9_BF+Aerobic Power_v2

I. Anatomy of the Circulatory System

  • Heart: Central component of circulatory system.

  • Conductance System of the Heart: System that regulates the heartbeat.

  • Blood Supply to the Heart: Vessels supplying oxygenated blood to heart tissues.

  • Blood Vessels: Arteries, veins, and capillaries involved in circulation.

  • Blood: The transport medium for nutrients, oxygen, and waste.

II. Gas Exchange

A. Partial Pressure of Gases in a Gas Mixture

  • Gas pressure is determined by total (barometric) pressure and fractional concentration of gases.

  • Example at sea level: Total pressure = 760 mm Hg

B. Partial Pressure of Gases in a Liquid (Blood)

  • Henry's Law: Gas dissolving in fluid depends on:

    1. Pressure of gas above the fluid.

    2. Solubility coefficient of gas.

    • CO2 is 20.3 times more soluble in water than O2.

C. Lung Diffusion Capacity

  • Measures volume of O2 crossing the alveolar-capillary membrane per minute per mmHg.

III. Gas Transport

A. Transport of Oxygen by Blood

  • 98% of oxygen carried in red blood cells as oxyhemoglobin (HbO2).

  • 2% is dissolved in plasma.

B. Hemoglobin and Oxygen Carrying Capacity

  • Hemoglobin binds 1.34 mL of O2 per gram.

  • Typical hemoglobin concentration is 15 g/100 mL of blood, resulting in 20.1 mL O2/100 mL blood.

C. Percent Saturation of Hemoglobin with O2 (%SO2)

  • At rest, arterial blood saturation is 97.5% O2.

  • Venous blood saturation is 75% O2.

IV. Oxyhemoglobin Dissociation Curve

  • Plateau Portion: 60-100 mm Hg, oxygen saturation remains stable.

  • Steep Portion: 0-40 mm Hg, allows for increased O2 release with small changes in PO2.

A. Bohr Effect

  • Right Shift: More O2 is released at a given PO2 (decreased affinity).

  • Left Shift: Less O2 is released at a given PO2 (increased affinity).

V. Physiological Values and Changes With Exercise

  • Cardiac Output (Q): Volume of blood pumped by the heart per minute; increases with exercise.

  • At rest: 5 L/min; trained individuals can exceed 30 L/min.

  • Stroke Volume (SV): Volume of blood pumped per heartbeat; increases with exercise.

  • Ejection Fraction (EF): Percentage of blood ejected with each heartbeat increases with exercise.

VI. Distribution of Blood Flow During Exercise

  • At rest: 15-20% blood flow to skeletal muscles; during max exercise, 85% can go to muscles.

  • Blood flow regulated by sympathetic stimulation and muscle contraction factors.

VII. Factors Affecting VO2max

A. Determinants of VO2max

  1. Lung ventilation and blood oxygenation.

  2. Cardiac output and hemoglobin capacity.

  3. Muscle ability to extract oxygen.

  4. Aging impacts on VO2max; generally declines with age fuckinganced by exercise and conditioning.