Chapter 22: Mammalian Fuel Metabolism Flashcards
How do organisms coordinate their metabolic processes?
So opposing pathways do not operate simultaneously. And so organism can respond to changing external conditions like nutrient availability.
What is the interconnectedness of various tissues ensured by?
Neuronal circuits and hormomes.
Overview of metabolism:
What organ carries out all metabolic pathways?
Liver
Most to least metabolically active tissues:
Liver > Adipose Tissue > Muscle Tissue
How much glucose does the brain require?
~ 20% of O2 and ~20% of glucose
What does the brain use O2 and glucose for?
Aerobic energy powers the Na+K+ ATPase that maintains membrane potentials to conduct nerve impulse transmission.
The brain does not store _____ well.
Glycogen
_____ and ______ function to support nerve cells.
Astrocytes, Oligodendrocytes
*Carry out anaerobic metabolism and can supply lactate to nerve cells for further break down.
How much glycogen do muscles store?
1-2% of its mass is glycogen.
If fatty acids are a more energy-dense fuel, then why is it not preffered?
Glucose is easier to burn and can burn aerobically or anaerobically. Fatty acids can ONLY be burned under aerobic conditions.
In what conditions is muscle contraction anaerobic?
High exertion. At rest muscle consumes ~30% O2.
How does muscle respiration rate change?
Under strenuous exercise, it will increase by 25% or more and ATP hydrolysis can increase even more.
How can ATP be regenerated for muscles?
Phosphocreatine, but only lasts for about 4 seconds. Then the muscle switches to anaerobic metabolism.
The heart cells have how many mitochondria?
~40% of cytoplasm is mitochondria in cardiomyocytes (cardiac muscle cells) .
What is the resting hearts fuel of choice?
Fatty acids, but will switch to glucose as heart rate increases.
The heart has a ____ supply of glycogen.
limited
What are the fuels that the heart uses?
Fatty acids
Ketone Bodies
Glucose
Pyruvate
Lactate
What is the function of adipose tissue?
To store and release fatty acids as needed for fuel as well as to secrete hormones involved in regulating metabolism.