digestive tract 2 duodenum to anus Flashcards
what is the peritoneum
continuous sheet of serous membrane
what does the serous membrane secrete
serum and forms the mucous membrane
what does the parietal peritoneum line
lines the abdominal and pelvic cavities- it wraps around them
what does the visceral peritoneum cover
covers most abdominal organs
it folds in on itself
what is the peritoneal cavity
potential space between two peritoneum
what is introperitoneal
sit in peritoneal
what is retroperitoneal
behind peritoneal
what are mesenteries
the peritoneal folds
what are the functions of mesenteries
- connect organs to each other
- connect organs to the abdominal wall to stop organs from moving around and colliding into each other
what is the omentum
it covers all organs in the abdominal cavity
it is the largest piece of peritoneal
what is mesentery proper
mesentrial sheet that has a lot of blood vessels
what occurs in the small intestine
90% of nutrient absorption occurs here
subdivisions of the small intestine
duodenum (30cm)
jejunum (2.5m)
ileum (3.5m)
what is the duodenum
c shaped structure adjacent to head of pancreas
extends from pyloric sphincter to jejenum
has an alkaline environment of pH9
characteristics of the superior part of the duodenum
short, only section of duodenum peritonised (within the peritoneal lining)
characteristics of the descending part of the duodenum
it has major and minor duodenal papillae
what is the jejenum
- extends from the duodenojejunal flexure to the ileum
- it is completely peritonised
- has villi
what is the ileum
- extends from the jejunum to the large intestine to the ileocecal junction
- completely peritonised
- no villi
- smaller in diameter
what are plicae circularis
circular folds formed by mucosa and submucosa
unlike rugae, these are permanent
have projections - villi
these plicae villi is less prominent distally in the small intestine
how does the intestinal walls change
diameter and thickness of intestinal walls decrease
where is most of the mucus
in the submucosa of the duodenum - secreting duodenal (Brunner) glands that help maintain alkaline environment
where are most of the lymphoid follicles
in the submucosa of ileum -Peyer patches
lining of villi
covered with simple columnar epithelium (4 types):
- absorptive: digestive enzymes
- goblet: mucus secretion
- granular or paneth: lyzozyme
- endocrine: hormones
intestinal glands
where the 4 different types of villa are produced
located at the bottom of villi
locations of types of cells in villi
absorptive and goblet migrate to cover the surface of the villi
granular and endocrine remain in the bottom
what is the lacteal
is a lymphatic capillary that absorbs dietary fats in the villi of the small intestine.
what is the function of the lymphs
drainage of water
functions of the large intestine
- re-absoprtion of water
- compact intestinal contents into faeces
- absorption of vitamins
- storage of faecal material
length of large intestinal
extends from ileocecal junction to anus
what is the illeocecal sphincter
opening between ileum and large intestine
guarded by fold of mucous membrane
how is the mucosa in the large intestine
simple columnar epithelium
has no villi or plicae circularae
what are crypts
straight tubular glands formed by the mucosal lining
types of cells in crypts
absorptive, granular and goblet (predominant)
muscle layers of large intestine
longitudinal and circular layers
what are taeniae (teniae) coli
3 bands formed by the longitudinal layer of large intestine
what are the haustra
gathering of colon into pouches formed by the contractions of taeniae coli
permits expansion and elongation of intestine
serosa
contains fat-filled pouches
epiploic appendages (mental appendages)
fat-filled pouches within the serosa
attaches to peritoneum
what is peristalsis
series of wave-like muscle contractions that move food to different processing stations in the digestive tract
begins in the oesophagus when a bolus of food is swallowed
what is the rectum
terminal part of the large intestine
folds inside
what are rectal valves
transverse rectal folds in rectum
how is the rectal mucosa
simple columnar epithelium with tubular glands housing large numbers of mucus-secreting goblet cells
what is the muscularis
thick muscular tunic in rectum
what is the anal canal
final part of rectum
mucosa in anal canal
superior part simple columnar
inferior part stratified squamous epithelium
what are anal columns
epithelium arranged in longitudinal folds (arteries and veins)
anal sinuses between columns exude mucus
what is the internal anal sphincter
formed by the thickening of the layer muscularis
movement is involuntary
what is the anal sphincter
formed by skeletal muscle
voluntary movement
major sphincters of the GI tract
formed by thickening of inner circular muscle layer (muscularis)
- upper and lower oesophageal sphincters
- pyloric sphincters
- ileocaecal valve
- internal and external anal sphincter
