LESSON 10 - hormonal control during exercise Flashcards
what are the four ways of substrate utilization during exercise ?
- muscle glycogen
- muscle triglycerides
- plasma Free Fatty Acids
- plasma glucose
“during exercise, a significant quantity metabolic substrate comes from ________ “
the blood
how do we maintain adequate levels of these substrate and regulate the delivery of these substrates ?
homeostasis
what is blood glucose homeostasis ?
ability to maintain blood glucose at resting levels
what are the two reasons maintenance of blood glucose levels during exercise is critically important ?
- glucose is a major substrate for metabolism
- glucose is the only fuel acceptable to the brain and other CNS tissues
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“a lot of the energy that our muscles cells / all the tissues in our body produce come from ________ “
glucose that is stored
what is our main energy source ?
glucose levels
what is the term given to those who cannot control their level of blood glucose very well ?
diabetic
why can CNS tissues only use glucose ?
glucose recevoir for the brain
what is normal resting blood glucose concentration in Canada ?
4.0 - 5.5 mol/L
what is normal resting blood glucose concentration in the US ?
90 - 100 mg/dL
does exercise increase or decrease glucose uptake from blood ?
increase
with every contraction what do we take more of ?
ATP
what initiated a cascade of signalling pathways that leads to the glucose uptake from blood ?
muscle contractions
what is the order of signalling pathways for glucose uptake ?
- contraction
- increase AMP, ATP ratio
- AMPK
- glut-4 vesicle
- glut-4 in plasma membrane
(goes either to blood vessel or ATP)
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“the more we overuse glucose, the more we ________ “
deplete
with every contraction what do we take more of ?
more ATP
where does insulin attach to glucose ?
glut-4 vesicle
when insulin attaches to glucose what receptor does it go to ?
glut-4 vesicle
what causes an increase in glut-4 vesicle transporters ?
exercise
what are glut-4 vesicles ?
transporters to the sarcolemma or plasma membrane of the muscle cells
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“glucose cannot enter the cell unless these ___________ for transporters are present on the plasma membrane “
glut-4 vesicles
TRUE OR FALSE
we store much glucose in our blood
FALSE
we do not store much glucose in our blood
can we rely on the glucose thats stored in the blood on its own ?
NO - we cannot rely on the glucose thats stores in the blood on its own to allow us to sustain any level of exercise or exercise intensity
what would happen if glucose stored in blood were the only fuel ?
(and its use was not immediately compensated for) blood glucose would fall rapidly
what happens to insulin as you exercise ?
- insulin drops as you exercise
- your body wants glucagon
a trick to know when glucagon is needed :
glucagon = glucose is gone
what does glucagon do?
when we do not have enough glucose it raises blood glucose levels
what is glucagon ?
hormone the breaks down glycogen
what is insulin ?
peptide hormone produced by beta cells in the pancreas
what does insulin do ?
takes glucose and stores it in the liver till your body needs it
what are the two ways we replenish blood glucose ?
glycogenolysis and glycogenesis
what is glycogenesis ?
production of new glucose molecules
what is glycogenolysis ?
breakdown of glycogen
what organ is a major player in the maintenance of glucose in the blood during exercise & the delivery of glucose to muscles during exercise ?
the liver
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increase release of glucose into the blood come from the ______, _____ and _______-
liver, gut and kidneys
what is hepatic glucose production ?
release of glucose from the liver
between gluconeogenesis and glycogenolysis, which is anabolic vs catabolic ?
gluconeogenesis = anabolic reactions
gycogenolysis = catabolic reactions
what are the two ways in which the liver can help maintain blood glucose from the liver ?
gluconeogenesis and gycogenolysis
between gluconeogenesis and gycogenolysis which has pyruvic acid and which glycogen ?
gluconeogenesis = pyruvic acid
gycogenolysis = glycogen
what are the steps of glycogenolysis ?
glycogen - >
< - glycogen phosphorylase
glucose 1 phosphate
< - phosphoglucomutase
G6P
becomes glucose
what are the steps of gluconeogenesis ?
( from lactic acid ) pyruvic acid - >
< - some amino acids (oxalic acid)
< - (from breakdown triglycerides) glycerol from lipids (DHAP)
G6P
becomes glucose
what is lipid mobilization ?
run out of glucose so you use triglycerides
where does lipid mobilization travel starting from adipose tissue and ending with the muscle ?
adipose tissue - blood plasma - muscle
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“thorough ______ we can release those free fatty acids into the blood”
lipolysis
triglycerides are how many kcal ?
50,000-100,000 kcal
what are the two pathways that triglycerides go to ?
FFA or glycerol
how do triglycerides travel through glycerol ?
- triglycerides in adipose tissue
- glycerol in blood plasma
-intramuscular triglyceride also to glycerol in blood plasma
how do triglycerides travel through FFA ?
- triglycerides in adipose tissue
- FFA in adipose tissue
- FFA-albuilmin-> FFA
- Fatty Acids in muscle
how does the body “know” to increase glucose production in liver or to mobilize fat stores ?
glucose homeostasis
glucose homeostasis during exercise is maintained through what two physiological regulations ?
endocrine and nervous system
what is endocrine system ?
chemical communication
what is nervous system ?
electrical communication
what does the endocrine system do ?
controls all physiological processes that support exercise and maintain homeostasis
how does the endocrine system do its job ?
by releasing hormones
how do hormones work ?
signaling molecules, produced and released by glands that are transported by the circulatory system to target organs where they act to regulate physiology
what triggers the secretion of hormones ?
triggered by negative feedback
what is a negative feedback ?
correcting an “error signal” - like your thermostat !!
how are hormones secreted ?
secreted in pulsatile bursts (plasma concentration fluctuates by minutes to hours, days to weeks)
how do hormones bind to receptors ?
bind to specific receptors (no receptor = no effect)
give two examples of receptors :
- insulin binds to insulin receptors
- norepinephrine binds to alpha receptors
what is the action of hormones ?
exert effect after binding with receptor (do not directly affect cell activity)
what are the four important endocrine glands we’re talking about for metabolic regulation ?
- pancrease
- adrenal gland
- anterior pituitary gland
- thyroid gland
what do the hormones released by the pancrease, adrenal gland, anterior pituitary gland and thyroid gland regulate ?
mobilization of fats and carbs `
what does the hypothalamus do ?
regulates homeostasis
what are the two parts of the pituitary glands ?
anterior and posterior
what is the posterior pituitary gland responsible for ?
ADH and oxytocin
what is the anterior pituitary gland responsible for ?
everything else
what is the thyroid gland responsible for ?
TSH and Basal Metabolic Rate
what are the two hormones released by the thyroid gland ?
T3 and T4
what are the four main parts of the adrenal glands ?
- aldosterone
- cortisol
- androgens
- epinephrine
what happens to cortisol levels when stressed ?
cortisol levels elevated
what is the pancreas responsible for ?
endocrine regulation of metabolism
what are the two things the pancreas is responsible for ?
insulin and glucagon
what does insulin do ?
lowers blood glucose
what does glucagon do ?
raises blood pressure
what does insulin counter and oppose ?
counters hyperglycaemia and opposes glucagon
what does glucagon counter and oppose ?
counters hypoglycaemia and opposes insulin
which type of diabetes is more autoimmune ?
type 1
describe type 1 diabetes :
- absolute insulin deficiency
- no insulin production
which type of diabetes is more genetic link ?
type 2
describe type 2 diabetes :
- impaired glucose control
- inadequate insulin production
- reduced effect of insulin
in which diabetes are beta cells overworked ?
type 2
which diabetes type has an inadequate insulin production ?
type 2
which diabetes type has no insulin production ?
type 1
does insulin lower or raise glucose ?
lowers
does glucagon lower or raise glucose ?
raises
what are the two organs that take up glucose from bloodstream ?
muscle and liver
what two types of cells are found in the pancreas ?
alpha and beta cells
does glucose increase or decrease beta cells in the pancreas ?
increase
does glucose increase or decrease alpha cells in the pancreas ?
decreases
what does insulin bind to ?
insulin sensitive receptor
what is “released by vesicles within the cytosol of the muscle and translocates to the plasma membrane where they can then accept glucose from the blood”
glut-4 vesicle
what does the glut-4 vesicle open up ?
the plasma membrane
once glucose enters the plasma membrane how many options (pathways) does it have ?
2
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where does glucose go once in the plasma membrane ? _________ or ________
blood vessel or glycolysis to form ATP
in a healthy individual, during moderate to heavy exercise, does blood glucose change much (even after 3 hours) ?
blood glucose does not change much even after 3 hours
during moderate-to-haevy exercise, describe insulin concentration :
insulin concentration falls
why does insulin concentration fall during moderate-to-heavy exercise ?
less glucose uptake; more plasma glucose
during moderate-to-haevy exercise, describe glucagon concentration :
glucagon concentration raises
why does glucagon concentration raise during moderate-to-heavy exercise ?
more liver glycogenolysis and glucose raises
where is the adrenal medulla located ?
above each kidney
what does the adrenal medulla release ?
catecholamines (fight or flight)
where is epinephrine and norepinephrine released by ?
adrenal glands
does exercise increase or decrease the sympathetic nervous system ?
increases
what does increased sympathetic nervous system do in regards to epinephrine and norepinephrine levels ?
increases
what does epinephrine and norepinephrine release cause :
- stimulate glycogenolysis in muscle and liver
- stimulate and maintains lipolysis (epi)
- suppress insulin secretion
what does all of the following have in common :
- heart rate, contractile force, blood pressure
- blood flow to skeletal muscle
increased delivery of glucose and FFA to active muscle
cellular glucose uptake is the metabolic effect from what hormone ?
insulin
lipolysis is the metabolic effect from what hormone ?
cortisol, epinephrine and growth hormone
glycogen synthesis is the metabolic effect from what hormone ?
insulin
muscle glycogenolysis is the metabolic effect from what hormone ?
epinephrine, norepinephrine and cortisol
liver gluconeogenesis is the metabolic effect from what hormone ?
glucagon
liver glycogenolysis is the metabolic effect from what hormone ?
glucagon, epinephrine and norepinephrine
decrease in blood glucose is the metabolic effect from what hormone ?
insulin
triglyceride synthesis is the metabolic effect from what hormone ?
insulin
what regulates the shift in substrate utilization throughout exercise ?
hormones
what is the skeletal muscles preferred source of fuel ?
stored glycogen
with prolonged exercise, when muscle glycogen stores are depleted, what do we rely on ?
rely increasingly more on delivery of fat in the form of free fatty acids
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_________ must remain available to the brain always.
glucose
what regulates the shift in substrate utilization and mobilization of fat and carbohydrate stores ?
hormones
