EKG test 1 Flashcards
Part of the chest wall overlying mediastinum is
Precordium
The heart
-delicate muscular structure lies in the mediastinum protected by the rib cage
usually simulated left of the midline and above the diahgram
Four pumping chambers of heart
Right atrium
Right ventricle
Left atrium
Left ventricle
The heart dimensions
- 5 inches long
- 3.5 inches wide
- 2.25 inches thick
- Weighs 250-350 grams 11 ounces
- the size of an adult closed fist
Four Chambers
: right atrium
: right ventricle
: right ventricle
: left ventricle
Endocardium
Allows blood to go through smooth , smooth layer inside layer of heart
Myocardium
Thickest layer muscular middle layer
Pericardium
Double layer membrane covers the outside of the heart keeps heart lubricated
Septum
Muscular wall that separates heart into a right and left side
Prevents blood from moving between the right and left side of the heart
Major electrolyte that determines cardiac contractivity
Calcium
Possible causes of myocardial infarction
- anemic
- inadequate oxygen supply
- hypoemia
- coronary artery narrowing(blockage)
- exercise
- smoking
- eat heavy meals
- congestive heart failure
Basic needed to perform EKG
- machine
- electrodes
- leads
Function of the sympathetic nervous system
Flight fight response
Sympathetic system increases automaticity
Parasympathetic system inhibits
Right atrium
Receives blood as it returns from the body cells.
Upper most chamber of the heart
Venous circulation from the test if the body empties into right atrium through superior vena cava. Venous blood from coronary circulation also empties into the tight atrium through coronary sinus
Has an embedded natural pacemaker called Sino Atrial node (SA node)
Tricuspid valve
Located between the right atrium and right ventricle
Allows blood to flow only in downward direction
Right ventricle
Receives blood from the right atrium and pumps blood into the pulmonary artery which carries blood to the lungs for oxygen
Left atrium
Receives oxygenated blood from the lungs ( pulmonary circulation through two pairs of pulmonary veins)
Left ventricle
Most important pumping chamber of the heart
Receives blood from the left atrium and pumps blood into the aorta for transport to the body cells
Aortic valve
Largest artery in the body
Located between the aorta and left
Regulates possible back flow of blood during ventricular diastole ( relaxation)
Mitral valve
Located between the left atrium and the left ventricle
Closes when the left ventricle is contracting allows blood flow into aorta for transport to the body prevents blood from flowing back into the left atrium
Cardiac cycle
Represent the series of events happen with each heartbeat
Events during Cardiac Cycle
-ventricular systole(contraction )
Blood ejects out
-ventricular diastole(relaxation)
Empties and allowed to fill
-
-ventricular systole(contraction )
Blood ejects out
-atrial systole(contraction)
Performance of Cardiac Muscle depends on three main factors
Preload- amount of muscle stretch at the beginning of contraction
Afterload- the pressure against which it has to pump
Contractility- the force of contraction
Frank Sterlings law
The longer the stretch of cardiac muscle before contraction, the stronger the contraction will be
Coronary circulation
The heart being the major pumping organ of the body supplying blood to all of the organs it itself gets blood supply through a system of circulation called Coronary Circulation.
The coronary arteries supply blood to the myocardium during diastole
