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Blood pressure Dynamics

A lot of students struggle when learning about the cardiovascular system. This is often because they try and learn some of the more complicated theories before they really understand the basics. 

This video aims to teach the basic concepts that makeup blood pressure using some simple animations and visual imagery. Once you've learnt the basic principles then you can move on to some of the more complicated stuff!

Key terms

Cardiac Output: Volume of blood pumped out of the (left ventricle of the) heart over one minute. Calculated as Heart Rate x stroke Volume

Heart Rate: Number of contractions of the heart in one minute.

Stroke Volume: Volume of blood pushed out of the left ventricle of the heart per contraction.

-Contractility: The amount of effort the cardiac muscle puts into squeezing on contraction.

-Preload: The volume of blood in the ventricles just before contraction (see separate video below).

Systemic Vascular Resistance: The resistance to cardiac output created by the body's blood vessels. Greater resistance generates greater pressure.

Cardiac Preload

The importance of preload is often underestimated. It's another one of those terms that a lot of us have heard of but don't necessarily understand. However, everyone who delivers interventions for patient blood pressure should have at least a basic knowledge of the subject!

This video covers some of the basics including;

  • A basic definition,

  • how a slingshot can teach us about preload,

  • basic physiology

  • The Frank-Starling law of the heart,

  • Factors effecing Preload.

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