Cardiology Flashcards
Describe the Cardiac Cycle
Diastole (Relaxation of the Heart) is the first phase. This is when ventricular filling begins.
Systole is the 2nd phase first with the Atria contracting which causes the blood in the atria to finish filling the ventricles (atrial kick). The ventricles then contract pushing blood through the pulmonary and aortic valves.
What is the Ejection Fraction?
The ratio of the amount of blood pumped out of the ventricles in a contraction. Typically about 2/3rds the total volume.
What is stroke volume?
The amount of blood ejected. Normally it is between 60-100ml’s. Avg. is 70ml
What does stroke volume depend on?
Preload, Cardiac Contractility and Afterload.
Describe Preload
The pressure in the filled ventricle at the end of diastole. It is also called End-Diastolic Volume.
It influences the force and amount of the next contraction.
Starling’s law of the Heart states what?
The more the myocardial muscle is stretched the greater its force of contraction will be.
Therefore, the greater the venous return, the greater the preload (filling/stretching of the muscle) and the greater the stroke volume.
What landmark denotes the 2nd rib and superior border of the middle mediastinum?
The Sternal Angle
Explain the pericardium and its layers.
It is a sac that surrounds the heart. The Fibrous pericardium attaches to the sternum and surrounding structures and protects the heart. It is VERY strong and is why then the pericardial cavity gets fluid in it a Cardiac Tamponade can result.
The Serous layer of the pericardium has a Visceral layer and a Parietal layer. The Visceral layer is the same layer as the epicardium and lies on the hearts outer surface. The Parietal later is the layer ontop of the Visceral Pericardium.
The pericardium contains a pericardial cavity which a lipid based solution resides that allows the heart to beat without friction.
Explain the complete flow of blood through the heart.
Blood enters the R. Atrium from the Superior and Inferior Vena Cava as well as the Coronary Sinus. Blood passes through the Tricuspid or Right Atrioventricular valve to the R. Ventricle where it is pumped through the Pulmonary Valve to the Pulmonary Trunk then to the Right and Left lung via the Pulmonary Arteries. The blood flows back to the Left Atrium from the Right and Left Pulmonary Veins. The blood flows through the Mitral or Left Atrioventricular Valve to the Left Ventricle where it is pumped through the Aortic Valve to the Ascending Aorta.
Where do the coronary arteries originate? When do they fill?
They originate in the Aorta just after the Aortic Valve. They fill during Diastole.
Which nerve controls Parasympathetic Responses in the heart?
The Vagus (10th) Cranial nerve.
Trace the normal cardiac conduction system pathways.
SA Node, Internodal Pathways to AV Node, AV Node to the AV Bundle (of His) to the Left and Right Bundle Branches.
What are the Inherent Rates for the SA Node, AV Junction and the Purkinje Fibers in the Ventricles?
SA Node 60-100 bpm
AV Junction 40-60 bpm
Ventricle 20-40 bpm
What is the “Primary Pacemaker” for the heart? What is it’s rate and how much of it is actual pacemaker cells?
Sinoatrial Node
Rate 60-100
50% Actual Pacemaker Cells
Where does the electrical Impluse travel after the SA Node?
Through the Internodal Pathways to the AV Node and AV Junction.