The heart is a muscular pump in the mediastinum, between the lungs and behind the sternum. To learn it efficiently, connect three things every time you review: the chamber, the valve that controls its exit, and the vessel that carries blood next.
How many chambers does the heart have?
There are four chambers. The right atrium receives deoxygenated blood from the superior and inferior venae cavae. The right ventricle pumps it through the pulmonary valve and pulmonary arteries to the lungs.
The left atrium receives oxygenated blood from the pulmonary veins. The left ventricle pumps it through the aortic valve into the aorta and systemic circulation. Its wall is thicker because systemic circulation has higher resistance than pulmonary circulation.
Heart valves and what they prevent
| Valve | Between | Opens to allow |
|---|---|---|
| Tricuspid | Right atrium and right ventricle | Right ventricular filling |
| Pulmonary | Right ventricle and pulmonary trunk | Blood leaving for the lungs |
| Mitral (bicuspid) | Left atrium and left ventricle | Left ventricular filling |
| Aortic | Left ventricle and aorta | Blood leaving for the body |
Valves open when pressure behind them is greater and close when pressure reverses. They do not actively pump blood. The chordae tendineae and papillary muscles support the atrioventricular valves during ventricular contraction.
Pulmonary versus systemic circulation
Pulmonary circulation moves blood from the right ventricle to the lungs for gas exchange and back to the left atrium. Systemic circulation moves blood from the left ventricle to the tissues and back to the right atrium.
“Artery” means a vessel carrying blood away from the heart, not necessarily oxygen-rich blood. The pulmonary arteries are the important exception students should remember: they carry deoxygenated blood toward the lungs. Pulmonary veins return oxygenated blood to the heart.
Coronary circulation
The myocardium needs its own blood supply. The right and left coronary arteries arise near the start of the aorta and branch across the surface of the heart. Cardiac veins drain into the coronary sinus, which empties into the right atrium.
Coronary arteries fill mainly during diastole. This is why obstruction of a coronary vessel can injure the myocardium even while the chambers continue to contain blood.
Surface landmarks for nursing students
- The apex is usually directed down, forward, and left.
- The apical impulse is commonly assessed around the left fifth intercostal space at the mid-clavicular line, with patient factors and clinical context in mind.
- Heart sounds are best understood by linking each listening area to the valve region and direction of blood flow, not by memorising a flat list.
- Pulse, blood pressure, capillary refill, skin temperature, and level of consciousness help you reason about perfusion and cardiac output.
Use a 3D atlas to make the relationships stick
Open the Testwiz 3D heart view. Start with the heart layer, then turn on arteries and veins. Rotate to a front view, select the heart, and isolate it. Say the flow pathway aloud while you trace the vessels. Finish by hiding the labels and identifying the chambers from shape and position alone.
Quick check
Which side of the heart pumps to the lungs?
The right side. The right ventricle sends blood through the pulmonary valve and pulmonary arteries.
Why is the left ventricular wall thicker?
It generates pressure for systemic circulation, which has greater resistance than the pulmonary circuit.