63 terms

Test 3- Nutrition and Metabolism (part 2)

Lipolysis and Oxidation of Glycerol and Fatty Acids
eating too much, storing fats
Lipids =
lipids ->Triglycerides
between meals, broken down to: 1) glycerol and 2) fatty acids
occurs in response to:
epinephrine, norepinephrine, glucocorticoids, thyroid hormone, GH
products released into bld stream
serve as source of energy for other cells
-- converted to G3P via gluconeogenesis
-- enters glycolysis -> produces NADH & 2 ATP
-- continues thru Citric Acid cycle
[Free] Fatty Acids
-- beta-oxidation to form acetyl-CoA
-- enters Citric Acid cycle
-- production of lipids (fat stores)
-- excess glucose -> G3P -> glycerol
-- excess a.a.'s -> acetyl-CoA -> fatty acids
Protein Metabolism
protein taken in from diet -> broken down to amino acids
Oxidation of Amino Acids
amino acids broken down into intermediates (keto acids) -> enter Citric Acid cycle
first step = deamination
removal of amine grp -> converts amino acid into keto acid
Protein Synthesis
all composite amino acids need to be present in order to make the protein
-- if one missing, protein not made -> a.a.'s used for energy
Absorptive State
'Fed' State
Absorptive State
-- 4 hrs during & after each meal
-- nutrients from food in bld stream
-- ANABOLIC rxns exceed catabolic rxns
Absorptive State
excess metabolites, regardless of source, converted to fat
Fed State- Carbohydrate Absorption
all absorbed monosaccharides -> go to liver
Fed State- Triglycerides
primary energy source for: - adipose cells
- liver cells
- heart
- skeletal muscle cells (resting)
Fed State- Triglycerides
used by other cells when carbohydrates are limited
Fed State- Triglycerides
most fatty acids & glycerol -> converted to triglycerides -> stored in adipose tissue
Fed State- Amino Acids
to keto bodies
to body to make proteins
Fed State- Insulin
primary hormone promoting absorptive state
Fed State- Insulin
insulin -> b cells (pancreas) -> tissue cells -> active transport or facillitated diffusion of glucose into cells -> proteinsynthesis or ATP, glycogen, fatty acid&glycerol -> tryglyercide
Postabsorptive State
in btw meals; after nutrients from meal absorbed from bld
Postabsorptive State
-- net synthesis of protein, fat, glycogen STOPS
-- CATABOLIC rxns of glycogen, fat, protein BEGINS
Postabsorptive State
goal: maintain bld glucose between 70-110 mg/dL bld (for brain)
Postabsorptive State - Glucose sources
Glycogen breakdown (glycogenolysis) in liver -> release glucose to bld stream
Postabsorptive State - Glucose sources
Glycogen breakdown in skeletal muscle -> used in muscle itself
Postabsorptive State - Glucose sources
Fat breakdown (lipolysis) in liver & adipose
Postabsorptive State - Glucose sources
Cellular protein breakdown in liver & muscle
Postabsorptive State - Glucagon
strongly promotes postabsorptive pathways to increase bld glucose
Postabsorptive State - Glucagon (fight or flight, sympathetic)
glucagon -> liver (glycogenolysis or gluconeogensis to incre. glucose) OR glucagon -> adipose tissue -> fat brkdown (lypolysis) -> glycerol and fatty acids -> bldstream -> used by other cells in body
Cholesterol Supply
-- 15% comes from diet
-- 85% is made by liver from acetyl-CoA
Cholesterol Supply
in liver, cholesterol is catabolized to bile salts excreted in feces
Cholesterol Transport and Function
cholesterol not water-soluble -> transported in lipoprotein complexes
Cholesterol Transport and Function
start= triglyeride 90% , cholesterol 5%
end= triglercride 5%, cholestrol 20%

*low density lipoprotein (LDL) to high density (HDL)
HDL= good cholesterol
Recommended Cholesterol Levels
total = LDL + HDL
less than 200 mg/dl or mg/100ml
HDL (good)
above 40mg/dl. increase by excercise, monounsaturated fatty acids (canola oil, olive oil). decrease by cigarattes stress coffee
LDL (bad)
less than 130 mg/dl
decre. by excercise, increase by trans fats and overeating
regulation of food intake
energy input = energy output
energy input
digested and absorbed food
energy output
1 heat 2 atp -> work 3 storage (growth, fat)
Neural signals from digestive tract
vagal signals from chemoreceptors & stretch receptors -> inhibit appetite
Nutrient Signals
-- incr blood levels of glucose, amino acids, fatty acids -> inhibit appetitie
insulin, CCK -> inhibit appetite
glucagon (from pancreas), ghrelin (produced by stomach) -> stimulate appetite
Body Temperature
incre. body temp -> inhibit appetite
Psychological Factors
-- appearance, smell, taste of food
-- depression/anxiety -> stimulate or inhibit appetite
-- compulsive behavior
Metabolic Rate
total heat produced by all chemical rxns and mechanical work by body
Basal Metabolic Rate (BMR)
energy burned to perform only essential activities (~1400 kcal/day)
(e.g. breathing; resting levels of organ function)
Basal Metabolic Rate (BMR)
lowest metabolic rate occurs during sleep
Basal Metabolic Rate (BMR)
related to body surface area -> heat loss
Total Metabolic Rate
energy burned for all activities
-- most increases come from skeletal muscle activity
2000 cal for men; 1800 cal for women
Total Metabolic Rate increased by
pregnancy, anxiety (epinephrine -> msucle tension), fewer/incr body temp, thyroxine (TH)
Total Metabolic Rate decreased by
depression, cal defficiency, age
Heat Production
-- produced by all organs of body
-- incr dramatically by muscular activity
body temp
~37oC (98.6oF) (35.8—38.2 oC) for proper rates of biochem rxns
if too high ->
neurons depresed, proteins denature -> enzymes stop working
if too low ->
bio chem rxns slower, but usually ok if not very cold
Body Temperature Regulation
Hypothalamus is main integration center for thermoregulation
controlled hyperthermia, ususally due to infection
pyrogen cytokines released by macrophages stim. hyptothalamus; hypothalamus temporarily set body temp higher
vasoconstriction in skin; shivering
when Fever breaks->
sweating and vasodilation in skin