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
what does NaHCO3 do
Neutralize acid chyme and makes small intestine pH basic
what 3 enzymes do pancreatic juice contain
Pancreatic amylase
trypsin
Lipase
what is the function of pancreatic amylase
digest starch to maltose
what is the function of trypsin
digests pepsin to peptides
what is the function of lipase
digests fat to fatty acids and glycerol
what are two important intestinal juice enzymes and their funtions are
Peptidases: degest pepsin to amino acids
Maltose: digests maltose to glucose
where does absorption take place
across each villus into blood and lymph vessels
is absorption passive? what does it require?
-can happen passively or when activates
-active transport requires ATP
Where do sugars and amino acids go when absorbed
into the blood via capillaries
where do glycerol and fatty acids go when absorbed
recombined into lipids and enter lacteal (leads to lymph system)
what is the function of the hepatic portal
blood vessels from velli merge to hepatic portal vein which carries nutrients to the liver
what are 6 functions of the liver
-produce bile
-keeps blood glucose constant
-detoxifies blood
-destroys old RBCs
produces urea (deamination of AAs)
-makes blood protiens from AAs
what is the main different function of the large intestine from the small
the large does not absorb nutrients like the small but instead absorbs water.
what is the main bacteria in the large intestine
e.coli
where is gastrin released from and why
from the gastric gland in upper stomach
it perfroms secretion of gastric juices (pepsinogen and HCl)
what are carbs broken into
glucose
what are fats broken into
glycerol+fatty acids
what are proteins broken into
AAs
what are the two sphincters at the top and bottom of the stomach
pylroic sphincter (bottom)
cardiac sphincter (top)
what substance does the stomach digest
proteins (breaks them down into smaller chains of amino acids (peptides))
what are 2 pancreatic secretions
pancreatic juice
Insulin and glucagon
what is the function of e coli in the large intestine.
break donw indigestable foods, produces vitamins, AAs and other growth factors that get absorbed by the colon
what blood vessels do products of digestion enter
most of the digestive process enters the capillary system, fats and fat soluble nutrients diffuse into the lymphatic vessels
what problems would occur if the liver stopped functioning
blood woulf become toxic
fats cant be broken down (no bile)
blood glucose would not be constant
plasma protien + cholesterol would not be produced
Carb digestion
Mouth: salivary amylose breaks down starch to maltose
-Pancreatic amylose does the same
-Intestinal glands produce maltose that digests maltose to glucose
-glucose absorbed by blood vessels
protein digestion
-pepsin in stomach breaks down protein into polypeptide
-trypsin breaks polypeptide into a peptide
-peptidases from intestinal land break peptides into amino acids
-AAs are absorbed into bloodstream thru villi
Fat digestion
-enters duodenum where bile salts break fat down into droplets
-fat droplets are broken into glycerol and fatty acids by lipase in pancreatic juice
-glycerol and fatty acids are absorbed by lacteals and enter lymphatic system
Salivary amylase breaks down what to what
starch to maltose
pepsin breaks down what to what
proteins to peptides
peptidase breaks down what to what
peptides to amino acids
maltose breaks down what to what
maltose to glucose
lipase breaks down what to what
fats to glycerol/fatty acids
trypsin breaks down what to what
polypeptides to peptides
pancreatic amylose breaks down what to what
starch to maltose
What part covers the trachea when swallowing
epiglottis
What is the movement of the esophagus when swallowing called
peristalsis
