Chapter 5
Hormonal Responses
to Exercise

EXERCISE PHYSIOLOGY

Neuroendocrinology
The study of the interaction between the CNS and Endocrine System
The Neuro/Endrocrine Systems work together to maintain homeostasis

•____________________ glands release hormones directly into the blood

•Hormones _____________ the activity of tissues that possess ____________________ to which the hormone can bind

•The plasma hormone concentration determines the ____________________of the ____________________

Blood Hormone Concentration
Hormones are chemical ____________________

Blood Hormone Concentrations are Determined by:

•Rate of ____________________ of hormone from endocrine gland

•Rate of ____________________ or excretion of hormone

•Quantity of ____________________ protein

•Changes in____________________volume

Control of Hormone Secretion
RATE FACTORS

•Rate of insulin secretion from the pancreas is dependent on:

–Magnitude of input

–Stimulatory vs. inhibitory

–Control Example

What happens to glucose when plasma glucose levels increase?

–____________________secretions increase

–____________________ responds to decreased insulin secretions.

•There are several classes of hormones

2.____________________

3.____________________

4.____________________

4.All are measured in small quantities in the blood (micrograms / nanograms and picograms)

Factors That Influence the Secretion of Hormones

Hormone-Receptor Interactions

•Trigger events at the cell

•Magnitude of effect dependent on:

–____________________ of the hormone

–____________________ of receptors on the cell

–____________________ of the receptor for the hormone

Hormone-Receptor Interactions

•Hormones bring about effects by:

–Altering ____________________ transport

–Stimulating ____________________ to increase protein synthesis

–Activating ____________________ messengers

•Cyclic AMP

^•Ca⁺⁺

•Inositol triphosphate

•Diacylglycerol

Mechanisms of Hormones

–Hormones ____________________cellular activity through differing mechanisms.

–Membranes are like bus stations: Carrier molecules line up some protein carrying hormones near the surface of the cell to increase the movement of substrates or ions in and out of the cell

•Example: ____________________________________________________________

Mechanism of Steroid Hormones

Complex Hormones

Cyclic AMP
“____________________ Messenger” Mechanism

Other “Second Messenger” Systems

Hormones:
Regulation and Action by
Major Endocrine Glands

Hormones are secreted from endocrine glands

–____________________ and ____________________ glands

–Others:

–____________________ and ____________________ glands

–____________________ glands

–____________________

–____________________ and ____________________

Hypothalamus

•Controls activity of the anterior and posterior pituitary glands

•Influenced by ____________________ and ____________________ input

Examples:

–____________________ (GH) are released from the ____________________, yielding essential normal growth.

•GH ____________________ during exercise to mobilize FFA from fat to maintain blood glucose.

–Posterior pituitary releases ____________________ hormone (ADH) reducing H20 loss). Two stimuli that cause

ADH secretions occur when there are:

•____________________ H20 plasma concentration

•____________________ plasma volume (caused by loss of sweat or blood)

Positive and Negative Input to the Hypothalamus

Anterior Pituitary Gland
Fig. 5.5 shows the summary of hormones released from the anterior pituitary gland

Growth Hormone

•Secreted from the anterior pituitary gland

•Essential for normal ____________________

–Stimulates ____________________ synthesis and ____________________growth

•____________________ during exercise

–Mobilizes ____________________ acids from ____________________ tissue

–Aids in the maintenance of blood ____________________

Growth Hormone

Posterior Pituitary Gland

•Secretes ____________________ hormone (ADH) or vasopressin

•____________________ water loss from the body to maintain plasma volume

•Stimulated by:

–High plasma osmolality and low plasma volume due to sweating - or blood loss

–Exercise (See Next Slide)

Change in the Plasma ADH Concentration During Exercise

Thyroid Gland
Thyroid hormones are____________________to metabolic rate

Triiodothyronine (T₃) and thyroxine (T₄)

–Important in maintaining ____________________ rate and allowing full effect of other hormones

Calcitonin

^–Regulation of ____________________ ______

–Remember CA++ is essential for muscle contraction as well as bone maintenance and nerve function.

^–As CA++ increases, the hormone calcitonin increases, blocking the release of CA++ from bone (neg. effect), but increases the release of CA++ in the kidneys to decrease the concentrations of plasma CA++

Parathyroid Hormone

–Also involved in plasma Ca⁺⁺ regulation

Adrenal Medulla
Part of the ____________________

Secretes ____________________ (Adrenaline) and ____________________

•E & NE Hormones Increase

____________________, ____________________, ____________________,

•E and NE bind to Alpha & Beta protein receptors on cells to bring about change in cell activity

•Functions To: ____________________________________________________________

____________________of the (E) adrenaline comes from the Adrenal Medulla. Adrenaline effects the receptors on cells in the cardiovascular and respiratory systems.

Adrenal Cortex
Secretes Various ____________________ Hormones

Mineralcorticoids (aldosterone)

^–Maintain plasma Na⁺ and K⁺ (potassium)

– Regulation of blood pressure

– Regulation of Glucose

– Sex steroids - e.g.: ____________________ and ____________________.

–A precursor common to these hormones:

____________________

Change in Mineralcorticoids During Exercise

Adrenal Cortex
____________________l is secreted by the Adrenal Cortex

•Glucocorticoids (Cortisol)

–Cortisol contributes to the maintenance of plasma ____________________ in fasting and exercise.

–Stimulated by ____________________ and long-term fasting

–Promotes the use of ____________________as fuel

–Stimulates ____________________ synthesis

–Promotes protein breakdown for gluconeogenesis and tissue repair

Control of Cortisol Secretion

•____________________

•Secretes digestive enzymes and bicarbonate into small intestine

•Releases

–____________________ - Promotes the storage of glucose, amino acids, and fats

–____________________ - Promotes the mobilization of fatty acids and glucose

–____________________ - Controls rate of entry of nutrients into the circulation

Testes
____________________ and ____________________ are primary sex hormones secreted by the testes and ovaries respectively

•Release testosterone

–____________________ steroid

•Promotes tissue (muscle) ____________________

•____________________ enhancement

–____________________ steroid

•Promotes____________________characteristics

•Stimulates protein synthesis responsible for characteristic changes in boys at adolescence.

Control of Testosterone Secretion

Anabolic Steroids and Performance

Estrogen

•Establish and maintain ____________________ function

•Levels vary throughout the menstrual cycle

•> ____________________

•> ____________________

•> other secondary sex characteristics

Control of Estrogen Secretion

Muscle Glycogen Utilization
During exercise: Food substrate use is related to rate, intensity and duration

•Breakdown of muscle glycogen is under dual control

____________________

____________________

•Delivery of glucose parallels activation of muscle contraction

•Glycogenolysis – ____________________ of glycogen

____________________ is primarily believed to be responsible for glycognolysis

Control of Glycogenolysis

Muscle Glycogen Utilization

•Glycogenolysis is related to exercise ____________________

–High-intensity of exercise results in greater and more rapid ____________________ depletion

Plasma epinephrine is a powerful ____________________ of glycogenolysis

High-intensity of exercise results in greater increases in plasma epinephrine

Glycogen Depletion During Exercise
(at differing intensity levels)

Plasma Epinephrine Concentration During Exercise

Maintenance of Plasma Glucose During Exercise

Plasma glucose is maintained through 4 differing processes

•Mobilization of ____________________ from ____________________ glycogen stores

•Mobilization of ____________________ from ____________________ tissue

Spares blood glucose

Gluconeogenesis from amino acids, lactic acid, and glycerol

•____________________ the entry of glucose into cells

– Forces use of ____________________ as a fuel

Each of these processes are controlled by ___________ or more hormones.

Some _____________, some _____________, and some react ___________

The overall purpose of these processes is to provide fuel for work while maintaining plasma glucose concentrations (blood glucose)

AN ADAPTATION

Blood Glucose Homeostasis During Exercise

•Permissive and slow-acting hormones

–____________________

–____________________

•____________________

Act in a permissive manner to support actions of other hormones

Cortisol
(Glucocorticoid)
A plasma glucose maintainer

Stimulates ____________________ mobilization from adipose tissue

•Mobilizes ____________________for gluconeogenesis

•____________________ entry of glucose into cells

____________________ in secreting as intensity increases but when duration increases, cortisol in plasma increases exponentially.

Role of Cortisol in the Maintenance of Blood Glucose

Plasma Cortisol During Exercise
(____________________)

At low intensity

–plasma cortisol ____________________

•At high intensity

–plasma cortisol ____________________

Changes in Plasma Cortisol During Exercise

Growth Hormone

•Important in the maintenance of plasma glucose

–____________________ glucose uptake

–Increases ____________________ mobilization

____________________ gluconeogenesis

So, GH as well as Cortisol can provide a “slow acting” effect on CHO and Fat metabolism during exercise, but as intensity increases, there is a faster rate effect.

Growth Hormone in the Maintenance of Plasma Glucose

Growth Hormone During Exercise:
Effect of Intensity

Growth Hormone During Exercise:
Trained vs. Untrained

Blood Glucose Homeostasis During Exercise

•____________________-acting hormones

–____________________ and ____________________

Related to ____________________, viewed as the primary ____________________ in mobilization of glucose.

Insulin and glucagon

Maintain plasma glucose

–____________________ liver glucose mobilization - from liver

–Increased levels of plasma ____________________ - from adipose

–____________________ glucose uptake

–Increasing ____________________

–

–Role of Catecholamines in Substrate Mobilization

Epinephrine & Norepinephrine During Exercise

•____________________ linearly during exercise

•Favor the mobilization of ____________________ and maintenance of ____________________

Change in Plasma Catecholamines During Exercise

Epinephrine & Norepinephrine Following Training

•____________________ plasma levels in response to exercise bout

Parallels reduction in ____________________ mobilization

Plasma Catecholamines During Exercise Following Training

Effects of Insulin & Glucagon

Insulin During Exercise

•Plasma insulin ____________________ during exercise

–Prevents rapid uptake of plasma glucose

–Favors mobilization of ____________________ glucose and lipid ____________________

Trained subjects during exercise

– More rapid ____________________ in plasma ____________________

– Increase in plasma ____________________

Changes in Plasma Insulin During Exercise

Effect of Training on Plasma Insulin During Exercise

Effect of Training on Plasma Glucagon During Exercise

Effect of SNS on Substrate Mobilization

Hormonal Responses to Exercise

Hormonal Responses to Exercise

Free Fatty Acid Mobilization During Heavy Exercise

•FFA mobilization ____________________ during heavy exercise

–This occurs in spite of persisting hormonal stimulation for FFA mobilization

•May be due to high levels of ____________________

–Promotes ____________________ of triglycerides

–Inadequate blood flow to adipose tissue

–Insufficient transporter for FFA in plasma

Effect of Lactic Acid on FFA Mobilization