Integrative Physiology III: Exercise Chapter 25 Integrative Physiology III: Exercise

About this Chapter Overview of how major systems are involved in the metabolism for skeletal muscle contraction How the extreme activities of exercise disrupt homeostasis Focus on how the circulatory & respiratory systems integrate their responses to exercise demands How exercise impacts health

Integration of Metabolism: Review of Roles of Systems in Muscle Contraction Reactants Transport Conversions Energy produced Contractions Respiration Excretion Endocrine Nervous

Integration of Metabolism: Review of Roles of Systems in Muscle Contraction Figure 25-1: Energy metabolism in skeletal muscle

Energy for Skeletal Muscle Contraction ATP & ADP Phosphocreatine Aerobic paths Anaerobic paths (glycolytic metabolism)

Sustaining Muscle contractions: ATP Sources/Time Phosphocreatine: Short bursts at maximal effort Anaerobic: Intermediate duration intense effort Aerobic: Long duration at reduced effort Figure 25-2: Speed of ATP production compared with ability to sustain maximal muscle activity

Fat mass, adipose tissue and energy stores Liver triglycerides = 450 kcal Muscle triglycerides = 3000 kcal Liver glycogen = 400 kcal Muscle glycogen = 2500 kcal Adipose tissue triglycerides = 120,000 kcal Data for a 70 kg lean subject.

Hormonal regulation of Energy Source for ATP Production (Huge body reserves – glucose 2000 & FFAs 70,000 Kcal) Exercise intensity Glucose Fatty acids

Hormonal regulation of Energy Source for ATP Production Metabolic Shifts Glucagon Cortisol Epinep./NE GH (insulin)

Hormonal regulation of Energy Source for ATP Production Figure 25-3: Use of carbohydrates and fats with increasing exercise

Oxygen Consumption: Factors Sustaining or Limiting Exercise O2 consumption:: to  exercise (measure w/Vo2 max) Limiting factors: O2 – cell availability, (O2 deficit) O2 – transport to: mitochondria, to cell, to blood, or to lung

The Canadian Study of Health and Aging (CSHA) Clinical Frailty Scale (CFS). The Canadian Study of Health and Aging (CSHA) Clinical Frailty Scale (CFS). Reproduced from Rockwood et al19 with permission of the publisher. Copyright © CMAJ, 2005. Ekerstad N et al. Circulation. 2011;124:2397-2404 Copyright © American Heart Association, Inc. All rights reserved.

Oxygen Consumption: Factors Sustaining or Limiting Exercise Figure 25-4: Changes in oxygen consumption during and after exercise

Respiratory Ventilation: Exercise Induced hyperventilation Feed forward Reflex: CNS Feedback reflexes: Motor sensors Joint movement Muscle contraction Chemo sensors O2 & CO2 levels Synchronized w/ cardiac output Plasma: [O2], [CO2] & [ pH]

Respiratory Ventilation: Exercise Induced hyperventilation Figure 25-5: Changes in ventilation with submaximal exercise

Respiratory Ventilation: Exercise Induced hyperventilation Figure 25-6: Changes in blood gas, partial pressures, and arterial pH with exercise

Cardiovascular Response to Exercise Cardiac output  5 to 35 L/min Rate  2-3 X Blood distribution  muscles to 88% of all blood  other tissues (except brain)

Cardiovascular Response to Exercise Figure 25-7: Distribution of cardiac output at rest and during exercise

Homeostatic Balancing of Exercise: “Controlled Disruption” Feed forward reflexes Anticipate demand Heart & lungs Protective reflexes Stretch damage Temperature  sweating  peripheral blood flow redistribution Blood pressure  constant

Homeostatic Balancing of Exercise: “Controlled Disruption” Figure 25-8: Peripheral resistance and arterial blood pressure during exercise

Health Advantages of Regular Exercise: Quality of Life  Cardiovascular disease risks: heart attack, stroke, high BP  blood pressure  LDL & triglycerides  HDL  risks for diabetes [blood glucose]  obesity  stress association  immune function (to a point)

Health Advantages of Regular Exercise: Quality of Life Figure 25-9b: The effect of exercise on glucose tolerance and insulin secretion

Health Advantages of Regular Exercise: Quality of Life Figure 25-10: Immune function and exercise

Summary Exercise challenges a range of many systems involved in metabolism to produce maximal energy from various nutrient sources Phosphocreatine most quickly produces ATP for muscle contraction while anaerobic glycolysis is intermediate Aerobic ATP production is needed for endurance exercise

Summary Ventilation and cardiac rate and output undergo huge changes which are anticipated by feed forward reflexes and protected by other reflexes to keep BP and temperature in homeostatic Exercise reduces risk factors in some most common health problems: heart disease, obesity , diabetes, and stress