Specific+Hormones+response

Specific Hormones Overview

• Discussion focused on specific hormones, their functions, and exercise impact on hormone levels.

• Review of basics of the endocrine system and its components.

Endocrine System Basics

• Endocrine Glands: Secretes hormones into the bloodstream.

• Hormone Transport: Hormones travel in blood to target cells, which must have specific receptors for interaction.

• Cell Types: Not all cells respond to all hormones.

Types of Hormones

• Steroid Hormones:

  • Traverse cell membrane, bind to internal receptors, and affect the nucleus.

• Non-Steroid Hormones:

  • Bind to receptors outside cell and use secondary messengers to enact effects.

• Potency Changes: Adjusting hormone or receptor levels affects hormonal potency.

Insulin

• Source: Released from pancreas when blood glucose increases post-meal.

• Functions:

  • Signals cells to uptake glucose for glycolysis or store as glycogen, thereby lowering blood glucose.

  • Promotes protein synthesis.

• Insulin Resistance: Impaired signaling leads to elevated blood glucose and risk of Type 2 diabetes.

Exercise and Insulin

• Exercise lowers insulin production due to cellular energy needs.

• Promotes lipolysis (fat breakdown) and increases muscle sensitivity to insulin due to GLUT4 transporter activation.

Glucagon

• Source: Released from pancreas when glucose levels are low.

• Function: Opposite of insulin; stimulates glycogenolysis and gluconeogenesis to increase blood glucose levels.

• Exercise Impact: Glucagon levels rise during exercise to maintain blood glucose.

Growth Hormone

• Source: Secreted by anterior pituitary.

• Role: Crucial for growth and exercise metabolism; promotes fat metabolism for ATP production and protein synthesis.

• Exercise Impact: Levels increase during both resistance and aerobic exercise - higher intensities lead to more significant releases.

Thyroid Hormone (T3 and T4)

• Source: Released in response to TSH from anterior pituitary.

• Function: Increases metabolic rate, oxygen consumption, and overall metabolism via glycolysis and lipolysis.

• Exercise Effect: Exercise stimulates TSH, leading to increased T3 and T4 levels.

• Dysfunction: Hypothyroidism can cause exercise intolerance.

Cortisol

• Source: Secreted by adrenal cortex; a key stress hormone.

• Functions: Immunosuppression, inflammation reduction, protein degradation, lipolysis, and gluconeogenesis.

• Exercise Response: Levels increase with exercise intensity; initially rise then fall after 20-30 minutes.

Catecholamines (Epinephrine and Norepinephrine)

• Function: Enhance fight or flight response, increase metabolism, and regulate glucose and fat metabolism.

• Exercise Threshold: Levels increase during exercise above 50% of VO2 max.

Estrogen and Testosterone

Estrogen

• Source: Released from ovaries; influences fat oxidation versus glucose oxidation.

• Exercise Effect: Acute exercise can increase estrogen levels, potentially affecting hormonal responses in males and females.

Testosterone

• Source: Released from testes; anabolic hormone promoting growth and protein synthesis.

• Exercise Levels: Increases with intensity in men; minimal changes in women and children.

Appetite Hormones

• Hormones regulating appetite and caloric consumption include PYY, GLP-1, CCK, Leptin (satiety) and Ghrelin (hunger).

• Exercise Influence: Reduces ghrelin and increases satiety hormones, leading to decreased hunger post-exercise.

Carbohydrate Regulation

• Requirements for Glycolysis:

  • Glucose availability in blood and uptake by working tissues (muscles).

• Hormonal Influence: Glucagon, epinephrine, norepinephrine, cortisol, growth hormone, T3/T4 drive up blood glucose.

Fat Regulation

• Lipolysis requires decreased insulin levels and increased levels of catecholamines, growth hormone, and cortisol to promote fatty acid oxidation.

Conclusion

• Understanding hormone interactions and their responses to exercise is essential for optimizing metabolic function and health.