Digestive System Flashcards
adventitia (outer)
organs covered by a serous membrane- peritoneum
what is the peritoneum
largest serous membrane which has a double layer closed sad which contains serous fluid, it has a rich supply of blood vessels and lymph vessels. Invaginated arrangement, so pushes below, behind and above
role of peritoneum
barrier against local infection
serous fluid prevents friction, this is secreted by periteal cells
describe the peritoneum in males and females
cavity is closed in males
females the uterine tubes opens into, with the ovaries being the only thing within
where about the pelvic organs covered
ONLY superiorly
describe the stomach and intestine regarding the peritoneum
they are almost entirely covered, which have a double fold (mesentry) which attaches to the post wall, this extends to the greater curvature of the stomach
greater omentum
stores fat for insulation and energy
retroperitoneal
only covered on the anterior surface
pancreas, spleen, adrenal gland and kidneys
what organ is nearly entirely covered
liver, attaches to the inf surface of the diaphragm
what is found in the peritoneum
main blood vessels and nerves pass close to the posterior abdominal wall, which send impulses to organs between the peritoneal folds
secretion
substances secretes into the canal where they pass from the ducts to the tracts
visceral
covers organs within abdominal and pelvic cavities
parietal
lines the abdominal wall
peritoneum function
supports abdominal organs in cavity
pathway of vessels and lymph to pass to and from organs
protection against inflammation through LN
fat store
retroperitoneal organs
duodenum
kidney
ureters
IVC
rectum
adrenal gland
pancreas (not tail)
oesophagus
intraperitoneal
fully enclosed by the peritoneum extends to the posterior wall of sac remains tethered to the posterior wall by the double fold - lack movement
digestion
release its constituents: AA, minerals, salts, fats and vitamins
enzymes are secreted by specialised glands inside and out of the canal
ingestion
consumption of food at the alimentary canal
absorption
digested food which travels and passes into the blood and lymph capillaries for circulation and for body cells
nutrients can manufacture new cells, hormones and enzymes
elimination
removal of undigested food, defecation
ascites
build up of serous fluid in cavity
lesser omentum
stomach and 1st part of duodenum, suspended by the lower surface of the Uber by a double fold of peritoneum
greater omentum role
gastrointestinal -immunity
minimising spread of intraperiotneal infections hangs down from the greater curvature of the stomach in front of abdominal organs
transverse mesocolon
two peritoneum layers cover the transverse colon, passing to the posterior abdominal wall, holds the colon in place
SI mesentry
arises from the mesentry root, the fold fans out to be attached to the SI, which has high blood supply, venous drainage and lymphatics
muscle layer
two layers
outer layer: longitudinal
inner: circular fibres
between the two are fibres, nerves and blood vessels
mesenteric plexus, supplies the smooth muscle and the blood vessels
what is peristalsis under the influence of
para and sympathetic vessels
mucosa
- mucous membrane: columnar epithelium: protection, secretion, absorption
- lamina propria: loose connective tissue which supports blood vessels fro nourishments and protection against microbes due to lymphoid tissue
- muscular mucosa: outer layer of smooth muscle
sub mucosa
loose areolar connective tissue with collagen and elastic fibres which binds to the muscular layer if the mucosa. the vessels have varying amounts of lymphoid tissue
the nerve plexus is the submucosal plexus which contains sympathetic and parasympathetic nerves
what is found in wear and tear regions
layer of stratified epithelium with mucus secreting glands
where is columnar epithelium found
areas of secretion and absorption with goblet cells interspersed, mucus lubricates the wall providing a barrier against enzymes
why is there lymphoid tissue under epithelium
to aid protection due to the digestive juices containing enzymes which cause chemical digestion
stomach digestion time
4-6 hours
SI digestion time
5-6
large intestine
12-24 hours
parasympathetic
one pair of cranial nerves, the vagus nerves supplies most of the canal and accessory organs. Sacral nerves supply most of the distal parts of the tract
parasympathetic effects
increased muscular activity, peristalsis through increased activity in the myenteric plexus
sympathetic
provided by numerous nerves which emerge from the spinal cord.
these form the ganglia in the thorax, pelvis and abdomen, which pass through into organs in the alimentary tract
sympathetic stimulation
decrease in muscular activity, peristalsis will decrease
decrease in glandular secretion less stimulation from submucosal plexus
what happens if the lining is damaged
absorption is less efficient so nutrients can’t be absorbed = loss of weight
functions in lower GI
ingestion: maximises contact with surfaces
digestion: mechanical and chemical (mechanical: large molecules are hydrolysed to small ones so can be absorbed)
absorption and metabolism: nutrients pass into the bloodstream
storage and excretion: undigested and unabsorbed
defence: non specific, prevent against infection
