Chapter 17: Digestive Physiology Flashcards
6 classes of nutrients
carbohydrates proteins fats vitamins minerals water
what are the major nutrients?
carbs
proteins
fats
what do major nutrients provide?
- building blocks used to produce cellular structures such as plasma membranes, collagen, muscle proteins, and myelin sheaths
- provide energy (cells break them down and use the energy in their chemical bonds to produce ATP)
function of vitamins
function as coenzymes - they act with an enzyme to accomplish a particular chemical reaction
function of minerals
-they are ionized in the body fluids or attached to organic compounds and they are essential for binding oxygen, nerve impulse production, muscle contraction
function of water
- dissolving medium
- all chemical reactions occurring in the body depend on water’s solvent properties
- water is a reactant in some metabolic processes
to be be used by the body nutrients must undergo some processes. what are they?
- ingestion
- propulsion
- mechanical breakdown
- digestion
- absorption
- defecation
ingestion
taking food into the digestive tract via the mouth
propulsion
moves food through the digestive tract
-includes deglutition (chewing) and peristalsis
mechanical breakdown
increases surface area of ingested food physically preparing it for digestion by enzymes
what are the mechanical breakdown processes
mastication
mixing food with saliva by the tongue
churning food in the stomach
segmentation (rhythmic contractions of the small intestine that mix food with enzymes and other digestive secretions)
segmentation
rhythmic contractions of the small intestine that mix food with enzymes and other digestive secretions
digestion
process in which complex molecules are chemically broken down into simpler molecules
hydrolysis
breaks down the major nutrients into their basic units by adding water molecules at the bond sites
monosaccharides
the basic units of carbohydrates
amino acids
the basic unit of a protein
true or false: fats are very diverse and do not have a defined basic unit
true
most dietary fats are triglycerides which are digested into ____ and _____.
fatty acids and glycerol
hydrolysis is catalyzed by ____.
enzymes
a substance upon which an enzyme acts thereby causing that substance to undergo a chemical reaction is the ______ of that enzyme.
substrate
to catalyze a reaction, an enzyme must :
temporarily bind to a substrate
denaturing
the shape of an enzyme changes
most enzymes and other proteins are denatured by :
high temperatures and changes in pH
absorption
the movement of nutrients in the tracts lumen through the epithelium into blood or lymph capillaries in the lamina propria of the tracts mucosa
defecation
eliminates indigestible substances and any unabsorbed nutrients from the body via the anus in the form of feces
vitamins, minerals, and water must undergo _____, ____, ____.
ingestion
propulsion
absorption
indigestible materials and any nutrients that are not absorbed undergo _____.
defecation
which classes of nutrients must be digested into simpler molecules before they can be absorbed?
carbs, proteins, fats
in digestion, bonds are broken by adding _____ at the bind sites.
water: (this is hydrolysis)
polypeptides
long chains of amino acids
pepsin
protein digesting enzyme (protease)
the stomach secretes _____ and ____ into its lumen, where _____ converts ______ into active pepsin.
the stomach secretes pepsinogen (an inactive form of pepsin) and hydrochloric acid into its lumen where HCL converts pepsinogen into ACTIVE pepsin
what is a protease?
protein digesting enzyme
what is the substrate of pepsin?
hydrochloric acid (HCl)
digestion is considered to have occurred only if a piece of egg white or potato is quite a bit smaller than that in tube 1 or 6. explain why a slight change in size is not an indication that digestion occurred.
because it just mushes it by dissolving it a tiny bit
is the presence of pepsin necessary for protein digestion to occur? support your answer using experinebtal results
yes; because we compared it to test tube 2 and 3 which had the same temp, the only difference was pepsin was in one and dH2O was in the other. the pepsin tube digested it the other did not
does the pH of a test tube affect the activity of the pepsin?
yes; when we compare test tube 2 which had a pH of 1 to test tube 4 that had a pH of 8 the more acidic one digested it
pepsin catalyzes the digestion of a _______. support your answer
protein: the potato with pepsin did not digest but the egg white did
HCl makes the stomach contents:
extremely acidic
most ____ function as coenzymes.
vitamins
water is a ______, ______, and ______.
dissolving medium
solvent
reactant
