NASM 6th Edition chapter 3: The cardiorespiratory system

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Chapter 3 NASM Study Guide

Important definitions

The cardiorespiratory system: Composed of the respiratory and cardiovascular system

The cardiovascular system: Blood vessels, blood, and the heart

Arteries: Carry blood away from the heart to the rest of the body

Veins: Return blood to the heart from the rest of the body

Stroke volume: The amount of blood pumped out the heart with each contraction

Cardiac output: Heart rate × stroke volume

Sinoatrial (SA) node: The “pacemaker” of the heart because it initiates the heartbeat

Typical heart rate for an adult: 70-80 BPM

The atria and ventricles:

The heart has two pairs of different chambers. These chambers are called the atriums and ventricles. Here are the functions of the chambers.

The right atrium receives blood coming from the body while the left atrium receives the blood (oxygen-rich) that comes from the lungs and the heart.

The right ventricle has thinner walls because it only needs to pump blood a short distance back to the heart and the lungs. The left ventricle, on the other hand, has much thicker walls and is a much higher pressure pump because it is required to push blood to the rest of the body.

The functions of blood:

  1. Protection: The white blood cells help to protect your body against diseases and blood clotting helps with fluid loss.
  2. Regulation: Blood helps keep a stable body temperature, electrolyte, and water level as well as pH.
  3. Transportation: The primary function of blood is to transport nutrients and oxygen to the cells of the body. It also takes away CO2 and various wastes from the cells and delivers hormones to specific tissues.

The respiratory pump:

These are the thoracic and abdominal structures that help with the contraction and expansion of the lungs.

The muscles that comprise the respiratory pump are:

    • For inhalation: The Scalene muscles, the pack minor, sternocleidomastoid, and the diaphragm.
    • For exhalation: The internal intercostals and the abdominal muscles

Here is the cycle of the respiratory pump (venous return):


  1. The thoracic cavity expands new
  2. The pressure within the pleural cavities drop
  3. This pulls air to the lungs
  4. It also brings blood into the IVC and the right atrium from the smaller veins that exist in the abdominal cavity


  1. The pressure in the pleural cavities rise
  2. This forces blood into the right atrium
  3. This is important especially for heavy exercises


NASM practice quiz for chapter 3

NASM flashcards for chapter 3