lec 8 pt2 nutrition and digestion Flashcards
living organisms require ____ as nutrients
elements
what are macronutrients?
elements needed in large amounts
which 3 macronutrients make up 93% of our weight?
C, H, O
what are micronutrients? whats an example?
tiny amts necessary for life
eg. vitamins
which element is needed in a small amount to be used to make hormones?
iodine
what are 3 main categories of human dietary requirements?
-carbohydrates
-fats (lipids)
-protien
explain why we need each of the 3 categories of human dietary requirements?
carbs:
-source of energy+carbon
fats:
-concentrated form of energy
-essential fats: required to make certain compounds
protein:
-source of amino acids
-b/c we cant make all AA
what are essential amino acids?
amino acids we MUST obtain from food
how to animals obtain nutrients?
digesting food in order to absorb necessary molecules
one way system that carries food from mouth to anus
digestive system (gut)
what are two roles of saliva?
-moistens food to aid in digestion
-breaks starch–> sugar w/ enzyme amylase
what is the route food takes after leaving the mouth?
esophagus–> stomach–>small intestine–>colon–> anus
once food reaches the stomach, what does the stomach do?
mixes food with acid + stores it
where does food go after the stomach? what happens here?
small intestine
breaks down macromolecules for easy absorption
-small intestine’s epithelial cells absorb
removes additional water and nutrients from food
colon/large intestine
what happens after food passes through the colon?
food becomes feces
expelled thru anus
the animal digestive system involves ______, ________ and waste.
breakdown, absorption
specialized epithelial cells in the stomach secrete…?
HCl- hydrochloric acid
what is the role of hydrochloric acid in the stomach?
-kills most microbes present in food
-breaks down extra-cellular matrix of food
what is the purpose of mucous in the stomach? where is it produced?
-protects epithelial cells from HCl (acid)
-secreted from epithelial cells
the stomach grinds food by….?
peristalsis: muscle contraction
what is peristalsis?
muscle-driven movement of the gut
what are proteases in the stomach? what is an important protease? where are they produced?
enzymes secreted by epithelial cells
Pepsin: breaks down protein
what is the role of epithelial cells in the small intestine?
-secrete digestive enzymes
-absorb nutrients thru active transport
what is the pancreas?
source of digestive enzymes
what are 3 important digestive enzymes from the pancreas? what do they do?
lipase- breaks down fats
protease- breaks down protiens
amylase- breaks down carbs
what is bile? where is it produced? where is it stored?
liquid that emulsifies lipids, increases efficiency of lipase
produced in liver
stored in gallbladder
explain how the anatomy of the small intestine makes it the ultimate absorber
cavity lined with villi (finger-like projections of epithelial cells)
villi increase # of epithelial cells, therefore increasing absorption
villi kinda look like a microfiber duster
why must food be broken down by enzymes during the digestion process?
in order to enter epithelial cells
what occurs in the colon(large intestine) when it receives digested food?
-mostly water and some nutrients are absorbed
-food becomes feces
the bacteria that heavily colonize the colon are called? what are two functions of this bacteria?
the normal flora
-produces certain vitamins (K)
-repels+inhibits pathogenic (harmful) bacteria
the human digestive system is regulated by…?
hormones
what is a common example of missing enzymes we see?
lack of lactase
causes lactosis/ lactose intolerance
what is one enzyme that all animals are missing? what does it cause?
lack cellulase
cant digest cellulose so we don’t get much energy from plants
how are herbivores able to survive off of plants if they lack cellulase?
intestinal microorganisms (bacteria, fungi, protists)
digest cellulose, release glucose
filtering unit of the kidney
nephron
what does the hormone gastrin do?
causes stomach to produce acid
what is the role of secretin?
causes pancreas to send out digestive juice
stomach-pepsin
liver-bile
hormone produced in the stomach and upper intestine when food is absent, stimulates appetite.
ghrelin
produced in the GI tract when food is present,
inhibits appetite
peptide YY
