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nutrition chapter 7
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Undergraduate 1
02/07/2013

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Term
Stored energy
Definition
can be used during times of sleep, fasting, or exercise
Term
Extra energy as carbohydrates
Definition
stored in limited amounts as liver and muscle glycogen
Term
Extra energy as fat (triglycerides(
Definition
stored in unlimited amounts
Term
gluconeogenesis
Definition
making new glucose from non glucose substrates

glucogenic amino acids

glycerol

maintains blood glucose during sleep, fasting, trauma, and exercise
Term
protein catabolism
Definition
for glucose production can draw on vital tissue proteins (skeletal and heart muscles and organ proteins)
Term
Lipogenesis
Definition
making fat from nonfat substances such as carbohydrates, amino acids, and alcohol

when consuming excess calories, acetyl CoA unites form fatty acid chains

fatty acids combine with glycerol to form triglycerides

mostly occurs in liver cells
Term
Amino acid synthesis
Definition
the body makes the carbon skeleton of nonessential amino acids (NEAA)

amine group comes from transamination

synthesis of NEAA occurs only when the body has enough energy and nitrogen

since essential amino acids cannot be synthesized, they must be consumed
Term
Insulin
Definition
primary anabolic hormone

increases in the blood after a meal

activates storage enzymes

signals cellular uptake of glucose, fatty acids, and amino acids
Term
catabolic hormones
Definition
glucagon, epinephrine, and cortisol

triggers the breakdown of stored triglycerides, glycogen, and body protein for energy
Term
Anabolic state
Definition
bloodstream enriched with glucose, fatty acids, and amino acids

glucose stored as glycogen

glycogen stores are saturated, remaining glucose is stored as triglycerides

fatty acids are stored as triglycerides mostly in adipose tissues

amino acids are deaminated and carbon skeletons are converted to fatty acids for storage as triglycerides
Term
Metabolic responses to fasting
Definition
liver glycogen is utilized

blood glucose released

muscle glycogen reserved for muscle

most cells can switch to using fatty acids

ketones form as acetyl CoA units

glycogenesis
Term
Glycogenesis
Definition
glucogenic amino acids and glycerol
Term
Metabolic responses to starvation
Definition
body shifts to survival mode after 2-3 days

blood glucose is maintained to support brain and red blood cells

decline in activity, body temperature, and resting metabolic rate

fatty acids become the primary fuel

brain cells start to use ketone bodies

muscle protein sacrificed to supply glucose
Term
metabolism
Definition
the sum of all chemical and physical processes by which the body breaks down and builds up molecules
Term
anabolism
Definition
the process of making larger, chemically complex molecules from smaller ones
Term
catabolism
Definition
breakdown of larger, complex molecules to smaller, more basic ones

begins with digestion, old cells or tissues are broken down, releases energy
Term
Adenosine Triphosphate (ATP)
Definition
an organic compound used by cells as a source of energy
Term
Metabolic pathways
Definition
clusters of chemical reactions that occur sequentially and achieve a particular goal, such as the breakdown of glucose for energy

cells use different, yet related, metabolic pathways to release the energy
Term
Mitochondria
Definition
the primary site of chemical energy (ATP) production
Term
enzyme
Definition
mediates chemical reactions
Term
coenzymes
Definition
non-protein substances necessary for enzyme activity

provide functional group that either enhance or is necessary for enzyme activity
Term
cofactors
Definition
typically minerals required for enzyme activity, may help bind different parts of an enzyme together
Term
when glucose is transported to the liver it is...
Definition
-phosphorylated and metabolized for energy or stored as glycogen
-glucose can be phosphorylated and metabolized for energy
-released into circulation for other cells or stored as glycogen (muscle tissue)
-converted to fatty acids and stored as triglycerides in adipose tissue
Term
fructose and galactose are converted to...
Definition
glucose; converted through a series of reactions or channeled into the glycolysis pathway for energy production
Term
glucose oxidation through 3 stages
Definition
1) glycolysis
2) tricarboxylic acid cycle (Krebs Cycle)
3) oxidative phosphorylation
Term
glycolysis
Definition
occurs in the cytosol
anaerobic reaction
glucose converts to pyruvate
Term
absence of oxygen...
Definition
the body converts pyruvate to lactate

occurs in cells with few or no mitochondria
Term
oxidative phosphorilation
Definition
third and final stage of glucose oxidation

occurs in the electron transport chain

takes place in the inner membrane of mitochondria

series of enzyme-driven reactions

electrons come from NADH and FADH2, generated during glycolysis
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