Cardiovascular System 3.1

Blood Vessel Layers

1. Tunica Externa - Connective Tissue

2. An External Elastic Membrane

3. Tunica Media - Smooth Muscle (Determines diameter of vessel)

4. An Internal Elastic Membrane

5. Tunica Intima/Internal - Single layer of Endotheluum

Arteries

• Move blood away from heart

• Thicker muscle layers

• Are under higher pressure

• Maintain shape

• Have 2 different layers of Elastic Membranes: Internal & External

Veins

• Move blood toward heart

• Have valves to prevent backflow

Which Large Artery Carries Deoxygenated Blood?

Pulmonary Trunk & Pulmonary Arteries

Which Large Veins Carry Oxygenated Blood?

Pulmonary Veins

Pulmonary Circuit of Blood Flow

Systemic Circuit of Blood Flow

Heart Valves and their Purpose

• AV Valves: Tricuspid and Bicuspid; prevent backflow into the Atria

• Semilunar Valves: Aortic and Pulmonary; prevent backflow in the Ventricles

Role of Papillary Muscles and Chordae Tendinae

They anchor and control the movements of the Av Valve leaflets (cusps) so that they don’t swing into Atria.

SA Nodes

• Located in superior wall of Right Atrium

• Consists of nerves that fire eclectically impulses (go through heart)

Atria

• Impulses from SA Nodes goes here first

• Contracts Atrial muscles

AV Node

• Located in inferior wall of Right Atrium

• Gets electric impulse from Atria

AV Bundle

• Get electrical current from AV Node

• Splits, conducting the electrical impulses into the Right/Left Bundle branches

Purkinje Fibers

• Branches from AV Bundles feed into these

• Cause Ventricular Contraction

Conduction System of the Heart

SA Nodes → Internodal Pathways → AV Node → AV Bundle → RBB/LBB → Purkinje Fibers

What are the Septum’s?

• Interatrial Septum (Between Aorta and PT)

• Interventricular Spectrum (Between LV and RV)

• Atrioventricular Spectrum (Between Atriums and Ventricles)