Nursing Assessment: Cardiovascular System
Structures and Functions of Cardiovascular System
• Heart
• Four chambers
o It lies within the thorax in
... [Show More] the mediastinal space that separates the right and left pleural cavities.
• Composed of three layers
o Endocardium
o Myocardium
o Epicardium
• Pericardium (fibrous sac)
• Left ventricular wall 2-3 times thicker than right
• APPLICATION: which problem will kill faster? LEFT (pumping blood)
o If in tissue (bruise), CANNOT move so CANNOT get PE
o Stroke has to come from LEFT side
o Immobile –risk for DVT
Blood Flow Through the Heart
• KNOW THIS!!!
• The right atrium receives venous blood from the inferior and superior venae cavae and the coronary sinus. The blood then passes through the tricuspid valve into the right ventricle. With each contraction, the right ventricle pumps blood through the pulmonic valve into the pulmonary artery and to the lungs.
• Blood flows from the lungs to the left atrium by way of the pulmonary veins. It then passes through the mitral valve and into the left ventricle. As the heart contracts, blood is ejected through the aortic valve into the aorta and thus enters the systemic circulation.
• STEPS:
o 1. A red blood cell will come from either the superior vena cava or the inferior vena cava and enter into the right atrium
2. the blood then flows across the tricuspid valve to the right ventricle
3. the right ventricle then squeezes and ejects that blood cell into a vessel called the “pulmonary artery”
4. the pulmonary artery splits into two vessels each going to the lungs
5. as the red blood cell makes its way through the lungs, it returns through the pulmonary veins to the left atrium
6. that blood is now oxygenated
7. its picked up oxygen then goes across the mitral valve into the left ventricle, which does most of the work in terms of delivery of blood flow to the body
8. that blood cell is now ejected into the aorta to some organ or muscle or skin in the human body
Cardiac Valves
• Valves are structural
• Thickness is mechanical
• Main places get vegetations and problems are with AV valves
• Aortic (tight noise aortic stenosis) --> low BP (LOW cardiac output)
o Tx: replace valve (tavern) – transaortic valvular repair
o This person is in need of anticoagulation
o Sutured in (going back and forth between if can have MRI or not)
• The four valves of the heart serve to keep blood flowing in a forward direction.
• The cusps of the mitral and tricuspid valves are attached to thin strands of fibrous tissue termed chordae tendineae. Chordae are anchored in the
papillary muscles of the ventricles. This support system prevents eversion of the leaflets into the atria during ventricular contraction.
• The pulmonic and aortic valves (also known as semilunar valves) prevent blood from regurgitating into the ventricles at the end of each ventricular contraction.
Coronary Arteries and Veins
• Can’t fix microvascularity
o Most women who have heart attack die within a year (they don’t present with chest pain)
▪ Stents may not work (only thing we can do is give calcium channel blockers and other pharmacology)
• The myocardium has its own blood supply, the coronary circulation.
• Blood flow into the two major coronary arteries occurs primarily during diastole (relaxation of the myocardium).
• The left coronary artery arises from the aorta and divides into two main branches: the left anterior descending artery and the left circumflex artery. These arteries supply the left atrium, the left ventricle, the interventricular septum, and a portion of the right ventricle.
• The right coronary artery also arises from the aorta, and its branches supply the right atrium, the right ventricle, and a portion of the posterior wall of the left ventricle. In 90% of people, the atrioventricular (AV) node and the bundle of His, part of the cardiac conduction system, receive blood supply from the right coronary artery. For this reason, obstruction of this artery often causes serious defects in cardiac conduction.
• The divisions of coronary veins parallel those of coronary arteries. Most of the blood from the coronary system drains into the coronary sinus (a large channel), which empties into the right atrium near the entrance to the inferior vena cava.
Conduction System
• The conduction system is specialized nerve tissue responsible for creating and transporting the electrical impulse, or action potential. This impulse starts depolarization and subsequently cardiac contraction.
• The electrical impulse is normally started by the sinoatrial (SA) node (the pacemaker of the heart). Each impulse coming from the SA node travels through interatrial pathways to depolarize the atria, resulting in a contraction.
• The electrical impulse travels from the atria to the AV node through internodal pathways. The excitation then moves through the bundle of His and the left and right bundle branches. The left bundle branch has two fascicles (divisions): anterior and posterior. [Show Less]