CASE 9 Flashcards
peritoneum
- most extensive membrane
- visceral peritoneum -> covers external surfaces of most digestive organs and is continuous with parietal peritoneum –> lines the body wall
- peritoneal cavity –> between 2 peritoneums, contains serous fluid that lubricate the mobile digestive organs
- mesentery –> double layer of peritoneum, extends to digestive organs from body wall, provides routes for blood vessels, lymphatics and nerves to reach the digestive viscera, holds organs in place and store fat
- there are dorsal and ventral mesenteries
retroperitoneal organs
- pancreas, duodenum and parts of large intestine have no mesentery.
intra peritoneal/ peritoneal organs
- stomach, keep mesentery and remain in the peritoneal cavity
digestive system begins with oral cavity (mouth and pharynx)
- three pairs of salivary glands:
1. sublingual glands
2. submandibular glands
3. parotid glands - swallow
- epiglottis
- pharynx
- larynx
- esophagus
- stomach
epiglottis
prevents food from going to the trachea
esophagus
travels through the thorax to the abdomen
- wall is skeletal muscle initially
- but smooth muscle 2/3 length
- ends in stomach
stomach
3 sections
- upper fundus
- central body
- lower antrum -> facilitates the emptying of the contents into the small intestine
cardia
point where the esophagus connects to stomach
chyme
stomach continuous digestion that started in the mouth by adding acid and enzymes to food creating chyme
pylorus
opening between stomach and small intestine is guarded by pyloric valve –> thickened band of smooth muscle relaxed to allow only small amounts of chyme into the small intestine
small intestine
divided into three sections
- duodenum
- jejunum
- ileum
- more digestion takes place here, nearly all digested nutrients and secreted fluids are absorbed there
accessory glandular organs
- pancreas
- liver
- exocrine secretions secrete intestinal enzymes which carry out digestion
- secretions enter the initial section of duodenum through ducts.
- sphincter of Oddi keeps pancreatic fluid and bile from entering the small intestine
large intestine
five main regions
- ileocecal valve
- cecum
- colon
- rectum
- anal canal
ileocecal valve
- located between ileum and cecum
- controls flow of chyme from small intestine to large intestine
cecum
- absorption of water and salts
- appendix is tube that attaches to the cecum
colon
consists of
- ascending colon
- right colic flexure
- transverse colon
- left colic flexure
- descending colon
- sigmoid colon
- watery chyme is converted into semisolid feces, as water and electrolytes are absorbed out of the chyme into the ECF
rectum
- rectal valves: three lateral bends that create a trio of internal transverse folds –> help separate the feces from gas to prevent simultaneous passage of feces and gas
anal canal
- has two sphincters:
internal and external anal sphincter
internal : smooth muscles
external : skeletal muscle
gut
portion of GI tract from stomach to anus
The basic structures of the gastrointestinal wall is similar in the stomach and intestines. Layers
- an inner mucosa facing the lumen
- submucosa
- layers of smooth muscle known collectively as muscularis mucosae, thin layer of smooth muscle
Mucosa
- inner lining of GI-tract. Created from:
1. single layer of epithelial cells
2. lamina propria
3. muscularis mucosae
increase amount of mucosal surface area to enhance absorption
- rugae in stomach, folds
- plicae, folds in small intesine
- villi, small fingerlike extensions project into the lumen
- gastric glands: tubular invaginations of surface that extend down into supporting connective tissue in stomach
- crypts: tubular invaginations of surface that extend down into supporting connective tissue in intestine.
transporting epithelial cells, enterocytes
- endocrine, secrete in blood
- exocrine, secrete on to an epithelium
- secrete ions and water into lumen and absorb ions, water and nutrients into the ECF
- mucosal surface (apical), secretory cells release enzymes, mucus and paracrine molecules into lumen
- serosal surface (basolateral), secretory cells secrete hormones into blood or paracrine messengers into the interstitial fluid
paracellular pathway
- because intestinal epithelium is leaky, water and solutes can be absorbed between cells instead of through them