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Hormonal Responses to Exercise Chapter 5
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Neuroendocrinology Endocrine Glands –Release messengers: hormones Hormones –Circulate in blood –Affect tissue with receptors –Concentration affects action –Inactivated or metabolized
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Neuroendocrinology Hormone-Receptor Interaction –Receptor Concentration Down regulation Up-regulation –Receptor Blocking
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Neuroendocrinology Mechanisms of Action –Alter membrane transport –Stimulate DNA for protein synthesis –Activate “Second Messengers” Examples: Hormones and Exercise
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Hormones and Exercise Insulin –Beta cells in Pancreas –Responds to high blood glucose (hyperglycemia) –Alter membrane transport of glucose –Stimulates glucose uptake (blood to cells) Muscle cells – can only “fill” so much Adipose cells – unlimited “filling” Other cells – liver, etc.
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Hormones and Exercise Diabetes Mellitus –Type I (Juvenile Onset – Insulin Dependent) Non-functioning Beta cells – no insulin Chronic hyperglycemia results in: –Poor circulation –Neuropathy –Limb loss –Blindness –Hypertension Need an exogenous source of insulin - injection
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Hormones and Exercise Diabetes Mellitus –Type II (NIDDM) Functioning Beta cells High CHO / calorie diet Plenty of insulin – in fact, too much? Chronic hyperinsulinemia results in: –Down-regulation of receptors –Poor insulin sensitivity** –Hyperglycemia and its effects
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Hormones and Exercise During Exercise –Glucose availability increases - glycogenolysis –Insulin production decreases –M. cell need for energy increases –Increased glucose transport occurs without insulin –Transport of gluc. & FFA into M. cells increases –Transport of gluc. & FFA into other cells decreases –Energy available for M. contraction
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Hormones and Exercise Effect of Exercise on NIDDM Diabetes –During Ex. Transports glucose into cell without insulin –Result of Ex. (after ex.) Increases sensitivity of m. cells to insulin –Up-regulation of receptors occurs Improves (reverses) Type II
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Hormones and Exercise Glucagon –Alpha cells of pancreas –Mobilizes glucose from liver –Mobilizes FFA from adipose –Makes substrates available when blood levels are low
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Hormones and Exercise Cortisol –Adrenal cortex –Stimulates FFA and AA mobilization –Decreases rate of glucose utilization –Used for energy regulation and tissue repair
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Hormones and Exercise “Sparing Glucose” –Muscle glycogen = limited fuel source –Use fat instead –Put glucose in blood –Make more glucose “gluconeogenesis” (Cs from AA) Cori cycle (Cs from lactate)
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Hormones and Exercise Growth Hormone (GH) –Pituitary gland –Stimulates tissue protein synthesis & bone growth –Increases during exercise for energy regulation –Do exercisers grow bigger? –Should I take this to grow bigger?
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Hormones and Exercise Testosterone –From testes and ovaries (anterior pituitary) –Anabolic and androgenic effect –Stimulates protein synthesis Negative affects? Balance
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Questions?
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