Transcript Food Utilization

Unit I: Metabolism
Food Utilization
Chapter 22
Nutrition provides raw materials.
Metabolism provides chemical change of the nutrients.
Body Weight
• Energy balance
– homeostatic set point
• Environmental and hereditary factors
Gut-Brain Peptides
Appetite regulators
– short term
CCK – stop eating
Peptide YY - satiety
Ghrelin - hunger
– long term
Leptin – levels proportional to fat stores
insulin – index of body fat
Hypothalamus
2 neural networks:
•
Receptors for gut-brain peptides that regulate release of:
1. Neuropeptide Y
2. Melanocortin
Appetite Regulation
Other Factors in Appetite Regulation
• Briefly satisfied by:
– chewing
– swallowing
– stomach filling
• Gastric Peristalsis
• Neurotransmitters
– norepinephrine – carbohydrates
– galanin – fats
– endorphins – protein
Calories
• One calorie - amount of heat required to raise temperature of 1 g of
water 1 °C
• Fats contain about 9 kcal/g
• Carbohydrates and proteins, about 4 kcal/g
– sugar and alcohol are “empty” calories
Activity
• Fuel
The MyPyramid.gov Steps to a Healthier You
GRAINS
Make half your grains whole
VEGETABLES
Vary your veggies
FRUITS
Focus on fruits
O
MEAT & BEANS
MILK
I
Go
lean with proteins
Get
your
calcium-rich
foods
L
Nutrients
• Ingested chemical used for growth, repair or maintenance
• Macronutrients
• Micronutrients
• Recommended daily allowances (RDA)
– safe estimate of daily intake for standard needs
• Essential nutrients can not be synthesized
– minerals, vitamins, 8 amino acids and 1-3 fatty acids
Glycogen Metabolism
• Glycolysis
• Glycogenesis -– stimulated by insulin
– average adult contains 440 g
• Glycogenolysis -– only liver cells can release glucose back into blood
• Gluconeogenesis –
• Require 125 – 175 grams/day
Lipids
CYTOSOL
• Triglycerides are stored in adipocytes
Steroids
Triglycerides
Glucose
• Lipogenesis -Glycerol
Cholesterol
• Lipolysis –
Prostaglandins
Fatty acids
Pyruvate
Phospholipids
Glycolipids
• Require 80 – 100 grams/day
CO2
Coenzyme A
ADP
ATP
Acetyl-CoA
Citric
acid
cycle
MITOCHONDRIA
Proteins
• Amino acid pool – May be used to synthesize new proteins
– As fuel
• Require 44 – 60 grams/day
Other Nutrient Classes
• Water
– require 2.5 liters/day
• Minerals
– require 0.05 – 3,300 mg/day
• Vitamins
– require 0.002 – 60 mg/day
Vitamins
• Fat-Soluble
– vitamins A, D3, E, and K
– hypervitaminosis
• Water-Soluble
– vitamins B & C
– coenzymes
– avitaminosis
Disorders
• Eating Disorders
– anorexia – lack of appetite
– Bulimia – “eating binge”
• Obesity – 20% over ideal weight
• Protein Deficiency disease
– Kwashiorkor
deficient in essential amino acids
Absorptive State
Insulin
LIPIDS
Triglycerides
Insulin
Lipid levels
elevated
Fatty acids Glycerol
• 4 hours
during and
after a
meal
• Regulated
by insulin
KEY
= Catabolic
pathway
Glucose
levels elevated
= Anabolic
pathway
= Stimulatio
CARBOHYDRATES PROTEINS
Glycogen
Proteins
Insulin
Glucose
G
l
Insulin
Androgens
y
Estrogens
c ATP
Growth hormone
o
Amino acids
l
Amino acids
elevated
y
s
Insulin
i
s
Pyruvate
CO2
Insulin
Acetyl-CoA
Citric
acid Coenzymes ETS
cycle
MITOCHONDRIA
CO2
ATP
O2
H2O
O2
KEY
= Catabolic pathway
Glucose levels decreased
For use primarily
by neural tissues.
Postabsorptive State
= Anabolic pathway
Glucose released
by the liver
LIPIDS
Triglycerides
PROTEINS
Proteins
Glucagon
Epinephrine
Lipid levels decreased
Glucose
Absorbed by
other tissues.
Fatty acids
released by
adipocytes
CARBOHYDRATES
Glycogen
= Stimulation
G
l
u
c
o
n
e
o
g
e
n
e
s
I
s
Glucagon,
Epinephrine,
Growth hormone
Fatty acids
Glycerol
ATP
Homeostasis of
blood glucose
critical to brain
Amino acids
released by
the liver
Amino acids
Glucagon
Growth hormone
Pyruvate
CO2
ATP
Acetyl-CoA
Various hormones trigger
glycogenolysis,
gluconeogenesis,
lipolysis
Amino acid
levels decreased
Glucocorticoid
Citric Coenzymes
acid
cycle
Ketone bodies
ETS
O2
MITOCHONDRIA
H2O
CO2
O2
Metabolic Rate
• Amount of energy used in the
body in a given period of time
(kcal/hr or kcal/day)
– measured directly in
calorimeter
– measured indirectly by a
spirometer
1 L O2 = 4.82 Cal/L
1000
Calories per hour
• Basal metabolic rate (BMR)
– adult male BMR is 2,000
kcal/day
800
Estimated Calories expended
by a 70-kg individual
600
400
200
• Total metabolic rate (TMR)
0
Resting
Slow
walking
Speed
walking
Climbing
stairs
Jogging Competitive
swimming
Exam 1
Chapters 21 & 22
• Multiple Choice
• Fill in the blank
• Matching
•Short answer
• True/False
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