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Exercise Physiology > Lecture 10 - Hormonal Control During Exercise > Flashcards

Lecture 10 - Hormonal Control During Exercise Flashcards

1
Q

How does the proportion of plasma energy change in relation to intensity increasing (VO2 max increasing)?

A
  • the portion of plasma stays relatively stable
  • the proportion is reduced because muscle energy increases significantly
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2
Q

what is blood glucose homeostasis?

A
  • maintenance of blood glucose levels during exercise
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3
Q

what are the two reasons in which maintaining blood glucose homeostasis is important?

A
  • glucose is a major substrate for metabolism
  • glucose is the only fuel acceptable to the brain and other CNS tissues
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4
Q

what is normal resting blood glucose concentration?

A
  • 4.0-5.5 mmol/L
  • 90-100 mg/dL
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5
Q

what is the term for someone who cannot regulate blood glucose levels well?

A
  • diabetic
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6
Q

how does exercise affect blood glucose?

A
  • causes a massive increase in glucose uptake from the blood
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7
Q

why is it necessary for glucose uptake from the blood to increase?

A
  • maintain energy for muscle contraction during exercise
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8
Q

what are glut-4 transporters?

A
  • transporters on the plasma membrane
  • must be present to allow glucose to enter into the cell
  • the amount of glut-4 is affected by exercise –> this affects the amount of glucose able to enter the cytosol
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9
Q

why must glucose be restored in the blood immediately?

A
  • if we only used the glucose stored in the blood, we would only have 25 calories worth of energy
  • must be replenished or it would fall rapidly
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10
Q

what organ is responsible for blood glucose?

A
  • the liver
  • also the gut and kidneys
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11
Q

what are the two systems in the liver that release glucose into the blood?

A
  • gluconeogenesis
  • glycogenolysis
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12
Q

what is hepatic glucose production?

A
  • “the release of glucose from the liver”
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13
Q

what are the steps for how gluconeogenesis produces glucose?

A
  • start with pyruvic acid (aka lactic acid)
  • creates glucose-6-phosphate (also can be produced by amino acids or glycerol)
  • makes glucose
  • *this is an anabolic system
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14
Q

what are the steps for how glycogenolysis produces glucose?

A
  • start with glycogen
  • breaks down to produce glucose-1-phosphate
  • breaks down again to produce glucose-6-phosphate
  • this makes glucose
  • *this is a catabolic system
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15
Q

what is lipid mobilization?

A
  • a strategy to reduce glucose from falling during exercise (supports the metabolism at the muscle level)
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16
Q

How does lipid mobilization work?

A
  • use free fatty acids to provide acetyl-CoA to the Krebs cycle
  • increase in fat metabolism (means we can use less glucose in the muscles)
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17
Q

what are adipocytes?

A
  • subcutaneous fat (adipose tissue)
18
Q

what is the role of adipocytes in lipid mobilization?

A
  • release fatty acid chains (from the triglycerides) through lipolysis
  • into the blood
  • transported with albumin
  • taken up at the muscle
  • form fatty acetyl CoA
  • produce energy through the Krebs cycle and electron transport
19
Q

how is glucose regulated during exercise?

A
  • homeostasis
  • through the endocrine system (chemical communication) aka hormones
  • through the nervous system (electrical communication) aka sympathetic nervous system
20
Q

what is the role of the endocrine system?

A
  • controls all physiological processes that support exercise and maintain homeostasis
  • does this by releasing hormones
21
Q

what are hormones?

A
  • signalling molecules to trigger physiological processes within the body
22
Q

where are hormones produced and released?

A
  • by glands transported by the circulatory system to target organs for regulating physiology
  • specifically the endocrine glands (for exercise metabolism)
23
Q

how are hormones secreted?

A
  • in pulsatile bursts (plasma concentration fluctuates)
  • triggered by negative feedback - correcting an “error signal”
24
Q

what is the role of hormone receptors?

A
  • hormones bind to specific receptors
  • without receptors, hormones have no effect
  • receptors are located at the target organ
25
Q

what is the action of hormones?

A
  • exert effects after binding with receptor - do not directly affect cell activity (indirect causation)
  • initiate a predictable series of chemical reactions
26
Q

what are the 4 important endocrine glands for metabolism?

A
  1. pancreas
  2. adrenal gland
  3. anterior pituitary gland
  4. thyroid gland
27
Q

what is the role of endocrine glands?

A
  • regulate the mobilization of fats and carbohydrates
  • influence the fuel utilization we use during exercise
28
Q

what is the role of the pancreas?

A
  • endocrine regulation of metabolism
  • a gland important for regulating metabolism through the release of glucagon and insulin
29
Q

what is the importance of insulin?

A
  • lowers blood glucose
  • counters hyperglycemia, opposes glucagon
  • facilitates glucose transport in cells
  • enhances synthesis of glycogen, protein and fat
  • inhibits gluconeogenesis
  • is not present in individuals with diabetes
30
Q

what is the importance of glucagon?

A
  • raises blood glucose
  • counters hypoglycemia, opposes insulin
  • promotes glycogenolysis, gluconeogenesis
31
Q

What is type I diabetes?

A
  • absolute insulin deficiency
  • no insulin is produced
  • exercise is important because of glut-4 and uptake (to help regulate glucose)
32
Q

what is type II diabetes?

A
  • impaired glucose control
  • inadequate insulin production
  • reduced effect of insulin
  • negative feedback loops are disrupted
33
Q

how is blood glucose controlled?

A
  • (understand diagram)
  • work in a negative feedback system
  • increase in glucose signals the release of insulin so glucose lowers and vice versa
34
Q

what is a sign of hypoglycemia?

A
  • craving for candy/cereal etc.
35
Q

what is insulin-stimulated glucose uptake?

A
  • insulin binds to the insulin receptors in the plasma membrane
  • initiates the same results as exercise does
  • glycogen synthesis = glucose uptake, stimulated by insulin
36
Q

how is glucose regulated by pancreatic hormones during exercise?

A
  • blood glucose does not change even during moderate-to-heavy exercise for long periods of time
  • insulin falls during exercise (helps maintain glucose)
  • glucagon rises (more glucose is released)
37
Q

how does glucagon change during exercise?

A
  • has a large percent increase at the beginning
  • remains high (to stop hypoglycemia)
  • insulin falls and glucose hardly changes
38
Q

what is the adrenal medulla?

A
  • endocrine regulation of metabolism
  • a gland located above each kidney
  • releases catecholamines (epinephrine and norepinephrine) –> “fight or flight”
39
Q

what is the effect of epinephrine and norepinephrine release during exercise?

A
  • increase sympathetic nervous system
  • stimulate glycogenolysis in muscle and liver
  • stimulate and maintain lipolysis (Epi) –> increase free fatty acids in the blood
  • suppress insulin secretion
  • supply blood to skeletal muscle
  • increase heart rate, increases blood pressure and increases contractile force
  • Norepinephrine also causes vasoconstriction to non-active areas to send more blood to the active muscles
40
Q

how does exercise influence norepinephrine and epinephrine?

A
  • both are increased as exercise continues
  • this increases the fat metabolism so you can exercise for longer periods of time

Exercise Physiology (12 decks)

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