CSEP421 - Cardiovascular System 1 (9.1) Notes

Cardiovascular System

Part 1 Objectives

• List selected components of the cardiovascular system and state the functions of each.
• Label a diagram of the heart and blood vessels and trace the flow of blood through the heart.

Introduction

• The cardiovascular system consists of the heart, blood vessels, and blood.
• Function of the heart: to pump blood into the arteries.
• Blood circulates through an estimated 100,000 km of blood vessels.
• Function of the blood vessels: to carry blood near to every cell.
• Blood vessels help regulate body temperature and blood pressure by constricting and dilating.

Functions of the Blood

• To supply cells with required materials ($O_2$ and nutrients).
• To remove wastes ($CO_2$ and urea) produced by the cells.
• To transport hormones, heat, and pressure.
• To contribute to body defense.
• To help regulate pH, temperature, and water content.

Location of the Heart

• The heart is situated medial to the lungs in the mediastinum, with about two-thirds of its mass to the left of the midline.

Chambers of the Heart

• Four chambers:
  • 2 upper atria
  • 2 lower ventricles
• Right Atrium, Right Ventricle, Left Atrium, Left Ventricle.
• The right and left chambers are separated by a muscular wall (septum).

Right Side of Heart

Right Atrium

• Receives blood from the superior vena cava and inferior vena cava.

Tricuspid Valve (Right AV Valve)

• Allows blood to flow through into the right ventricle.
• When closed, it prevents blood from flowing back into the right atrium from the right ventricle.

Right Ventricle

• Receives blood from the right atrium.

Pulmonary Semilunar Valve

• Allows blood to flow into the pulmonary trunk (towards the lungs).
• When closed, it prevents blood flowing back into the right ventricle from the pulmonary trunk.

Structure of the Heart: Internal Anatomy, Right Side

• Includes the right atrium, right ventricle, tricuspid valve, superior vena cava, inferior vena cava, and pulmonary semilunar valve.

Left Side of Heart

Left Atrium

• Receives blood from the 4 pulmonary veins (2 from the right lung + 2 from the left lung).

Bicuspid Valve (Left AV Valve)

• Allows blood to pass through into the left ventricle.
• When closed, it prevents blood from flowing back into the left atrium from the left ventricle.

Left Ventricle

• Receives blood from the left atrium.

Aortic Semilunar Valve

• Blood passes through the valve into the ascending aorta.
• When closed, it prevents blood from flowing back into the left ventricle.

Structure of the Heart: Internal Anatomy, Left Side

• Includes the left atrium, left ventricle, bicuspid valve, ascending aorta, aortic arch, and aortic semilunar valve.

Heart and Blood Vessels

• Key components include the superior vena cava, aortic arch, pulmonary trunk, right and left pulmonary arteries, right and left pulmonary veins, pulmonary valve, right atrium, tricuspid valve, right ventricle, inferior vena cava, left atrium, aortic valve, bicuspid valve, left ventricle, and descending aorta.

Heart Valves

• Valves open and close in response to pressure changes as the heart muscle contracts and relaxes.
• There are two sets of valves:
  • Atrioventricular valves (AV valves):
    • Tricuspid (R) and bicuspid valves (L).
  • Semilunar valves (SL valves):
    • Pulmonary and aortic semilunar valves.
• Closure of the valves produces the heart sounds (lubb, dupp) heard during each heartbeat.

Atrioventricular Valves (AV Valves)

• Right and left AV valves open and allow blood to flow from atria into ventricles.
• AV valves close, preventing backflow of blood into atria.
• This occurs when ventricles contract, pushing valve cusps closed.

Semilunar Valves

• Pulmonary and aortic semilunar valves open with ventricular contraction (allowing blood to flow into the pulmonary trunk and aorta) and close with ventricular relaxation (preventing blood from returning to ventricles, as blood pushes against the valve cusps, tightly closing them).

Blood Circulation

• Two closed circuits: pulmonary and systemic.
  • Pulmonary circulation: Heart -> lungs -> heart.
  • Systemic circulation: Heart -> body -> heart.

Blood Flow

• Deoxygenated blood is typically represented in blue, while oxygenated blood is represented in red.
• The flow includes the superior and inferior vena cava, right atrium, tricuspid valve, right ventricle, pulmonary valve, pulmonary trunk and pulmonary arteries (to the lungs where CO2 is dropped off and O2 is picked up), pulmonary veins (oxygenated blood) to the left atrium, bicuspid valve, left ventricle, aortic valve, aorta and systemic arteries, and then to body tissues where O2 is dropped off and CO2 is picked up.

The Heart - External View

• Key structures include the brachiocephalic trunk, left common carotid artery, left subclavian artery, superior vena cava, ascending aorta, right pulmonary artery, parietal pericardium, right pulmonary veins, arch of aorta, ligamentum arteriosum, left pulmonary artery, pulmonary trunk, left pulmonary veins, left auricle of left atrium, right auricle of right atrium, right coronary artery, right atrium, coronary sulcus, right ventricle, inferior vena cava, branch of left coronary artery, left ventricle, anterior interventricular sulcus, and descending aorta.