Digestion Flashcards
What is digestion
mechanical and chemical breaking down of food into particles small enough for the body to absorb
What is absorption
when the small molecules pass from the lumen of the gut into the blood or lymph
what is the difference between chemical and mechanical digestion
mechanical= the physical breaking down of injested food by things like teeth or stomach thurning
Chemical= the use of the bodys hydrolytic enzymes and HCl to break down food
What is a hydrolytic enzyme
an enzyme that breaks down macromolecules by adding water
what is the enzyme in saliva
Salivary amylase
What is a substrate of salivary amylase and what are the products
substrate is starch
products are maltose
(starch+h2o=maltose)
What is peristalsis
rhythmic waves of muscle contractions that pushes food down the esophagus
What are 3 functions of the stomach
1) stores food until small intestine is ready for another small quantity
2) churns the food with its muscles mixing it with gastric secretions
3) produces gastric juices containing HCl
what does HCl do in the stomach
kills bacteria
breaks down connective tissue
creates an acidic environment which activates the digestive enzyme pepsin
what does pepsin do in the stomach
breaks down proteins into peptides
How is pepsin made
gastric juices produced by gastric gland in stomach consist of HCl, pepsinogen, and water. The HCl mixes with pepsinogen to make the active enzyme pepsin
What is the Pharynx
region between mouth and esophagus where swallowing occurs
what does the epiglottis do
is a flap of tissue that covers the opening to the trachea when swallowing
what is the cardiac sphincter
circular muscle that can open and close the control movement of food into stomach from esophagus.
What is the esophagus
a long muscular tube that uses perstalsis to send food from mouth to stomach
what is pepsinogen
a precursor molecule of gastric juice that forms pepsin when mixed with HCl
Where does the majority of digestion take place
In the duodenum
3 parts of the small intestine are
duodenum
jejenum
ilium
what controls the flow of material into the duodenum
pyloric sphincter at bottom of stomach, opens periodically to empty some chyme into duodenum
the material the enters the duodenum is called
chyme
what is the funtion of the duodenum
secretions from liver (bile) and pancreas break down fats and peptides
what does the liver produce for the duodenum
bile
what do bile salts do
emulsifying agent for fats to break up
what sodium compound does pancreatic juice contain
NaHCO3