Lecture 58 Flashcards
Macronutrients (Park)
Digestion of Proteins
3 stepped process (gastric digestion –> intestinal digestion of peptidases –> intestinal digestion of intracellular peptidase)
only free amino acids are released into the blood
gastric digestion of proteins
low pH of the stomach denatures the proteins
first step in digestion
exception is pepsin which is stable and active in acidic pH
intestinal digestion of proteins (2)
peptidase at the luminal surface produces free amino acids and di/tripeptides
intestinal digestion of proteins (3)
intracellular peptidases hydrolyzes di/tripeptides
digestion of carbohydrates
through a-amylase and enzymes on the luminal surface
only monosaccharides are absorbed in the body
a-amylase
turns starch and glycogen to maltose and maltotriose in the saliva and pancreatic juice
enzymes on the luminal surface of small intestine
maltase (converts maltose –> glucose)
sucrase (converts sucrose –> glucose/fructose)
lactase (converts lactose –> glucose/galactose)
Raffinose
oligosaccharide
cannot be hydrolyzed by human enzymes
digestion of lipids
solubilized first by bile acid then gastric and pancreatic lipase hydrolyzes tricylglycerols to fatty acids and monoacylglycerols
trans fats
raise blood cholesterol levels and increase the risk of heart disease
role of essential fatty acids
synthesize eiconsanoids
chylomicron
delivers lipids to tissues
macronutrients in muscle
lipids - energy source
carbohydrates –> glycogen - used during exercise
protein - storage
macronutrients in adipose tissue
lipids - fat storage
excess proteins - converted to triacylglycerol
excess carbohydrates - triacylglycerol
lipids in the brain
stored, but fat cannot be used as an energy source
macronutrients in the liver
lipids - converted to ketone bodies in ketogenesis when starved
carbohydrates –> glycogen - used to maintain blood glucose levels
essential fatty acids
omega-3 (w-3) fatty acids
omega-6 (w-6) fatty acids
omega-3 (w-3) fatty acids
a-linolenic acid (18:3)
eicosapentaenoic acid (EPA)(20:5)
docosahexaenoic acid (DHA)(22:6)
omega-6 (w-6) fatty acids
linoleic acid (18:2)
arachidonic acid (20:4)
essential aa that cannot be synthesized
histidine
isoleucine
leucine
lysine
threonine
tryptophan
valine
essential amino acid categories
cannot be synthesized in the body
not enough synthesis by the body to be sufficient
essential aa that are not synthesized enough
arginine
methionine
phenylalanine
deficiency in essential lipids
changes to the regulatory processes of blood pressure, blood clotting, and immune functions
deficiency in essential proteins
negative nitrogen balance