2.1 Digestion: From Food to Fuel Flashcards
What is digestion?
the process of transforming food into basic nutrients that can be absorbed and used by the body
What are the three uses of nutrients once they are absorbed by the body?
- fuel cellular growth
- fight infections
- provide energy to muscles and brain
What are the stimuli that cause that cause a cascade of events by the nervous system and hormones prior to food entering the mouth?
- cognition
- sound
- odor
- appearance
- taste
What are the two processes that break down food into smaller units?
mechanical
chemical
What is the mechanical process of food breakdown in the mouth?
chewing
What is peristalsis?
involuntary muscle contractions used to move food mixtures along the GI tract
What are chemical means of breaking down food?
enzymes
acid
bile
mucus
What are enzymes?
proteins that catalyze chemical reactions
What is the GI tract?
long hollow consisting of several layers of tissue that begins with the mouth and ends at the anus
What is the mucosa?
inner most layer of the intestinal wall made of absorptive cells and glands
What are the circular and longitudinal muscles of the GI tract?
outer layer of the tract that function to mix and move food along
Where are circular muscle bands most often found? What are the main functions?
where one part of the body connects to another; serves as a valve to control the flow of food particles
What are the three processes the body can use to move nutrients from the GI tract into the blood/lymph system?
- passive diffusion
- facilitated diffusion
- active transport
What is passive diffusion?
substances move into and out of cells without the use of energy down their concentration gradient
What is facilitated diffusion?
special protein carrier is required to help substances move in or out of a cell; does not require energy; moves down concentration gradient
