Anatomy stomach/Intestins 2 Flashcards
What are the primary functions of the stomach?
Storage of ingested food
Mechanical disruption
Enzymatic breakdown
Production of “intrinsic factor”
What substances do the following secrete?
- Stomach epithelium mucous cells
Epithelium = simple columnar with mucous cells that produce an alkaline mucous.
pH of the stomach is around what?
Acidic pH will not digest what?
1.5-2.0
Chyme
What are the functions of stomach pH?
Kills any microorganisms
Denatures proteins and inactivates enzymes
Breaks down plant cell walls and connective tissues in meat
Pepsin only functions at low pH
What controls gastric activity?
CNS
Reflexes of the enteric nervous system in the wall of the stomach
Hormones of the digestive tract
Amylase and lipase in saliva continue to work until stomach pH drops below pH___
Pepsin activity kicks in around pH___
Amylase and lipase in saliva continue to work until stomach pH drops below pH4.5
Pepsin activity kicks in around pH2.0
(if pH isn’t good at digesting food it
Kills microbes or bacteria in food
What is most important to digestion(stomach, large intestine or small intestine)?
What percent of absorption happens there?
Most important digestion and 90% of absorption occurs in the small intestine
What is the major gross feature of the intestinal lining?
Transverse folds also called circular folds or plicae circulares
What are the absorptive cells of the small intestine?
Secretory cells?
Enterocytes
Secretory cells:
Goblet cells
Paneth cells
Enteroendocrine cells
What is secreted by goblet cells?
secrete mucins
What is secreted by paneth cells
secrete antimicrobial compounds
What is secreted by Enteroendocrine cells
cells found in epithelium produce hormones like gastrin, cholecystokinin and secretin
What is secreted by Enterocytes?
(peptidases and carbohydrases), produced by these cells, finalize the digestive process right at the absorption site.
What stimulates Myenteric reflexes?
Myenteric reflexes stimulated by entry of chyme to duodenum stimulate the weak peristalsis that delivers it to the jejunum
What stimulates parasympathetic reflexes?
Parasympathetic stimulation promotes a more active peristalsis and segmentation
What stimulates stretch receptors?
Stretch receptors and hormones may stimulate neuronal control of peristalsis and sphincter relaxation
What is the function of the pancreas?
What does it produce?
Primarily and exocrine organ producing digestive enzymes and buffers, the pancreatic duct delivers secretions to duodenum.
Also an endocrine organ, Islets of Langerhans cells (1% of pancreas) produce a number of hormones including insulin and glucagon
Acinar and epithelial cells secrete what?
Acinar and epithelial cells secrete pancreatic juices (about 1000 ml) (enzymes, water and ions) into the small intestine
What are the pancreatic enzymes?
What do they each break down.
Alpha-amylase – breaks down starches
Lipase – breaks down lipids
Nucleases – break down RNA, DNA
Proteolytic enzymes – break down large proteins
Peptidases break down small peptides into AA
What substances do the following secrete?
- Gastric glands
Gastric glands produce 1.5 L of gastric secretion each day:
What substances do the following secrete?
- Parietal cells
Parietal cells secrete intrinsic factor and HCl
What substances do the following secrete?
- Chief cells
Chief cells secrete pepsinogen which becomes active pepsin, to digest proteins
What substances do the following secrete?
- Pyloric Glands
Pyloric Glands secrete mucous and hormones like gastrin, that stimulates parietal and chief cell secretion
- What are the mucosal folds or ridges in the stomach lining called?
reggae
- Name the two sphincters that control the stomach entrance and exit
Cardiac sphincter-Entrance
Illoric splinter- Exit
