Cardiovascular System Notes

Chapter 17: Cardiovascular System

Introduction

• Chapter 17 focuses on the cardiovascular system.

• The professor will not cover every slide in the PowerPoint but specifies which slides are important.

• Material covered verbally and on PowerPoint is testable.

• Taking notes alongside the PowerPoint slides is advisable.

Anatomy and Physiology Review

• Each unit starts with a review of normal anatomy and physiology before discussing pathology.

• The professor emphasizes that all necessary information is self-contained within the course, even if students are simultaneously taking Anatomy and Physiology courses.

Primary Function of The Heart

• The primary function of the heart is to efficiently pump blood through the vessels.

Anatomical Overview

• Blood flow through the heart is explained to understand the anatomical picture.

• Deoxygenated blood from the head, neck, shoulders, and arms returns to the right atrium via the superior vena cava.

• Blood from the rest of the body returns to the right atrium via the inferior vena cava.

• Deoxygenated blood from the heart itself returns via the coronary sinus and great cardiac vein into the right atrium.

• Blood then flows from the right atrium to the right ventricle.

Heart Valves

• The heart has two atria and two ventricles separated by valves called atrioventricular (AV) valves.

• AV valves are anchored by chordae tendineae to papillary muscles in the ventricle walls.

• Chordae tendineae prevent AV valves from inverting into the atria during ventricular contraction.

• Only AV valves have chordae tendineae; semilunar valves do not need them.

• The AV valve on the right side is called the right atrioventricular valve or tricuspid valve.

• The AV valve on the left side is called the left atrioventricular valve, mitral valve, or bicuspid valve (due to having two cusps).

Heart Function During Diastole

• During diastole (rest), the atria squeeze blood into the ventricles.

• Atrioventricular valves are open, and semilunar valves are closed during this phase.

Preload

• Preload refers to the volume of blood in the ventricles at the end of diastole.

• Cardiovascular exercise can increase preload capacity and stroke volume.

Contractility

• Contractility refers to the force of ventricular contraction.

• The amount of contractile proteins in muscle cells is a key factor; this amount can be affected by myocardial infarction (heart attack) or ischemia (reduced oxygen supply).

• Myocardial infarction involves the death of heart cells, which contain contractile proteins.

• Ischemia can reduce the recruitment of contractile proteins due to insufficient oxygen supply.

• Calcium availability is important for myosin to bind to actin.

Afterload

• Afterload is the resistance the ventricles must overcome to eject blood.

• Aortic stenosis is an example of increased afterload, where the aortic valve doesn't open enough, causing the left ventricle to work harder.

• Elevated blood pressure is another cause of increased afterload.

Cardiac Workload

• Cardiac workload depends on preload, contractility, and afterload.

Atrial Natriuretic Peptide (ANP) and B-type Natriuretic Peptide (BNP)

• Atrial natriuretic peptide (ANP) is released when the atria are stretched due to excess fluid.

• ANP inhibits aldosterone, promoting sodium and water excretion, which lowers blood pressure.

• B-type natriuretic peptide (BNP) is released from the ventricles during heart failure or fluid overload.

• BNP functions similarly to ANP.

Diagnostic Devices

• Slides 62 onward cover diagnostic devices.

• These devices are only relevant as they are used and explained by the professor.