The heart Flashcards
What are the characteristics of the heart?
Its a hollow muscular bag, positioned between lungs (mediastinum). it rests on the diaphragm, about 2/3 lies to left of the body but can alter between individuals
What is the function of the heart?
It is for blood circulation, delivering o2 and nutrients to body and removing wastes, is responsive to changing needs and can increase output by 7x
What is the pericardium?
The pericardium is the protective sac enclosing the heart and great blood vessels
What is the parietal pericardium?
The outer layer that anchors heart
What is the visceral pericardium?
The inner layer that secretes fluid
What is the fluid between the pericardium layers?
It is serosa and allows friction free movement
What are the 3 layers of the wall of the heart?
From closest to heart to furthest- Endocardium, myocardium and epicardium
What is the coronary sulcus?
A groove on the heart that divides the heart into left and right.
What are the chambers of the heart?
The right and left hand side which is divided into 4 chambers. Right atrium, Right ventricle, Left atrium, Left ventricle.
What are the chambers of the heart separated by?
They are separated by septa which is interatrial septa for the atriums and interventricular for the ventricles.
Which parts of the heart have thicker walls?
The ventricles have thicker walls as they have to pump blood up using more energy
Which chamber has the thickest wall and why?
The left ventricle as it has to force blood into aorta and through thousands of blood vessels all around the body
What are the walls of the ventricles lined with?
Ridges of muscles called trabeculae
What does the coronary sinus do?
Return blood to the heart that has supplied the heart wall itself
What are the valves of the heart?
The AV (atrioventrical) and the Aortic and Pulmonary valves
Where are the AV valves and what are their characteristics?
They are located between the atrium and ventricle on both sides of the heart. They stop blood from flowing back from the ventricle into the atrium. The right AV has 3 cusps and is tricuspid and the left AV has 2 cusps and is bicuspid
What is the purpose of the Chordae tendineae and papillary muscles?
They anchor the AV flaps so they dont blow back inwards
Where are the Aortic and Pulmonary vales and what are their characteristics?
They are located at the opening of the aorta and the pulmonary artery. They are called semilunar valves due to their shape
Explain the blood flow through the heart
Deoxygenated blood from body cells enter the right atrium via the superior and inferior vena cava. The blood then enters the right ventricle via the tricuspid valve, This then pumps the blood through a semilunar valve to the pulmonary arteries taking it to the lungs. Here the blood becomes oxygenated through diffusion and returns to the heart to the left atrium via the pulmonary veins. The blood then enters the left ventricle via the bicuspid valve. Here the left ventricle pushes the blood to the aorta via a semilunar valve and sends the body around the body in systemic circulation.
What is the cardiac cycle?
The sequence of a beat. It occurs 70x a minute, the cardiac muscle self excites which is pacemaker potential
What are the characteristics of the SA node?
Is the pacemaker of the heart. Is located in the right atrial wall just below superior vena cava, generates pulse of 75-100/min, sets pace for heart and rhythm.
What are the characteristics of the AV node?
Located just above tricuspid valve. Receives slightly delayed signal from SA node so atria relaxes before ventricles contract.
What are the characteristics of the AV bundle?
Only connection between 4 chambers
What are the characteristics of the Purkinje fibres?
Links valves and other areas and picks up SA and AV node slack.
What is the systolic phase?
Contraction phase of the cardiac cycle where blood is ejected from ventricles. BP- 120-140
What is the Diastolic phase?
Relaxation of the atrium phase which the ventricles fill with blood. BP- 60-80
What is the lubdub sound of the heart?
It is the valves of the heart closing. The first is the closure of the tricuspid and bicuspid valves. This represents the beginning of the ventricular systole. Second sound is beginning of ventricular diastole which is produced by the closure of the semilunar valves.
