Metabolism Flashcards
The control of metabolism is directed primarily toward
1.maintaining blood [glucose] sufficiently high for nervous tissue to function, and 2. insuring that other cells of the body have adequate substrates
name 6 hormones that influence metabolism
Insulin
Glucagon
Epinephrine
Norepinephrine
Growth Hormone
Cortisol
name 3 stored forms of energy
glycogen
protein
fat (triglycerides)
name 3 forms of energy in the blood
glucose
fatty acids
ketones
what is a difference between keto acids and ketones?
keto acids are intermediates of tricarboxylic acid cycle (Krebs cycle) ketones are derived from fatty acids
name 4 tissues controlling body metabolism
Liver
Skeletal muscle
Adipose tissue
Brain
list the functions of liver hepatocytes
- GLUCOSE <–> GLYCOGEN
- Release Glucose to blood
- Gluconeogenesis
- Formation of triglicerides
- Release triglycerides to blood
- TRIGLYCERIDES –> FATTY ACIDS
- FATTY ACIDS –> KETONE BODIES
- Releases Ketone Bodies to blood
Describe the process of export of triglycerides by hepatocytes
- synthesis of apoprotein, phosphotidylcholine, triacylglycerol, cholesterol in ER
- assembly into prelipoprotein in ER then transfer to Golgi
- Golgi processes
- Formation of secretory vesicle
- VLDL is released into circulation
describe 6 functions of the liver
- capable of gluconeogenesis (in common with kidney)
- high capacity for storing glucose as glycogen (muscle 3X better)
- capable of releasing glucose into the blood (unique to liver)
- can synthesize and catabolize fat (in common with adipose tissue)
- can export TG into the blood (unique to liver)
- can synthesize and export ketones (unique to liver)
why is skeletal muscle important to overall metabolism?
it constitutes a large percentage of body weight (20%)
Where do the long term and short term energy supply in skeletal muscle come from?
long term: protein
short term: glycogen
why is adipose tissue important for metabolism?
is important in metabolism because it is the great “energy depot” of the body
Fat supplies ___% of daily calories, carbohydrate ___%.
55%
45%
why is the brain important for metabolism?
- its need for a constant supply of metabolic fuels 2. controls the secretion of important hormones (catecholamines, growth hormone and cortisol) that insure the availability of substrates during acute hypoglycemia and and chronic starvation
the brain is only ___% of body mass but is responsible for ___% of total body metabolism
2%
15%
the brain burns what percent of all glucose used/day?
burns 45% of all of the glucose used/day.
what happens when the brain is without glucose for >10 mins?
coma and death
after 4 days postabsorptive the brain gets 70% of its energy from _____.
ketones
Whether we are in an anabolic or a catabolic state depends on ….
whether we are in the absorptive phase, having just eaten a meal or in the postabsorptive phase, having completely absorbed the nutrients of the last meal we consumed
During the absorptive phase we obtain nutrients from _________ sources
exogenous (external)
name Three forms of energy currency that become available from endogenous stores
glucose
fatty acids from adipocytes
ketones from hepatocytes
_____ is the most important hormone regulating daily metabolic transitions
insulin
The rate of insulin secretion is maximal when blood glucose is _________
about 25 mM
The ability of skeletal muscle fibers to take up glucose is nearly absolutely dependent upon ____
insulin
insulin (increase/decreases) in the absorptive phase and (increase/decreases) in the postabsorptive
increases decreases
The effect of insulin on blood sugar is to
lower blood sugar
Lowering blood sugar below 5 mM _____ glucagon secretion
enhances
Hour by hour maintenance of blood glucose near 90mg/dl (5 mM) is due to the balance between the influences of blood _______ and ______.
glucagon and insulin
______ elevate blood substrates when plasma glucose falls below 70 mg/dl
Catecholamines
_______ is secreted when blood glucose falls below 70 mg/dl for a sustained period
Growth hormone
Growth Hormone functions:
- increases sensitivity of adipocytes to lipolytic stimuli
- increases gluconeogenesis in liver hepatocytes
- reduces effect of insulin to stimulate glucose uptake in muscle and adipose tissue.
____ is secreted when blood glucose falls below 60 mg/dl for a sustained period
Cortisol
