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Access to HE Nursing: The Study Podcast
Episode 1 · 30 min · Published 1 March 2026

The cardiovascular system, explained

The cardiovascular system pumps blood through the body via the heart, arteries, veins and capillaries. In this episode we explain the four chambers of the heart, the cardiac cycle, and why understanding cardiac output is essential for clinical observation in nursing practice.

Updated: Last reviewed:

The cardiovascular system, explained
0:0030:45
Host
Dr Sarah Mitchell

In this opening episode, Dr Sarah Mitchell walks through the cardiovascular system from the ground up, the four heart chambers, the cardiac cycle, blood pressure, and what each clinical observation actually tells you about a patient's circulatory state. We also cover the most common Access to HE assignment on this topic and exactly how to structure your essay to hit the Level 3 grading criteria.

Companion lesson

The cardiovascular system

Read the full written lesson alongside this episode.

Key points

  1. 00:30

    The three components

    Heart, blood vessels, and blood, what each does.

  2. 03:15

    The four chambers explained

    How blood flows through atria and ventricles.

  3. 08:42

    The cardiac cycle

    Diastole and systole, what the "lub-dub" actually means.

  4. 14:20

    Clinical applications

    How pulse and BP tell you about cardiac output.

  5. 24:10

    Assignment guidance

    How to structure your Unit 1 essay for maximum marks.

What this episode covers

  • Cardiovascular system
  • Cardiac cycle
  • Blood pressure
  • Cardiac output
  • Clinical observations

Full transcript

Welcome to Access to HE Nursing: The Study Podcast. I'm Dr Sarah Mitchell, Lead Tutor for the nanoqual Access to HE Nursing pathway, and this is Episode 1, the cardiovascular system explained.

Let's start with the basics. The cardiovascular system has three core components: the heart, your muscular pump; the blood vessels, arteries, veins, and capillaries; and the blood itself, which carries oxygen, nutrients, hormones, and waste.

The heart has four chambers: two atria on top and two ventricles on the bottom. Deoxygenated blood from your body returns to the right atrium, drops into the right ventricle, and is pumped to the lungs through the pulmonary artery. In the lungs, it picks up oxygen, returns to the left atrium, drops to the left ventricle, and is pumped out through the aorta to the rest of the body.

The cardiac cycle, one complete heartbeat, takes about 0.8 seconds at rest. It has two main phases: diastole, when the chambers relax and fill, and systole, when they contract and eject blood. The "lub-dub" sound you hear through a stethoscope is the heart valves snapping shut at each phase transition.

Now, why does this matter for nursing? Because every clinical observation you take, pulse, blood pressure, capillary refill, is a window into how well this system is working. A weak, thready pulse tells you cardiac output is low. A blood pressure of 90/60 with a pulse of 120 tells you the body is compensating for something, maybe blood loss, maybe sepsis, maybe heart failure. Understanding the system means you can read those signs and escalate appropriately.

For your Access to HE assignment on this unit, you'll typically be asked to describe the cardiovascular system and apply that knowledge to a clinical scenario. The marking grid wants three things: accurate biological description, application to a real-world case, and use of academic sources.

I'll see you in Episode 2, where we'll tackle the respiratory system. Thanks for listening.

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