6.1 Flashcards
What makes up the digestive system
mouth salivary canal osophagus stomach pancreas liver bile duct small intestine large intestine duodenum gall bladder rectum anus pharynx
what is peristalsis
a wave of contraction and relaxation of the longitudinal and circular muscles of the alimentary canal by which the contents are forced along the tube
what happens when you eat something
in the mouth, you chew the food which is mechanically mixed with saliva. The saliva contains enzymes (amlyase) that start the digestion of starches. The saliva also moistens the mixture to help you swallow.
then the food mixture (bolus) enters the oesophagus (gullet) and moves by peristalsis
How do longitudinal and circular muscles work together
antagonistically, they work opposite with one another, when one contracts, the other relaxes.
the longitudinal muscle contracts to widen the lumen of the alimentary canal while the circular muscle contracts to constrict the lument
What happens when bolus enters the stomach
the food is churned with acid, becoming chyme.
the stomach acid kills the bacteria and starts the digestion of proteins
what happens to chyme after the stomach
it enters the small intestine, first the duodenum. the acid passing through the stomach needs to be neutralized so that the enzymes can function properly. the enzymes have an optimum pH of neutral to alkaline and some of them digest fats and lipid, others, further digest carbs. By the time the food reaches the end fo the small intestine, digestion has been completed ad the digested products have been absorbed from the last section the ileum.
what happens to the food after the small intestine
it enters the large intestine along with vitamins made by bacteria are reabsorbed the anaerobic bacteriaia in the law intestines can ferment undigested polysaccharides to produce energy. in the last part of the large intestine, faces is formed and store din the rectum prior to egestion
what other organs aid the digestive process
liver
gall bladder
pancreas
what does the pancreas secrete
amylase, lipase and protase
what does the liver secrete
bile to emulsify fats
what does the gall bladder store
bile
what are the tissue layers inside the small intestine
serosa - outer most layer (connective tissues)
longitudinal muscles
circular muscles
submucosa - connective tissue that supports the mucosa and that contains large veins and arteries which give rise to the capillary bed of the mucosa
mucosa - innermost layer forming the soft lining of the tube comprised of epithelium, connective tissue and smooth muscle
what digestive enzymes do acing cells secrete
amylase - starch into maltose
endopeptidase (trypsin) - protein to smaller polypeptides
lipases and phospholipase - breaks down lipids and phospholipids, glycerol and fatty acids
what is found in the pancreas
duct cells that transport the enzymes by the acing cells and secrete sodium hydrogen carbonate that neutralizes stomach acid
acing cells that secrete digestive enzymes
islets of langerhand (produce the hormones insulin and glucagon
what neutralizes stomach acid
sodium hydrogen carbonate transported by the duct cells in the pancrease
what do the islets in the pancreas do
produce hormones insulin and glucagon
what enzymes complete digestion in the small intestine
nucleases - break down DNA and RNA
maltase - breaks down maltose into glucose
lactase - breaks down lactose into galactose and glucose
exopeptidase - removes a single amino acid from the end of the small polypeptides
dipeptidase - breaks down a dipeptide into the two amino acids
what feature increases the absorption of food molecules in the small intestine
villi
What happens when the circular and longitudinal muscles of the small intestine contract?
food is mixed with enzymes and moved along the gut
where does the absorption of food molecules acc take place
in the small intestine,e across the epithelium.
how is the surface area od small intestine increased
by villi
what are vili
they are the location of absorption of all the monomers produced by the digestive processes in the small
what is found in a villus
goblet cells on the outside
epithelium lamina propria nerve capillary network lacteal venule arteriole lymphatic vessel
where does absorption take place
on the epithelial cells