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Biochemistry > W2 - Metabolic effects of hormones & cytokines during exercise > Flashcards

W2 - Metabolic effects of hormones & cytokines during exercise Flashcards

1
Q

Define Metabolism

A

the biochemistry in the cell to keep the e.g.: muscle functioning

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2
Q

Name some hormones which are effecting during exercise

A
  • Glucagon
  • Insulin
  • Adrenaline
  • Steroid/sex hormones
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3
Q

Where are the MAIN hormones in the body? Where are they produced?

A
  • Adrenaline - adrenal glands
    • Thyroid hormones - thyroid glands
    • Pancreas - Insulin
    • Muscles & Adipose tissues - cytokines (very metabolically active in their endocrine function)
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4
Q

What are the main functions of hormonal changes during exercise

A
  • Maintain blood pressure
  • Redistribution of blood to working
    muscle
  • Increase fuel mobilisation: glucose and free fatty acids (FFA)
  • Maintain blood glucose concentration
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5
Q

Name the hormones which rise during exercise:

Name the hormone that is reduced in production during exercise:

A

+ adrenaline (vasomotor tone, heart rate & contractility)
+ noradrenaline (above & lipolysis, glycogenolysis)
+ cortisol (Gluconeogenesis, anti-inflammatory)

  • Insulin (lipolysis, liver glucose release)
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6
Q

Name some examples of steroid hormones?

A

cortisol, progesterone, testosterone, aldosterone

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7
Q

Describe how steroid hormones(lipid soluble) cross a cell membrane and form a protein

A
  • Steroid Hormone enters cell
  • Hormone binds to specific receptor in cytoplasm/in nucleus
  • Hormone receptor complex activates the cell’s DNA = forms RNA
  • The mRNA leaves the nucleus & enters the cytoplasm
  • The mRNA directs protein synthesis in the cytoplasm

Hormone at beginning –> Protein at end
* e.g.: testosterone, Progesterone, cortisol

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8
Q

Explain how non-steroid hormones cross a cell membrane and create hormonal effects

A
  • Nonsteroid hormones can’t pass through the cell membrane
  • Hormone binds to specific receptor on the cell membrane
  • The hormone receptor complex activates adenylate cyclase within cell membrane
  • Adenylate cyclase catalyses the formation of cAMP
  • cAMP activates protein kinases (enzymes) that lead to cellular changes & hormonal effects
  • second messengers: cAMP, cGMP, IP3
  • e.g.: Adrenaline, Insulin
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9
Q

What is insulin?

A
  • Insulin regulates glucose entry into tissues
  • Insulin insensitivity (→ Diabetes): inability to control blood glucose levels
  • Neurones are dependent on blood glucose e.g.: brain cells, which can cause problems with neurones
  • Can be used as a murder weapon: Insulin shock
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10
Q

What hormone inhibits insulin secretion and why?

A

Adrenaline inhibits Insulin secretion during exercise → increasing a cells’ sensitivity to insulin
○ More glucose is therefore present in blood stream for muscle cells
○ Insulin causes glucose uptake into cells
○ For same concentration of insulin MORE glucose can be taken up into the cell (insulin sensitivity)
○ A healthy lifestyle helps to increase cell insulin sensitivity

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11
Q

What are insulins effect of blood vessel size?

A
  • Insulin creates a vasodilation action
  • Insulin induces greater blood flow to e.g.: muscle cells
  • Action via nitric oxide (NO)
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12
Q

What is the role of glucagon?

How is it’s release stimulated?
Where is it released from?

A
  • Increases blood glucose levels but stimulating the breakdown of glycogen (glycogenolysis) in the liver.
  • Promotes the formation of glucose from non-carbohydrate precursors (gluconeogenesis) in the liver.
  • Glucagon has the opposite effect to insulin
  • Stimulated by the fall in blood glucose levels
  • Released by a cells of the pancreas
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13
Q

What effect does insulin have on GLUT4 transporters?

What is the role of GLUT4?

A
  • Insulin signalling changes the concentration of glucose transporters at the cell membrane
  • GLUT4 acts on the cell membrane of muscle and adipose tissue
  • translocation to cell membrane from intracellular space
  • Muscle contraction independently can move the GLUT transporter to the membrane
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14
Q

Describe the hormonal activation of glycogenolysis

A

Adrenaline turns ATP into cAMP, which can trigger reactions

  • Kinase puts a phosphate group onto another cell
  • Changes the cell from being inactive to active
  • Allows for 1 glucose molecule to be broken off from a chain of glycogen e.g.: a liver cell
  • Releases glucose into the muscle, which can be taken up by muscles for contraction
  • Adrenaline is involved when bringing glucose OUT the cell (gluconeogenesis) & lipolysis in adipose tissue
  • Insulin can convert cAMP to AMP (change the reaction)
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15
Q

Explain the hormonal activation of lipolysis

A
  • when adrenaline converts ATP into cAMP, it causes an onset of multiple reactions
  • Active HSL when activated can breakdown fat
  • FFA into blood stream
  • FFA in blood stream can be used for energy in cell when taken up
  • Insulin can convert cAMP to AMP (to keep energy dense molecules in cells)
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16
Q

What are the intracellular factors that are involved in muscle glycogen breakdown and glycolysis during exercise?

A

Intracellular factors
* Increased Ca2+
* Increased AMP and Pi
* Decreased ratio of ATP:ADP
* Decreased PCr
* Increased fructose 6-phosphat

17
Q

What hormones involved in muscle glycogen breakdown and glycolysis during exercise

A
  • increased adrenaline and noradrenaline
  • decreased insulin
  • increased glucagon
18
Q

How does the multitude of the hormonal influence differ in contracting to non-contracting muscles during exercise?

A
  • Glycogen breakdown in non-contracting muscles(exposed to hormonal changes) is NOT significant compared to contracting muscles(because they are metabolically active)
19
Q

How do intracellular factors change enzyme function?

Name some activators
Name some inhibitors

A

These are molecules produced in a cell with a capacity to activate or inactivate enzymes by binding to binding to allosteric sites
- e.g.: Phosphofructokinase (phosphorylates fructose 6-phosphate in glycolysis
- Activators: AMP, Pi, ADP
- Inhibitors: ATP PCr

20
Q

What are the mechanisms of changed hormone secretion during exercise?

A

CNS:
- Metaboreceptors in working muscles
- Thermoreceptors
- Motor centres of brain
- Fall in blood glucose (glucagon)
Hypothalamus:
- Pituitary gland (ACTH, vasopressin, cortisol)
Increased SNS activity:
- nor/adrenaline, renin, aldosterone

21
Q

How do hormonal changes during exercise act on the kidney?

A
  • Increased WATER and SODIUM retention
    • Helps to maintain blood volume and change blood pressure
      –> INCREASE vasopressin (from pituitary) = helps retain water
      –> INCREASE aldosterone (from adrenal cortex) = helps to retain sodium
22
Q

What are cytokines?

A

○ Secreted molecules that can cause specific effects both on the cell that they are secreted (autocrine effects) and on other cells (paracrine effects)
* Cytokine: cell- movement
* Interleukin (IL): communication between leukocytes
* Messenger molecules to communicate between (white blood) cells, important in cell signalling

23
Q

How are cytokines different to hormones?

A
  • Both are secreted into circulation and modify the behaviour of cells elsewhere
    – Cytokines
    • Proteins
    • Originally in white blood cells (→interleukins), but secreted by other tissues

– Hormones
* Can be proteins e.g. insulin, testosterone/ FA derivatives
* Produced by specific cells (e.g. insulin by pancreas, adrenaline by adrenal glands etc.)

24
Q

What can the anti-inflammatory effects of exercise lead to?

A
  • Decrease in visceral fat accumulation(lipolysis and fat oxidation)
  • Decreased inflammation (ageing)
  • Decreased chance of Chronic disease: diabetes, CVD
25
Q

What role does IL-6 play at rest?

A
  • Reduces resting levels of inflammation (tested through inflammatory markers in the blood)
  • IL-6 increase triggers increase in anti-inflammatory cytokines
  • IL-6 released into blood when strenuous exercise is taking place
    —-> this triggers inflammation, from contracting myofibers
    —->Induces an increase in other (inflammatory) cytokines
  • Prevents CVD, diabetes etc. as they are all associated with inflammation
26
Q

What are the metabolic actions of IL-6?

A

Increased:
- Glycogenolysis
- Lipolysis
- Fat oxidation
- Triacylglycerol
(decreased: type 2 diabetes, athesclerosis and autoimmune disease)

27
Q

What are the anti-inflammatory actions of IL-6?

A

Increased:
- IL-10
- cortisol
- TNF-α

28
Q

When is IL-6 produced?

A

More IL-6 produced when there is a NEED for energy
Induces an anti-inflammatory environment

29
Q

What are the factors affecting the magnitude of hormonal response to exercise?

A

Intensity of exercise increases
* Duration of exercise increases
* Increase body temperature
* Psychological stress increases
* Hypoxia (altitude) increases
* Nutritional status (more with fasting)

Biochemistry (9 decks)

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