digestive system (theory) Flashcards
main organ vs accessory organ distinction
organs that are directly involved in the alimentary canal are main digestive organs
organs that secrete things and help move food along are accessory organs
notable accessory organs
- teeth
- tongue
- pancreas
- liver
- gallbladder
- salivary glands
stomach cells
- parietal –> HCL and IF
- chief –> pepsinogen
- chromatin cells –> histamine
- G cells –> gastrin
histamine and gastrin function
to increase motility and secretion in the stomach
muscularis externa layer of the stomach
- inner circular
- outer longitudinal
- oblique layer
example of stratified epithelium in the GI tract
- oral cavity
- esophagus
example of simple columnar epithelium
- stomach
- small intestine
- large intestine
submucosal plexus
between the submucosa and the muscularis layers
this plexus has an effect on secretion of the small intestine
myenteric plexus
between the muscularis layers
this plexus helps with peristaltic movements
muscularis mucosae function
helps push recently absorbed nutrients down closer to the blood vessels during maximum absorption
this is not involved in peristalsis
serosa secretion and function
secretes serous fluid to reduce friction of the visceral organs
pacemaker cells of the muscularis externa
the pacemaker cells lend themselves to producing peristaltic and segmentation movements
intraperitoneal organs
organs within the peritoneal cavity
- stomach
- liver
- ileum
retroperitoneal organs
organs that sit behind the peritoneum
- kidneys
- ureters
- abdominal aorta
secondary retroperitoneal organ
organs that were initially in the peritoneal cavity but then become retroperitoneal
- pancreas
- duodenum
mesentery function
a fused sheet of peritoneal membrane
- stabilizes organ position
- stabilizes blood vessel position
- provides attachment of blood vessels to the small intestine
mesocolon
mesentery attached to the large intestine
transverse mesocolon
attached to the transverse colon
sigmoid mesocolon
attached to the sigmoid colon
fusion fascia
helps attach the ascending, descending colon and rectum to the posterior abdominal wall
lesser omentum
comes from the lesser curve of the stomach and attaches the stomach to the liver
greater omentum
extends from the greater curve of the stomach and covers the rest of the abdominal organs
2 pouches of the peritoneum present in females and are a concern for blood pooling after trauma
- recto-uterine pouch
- urino-uterine pouch
what consist of the roof of the oral cavity
- hard palate
- soft palate
hard palate characteristics
- the palatine process of the maxilla
- separates the oral cavity from the nasal cavity
soft palate characteristics
- makes up the palatoglossal arch and palatopharyngeal arch
the two arches of the soft palate
- palatoglossal arch
- palatopharyngeal arch
the palatine tonsils sit between the arches
the uvula is a continuation of the palatoglossal arch
lingual frenulum
tissue that attaches the tongue to the bottom of the mouth
AKA tongue tied
intrinsic tongue muscle functions
- extend the tongue
- rotate the tongue
superior
inferior
transverse
longitudinal
tongue functions
- move food
- taste
- secrete enzymes to start digestion
- help formulate words
tongue body
anterior portion
tongue root
posterior portion
dorsum
superior portion of the tongue that contains papillae and taste buds
extrinsic tongue muscles
- genioglossus
- hyoglossus
- styloglossus
- palatogossus
all are innervated by CN XII
teeth characteristics
- crown
- neck
- root
- dentine
- pulp cavity
- root canal
- apical foramen
- periodontal ligaments
teeth enamel
covers the crown and protects from cavities
gives the teeth their white color
periodontal ligaments
makes a synarthrotic gomphosis joint and keeps the dentine from touching the bone
root canal
highly vascularized part of the tooth
distribution of teeth types
8x incisors
4x cuspids
8x bicuspids
12x molars (8x if wisdom teeth are removed)
the two sets of teeth we have as we develop
- deciduous (20) –> we lose these teeth
- permanent (32)
surfaces of the teeth
- labial –> outer surface
- palatal –> inner surface
- mesial –> surface between teeth
- occlusal –> grinding surface
muscles of the pharynx
the pharynx can be considered part of the digestive and respiratory tracts
- pharyngeal constrictors
- laryngeal elevators
- palatal muscles
palatal muscles
- tensor veli palatini
- levator veli palatini
laryngeal elevators
- stylopharyngeus
- palatopharyngeus
pharyngeal constrictors
- superior
- middle
- inferior
buccal phase
food goes to the oropharynx, you can still spit it out
pharyngeal phase
epiglottis closes and you can no longer spit it out
esophageal phase
opening of the upper esophageal sphincter into the esophagus
does the esophagus have a serosa layer?
no, instead it has an adventitia
the serosa is continuous with the peritoneum and since the esophagus is continuous with the peritoneum, it doesn’t have a serosa
celiac trunk supply to the stomach
- left gastric artery
- splenic artery
- common hepatic artery
left gastric artery supply
the lesser curvature and cardia
splenic artery supply
the fundus and greater curve
common hepatic artery supply
the greater and lesser curves
differences between the stomach lining and small intestine lining
- no peyer’s patches in the stomach
- no villi in the stomach
- does have an oblique muscle layer
duodenum and enzymes
this part of the small intestine receives enzymes and secretions from the pancreas, liver and gallbladder
small intestine blood supply
- superior mesenteric artery
- inferior mesenteric artery
small intestine mesentery
the ileum and jejunum are supported by a mesentery
the duodenum is not associated with a mesentery
lacteal vessel of the small intestine
intake of fatty acids here
intestinal crypts and cholecystokinin and secretin
the enteroendocrine cells of the intestinal crypts secrete cholecystokinin and secretin
cholecystokinin = contracts the gallbladder and secretes bile
secretin = causes pancreas secretion and slows down gastric motility
pancreatic secretion and buffers
the pH of pancreatic secretions are alkaline which help neutralize the acidic chyme entering the small intestine
duodenal muscosal glands
glands of the duodenum that secrete mucus to act as a buffer against acidic chyme
ducts of the liver and gallbladder
right hepatic and left hepatic duct –> common hepatic duct
cystic duct and the common hepatic duct –> common bile duct
common bile duct and the pancreatic duct –> sphincter of oddi
large intestine blood supply
- superior mesenteric artery
- inferior mesenteric artery
vermiform appendix
extends from the cecum of the large intestine
colic flexures
bends in the large intestine
right colic flexure = from the ascending colon to the transverse colon
left colic flexure = from the transverse colon to the descending colon
omental appendices
tear drop shaped fat that is not present on the small intestine
taenia coli
smooth muscle band that runs parallel to the large intestine
haustra
contraction of the taenia coli produces bulb like sacs of the large intestine
is the large intestine thin or thick walled?
thin walled which is a concern for colon cancer because it can spread more easily
rectum function
stores waste material
the last part of the rectum is the anal canal
anal canal components
- anal columns
- anus
internal and external anal sphincter differences
the internal anal sphincter is above the external anal sphincter
the external anal sphincter is made up of skeletal muscle
large vs small intestine differences
- no villi
- thin walls
- more goblet cells
- lots of mucus production
- large lymphoid nodules
movement from the cecum to the transverse colon time
slow
mass movement from transverse colon to the rest of the large intestine
faster to force waste material to the rectum
rectal wall distension
stimulates the urge to defecate
liver functions
- metabolic regulation (detoxification)
- bile production
- hematological regulation
liver RBC management
phagocytic cells of the liver take care of old/damaged RBCs
liver and angiotensins
the liver also produces angiotensins which can regulate blood pressure by vasoconstriction
some of the liver’s functions
- produce cholesterol
- detoxification (ammonia)
- store fat soluble vitamins
- make clotting factors
- regulate blood pressure
falciform ligament of the liver
separates the right and left lobes
coronary ligament of the liver
superior portion of the falciform ligament that spreads
coronary = crown
blood vessels of the liver (2x)
- hepatic artery proper
- hepatic portal vein
liver organization
the liver is divided into lobules
pathway of blood through the liver
- hepatic portal vein
- liver sinusoids
- central vein
- hepatic veins
- inferior vena cava
the portal area of the liver
contains both the hepatic portal vein, hepatic artery proper and bile duct
portal triad
a triangle made by the central vein and a grouping of the hepatic portal vein, hepatic artery proper, and bile duct
what cells populate the liver sinusoids?
- capillaries
- kupffer cells –> phagocytes of the liver
hepatocyte function
produces bile
bile pathway
- bile enters the bile canaliculi
- bile ducts
- left and right hepatic duct
- common hepatic duct
- common bile duct
- sphincter of oddi
the 4Fs of stone formation in the liver/gallbladder
- female
- familial
- over 40 years old
- fat
having these increases one’s risk for stone formation
stones form with disturbances in the proportions of bile acid and salts
pancreas cell types (2)
- acinar cells
- pancreatic islets
acinar cell functions
produces digestive enzymes, there are far more acinar cells than pancreatic islet cells
secretions:
1. lipases
2. amylases
3. nucleases
4. proteinases
pancreatic islet cells
produces hormones
- alpha –> glucagon
- beta –> insulin
- delta –> somatostatin
F pancreatic islet cells
produces pancreatic polypeptide which stimulates secretions
