Chapter 5 Hormonal Responses to Exercise - PowerPoint PPT Presentation

1 / 53
About This Presentation
Title:

Chapter 5 Hormonal Responses to Exercise

Description:

Title: Chapter 5 Subject: Hormonal Responses to Exercise Author: Brian Parr Last modified by: Michael Yu Created Date: 2/8/2000 12:24:28 PM Document presentation format – PowerPoint PPT presentation

Number of Views:446
Avg rating:3.0/5.0
Slides: 54
Provided by: BrianP187
Category:

less

Transcript and Presenter's Notes

Title: Chapter 5 Hormonal Responses to Exercise


1
Chapter 5Hormonal Responses to Exercise
  • EXERCISE PHYSIOLOGY
  • Theory and Application to Fitness and
    Performance, 6th edition
  • Scott K. Powers Edward T. Howley

2
Neuroendocrinology
  • Neuroendocrine system
  • Endocrine system releases hormones
  • Nervous system uses neurotransmitters
  • Endocrine glands
  • Release hormones directly into the blood
  • Hormones
  • Alter the activity of tissues that possess
    receptors to which the hormone can bind

3
Blood Hormone Concentration
  • The free plasma hormone concentration determines
    the magnitude of the effect at the tissue level
  • Determined by
  • Rate of secretion of hormone from endocrine gland
  • Magnitude of input
  • Stimulatory vs. inhibitory input
  • Rate of metabolism or excretion of hormone
  • At the receptor and by the liver and kidneys
  • Quantity of transport protein
  • Steroid hormones
  • Changes in plasma volume

4
Factors That Influence the Secretion of Hormones
Figure 5.1
5
Hormone-Receptor Interactions
  • Hormone affect only tissue with specific
    receptors
  • Magnitude of effect dependent on
  • Concentration of the hormone
  • Number of receptors on the cell
  • Affinity of the receptor for the hormone
  • Downregulation
  • Decrease in receptor number in response to high
    concentration of hormone
  • Upregulation
  • Increase in receptor number in response to low
    concentration of hormone

6
Mechanisms of Hormone Action
  • Altering membrane transport
  • Insulin
  • Stimulating DNA to increase protein synthesis
  • Steroid hormones
  • Activating second messengers via G protein
  • Cyclic AMP
  • Ca2
  • Inositol triphosphate
  • Diacylglycerol

7
Mechanism of Steroid Hormone Action
Figure 5.2
8
Cyclic AMP Second Messenger Mechanism
Figure 5.3
9
Calcium and Phospholipase C Second Messenger
Mechanisms
Figure 5.4
10
Hormones Regulation and Action
  • Hormones are secreted from endocrine glands
  • Hypothalamus and pituitary glands
  • Thyroid and parathyroid glands
  • Adrenal glands
  • Pancreas
  • Testes and Ovaries

11
Hypothalamus and Pituitary Gland
  • Hypothalamus
  • Controls secretions from pituitary gland
  • Anterior Pituitary Gland
  • Adrenocorticotropic hormone (ACTH)
  • Follicle-stimulating hormone (FSH)
  • Luteinizing hormone (LH)
  • Melanocyte-stimulating hormone (MSH)
  • Thyroid-stimulating hormone (TSH)
  • Growth hormone (GH)
  • Prolactin
  • Posterior Pituitary Gland
  • Oxytocin
  • Antidiuretic hormone (ADH)

12
Hormones Released From the Anterior Pituitary
Gland
Figure 5.5
13
Growth Hormone
  • Secreted from the anterior pituitary gland
  • Stimulates release of insulin-like growth factors
    (IGFs)
  • Essential growth of all tissues
  • Amino acid uptake and protein synthesis
  • Long bone growth
  • Spares plasma glucose
  • Reduces the use of plasma glucose
  • Increases gluconeogenesis
  • Mobilizes fatty acids from adipose tissue

14
The Influence of the Hypothalamus on Growth
Hormone Secretion
Figure 5.6
15
Antidiuretic Hormone
  • Reduces water loss from the body to maintain
    plasma volume
  • Favors the reabsorption of water from the kidney
  • Stimulated by
  • High plasma osmolality and low plasma volume
  • Due to sweat loss without water replacement

16
Change in Plasma ADH Concentration During Exercise
Figure 5.7
17
Thyroid Gland
  • Stimulated by TSH
  • Triiodothyronine (T3) and thyroxine (T4)
  • Maintenance of metabolic rate
  • Allowing the full effect of other hormones
  • Calcitonin
  • Regulation of plasma Ca2
  • Parathyroid Hormone
  • Primary hormone in plasma Ca2 regulation

18
Adrenal Medulla
  • Secretes the catecholamines
  • Epinephrine (E) and norepinephrine (NE)
  • Bind to adrenergic receptors
  • Alpha (?)
  • Beta (?)
  • Effects depend on hormone used and receptor type

19
Adrenal Cortex
  • Aldosterone (mineralcorticoid)
  • Control of Na reabsorption and K secretion
  • Na/H2O balance
  • Regulation of blood volume and blood pressure
  • Part of renin-angiotensin-aldosterone system
  • Stimulated by
  • Increased K concentration
  • Decreased plasma volume

20
Change in Renin, Angiotensin II, and Aldosterone
During Exercise
Figure 5.8
21
Adrenal Cortex
  • Cortisol (glucocorticoid)
  • Promotes protein breakdown for gluconeogenesis
    and tissue repair
  • Stimulates FFA mobilization
  • Stimulates glucose synthesis
  • Blocks uptake of glucose into cells
  • Promotes the use of free fatty acids as fuel
  • Stimulated by
  • Stress, via ACTH
  • Exercise

22
Control of Cortisol Secretion
Figure 5.9
23
Pancreas
  • Both exocrine and endocrine functions
  • Secretes
  • Insulin (from b cells)
  • Promotes the storage of glucose, amino acids, and
    fats
  • Glucagon (from a cells)
  • Promotes the mobilization of fatty acids and
    glucose
  • Somatostatin (from d cells)
  • Controls rate of entry of nutrients into the
    circulation
  • Digestive enzymes and bicarbonate
  • Into the small intestine

24
Testes and Ovaries
  • Testosterone
  • Released from testes
  • Anabolic steroid
  • Promotes tissue (muscle) building
  • Performance enhancement
  • Androgenic steroid
  • Promotes masculine characteristics
  • Estrogen
  • Released from ovaries
  • Establish and maintain reproductive function
  • Levels vary throughout the menstrual cycle

25
Control of Testosterone Secretion
Figure 5.10
26
Control of Estrogen Secretion
Figure 5.11
27
Change in FSH, LH, Progesterone, and Estradiol
During Exercise
Figure 5.12
28
Muscle Glycogen Utilization
  • Glycogenolysis is related to exercise intensity
  • High-intensity of exercise results in greater and
    more rapid glycogen depletion
  • Plasma epinephrine is a powerful simulator of
    glycogenolysis
  • High-intensity of exercise results in greater
    increases in plasma epinephrine

29
Glycogen Depletion During Exercise
Figure 5.13
30
Plasma Epinephrine Concentration During Exercise
Figure 5.14
31
Control of Muscle Glycogen Utilization
  • Breakdown of muscle glycogen is under dual
    control
  • Epinephrine-cyclic AMP
  • Via b-adrenergic receptors
  • Ca2-calmodulin
  • Enhanced during exercise due to Ca2 release from
    sarcoplasmic reticulum
  • Evidence for role of Ca2-calmodulin in
    glycogenolysis
  • Propranolol (b-receptor blocker) has no effect on
    muscle glycogen utilization

32
Control of Glycogenolysis
Figure 5.16
33
Changes in Muscle Glycogen Before and After
Propranolol Administration
Figure 5.15
34
Blood Glucose Homeostasis During Exercise
  • Plasma glucose maintained through four processes
  • Mobilization of glucose from liver glycogen
    stores
  • Mobilization of FFA from adipose tissue
  • Spares blood glucose
  • Gluconeogenesis from amino acids, lactic acid,
    and glycerol
  • Blocking the entry of glucose into cells
  • Forces use of FFA as a fuel
  • Controlled by hormones
  • Permissive or slow-acting
  • Fast-acting

35
Permissive and Slow-Acting Hormones
  • Thyroid hormones
  • Act in a permissive manner to support actions of
    other hormones
  • Cortisol and growth hormone
  • Stimulate FFA mobilization from adipose tissue
  • Enhance gluconeogenesis in the liver
  • Decrease the rate of glucose utilization by cells

36
Role of Cortisol in the Maintenance of Blood
Glucose
Figure 5.17
37
Changes in Plasma Cortisol During Exercise
Figure 5.18
38
Role of Growth Hormone in the Maintenance of
Plasma Glucose
Figure 5.19
39
Changes in Plasma Growth Hormone During Exercise
Figure 5.20
40
Fast-Acting Hormones
  • Epinephrine and norepinephrine
  • Maintain blood glucose during exercise
  • Muscle glycogen mobilization
  • Increasing liver glucose mobilization
  • Increasing FFA mobilization
  • Interfere with glucose uptake
  • Plasma E and NE increase during exercise
  • Decreased plasma E and NE following training

41
Role of Catecholamines in Substrate Mobilization
Figure 5.21
42
Change in Plasma Epinephrine and Norepinephrine
During Exercise
Figure 5.22
43
Plasma Catecholamines Responses to Exercise
Following Training
Figure 5.23
44
Fast-Acting Hormones
  • Insulin
  • Uptake and storage of glucose and FFA
  • Plasma concentration decreases during exercise
  • Decreased insulin response following training
  • Glucagon
  • Mobilization of glucose and FFA fuels
  • Plasma concentration increases during exercise
  • Decreased response following training
  • Insulin and glucagon secretion influenced by
    catecholamines

45
Effects of Insulin and Glucagon
Figure 5.24
46
Changes in Plasma Insulin During Exercise
Figure 5.25
47
Changes in Plasma Glucagon During Exercise
Figure 5.26
48
Effect of Epinephrine and Norepinephrine on
Insulin and Glucagon Secretion
Figure 5.27
49
Effect of the SNS on Substrate Mobilization
Figure 5.28
50
Summary of the Hormonal Responses to Exercise
Figure 5.29
51
Hormone-Substrate Interaction
  • FFA mobilization decreases during heavy exercise
  • This occurs in spite of persisting hormonal
    stimulation for FFA mobilization
  • May be due to
  • High levels of lactic acid
  • Promotes resynthesis of triglycerides
  • Inadequate blood flow to adipose tissue
  • Insufficient albumin to transport FFA in plasma

52
Changes in Plasma FFA Due to Lactic Acid
Figure 5.30
53
Effect of Lactic Acid on FFA Mobilization
Figure 5.30
Write a Comment
User Comments (0)
About PowerShow.com