Cardiovascular & Respiratory Physiology

Key Concepts

This chapter covers the cardiovascular system (heart + blood vessels) and then maps blood flow through systemic (greater) and pulmonary (lesser) circulation. You need this because exam questions often test oxygenated vs deoxygenated blood pathways and “where blood goes next.”

Core ideas you MUST know:

• Cardiovascular system = heart + blood vessels; it drives the circulatory system (fluid transport around the body).
• Heart pumps blood into vessels; blood vessels distribute it to tissues and bring it back.
• Systemic circulation (greater):
• Blood leaves the left ventricle → arterial system → capillaries (tissue exchange) → venous system → right atrium.
• Pulmonary circulation (lesser):
• Blood leaves the right ventricle → pulmonary artery → lungs (gas exchange at alveoli) → pulmonary veins → left atrium.
• Oxygenated vs deoxygenated (high-yield pattern):
• Systemic tissues receive oxygenated blood (from the left side of the heart).
• Venous blood returning to the heart via the systemic veins goes to the right atrium.
• Pulmonary circulation is the “re-loading oxygen” loop: deoxygenated blood to lungs, oxygenated blood back to left atrium.

Before you continue: After studying this chapter, can you trace blood flow step-by-step from left ventricle to systemic capillaries to right atrium?

Key Terms

• Cardiovascular system - Heart + blood vessels that move blood through the body.
• Circulatory system - The fluid-transport network (cardiovascular + lymphatic systems).
• Systemic (greater) circulation - Loop supplying tissues: left ventricle → body capillaries → right atrium.
• Pulmonary (lesser) circulation - Loop for gas exchange: right ventricle → lungs → left atrium.
• Arterial system - Vessels that carry blood away from the heart (to tissues).
• Venous system - Vessels that carry blood back to the heart (from tissues).
• Capillaries - Small vessels where exchange happens between blood and tissues.
• Pulmonary veins - Veins that carry oxygenated blood from lungs to the left atrium.

Active Recall

• Cardiovascular system - __________

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• Circulatory system - __________

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• Systemic (greater) circulation - __________

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• Pulmonary (lesser) circulation - __________

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• Arterial system - __________

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• Venous system - __________

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• Capillaries - __________

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• Pulmonary veins - __________

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Worked Examples

Example 1 (straightforward): Identify the “loop”

1. Blood is pumped from the left ventricle.

2. It goes to tissues via arteries and exchanges at capillaries.

3. After exchange, it returns via veins to the right atrium.

Answer: This is systemic (greater) circulation.

Now you try:

A blood sample is found in systemic capillaries during tissue exchange. Where should it end up next?

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Example 2 (oxygen logic): Which circulation to lungs?

1. Blood starts in the right ventricle.

2. It goes to the lungs using the pulmonary artery.

3. Gas exchange happens in lung alveoli; oxygenated blood returns via pulmonary veins to the left atrium.

Answer: This is pulmonary (lesser) circulation.

Now you try:

Deoxygenated blood is leaving the heart to reach the alveoli. Name the chamber and vessel it travels through first.

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Example 3 (combined pathway): Trace one full circuit segment

1. Left ventricle → systemic arteries → capillaries (tissue exchange).

2. Capillaries drain into systemic veins → right atrium.

3. From right atrium → right ventricle → pulmonary artery → lungs for re-oxygenation.

Answer: Systemic loop completes at right atrium, then pulmonary loop begins.

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