hormonal control during exercise (exam 2 material)
Hormonal Control During Exercise
Chapter 4
Outline
Endocrine System
How Hormones Work
Types of Hormones
Hormones During Exercise
1. Endocrine System
Overview
Definition: The Endocrine System encompasses all tissues or glands that secrete hormones.
Main Purpose: It is responsible for fine-tuning physiological responses to changes in homeostasis.
Process: A gland or tissue secretes a hormone into the bloodstream, which then travels to target cells or organs to elicit a physiological response.
Hormone: Any chemical that controls and regulates the activity of certain cells and organs.
gland/tissue secretes hormone—>blood—>target cell/organ—>physiological response
hormones-day to day regulators of your body’s physiology
Key Components
Major Glands:
Pituitary Gland
Thyroid Gland
Adrenal Gland
Pancreas
2. How Hormones Work
Hormonal Action
Cell Sensitivity: Different cells have varying sensitivities to hormones due to the presence of specific hormone receptors on their surfaces.
Receptor Dynamics:
Effects of hormones are limited by the availability of hormone-specific receptors.
Absence of a receptor results in no physiological response.
The number of receptors can be regulated:
Downregulation: Decrease in the number of receptors.
Upregulation: Increase in the number of receptors.
Hormone Secretion Process
Detection: The gland senses a physiological disturbance.
Release: Hormone is released into the blood.
Binding: The hormone binds to a receptor on a target organ or cell.
Effect: The binding results in a specific physiological effect.
pulsatile secretion-pulsatility is a physiological ay of increasing hormone concentrations rapidly and sending distinct signaling information to target cells
Secretion Regulation
Hormonal secretion is regulated by feedback mechanisms:
High levels of downstream changes in physiological state result in decreased hormone secretion.
Low levels or need for more physiological change can lead to increased secretion.
Example of Negative Feedback
Scenario:
Eating increases blood glucose levels.
The pancreas senses this increase and releases insulin.
Insulin binds to its receptor, opening glucose channels in cells to lower blood glucose levels, leading to a decrease in insulin release.
3. Types of Hormones
Classification
Steroid Hormones:
Characteristics: Lipid-soluble, diffuse easily through cell membranes, bind to cytoplasmic or nuclear receptors.
Main Effects: DNA activation leading to protein synthesis. (direct gene activation)
DNA activation—>synthesis of mRNA—>proteins made
Examples: Testosterone, Estrogen, Progesterone, Cortisol, Aldosterone.
Nonsteroid Hormones:
Characteristics: Not lipid soluble, cannot diffuse through the cell membrane, bind to membrane receptors.
receptors must be on cell membrane
binds to membrane receptor—>triggers rxns (reactions)—>intracellular second messenger
Trigger reactions that amplify signals within the target cell (e.g., via cAMP).
Subdivided into: protein/peptide hormones and amino acid derived hormones
Protein/Peptide Hormones
Amino Acid-Derived Hormones (e.g., Thyroxine (T4), Triiodothyronine (T3), Epinephrine (EPI), Norepinephrine (NE)).
Prostaglandins
Definition: Local hormones acting through autocrine mechanisms that exert effects immediately around their site of production.
Functions: Inflammatory responses and nerve sensitization; notably affected by ibuprofen.
directly targets blood vessels and nerve endings
derived from fatty acids
4. Hormones During Exercise
Functions of Hormones in Exercise
Regulation of Metabolism: Hormones manage fuel (e.g., lipolysis for fat breakdown) to meet high ATP demands during exercise.
regulate fluid and electrolyte balance , ensuring proper hydration levels and electrolyte concentrations, which are critical for optimal muscle function and performance.
Prevent Physiological Deterioration: Ensure metabolic needs are satisfied to maintain homeostasis.
Major Endocrine Glands Impacting Metabolism
Anterior Pituitary Gland:
Hormones Released:
Growth Hormone (GH)
Thyrotropin/Thyroid Stimulating Hormone (TSH)
Adrenocorticotropic hormone (ACTH)
Prolactin
Follicle-Stimulating Hormone (FSH)
Luteinizing Hormone (LH)
Growth Hormone (GH): Promotes growth, cell reproduction, and regeneration during exercise.
Growth Hormone (GH)
Type: Anabolic agent, involved in building muscles.
Influence: Increased with aerobic and resistance exercise, proportional to intensity.
Effects: Increases muscle mass, decreases fat, shifts metabolism towards fatty acid utilization over carbohydrates, enhancing protein synthesis and lipolysis.
muscle hypertrophy-muscle growth
elevated with aerobic and resistance exercise
Thyroid Gland
Mechanism: Signaled by TSH from the anterior pituitary to release:
Triiodothyronine (T3)
Thyroxine (T4)
Net Effects: Increase muscle metabolism, enhance fatty acid and carbohydrate metabolism, improve mitochondrial biogenesis and protein synthesis, increase glycolysis and lipolysis.
Adrenal Gland
Structure: Consists of two parts: adrenal cortex and adrenal medulla.
Released Hormones:
From adrenal medulla: Epinephrine (EPI), Norepinephrine (NE)
From outer adrenal cortex: Glucocorticoids, such as cortisol.
Epinephrine & Norepinephrine
Stimulus: Released in response to stress and exercise by SNS
Effects:
Increases heart rate and contraction force
Enhances metabolic rates of carbohydrates and fatty acids
Stimulates glycogen breakdown and lipolysis
Increases respiration rates.
Pancreas
Function: Releases insulin and glucagon based on blood glucose levels.
Insulin:
Released in response to high glucose; promotes glucose uptake and storage, protein synthesis, and fat storage.
Glucagon:
Released in response to low glucose; enhances glucose production through gluconeogenesis and glycogenolysis.
Integration with Exercise
Insulin Response: Typically decreases during exercise, reducing inhibition on lipolysis, enabling fats to be utilized for energy.
Glucagon Response: Increases during exercise to stimulate glucose production and availability.
Hormonal Control of Electrolytes
Mechanism: In response to dehydration (sweating) and increased ion concentration, the posterior pituitary secretes hormones such as Antidiuretic Hormone (ADH) to promote water reabsorption in kidneys.
ADH Release Stimuli: Decreases in plasma volume, elevated osmolality, prompting the stimulation of osmoreceptors to release ADH.
Summary of Key Hormones
Hormones play significant roles in carbohydrate and fat metabolism, especially during physical activity, while also managing fluid balance.
Key hormones discussed include:
Growth Hormone (GH)
Thyroid Stimulating Hormone (TSH)
Triiodothyronine (T3) and Thyroxine (T4)
Catecholamines (EPI and NE)
Insulin
Glucagon
Antidiuretic Hormone (ADH)
Hormonal Control During Exercise
Chapter 4
Outline
Endocrine System
How Hormones Work
Types of Hormones
Hormones During Exercise
1. Endocrine System
Overview
Definition: The Endocrine System encompasses all tissues or glands that secrete hormones.
Main Purpose: It is responsible for fine-tuning physiological responses to changes in homeostasis.
Process: A gland or tissue secretes a hormone into the bloodstream, which then travels to target cells or organs to elicit a physiological response.
Hormone: Any chemical that controls and regulates the activity of certain cells and organs.
gland/tissue secretes hormone—>blood—>target cell/organ—>physiological response
hormones-day to day regulators of your body’s physiology
-
Key Components
Major Glands:
Pituitary Gland
Thyroid Gland
Adrenal Gland
Pancreas
2. How Hormones Work
Hormonal Action
Cell Sensitivity: Different cells have varying sensitivities to hormones due to the presence of specific hormone receptors on their surfaces.
Receptor Dynamics:
Effects of hormones are limited by the availability of hormone-specific receptors.
Absence of a receptor results in no physiological response.
The number of receptors can be regulated:
Downregulation: Decrease in the number of receptors.
Upregulation: Increase in the number of receptors.
Hormone Secretion Process
Detection: The gland senses a physiological disturbance.
Release: Hormone is released into the blood.
Binding: The hormone binds to a receptor on a target organ or cell.
Effect: The binding results in a specific physiological effect.
pulsatile secretion-pulsatility is a physiological ay of increasing hormone concentrations rapidly and sending distinct signaling information to target cells
Secretion Regulation
Hormonal secretion is regulated by feedback mechanisms:
High levels of downstream changes in physiological state result in decreased hormone secretion.
Low levels or need for more physiological change can lead to increased secretion.
Example of Negative Feedback
Scenario:
Eating increases blood glucose levels.
The pancreas senses this increase and releases insulin.
Insulin binds to its receptor, opening glucose channels in cells to lower blood glucose levels, leading to a decrease in insulin release.
3. Types of Hormones
Classification
Steroid Hormones:
Characteristics: Lipid-soluble, diffuse easily through cell membranes, bind to cytoplasmic or nuclear receptors.
Main Effects: DNA activation leading to protein synthesis. (direct gene activation)
DNA activation—>synthesis of mRNA—>proteins made
Examples: Testosterone, Estrogen, Progesterone, Cortisol, Aldosterone.
Nonsteroid Hormones:
Characteristics: Not lipid soluble, cannot diffuse through the cell membrane, bind to membrane receptors.
receptors must be on cell membrane
binds to membrane receptor—>triggers rxns (reactions)—>intracellular second messenger
Trigger reactions that amplify signals within the target cell (e.g., via cAMP).
Subdivided into: protein/peptide hormones and amino acid derived hormones
Protein/Peptide Hormones
Amino Acid-Derived Hormones (e.g., Thyroxine (T4), Triiodothyronine (T3), Epinephrine (EPI), Norepinephrine (NE)).
Prostaglandins
Definition: Local hormones acting through autocrine mechanisms that exert effects immediately around their site of production.
Functions: Inflammatory responses and nerve sensitization; notably affected by ibuprofen.
directly targets blood vessels and nerve endings
derived from fatty acids
4. Hormones During Exercise
Functions of Hormones in Exercise
Regulation of Metabolism: Hormones manage fuel (e.g., lipolysis for fat breakdown) to meet high ATP demands during exercise.
regulate fluid and electrolyte balance , ensuring proper hydration levels and electrolyte concentrations, which are critical for optimal muscle function and performance.
Prevent Physiological Deterioration: Ensure metabolic needs are satisfied to maintain homeostasis.
Major Endocrine Glands Impacting Metabolism
Anterior Pituitary Gland:
Hormones Released:
Growth Hormone (GH)
Thyrotropin/Thyroid Stimulating Hormone (TSH)
Adrenocorticotropic hormone (ACTH)
Prolactin
Follicle-Stimulating Hormone (FSH)
Luteinizing Hormone (LH)
Growth Hormone (GH): Promotes growth, cell reproduction, and regeneration during exercise.
Growth Hormone (GH)
Type: Anabolic agent, involved in building muscles.
Influence: Increased with aerobic and resistance exercise, proportional to intensity.
Effects: Increases muscle mass, decreases fat, shifts metabolism towards fatty acid utilization over carbohydrates, enhancing protein synthesis and lipolysis.
muscle hypertrophy-muscle growth
elevated with aerobic and resistance exercise
Thyroid Gland
Mechanism: Signaled by TSH from the anterior pituitary to release:
Triiodothyronine (T3)
Thyroxine (T4)
Net Effects: Increase muscle metabolism, enhance fatty acid and carbohydrate metabolism, improve mitochondrial biogenesis and protein synthesis, increase glycolysis and lipolysis.
Adrenal Gland
Structure: Consists of two parts: adrenal cortex and adrenal medulla.
Released Hormones:
From adrenal medulla: Epinephrine (EPI), Norepinephrine (NE)
From outer adrenal cortex: Glucocorticoids, such as cortisol.
Epinephrine & Norepinephrine
Stimulus: Released in response to stress and exercise by SNS
Effects:
Increases heart rate and contraction force
Enhances metabolic rates of carbohydrates and fatty acids
Stimulates glycogen breakdown and lipolysis
Increases respiration rates.
Pancreas
Function: Releases insulin and glucagon based on blood glucose levels.
Insulin:
Released in response to high glucose; promotes glucose uptake and storage, protein synthesis, and fat storage.
Glucagon:
Released in response to low glucose; enhances glucose production through gluconeogenesis and glycogenolysis.
Integration with Exercise
Insulin Response: Typically decreases during exercise, reducing inhibition on lipolysis, enabling fats to be utilized for energy.
Glucagon Response: Increases during exercise to stimulate glucose production and availability.
Regulation of Lipolysis
Definition: Lipolysis is the breakdown of triglycerides into fatty acids and glycerol, primarily for energy during exercise.
Hormonal Control:
Epinephrine (EPI) & Norepinephrine (NE): Directly stimulate lipolysis by activating hormone-sensitive lipase (HSL).
Growth Hormone (GH): Promotes lipolysis, contributing to a shift towards fatty acid utilization.
Glucagon: Indirectly promotes lipolysis by counteracting insulin's inhibitory effects and mobilizing energy stores.
Cortisol: Can enhance lipolysis, particularly during prolonged stress or fasting states, to provide fuel.
Insulin: Inhibits lipolysis. Its decrease during exercise removes this inhibition, allowing increased fat breakdown.
Hormonal Control of Electrolytes
Mechanism: In response to dehydration (sweating) and increased ion concentration, the posterior pituitary secretes hormones such as Antidiuretic Hormone (ADH) to promote water reabsorption in kidneys.
ADH Release Stimuli: Decreases in plasma volume, elevated osmolality, prompting the stimulation of osmoreceptors to release ADH.
Summary of Key Hormones
Hormones play significant roles in carbohydrate and fat metabolism, especially during physical activity, while also managing fluid balance.
Key hormones discussed include:
Growth Hormone (GH)
Thyroid Stimulating Hormone (TSH)
Triiodothyronine (T3) and Thyroxine (T4)
Catecholamines (EPI and NE)
Insulin
Glucagon
Antidiuretic Hormone (ADH)