into the lumen
in the stomach, how many layers make up the muscular layer?
3 layers of muscle (most visceral is oblique)
what are secreted by the parietal cells?
- HCl acid and intrinsic factors
what does the HCl acid do?
- converts pepsinogen to pepsin
- kills microbes and denatures proteins
- deactivates amylase and activates lingual lipase (breakdown triglycerides to fa and diglycerides)
what do intrinsic factors do?
it is important for b12 absorption
what do chief cells secrete?
pepsinogen and gastric lipase
what does pepsinogen do?
denatures proteins
what does gastric lipase do?
it breaks down fats
*not as affective in very acidic pH
what do g cells secrete?
the hormone gastrin
what does gastrin do?
it stimulates parietal and chief cells
constricts lower esophageal sphincters and relaxation (ish) of pyloric and ileocecal sphincter
what is chyme?
a soupy, liquid mixture that is created by mechanical and chemical digestion in the stomach
peristaltic waves increase in strength as they reach ______.
antrum (part of the pyloric part of the stomach)
what is gastric emptying?
when the peristaltic wave causes ~3 ml of food into the small intestine through the pyloric sphincter
what does pepsin do?
severs peptide bonds between amino acids
within _____ hours after eating, the stomach should have emptied contents into duodenum.
2-4 hours
what empties the slowest in the stomach? the fastest?
slowest - proteins and fats
fastest - carbs
where is the pancreas found?
posterior to the greater curvature of the stomach
pancreas has a head, neck and body and tail. t/f
true
where do you find the head of the pancreas?
near the curve of the duodenum
what are the two ducts that connects the pancreas to the duodenum?
- pancreatic duct
- accessory duct
what is another name for the pancreatic duct?
duct of wirsung
what is another name for the accessory duct?
duct of Santorini
what is the pancreatic duct called?
duct of Wirsung
what ducts join to form the ampulla of vater?
common bile duct + pancreatic duct
what is the sphincter of oddi?
sphincter at the end of the hepatopancreatic ampulla
- leads into the small intestine
what are some examples of enzymes in pancreatic juices?
pancreatic amylase, pancreatic lipase, nuclease and protein digestion
what does pancreatic amylase digest?
starches
what does pancreatic lipase digest?
triglycerides (fats)
what separates the lobes of the liver?
falciform ligament
what are hepatocytes?
major functional cells in the liver
what do the hepatocytes form?
hepatic laminae
what are bile canaliculi?
small ducts that collect bile that’s secreted by hepatocytes
what forms the portal triad?
bile duct + branch of hepatic artery + branch of hepatic PORTAL vein
what area hepatic sinusoids?
porous blood capillaries
the liver receives oxygenated blood from?
hepatic arteries
the liver receives deoxygenated blood from??
hepatic portal veins
what are Kupffer cells?
RES cells
- destroys worn out WBCs and RBCs, bacteria and foreign matter
what is the flow of blood in the liver?
sinusoids –> central vein –> hepatic vein
25% of blood to liver is through the _______
75% of blood to liver is through the _______
25% - hepatic artery
75% - hepatic portal vein
what is the blood supply to the liver?
1) nutrient-rich deoxygenated blood from hepatic portal vein + oxygenate blood from hepatic artery
2) liver sinusoids
3) central vein
4) hepatic vein
5) inferior vena cava
6) right atrium of heart
what are the functions of the liver?
- secrete bile (~1L/day)
- CHO metabolism (blood glucose level)
- lipid metabolism
- protein metabolism
- processing of drugs and hormones
- excretion of bilirubin
- synthesis of bile salts
- storage
- phagocytosis
- activation of vit d
what ducts converge to form the common hepatic duct?
right and left hepatic duct
what ducts converge to form the common bile duct?
common hepatic duct + cystic duct
what ducts converge to form the hepatopancreatic ampulla?
common bile duct + pancreatic duct
what is the flow of bile?
hepatocytes –> bile canaliculi –> bile ductules –> branch of bile duct (portal triad) –> all bile ducts from portal triads –> r and l hepatic ducts –> common hepatic duct + cystic duct –> common bile duct + pancreatic duct –> hepatopancreatic ampulla –> sphincter of oddi –> small intestine
what is the gallbladder fossa?
depression on the posterior surface of the liver where gallbladders sit
what are the three parts of gallbladders?
- fundus - broad base of the ‘pear’
- body
- neck
what is the function of the gallbladder?
to store and concentrate bile
when is bile expelled?
when the smooth muscles of the walls contract
flow of bile is _____ (same/oppo) direction to flow of blood.
opposite
what is the bile composed of?
- H2O
- bile salts
- cholesterol
- bile pigments
- ions
- phospholipid lecithin
what are bile salts for?
emulsification and absorption of fats
(increases the surface area of fats)
what is lecithin for?
needed and important for the breakdown of cholesterol
how do you get gall stones?
when not enough bile salts and lecithins are produced.
what is the primary bile pigment?
bilirubin
what are the three treatments for gallstones?
- drugs
- lithotripsy
- surgery - cholecystectomy
What does cholecystokinin do?
- stimulates the contraction = release of bile from gallbladder
- relaxes the sphincter of oddi
- increases bowel motility
What is the contraction of muscularis that results in waves of movement of food through the small intestine known as?
MMC (migrating motility complex)
What is the final coordinated muscle contraction in the transverse colon called?
mass peristalsis
what is the tubing order?
Cecum –> ascending colon* –> hepatic flexure –> transverse colon –> splenic flexure –> descending colon* –> sigmoid colon –> rectum –> anal canal –> anus
what stimulates the release of cck?
presence of fatty acids in chyme
what are the three parts of the small intestine?
- duodenum
- jejunum
- ileum
ileum joins the large intestine through ______.
ileocecal sphincter
which is the shortest portion of the small intestine?
duodenum
what are the 4 types of cells that make up the small intestines?
- absorptive cell
- goblet cell
- enteroendocrine
- paneth cell
what is the function of goblet cells?
secretion of mucus
what is the function of enteroendocrine cells?
secretion of hormones
what do intestinal glands do?
secrete intestinal juice
what layer isn’t found in the duodenum but are in the rest of the small intestines?
serosa
the submucosa in the duodenum has duodenal glands that secrete what?
alkaline mucus that neutralize acidic chyme
what are the 3 characteristics that allow for an increase in surface area in the small intestine.
- circular folds of mucosa and submucosa
- villi
- microvilli (with brush border enzymes)
what are the two types of mechanical digestion that occurs in the small intestine?
- segmentations
- migrating motility complex (MMC)
what is segmentation?
NOT peristalsis - coordinated constriction that causes bulging to increase contact with intestinal wall for absorption
what is mmc?
what peristalsis is called in the small intestine
occurs after segmentation stops
what is mmc?
what peristalsis is called in the small intestine
occurs after segmentation stops
what hormone causes the relaxation of the ileocecal sphincter?
gastrin
what are haustras?
pouches that occur due to bunches of longitudinal muscle
what amount of water is reabsorbed in the large intestine?
10%
what part of the large intestine attaches to the abdominal posterior wall?
mesocolon
where do you find the appendix?
hanging from the cecum
where do you find the cecum?
inferior to ileocecal sphincter + merging with the colon
what are the four parts the colon is divided into?
- ascending
- transverse
- descending
- sigmoid
what two parts of the colon is retroperitoneal?
ascending and descending colon
what are 2 flexures found in the large intestine?
- right colic (hepatic) flexure
- left colic (splenic) flexure
what are the two sphincters that keep the anus closed?
- internal anal sphincter
- external anal sphincter
what occurs in the large intestine after a meal?
it stimulates the gastroileal reflex which speeds up peristalsis to empty contents of the small intestine
what is the one movement of the large intestine called?
haustral churning
what is the gastrocolic reflex?
when the stomach is full, it results in the contraction of the transverse colon for the movement of feces to rectum
what does chemical digestion in the large intestine?
bacteria
what is bilirubin converted into in the large intestine?
stercobilin
mass peristalsis occurs how many times a day?
~3-4x/day
after ____ hours, chyme solidified due to water absorption and becomes ______.
3-10 hours, feces
what initiates the defecation reflex?
the distention of the rectal wall
what type of muscles are the internal sphincter? external?
internal - smooth (involuntary)
external - skeletal (voluntary)
