Digestive system Flashcards
how long is the GI tract, and what structures define it’s beginning and end?
23 feet long (in a live person)
mouth to anus
segmentation is primarily d/t
inner circular smooth muscle later of the GI tract
what is responsible for peristalsis
outer longitudinal
what type of cells absorb nutrients in the GI tract
simple columnar
four layers of the GI tact
mucosa, submucosa, muscularis, serosa
what type of cells makes up the mucosal layer?
simple columnar
what is the connective tissue that lies under the basement membrane of the GI tract?
lamina propria
what is the thin layer of smooth muscle in the mucosa of the GI tracts called
muscularis mucosa
what type of epithalial cells are in the mucosal layer in the mouth, pharynx, esophagus and anus
stratified squamous
the simple columnar cells found in the majority of the intestines contain intracellular…..
tight junctions
the cells of the intestines are replaced every…
5-7 days
what type of connective tissue is found in the lamina propria of the mucosa?
loose areolar
what are the vessels and nerves in the lamina propria are called:
MALTS: mucosal associated lymphoid tissue
submucosa consists of what type of connective tissue (and what do you find here)?
loose areolar.
arteries, veins, nerves and lymphatics
The part of the intrinsic nervous system of the GI tract (enteric nervous system) found in the submucosal layer is the:
submucosal plexus (Meissner’s plexus)
what is the function of the submucosal plexus? (Meissner’s plexus)
increase secretion from glands
the true muscular layer of the (majority of the) GI tract has what two layers:
a circular inner layer and an outer longitudinal layer
The portion of the enteric nervous system found in between the circular and longitudinal layers in the GI tracts is termed the
myenteric plexus (Auerbach's plexus) (it innervates both layers)
type of muscle tissue found in the tongue, oropharynx, larynx and 1/2 of the esophagus
skeletal muscle
the outer layer of connective tissue in the GI tract is called:
serosa
parasympathetic innervation of the GI tract is via the:
vagus nerve and spinal curve segments S2, 3 and 4
the effect of the vagus nerve and S2-4 is to…
increase the activity of the gut
the sympathetic innervation of the GI tract has what effect
decrease activity of GI tract
The serous membrane that is adherent to the coils of the intestine is :
the visceral peritoneum
The serous membrane that lines the abdominal cavity is the
parietal peritoneum
retro-peritoneal organs (6)
duodenum, pancreas, ascending colon, descending colon and kidneys.
what is the legit name for the fatty apron
greater omentum
what two places does the greater omentum origonate
the greater curvature of the stomach and the duodenum
what type of tissue is the greater momentum made of and what does it contain?
- adipose and lymphoid
- arteries, veins, nerves and lymphatics
what does the lesser omentum connect?
the lesser curvature of the stomach and the liver
what does the falciform ligament connect?
liver and the anterior abdominal wall
where does the coronary ligament lie?
superior to the liver and immediately below the diaphragm
mesentery anchors and connects the folds of what structure?
small intestine
what types of cells line the mouth?
stratified squamous
technical term for lips and gums
labia, gingiva
the connective tissue that anchors the lips and the tongue are called the …
fenulum
two arches of the palate:
Palatoglossal and palatopharyngeal
the space between the glossopharyngeal and palatopharyngeal arches
fauces
what structure is located on the fauces?
palatine tonsils
the fauces is the dividing line between the
oral cavity and the oropharynx
what are three lymphoid aggregates in the oropharynx?
palatine, pharyngeal (nasopharynx) and lingual tonsils
the 3 salivary glands
parotid, submandibular, sublingual glands
the largest salivary gland that produces the majority of the saliva (gland and what is it’s ducts)
parotid; stenson’s duct
where is the opening of Stenson’s duct?
2nd upper molar
what enzyme does saliva contain?
salivary amylase
what does salivary amylase degrade?
carbs and startches
other than enzymes, what else does saliva contain?
water, lysozymes, IgA, ions (Na, Cl, etc)
movement of the tongue is controlled by what CN?
hypoglossal (CN11)
what is the most abundant type of papilla on the tongue? What are they not used for?
filiform paplillae, detecting taste
what are the two types of papilla are used for detecting taste?
fungiform papilla, circumvallate
describe the placement/disbursement of the papilla on the tongue
filiform: all over
fungiform: scattered
circumvallate: posterio surface in a V shape
what are the six different tastes
sweet, sour, bitter, umami, metalic, salty
what do the extrinsic muscles of the tongue do?
movement of the tongue to shape food and move it posteriorly
what does the intrinsic muscle group of the tongue do?
alter the shape and size of the tongue for speech and swallowing
three major regions of the tooth
crown, neck and root
what are the upper teeth embedded in? the lower?
upper: maxilla
Lower: mandibular bone
teeth are what type of joint
gomphosis
what is the portion of the tooth that is uncovered by the gums called?
crown
what is the portion of the tooth embedded in the bone
root
what substance forms most of the tooth and is wicked hard
dentin
what is the hardest type of bone in the body which also makes up the most external part of the tooth?
enamel
the ligament that attaches the tooth to the bony socket and absorbs shock during chewing
periodontal ligament
bone-like substance covers the dentin and attaches the the root to the peridontal ligament?
cementum
what is the open space in the region of the crown?
pulp cavity
what is the passageway that connects the pulp cavity to the underlying connective tissue
root canal
what structures are found in both the root canal and the root cavity?
arteries, nerves, veins, lymphatics
how many primary or deciduous teeth are there?
20
primary teeth begin to erupt a what age? and at what rate
6 months; 2/month
ultimately all the primary teeth are lost by when?
6-12 yo
how many secondary/permanent teeth are there?
32
name the permanent teeth in a quadrant moving from medial to lateral
central incisor, lateral incisor, canine (cuspid), 1st and 2nd premolar; 1st, 2nd and 3rd molar (wisdom teeth)
what type of muscle is in the pharynx and what nerve innervates it?
skeletal muscle, vagus nerve
what type of epithelium is in the pharynx?
stratified squamous
what actions prevent the aspiration of food?
elevation of the palate, elevation of the larynx and closure of the epiglottis over the trachea
the esophagus (does/does not) play a role in digestion
does NOT!
the mucosal layer of the esophagus is lines by what type of cells?
stratified simple squamous
the thick part of the esophagus is called the:
muscularis
what type of muscle lines the upper 1/3 of the esophagus? the lower 1/3? and the middle?
upper 1/3: skeletal
middle: both
lower 1/3: smooth muscle (arranged in an inner circular and outer longitudinal pattern)
submucosa contains connective tissue that has what
vessels, nerves, lymphatics and glands that secrete mucus
the outer connective tissue layer of the esophagus is called the
adventitia
what opens during swallowing?
superior (upper) esophageal sphincter
what muscle causes the superior esophageal sphincter to open during swallowing?
cricopharyngeus muscle (elevates the larynx)
what structure of the esophagus is contracted during the resting state
lower esophageal sphincter
what is the clinical disorder associated with the lower esophageal dysfunction in which the sphincter remains relaxed and food ca reflux back into the esophagus?
gastroesophageal reflux disease (GERD
what can GERD lead to
ulceration, Barrett’s esophagus, esophageal cancer
what curvature of the stomach is larger and more inferiority located
greater curvature
what curvature of the stomach is smaller and more superior?
the lesser curvature
what structure is suspended from the greater curvature of the stomach?
greater omentum
what structure is attached to the lesser curvature?
lesser omentum
what is the region of the stomach that lies immediately below the esophagus?
cardia (cardiac region)
what is the domed portion of the stomach
fundus
what is the main portion of the stomach called?
body
what is the terminal portion of the stomach called? and what are its two parts?
pylorus, antrum and canal
what smooth muscle sphincter regulates the movement of food from the stomach into the duodenum?
pyloric sphincter
what type of cell lines the stomach?
simple columnar
what are the folds in the stomach called?
rugae
how many layers of tissue does the true muscularis layer of the stomach contain? What are they?
3; oblique, circular and longitudinal
what type of connective tissue is in the submucosa?
loose areolar
what is another name for the serosa?
visceral peritoneum
the microscopic anatomy of the stomach mucosa contains what structures?
gastric pits
what cells secrete mucus in the stomach?
goblet cells
what cells secrete HCL in the stomach?
parietal cells
what cell secretes intrinsic factor in the stomach?
parietal cell
what cell secretes pepsinogen?
cheif cell
what enteroendocrine cell secretes gastin?
g cell
where are the proton pumps located (what cell and where on the cell)
apical surface of the parietal cell
H is actively pumped into the stomach, which ion is pumped into the parietal cell in exchange?
K
What is H’s role in the lumen of the stomach?
it is made into HCl which activates/converts pepsinogen into pepsin which degrades proteins
what ion passes through the transport proteins on the basal surface of the parietal cell, which then lmove down the concentration gradient to the lumen of the stomach?
Cl
What gets exchanged for chloride through the transport proteins on the basal surface of the parietal cell?
bicarbonate, which then moves into the interstitial space and into the blood
what are the three things that will bind to receptors and increase the secretion of a parietal cell
gastrin, histamine and acetylcholine (PNS)
what are the two substances that inhibit the secretion of a parietal cell?
somatostatin and prostaglandins
what two functions do prostaglandins have in the stomach
inhibit secretion of the parietal cell and increase mucus production and blood flow when repair to the mucosa is needed
how much chyme is moved from the stomach to the duodenum at a time?
approx 2-3 teaspoons at a time
what happens to salivary amylases in the stomach?
they are deactivated
where are most nutrients absorbed?
in the small intestines
what gets absorbed in the stomach?
water, ions, short chain fatty acids and some drugs and alcohol
what response is triggered with the thought or smell of yummy food? what is this response mediated by and by what nerve does it act?
- cephalic phase of gastric secretion and motility
- hypothalamus
- vagus nerve
what phase is the smooth muscle of the stomach stretched and therefore contact?
gastric phase
what hormone is released in the gastric phase
gastrin
what hormones decrease the activity of the stomach once the chyme moves into the duodenum?
secretin and cholecystokinin
how long does gastric emptying take?
2-4 hours
in what order do the macromolecules move from fastest to slowest?
carbs, proteins, lipids
what are the three parts of the pancreas and where does it sit in the body?
head, body, tail
retroperitoneal
what are the majority of the cells in the pancreas? What do they secrete
acinar,
digestive enzymes
what are the endocrine and exocrine secretions of the pancreas?
endo: insulin and glucagon
exo: gastric enzymes
what are the structures that make the pancreas a endocrine gland?
islets of Langerhan
what two ducts empty into the duodenum at the same place?
the common bile duct
the main pancreatic duct (Wirsung)
what is the region called in which the common bile ducts and the main pancreatic duct (Wirsung) enter the duodenum? (what’s it’s common name and the sphincter that lives there)
hepatopancreatic ampulla (ampulla of Vater) sphincter of Oddi
is the pancreatic juice (and thus the small intestines) alkaline or acidic?
alkaline
what enzyme digests carbohydrates? lipids?
amylase
lipase
what four enzymes digest proteins?
trypsin, chumotrypsin, elastase, carboxypeptidase
what hormone is made in the small intestine that stimulates the production and secretion of pancreatic enzymes?
cholecystokinin
what hormone stimulates the production of alkaline pancreatic juice?
secretin
what do brush boarder enzymes do to trypsinogen?
activates it to trypsin; which can then activate other protein-digesting enzymes to their active state
what is the heaviest gland in the body?
the liver (3 lbs)
how is the liver held in place?
- attached to the anterior abd wall by the falciform ligament
- suspended from the diaphragm by the coronary ligament
how many (major) lobes does the liver have?
2
which lobe has two smaller lobes and what are they called?
left lobe, caudate and quadrate lobes
what is the remnant of the fetal vessel (shunt) that is on the underside of the liver?
ligamentum teres (remnant of ductus venosus)
which organ is a pear shaped sac that is suspended from the inferior side of the liver
gallbladder
what does the gallbladder store? What is absorbed through the gallbladder
bile, water and electrolytes are absorbed through the mucosa
what are the folds in the GB?
rugae
what is the name of the duct that comes off of the GB and is part of the billiary tree?
cystic duct
what are liver cells called?
hepatocytes
what are the blood vessels in the interior of the lobules of the liver called
sinusoids
what three vessels are in a portal triad?
portal arteriole, portal venule, bile duct
how many sides does a hepatocyte have and what % of the liver is hepatocytes?
5-12 sides, 80%
bile is made in the hepatocyte and released into what small biliary vessel?
caniliculi
bile travels out to the _____. What is this structure’s duct called?
portal triad, bile duct of portal triad
ultimately all of the billiary vessels from the right lobe of the liver merge and form the ….
right hepatic duct
ultimately all of the billiary vessels from the left lobe of the liver merge and form the ….
left hepatic duct
the left and right hepatic ducts merge to form the…
common hepatic duct
the common hepatic duct merges with the cystic duct from the GB to form the….
common bile duct
where does the common bile duct empty, and through what?
it empties into the duodenum at the ampulla of vater and the sphincter of Oddi
what does bile do?
emulsifies fat
how does bile emulsify fat?
breaking down large fat globules into smaller fat globules which can then be enzymatically degraded by pancreatic lipase
what are the macrophages in the liver called?
Kupffer cells
what is the hepatic acinus therory?
describes the zones created when the oval shaped area of two adjacent lobules are viewed. Inc portal triads and a line connecting the two central veins
where is zone 1 in the liver?
hepatocytes
what is special about the hepatocytes in zone 1? (4 “firsts” and 1 “last”)
they are the LAST to show signs of ischemia, first to convert glucose to glycogen, they are the first to regenerate after injury, they are the first to show the effect of toxins and biliary obstruction
where are the hepatocytes in zone 3 in relation to the branches of the portal triad?
they are the furthest away
what is special about the hepatocytes in zone 3? (2 “1st”s and 3 “lasts”)
“1st”: show effects of ischemia, accumulate lipids
“last”: to show damange d/t biliary obstruction/ toxins, to regenerate
what is the first branch off of the aorta below the diaphragm and and at what spinal cord level?
celiac, T12
what are the three major branched off of the celiac trunk?
left gastric artery, splenic artery and common hepatic artery
what is the smallest branch of the celiac trunk?
the left gastric artery
the left gastric artery branches to supply blood to which two structures?
esophagus and the lesser curvature of the stomach
what is the largest branch of the cephalic trunk? it travels to the left along side which organ?
splenic artery, pancreas
the splenic artery provides blood supply to which four organs/parts of organs
pancreas, greater curvature of the stomach, fundus of stomach, and the spleen (where it terminates)
what are the branches of the hepatic artery?
proper hepatic, right gastric artery, gastroduodenal artery
the common/proper hepatic arteries terminate where, and in what structure?
portal arteriole in the portal triad (carrying oxygenated blood)
what system drains the nutrients and oral meds from the GI tract and spleen?
portal venous system
which veins unite to form the hepatic portal vein before entering the liver?
superior mesenteric vein and splenic vein
the branches of the hepatic portal vein ultimately terminate at the portal triad as the…. (is this blood oxygenated or not).
portal venule, deoxygenated
where does the hepatic portal system drain blood from? (6 organs)
esophagus, stomach, pancreas, spleen, sm intestines, lg intestines
the blood entering the liver lobule via the portal arteriole and portal venule travels towards what?
centrally towards the central vein
blood draining from the liver via the central veins enters the 2-3 hepatic veins which ultimately drain into what vessel?
inferior vena cava and then into he right atrium of the heart
bile is a yellowish-brown liquid made by which organ and stored where?
made by liver, stored in the GB
bile contains what to emulsify lipids?
bile salts
what are the constituents of bile? (7)
bile salts, water, ions, cholesterol, bile acids, lecithin and bile pigements
what is the hormone that results in the contraction of the GB and release of bile via the cystic duct into the common bile duct?
cholecystokinin
what are the roles of the liver in relation to carbohydrate metabolism? (2)
formation and degradation of glycogen, gluconeogenesis
what are the roles of the liver in relation to proteins? (~3)
deamination of proteins, conversion of ammonia to urea and synthesis of the proteins: albumin, globulins, prothrombin and fibrinogen
what are the roles of the liver related to lipids? (5)
bile salts for the emulsification of lipids in the small intestines, formation of LDL transporters, storage of triglycerides, breakdown of triglycerides and synthesis of cholesterol
the role of the liver related to drugs
enzymatic conversion of drugs to other chemical forms
the role of the liver in relation to homeostasis
synthesis of many coagulation proteins and thrombopoietin for platelet production
the liver contains enzymes that convert bilirubin into (2)
stercobilin and urobilinogen
what does the liver store? (3)
glycogen, vitamins and minerals
the liver is one of the three organs required for the synthesis of what vitamin? What are the other 2 organs?
D; skin and kidney
what is the role of vitamin D?
works as a hormone to ensure the normal level of calcium
