stomach and intestines Flashcards
what is the stomach?
the stomach is the most distensible and widest organ of the alimentary canal.
The empty stomach possesses folds called gastric rugae, which disappears when the stomach is distended with food.
what are some of the earliest signs of stomach cancer?
Loss of gastric rugae is one of the earliest signs of stomach cancer.
what is the major part of the stomach?
1) cardiac part: oeso[gaus opens here
- Cardiac part is so-called because it is present near the heart. It is broad at the upper part with a cardiac sphincter which prevents regurgitation of food.
2) fundic part: it stores both undigested food and gases that are released during the process of chemical digestion.
3) body part: digestion of protein and fat
40pyloric part :opens into duodenum via pyloric sphincter
what is cardiac achalasia?
A rare disorder making it difficult for food and liquid to pass into the stomach.
Achalasia results from damage to nerves in the food tube (oesophagus), preventing the oesophagus from squeezing food into the stomach. It may be caused by an abnormal immune system response.
Symptoms include backflow of food in the throat (regurgitation), chest pain, and weight loss.
Achalasia can usually be managed with minimally invasive (endoscopic) therapy or surgery.
what is heartburn?
- Burning pain or discomfort in the upper chest and midchest
- Heartburn occurs when stomach acid backs up into the tube that carries food from your mouth to your stomach
what is regurgitation of food.?
Regurgitation is the spitting up of food from the oesophagus or stomach without nausea or forceful contractions of the abdominal muscles
explain compound stomach?
–stomach of ruminants
–4 major parts
1)rumen
-first and the largest part
stores food temporarily and pass it back to the
oesophagus for chewing
- stores food that a ruminant regurgitates
- water cells project from rumen in camels and deers
2) reticulum
- collect food after complete chewingand move them into the omasum
3) omasum
- absent in camels and deers
- absorbs water and other substances from digestive contents.
4) abomasum
- The pepsins carry out the initial digestion of microbial and dietary protein in the abomasum
- abomasum is the true stomach that secrets gastric juices
–digestion of cellulose is done through fermentation, with help of symbiont bacterias and protozoans
- rumen and reticulum harbour a large population of cellulolytic bacterias like rumencoccus that secrete cellulase enzyme for the fermentation of cellulose
- -cellulose is simplified into small chain fatty acids
what is the intestine?
the intestine is responsible for most of the digestion and absorption of food and usually the formation of dry faeces.
It is divided into two parts – the small intestine and the large intestine.
explain small intestine.
The small intestine is distinguishable into three regions:
1) duodenum,
- c shaped in humans
2) jejunum: a long and coiled middle portion
3) ileum. :
- highly coiled
- completes absorption and digestion
- Peyer’s patches are present(patches of lymphoid tissue)
- crypts of lebhrkhun secrets intestinal juice(succus entericus)(brush bordered enzymes)
- mucosa folded into plicae circulares and villi
secretion of panneth cells(lysosome production) and argentaffin cells(somatostatin cells)
explain large intestine?
- no digestion
- absorption of water and vitamins
- has three major parts:
1) caecum: - contains symbiotic bacteria that help in digestion
- associated with ileum via ileocaecal valve
- contains small finger-like vermiform appendix(used to digest cellulose, but vestigial now)
2)colon:
ascending, transverse,decending part and sigmoid part.
3) rectum: stores the faeces
- caecum and colon harbours symbiotic bacterias
describe the histology of the alimentary canal?
the wall of the alimentary canal comprises of:
1) mucosa: has brush border epithelium in some part
2) submucosa: Brunner’s gland in the duodenum.
- loose connective tissue + blood supply + nerve+ lymph supple
3) muscularis:
a) outer longitudinal
b) inner circular
c) oblique layer in stomach only
4) serosa
- Serous membrane (mesothelium) + connective tissue
- absent in upper one-third part of the oesophagus and rectum
what is Meissner’s plexus?
- Meissner’s plexus is situated in the submucosal region between the circular muscle and mucosa.
- This plexus regulates the configuration of the luminal surface, controls glandular secretions, alters electrolyte and water transport, and regulates local blood flow.
what is the myenteric plexus
- The myenteric plexus lies in between the outer longitudinal and inner circular smooth muscle layers of the intestines.
- The myenteric plexus is principally responsible for the peristaltic movement of the bowels. While it can act independently from the central nervous system, it receives innervation from the autonomic nervous system, connecting the central and enteric nervous systems.
