Lecture 3 exercise endocrinology
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Transcript of Lecture 3 exercise endocrinology
Types of Hormones
• Steroid Hormones:– Structure similar to cholesterol– Can pass through cell membranes– Direct gene activation
• Non-steroid Hormones:– Protein/peptide or amino acid-derived– Cannot pass through cell membrane– Second messenger activation
Steroid Hormones
Steroid Hormones
• Proteins formed from mRNA may be:– Enzymes– Structural Proteins– Regulatory Proteins
• Includes:– Cortisol– Aldosterone– Estrogen/Progesterone/Testosterone
Non-steroid Hormones
Non-steroid Hormones
• Second Messengers (cAMP) can:– Activate cellular enzymes– Change membrane permeability– Promote protein synthesis– Change cellular metabolism– Stimulate cellular secretions
• Includes:– Thyroid Hormones– Epinephrine/Norepinephrine
Overview• Hormones that mediate specific actions
during exercise:–Regulation of Glucose Metabolism–Regulation of Fat Metabolism–Regulation of Blood Plasma
Regulation of Glucose Metabolism
• Controlled by Five Hormones:– Insulin (Rest Only)– Glucagon– Epinephrine– Norepinephrine– Cortisol
• During Exercise Blood Glucose is affected by three factors:– Liver release of glucose– Muscle uptake of glucose– Dietary intake of glucose
Glucagon
• Secretion Site: Pancreas ( cells)
• Action: Cause liver glycogen breakdown and glucose release to blood
• Exercise Response: Positively correlated to exercise intensity
• Effect of Chronic Exercise: at given intensity compared to untrained individual
Epinephrine and Norepinephrine
• Secretion Site: Adrenal Medulla and SNS
• Action: Works with Glucagon
• Exercise Response: Positively correlated to exercise intensity (intensity >50-75% of max effort)
• Effect of Chronic Exercise: at given intensity compared to untrained individual
Cortisol
• Secretion Site: Adrenal Cortex
• Action: Increase in Protein Catabolism, Increase blood amino acids for gluconeogenesis (making glucose from other substrates)
• Exercise Response: Positively correlated to exercise intensity (>80% max effort)
• Effect of Chronic Exercise: Slight at given intensity compared to untrained individual
Short Duration Exercise
High intensity = Greater catecholamine release = Greater release of glucose from liver
40-50% increase in blood glucose
Replenishes muscle glycogen stores
Long Duration Exercise
• Glucose production = demand
• Liver glycogen stores are a limiting factor
• Blood glucose concentration may decrease
• Glucagon/Cortisol gluconeogenesis
• CHO intake beneficial
Blood Glucose Exercise Response
Exercise Duration (min)
Glucagon
Cortisol
15 60 90
E + NE
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Blood Glucose
Insulin
• Secretion Site: Pancreas ( cells)
• Action: Glucose uptake by muscle at rest, regulating blood glucose concentration
• Exercise Response: Not released during exercise; receptors more sensitive, thus less insulin required
• Effect of Chronic Exercise: No exercise response
Insulin, Blood Glucose, & Exercise
Exercise Duration (min)30 60 90
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Blood Glucose
Insulin
Regulation of Fat Metabolism• Controlled by Five Hormones:
– (Insulin)– Cortisol– Epinephrine– Norepinephrine– Growth Hormone
• Fat Metabolism is needed– When exercise depletes glycogen stores (long
duration exercise)– When diet depletes glycogen stores (fasting, low
CHO dieting, etc.)
Cortisol
• Secretion Site: Adrenal Cortex
• Action: Increase Liver Gluconeogenesis, blood Free Fatty Acids
• Exercise Response: Positively correlated to exercise intensity, but only acts during first 30-45 minutes
• Effect of Chronic Exercise: Slight at given intensity compared to untrained individual
Epinephrine and Norepinephrine
• Secretion Site: Adrenal Medulla and SNS
• Action: Activates hormone sensitive lipase, works with glucagon
• Exercise Response: Positively correlated to exercise intensity (intensity >50-75% of max effort)
• Effect of Chronic Exercise: at given intensity compared to untrained individual
Growth Hormone
• Secretion Site: Anterior Pituitary Gland
• Action: Maintains cortisol induced activation of hormone sensitive lipase
• Exercise Response: Positively correlated to exercise intensity
• Effect of Chronic Exercise: at given intensity compared to untrained individual
Fat Metabolism during Exercise
Exercise Duration (min)30 60 90
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Blood FFA
Cortisol
Growth Hormone
E + NE
Glycogen
Regulation of Blood Plasma
• Controlled by Five Hormones:– Aldosterone– Renin– Angiotensin I– Angiotensin II– Antidiuretic Hormone (ADH)
• Maintenance of Blood and Blood Plasma– Maintain blood supply to active tissue– Provide fluid for the production of sweat– Increased oxygen carrying capacity
Aldosterone
• Secretion Site: Adrenal Cortex
• Action: Increased Na+ and water reabsorption in the kidneys
• Exercise Response: Positively correlated to change in plasma volume
• Effect of Chronic Exercise: No effect
Signal for Aldosterone Release
1. Kidneys sense drop in blood pressure (due to decrease in plasma volume)
2. Kidneys release Renin
3. Renin is transformed to Angiotensin I, which is transformed into Angiotensin II
4. Angiotensin II stimulates Aldosterone release from the Adrenal Cortex
Renin-Angiotensin-Aldosterone
ADH
• Secretion Site: Posterior Pituitary Gland
• Action: Increases water reabsorption in the kidneys
• Exercise Response: Positively correlated to increase blood concentration (hemoconcentration)
• Effect of Chronic Exercise: at given intensity compared to untrained individual
ADH
Maintenance of Blood Plasma
Exercise Duration (min)30 60 90
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Plasma Volume
Aldosterone
-15%
ADH