Exam 1-Nutrition, Feeding and Digestion Flashcards
Unused Amino Acids
- into Krebs
- create ammonia (toxic-needs to be at low concentration) is converted to urea (less toxic)
essential amino acids
we don’t have enzymes to make them, must be consummed
kwashiorkor
- type of starvation
- children may have adequate calorie levels but low on protein (missing essential AA)
- lacking muscle (increase protein concentration)
- belly, osmotic pressures (plasma protein albumin in blood-tissue is hyperosmotic and blood hyposmotic-water moves from plasma to tissue b/c pressure created, [adema])
vitamin
essential organic compound needed in small quantities
(vitamin)
water soluble
don’t store in body, must be taken in daily
riboflavin, biotin, callogen
(vitamin)
lipid soluble
can be stored in fat, increase in body fat means increase in storage while decrease in body fat means more available vitamins
(vitamin A, D, E, K)
mineral
non-organic chemical (typically a metal) that is needed in small quantities
(Fe, Mg, Zn, Ca)
feeding
the obtaining and digestion of food
digestion
the process of splitting up ingested food molecules into smaller chemical compounds that can be absorbed
fermentation
anaerobic digestion involving symbiotic flora
absorption
transfer of digestion products from the GI tract (external( to the blood (internal)
suspension feeding
feeding on objects suspended in water that are very small by comparison to the feeding animal
crop
pouch in esophagus; temporary food storage
gizzard
contains pebbles/sand; grinds seeds/grains
headgut
mouth and esophagus
foregut
stomach
midgut
small intestine (digestion/absorption)
hindgut
large intestine (colon) (preparing things to exit body)
digestion basics
extracellular digestion
midgut is primary region of digestion and absorption
most enzymes hydrolytic
(digestive enzymes)
intralumenal enzymes
- released into open area
- salivary glands, cells of stomach wall, pancreas, liver/gall bladder
(digestive enzymes)
membrane associated enzymes (brush border)
- small intestine
- microvilli increase surface area, can trap enzymes
(digestive enzymes)
intracellular
-few
(carbohydrate digestion)
amylase
- starches into smaller starches (disaccharides)
- generic (breakdown anything)
(carbohydrate digestion)
disaccharidase
- disaccharides to monosaccharides
- more specific (ex: lactase)
(protein digestion)
zymogen (proenzyme)
pre-activated because it will breakdown any protein (including cells) making it difficult to store
(protein digestion)
endopeptidase
look for bonds and breakdown
make smaller amino acid strands
(protein digestion)
exopeptidase
start chewing protein from the end breaking it down
(lipid digestion) emulsifying agents (detergents)
disrupts bonds so you can disperse (breaks apart clusters of hydrophobic molecules)
(lipid digestion)
lipase
breaks down lipids
intracellular enzymes
foregut fermentation
- specialized gut chambers found in ruminants before the stomach
- synthesis of B vitamins, essential AA
- digestion of cellulose into short-chain fatty acids
- N recovery (urea into AA)
hindgut fermentation
enlarged cecum/colon
used by mammals, herbivorous birds, herbivorous lizards and turtles
eat feces, gives vitamins (don’t let anything get left behind)
(absorption)
simple diffusion
small, usually nonpolar
(absorption)
facilitated diffusion
salts, AA, bigger substances
(absorption)
active transport
requires energy, against gradient
big molecules
surface area in small intestine
200-250 m2 surface area
circular folds, villi, microvilli (brush border)
carbohydrate digestion
-mouth: salivary amylase (which denatures in stomach)
-stomach: holding place, might absorb
-SI: pancreatic amylase (make disaccharides)
BB enzymes (breakdown disaccharides)
carbohydrate absorption
- SGLT1: (secondary active) depends on Na gradient as cotransporter for glucose (no gradient for glucose)
- GLUT2: (facilitated) there is now a concentration gradient for glucose
protein digestion
- mouth: nothing
- stomach: HCl (denatures proteins, pH 3 between meals and pH 1 during meal)
- –pepsinogen (self activating in acidic becoming pepsin which is endopeptidase)
(protein digestion)
in small intestine
-SI: pancreas releases sodium bicarbonate (neutralize acid)
thin layer of mucus in SI because absorption needed
-trypsin (endopeptidase) self activated and activates chrymotrypsin (endopep.) and carboxypeptidase (exopep.)
-BB enzymes
protein absorption
transporters, most cotransport with sodium
lipid digestion
- mouth and stomach: none
- SI: emulsification (bile salts acts as detergent made of cholesterol and heme breaking up triglyceride clumps)
- –pancreatic lipase: take large fat droplets and create smaller micelles which can be absorbed
lipid absorption
- to enter cell, bile salts stay behind (simple diffusion)
- forms chylomicron (covered with protein coat)
- exocytosis into lacteal 1st (lymph, prevents huge influx of fat into blood stream
(hormonal regulation of digestion)
gastrin
- stimulus for release (partially digested protein in stomach)
- released into blood (positive feedback mechanism-endpoint is once proteins are gone and pH gets low)
- stimulates release of HCl and pepsinogen
(hormonal regulation of digestion)
secretrin
- released when acidic, stimulated by protein presence (somewhat lipids-stimulates liver to release bile)
- inhibits stomach activity (negative feedback)
- stimulates pancreas to release enzymes and bicarbonate
(hormonal regulation of digestion)
cholecystokinin (CCK)
- stimulated by lipids (cause liver/gall bladder to release bile)
- somewhat stimulated by proteins (causes pancreas to release enzymes and bicarbonate)
- satiety: sense of fullness
large intestine
- not much absorption
- bacterial flora: vitamin K
- defecation: 2 sphincters (internal-smooth, involuntary; external-skeletal, voluntary)
