Hormones, Exercise, & ES 335

Transcription

1 Hormones, Exercise, & Training ES 335 Spring 2010

2 Hormones help regulate: Growth Metabolism Reproduction Maintain homeostasis Help control ph levels Adjust metabolism based on energy needs

3 Endocrine System Organization Three components characterize the endocrine system: Host gland Hormones Target (receptor) cells or organs Endocrine Glands release hormones into extracellular space for body diffusion Exocrine Glands secrete hormones through duct system for local stimulation; controlled by CNS

4 What Makes a Chemical a Hormone? Ahormoneis: A chemical secreted by a cell or group of cells into the blood for transport to a distant target. (pg 405) Eventually exerts its effects at low concentrations (pg 405)

5 Hormone Actions Change how fast we create intracellular proteins Alter enzymatic activity Modify cell membrane transport Induce secretory activity

6 Hormone Effects on Enzymes Stimulate enzyme synthesis Increase or decrease an enzyme s ability to interact with a substrate Activate inactive enzyme forms to y increase total enzyme activity

7 Stimulating Hormone Release Hormonal some hormones affect the release of other hormones Humoral blood ph & nutrients stimulate release of specific hormones Neural release of hormones to maintain homeostasis

8 Reflex Arc for Hormone Secretion Reflex arc for insulin secretion Pancreas may also secrete insulin in response to high blood glucose levels Example of humoral stimulation

9 Hormones to Learn Human Growth Hormone Insulin Glucagon Thyroid Hormones Adrenal de Hormones o Tell us: What gland secretes them? What do they do? How do they respond to exercise?

10 Growth Hormone (GH) Released from the Pituitary Gland Promotes cell division and proliferation Increases amino acid transport through plasma membranes Stimulates RNA formation Activates cellular ribosomes that increase protein synthesis

11 Effects of GH on Energy Transfer Depresses carbohydrate utilization Increases fat utilization for energy

12 Exercise, GH, and Tissue Synthesis GH secretion a few minutes after exercise begins exercise intensity GH production & secretion GH promotes its tissue-building effects on diverse tissues including: bone skeletal l muscle

13 Adrenal Gland

14 Hormones of the Adrenal Medulla Catecholamines Neural outflow from the hypothalamus directly influences adrenal a medulla secretions et s Epinephrine (80%) and norepinephrine (20%) Increase heart rate, contractility, and blood pressure Rate of secretion is strongly influenced by exercise intensity

15 Hormones of the Adrenal Cortex Mineralocorticoids Aldosterone regulates sodium reabsorption in the kidneys distal tubules Aldosterone also affects levels of K & overall ph Glucocorticoids Cortisol regulates blood glucose concentrations via its permissive interactions with glucagon and catecholamines Androgens Dehydroepiandrosterone (DHEA)

16 Hormones of the Pancreas Insulin Regulates glucose metabolism by facilitating cellular glucose uptake in all tissues except the brain in response to hyperglycemia Glucagon Stimulates glycogenolysis and gluconeogenesis to increase glucose output in to prevent hypoglycemia

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22 Endurance Training and Endocrine Function Endurance training generally decreases the magnitude of hormonal response to a standard exercise level

23 What does this mean for diabetics?

24 Growth Hormone release over time w/ training Figure shows changes over 1 year for: Control group Group exercising at LT Group exercising above LT

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26 Adrenal Gland Response to Exercise Cortisol Less released in trained individuals during moderate exercise May be due to psychological stress in untrained people during exercise Works to break down FAs & Proteins Energy Tissue repair Nor/Epinephrine Training will lead to decreased release of catecholamines (see next slide) BP & HR are more controlled (decreased) at submaximal intensities

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28 Resistance Training Testosterone & Growth Hormone affected Training frequency of secretion Training how much is secreted Leads to muscle hypertrophy

29 Questions For Review

30 Questions Endocine glands are: A. Concentrated in sweat and upper digestive tract glands B. Ductile C. Hormone secreting D. Under somatic nervous system control

31 Questions Human Growth Hormone: A. Blunts skeletal growth B. Facilitates protein synthesis C. Increases CHO utilization D. Treats acromegaly

32 Questions Cortisol A. Activates the immune system B. Alters mood, memory, & learning C. Promotes skeletal muscle protein synthesis D. Suppresses lipolysis

33 Questions (T/F) 1. Endurance training increases the production and release of all hormones studied to date.

34 Questions (T/F) 1. The presence of specific receptors is required for cells acting as targets for a given hormone.

35 Questions (T/F) 1. Non-strenuous aerobic exercise or resistance training increases circulating levels of testosterone in previously untrained males

36 Questions (T/F) 1. In general, hormones function by altering the rates of cellular reactions rather than by initiating them or shutting them down.