The Heart Flashcards
Heart Covering Layers (Superficial to Deep)
Outer fibrous Layer
Parietal Pericardium
Visceral perocardium
Heart Wall Layers
Epicardium
Myocardium - Thick bundles of cardiac muscle
Endocardium - thin sheet of endothelial tissue
What are the 4 Heart chambers
Atria - Right atrium, Left atrium
Ventricles - Right ventricle, left ventricle
What is the right atrium filled by?
The superior vena cava, inferior vena cava, and coronary sinus
What is the left atrium filled by
4 pulmonary veins
Where does the right ventricle pump blood to
The pulmonary circuit (to become oxygenated)
- Makes up most of anterior heart surface
Where does the left ventricle pump blood to
The systemic circuit (to nourish all body tissue and organs
- Forms apex of heart
What are the 4 heart valves
Atrioventricular Valves (AV) - Right and Left
Semilunar Valves - Pulmonary and Aortic
Right AV valve function
Tricuspid Valve, prevents backflow into the right atrium
Left AV valve function
Bicuspid/Mitral valve, prevents backflow into left atrium
Pulmonary Semilunar valve function
Exit valve for the right ventricle, at the base of the pulmonary artery
Aortic semilunar valve function
Exit valve for the left ventricle, at the base of the aorta
When are the AV valves open/closed?
AV valves are open during ventricular relaxation and closed during contractions
When are semilunar valves open/closed
They are open during contractions and closed during ventricular relaxation
What is the pulmonary circuit?
The pulmonary circuit receives oxygen-poor blood from the body veins, brings it to the lungs for gas exchange and back to the heart. Operates on the right side of the heart
What is the systemic circuit?
Systemic circuit takes oxygen and nutrient-rich blood and supplies all organs and body tissues. Operates on the left side of the heart, has thicker walls and a stronger pump.
What is the Myocardium’s blood supply?
Left and right coronary arteries supply myocardium with blood. They branch from the base of the aorta and encircle the heart in coronary sulcus at the atria and ventricle junction.
Function of the Intrinsic Conduction System
Sets basic rhythm of the heart muscle’s contractions. Causes depolarization in one direction from atria to ventricles, sets contraction rate of approx. 75 bpm
Intrinsic Conduction System Components
Sinoatrial node (SA node)
Atrioventricular node (AV node)
Right + Left bundle branches
Purkinje Fibers
Where is the SA node found
In the right atrium, the heart’s peacemaker
Where is the AV node found
Atria and Ventricle junction
Where are the right and left bundle branches found
Interventricular septum
Where are the Purkinje fibers found
Spread within the walls of the ventricles
Intrinsic Conduction Impulse Pathway
Depolarization starts at SA node
Impulse spreads through atria to AV node
atrial contraction
Impulse delayed at AV node to allow contraction to finish
Passes through AV bundle, bundle branches and purkinje fibers
Ventricle contraction occurs
Blood is then pumped into pulomary and systemic circuit
Phases of the Cardiac Cycle
1) Atrial Diastole (ventricular filling)
2) Atrial Systole
3) Isovolumetric contraction
4) Ventricular Systole
5) Ventricular Diastole
Atrial Diastole (ventricular filling)
Blood is passively filling into and through the atria into ventricles, AV valves open, semilunar closed, Atria and Ventricles in relaxation
Atrial Systole
Atrial contraction occurs, any blood left is atria is forced into ventricles, AV valves open, Semilunar closed
Isovolumetric contraction
AV valves close to prevent backflow, produces 1st heart sound ‘lub’. Atrial systole ends and Ventricular systole begins
Ventricular Systole
Ventricles contract, semilunar valves are open and blood is ejected from the ventricles
Ventricular Diastole
Semilunar valves close to prevent backflow, causing 2nd heart sound ‘dub’. Pressure inside ventricles falls below pressure in major arteries.
