Cardiac- Anatomy

Question 1

Anatomy- pericardium, atria, ventricles

Answer 1

• The heart comprises two muscular pumps working in a series covered in a serous sac (pericardium) that allows free movementwith each heart beat and respiration
• The right heart (right atrum and ventricle) pumps deoxygenated blood returning from the systemic veins into the pulmonary circulation at relatively low pressures.
• The left heart (left atrium and ventricle) receives blood from the lungs and pumps it round the body to the tissues at higher pressures.

Question 2

Anatomy- valves

Answer 2

• Atrioventricular valves (tricuspid on the right side, mitral on the left) separate the atria from the ventricles.
• The pulmonary valve on the right side of the heart and the aortic valve on the left separate the ventricles from the pulmonary and systemic arterial systems, respectively.

Question 3

Anatomy- cardiac co-ordination

Answer 3

• Cardiac contraction is coordinated by specialised groups of cells.
• The cells in the SA node normally act as the cardiac pace-maker.
• Subsequent spread of impulses through the heart ensures that atrial contraction is complete before ventricular contraction (systole) begins.
• At the end of systole the ventricles relax and the atrioventricular valves open, allowing them to refill with blood from the atria (diastole).