Reading: Randall- Chapter 12

Regulation of Heart Rate

• neurogenic pacemakers
• myogenic pacemakers

Cardiac Output:

Fick's principle VO₂ = Q (CaO₂ - CvO₂)

Increased Oxygen extraction by tissue

Training Effects

VO_2, HR, SV, a-v O₂ difference

Blood Vessels:

Arteries

arterioles

capillaries

venules

Veins

Physics of Blood flow

velocity of blood flow

Blood pressure = Flow (Q) x Resistance (R)

Resistance

• viscosity
• total vessel length
• diameter of vessel R= 1/r⁴

Site of greatest resistance in vasculature. Why?

Law of Laplace: Tension in wall = Pressure across wall X radius (T=P x r)

size of arterial wall, venous wall, capillary wall

aneurysms- thinning of vessel wall

Diving Response

How to prevent asphyxia for air breathing mammals/avians while submerged?

1. Increase oxygen storage

2. bradycardia

3. maintain blood pressure with increased peripheral resistance

Reverse diving response in fish