Heart - LO 1

1. Describe the functions and locations of the four chambers of the heart, and understand basic terminology regarding the heart.

There are 4 chambers of the heart: right & left atria and right & left ventricles.

Atria: receive venous blood that will be pumped into ventricles; weak contraction
- Right atrium: receives de-oxygenated blood from the superior vena cava (SVC), inferior vena cava (IVC), coronary sinus, and anterior cardiac vv.
  - Pumps de-oxygenated blood into R. ventricle (through R. atrioventricular orifice)
- Left atrium: receives oxygenated blood from the pulmonary vv. (from lungs)
  - Pumps oxygenated blood into L. ventricle (through L. atrioventricular orifice)
Ventricles: discharge blood either into pulmonary trunk (from R. ventricle) or ascending aorta (from L. ventricle); more powerful contraction
- Right ventricle: receives de-oxygenated blood from R. atrium
  - Pumps de-oxygenated blood through the pulmonary trunk/arteries to the lungs (through pulmonary/semilunar valve)
- Left ventricle: receives oxygenated blood from L. atrium
  - Pumps oxygenated blood through the ascending aorta to the rest of the body (through aortic/semilunar valve)

Often the heart is divided into right and left parts, based on the composition of blood. These parts work at the same time and rate, with similar amounts of blood.

Right heart (R. atrium and ventricle)
- Relatively de-oxygenated blood
- Pulmonary circulation
Left heart (L. atrium and ventricle)
- Oxygenated blood
- Systemic circulation

Terms to be familiar with:

Diastole: relaxation
- Ventricles fill with blood
Systole: contraction; typically associated with ventricles contracting (ventricular systole)
- Ventricles empty blood into aorta & pulmonary trunk
Heart sounds: created by the shutting of valves (to prevent backwards flow)
- Lub (1st sound; S1)
  - Atrioventricular (AV) valves closure
  - loudest at the apex
- Dub (2nd sound; S2)
  - Aortic & pulmonic valve closure
  - loudest at base

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