digestive system

to invest food so as to chemically and physically break it down into monomers and absorb the nutrient molecules and eliminate wastes

• mouth-injest and mechanical digestion • tongue-shapes food into bolus-and pushes food to back of throat • tastebuds-evaluate food • teeth-bite crush tear • salivary glands- secrete amylase (ph 7) breaks starch into maltose • pharynx- common pathway for air and food • epiglottis-flap at larynx that blocks food from entering trachea • esophagus- pathway to stomach • cardiac sphincter • stomach- food storage and only digests proteins– gastric juices and churns food into chime • pyloric sphincter- • duodenum- first region of small intestine and it does the most digestion it breaks food down and absorbs it • liver- makes bile and destroys RBC ( does a lot) • gall bladder- stores bile • pancreas-makes digestive juices and enzymes • small intestine- absorbs food • appendix- immunity- has some lymph nodes • large intestine- recovers water and makes vitamins • rectum- stores and eliminates faces

oral cavity food is chewed and mixed with saliva the tongue rolls the food into bolus. when you swallow the tongue pushes the bolus into the pharynx and the soft pallet moves up to block the nasal cavity. epiglottis covers the trachea and the bolus enters the esophagus. peristalsis occurs and circular muscles contact, longitudinal muscles relax. the circular muscles in front of the bolus relax and the longitudinal muscles relax this alternate contraction and relaxation pushes bolus to stomach. *** swallowing is a reflex

pepsin and pepsinogen. hydrochloric acid. GOBLET CELLS PRODUCE MUCUS. gastric juice breaks down proteins using enzymes and a low ph

NAHCO3***** CREATES PH OF 8. trypsin lipase and nuclease amylose(further breaks down carbohydrates, lipids and proteins) also neutralizes chime and is released into the duodenum

mucus sodium bicarbonate and water— BRUSH BORDER ENZYMES

peptidase- break peptides into aa lactase and maltase these are produces by microvilli

bile is a salt and it EMULSIFIES FATS which is to physically break fats down. it breaks fat into smaller molecules and surrounds them so that lipase can break them down

stores glycogen makes bile detoxifies poisons coverts nitrogen into urea makes plasma proteins

long– more opportunity and time to digest villi- increase in sa circular and longitudinal muscle- movement of food all the many layers **length layers villus

-absorb monomers- capillaries absorb glucose aa and nucleotides lacteal- lymph vessel in vili absorbs glycerol and fatty acids capillaries to mesenteriess to mesentery vein to portal vein microvilli increase surface area and make brush border enzymes

makes vitamins

(hormone) gland- stomach epithelial lining stimulus- presence of protein target- gastric glands action- increase gastric juice

gland- duodenal mucosal epithelium stimulus- acidic chime target- pancreas action- increase pancreatic juice

gland-duodenal mucosal epithelium stimulus-partially digest proteins and fat target- pancreas action- increase pancreatic juice

gland-duodenal wall stimulus-fat and polypeptides in duodenum target- gastric glands action- decrease gastric juice (opposite of gastrin)

-salivary amylase- from salivary glands- convert starch to maltose- ph 7 -pancreatic amylase- from gland pancreas- convert starch into maltose -pH 8 -* pepsin- gland- chief cells in stomach- substrates are proteins and break them into polypeptides pH 2 -*trypsin secreted from pancreas and the substrate is proteins breaking them into polypeptides the pH is 8 lipase- secreted from pancreas substrate is lipids and breaks them into fatty acids and glycerol and the pH is 8 nuclease- from pancreas breaks nucleic acid into nucleotides ph 8 peptidase secreted from stomach lining breaks petite chain into aa and its pH is 2 maltase- microvilli breaks maltose into glucose and pH 8

pepsinogen + hydrochloric acid makes pepsin– pepsinogen is made in the cell and its the inactive form of pepsin, hydrochloric acid activates it. this is required because if pepsinogen was active in the cells then it would digest proteins trypsinogen + sodium bicarbonate makes trypsin– same idea but in the duodenum

1, small intestine absorbs monomers 2. monomers travel in hepatic portal vein to liver 3. liver monitors blood content 4.blood enters general circulation thru hepatic vein **unique path of blood it goes from blood vessel to capillaries(small intestine) to vein(anterior mesenteric vein) to another vein(hepatic portal vein) to capillaries(capillaries in liver) to vein (hepatic vein)