Chapter 15 Heart Flashcards
What tough fibrous sac encases the heart?
The pericardium
What is the thin outermost muscle layer, covers the surface of the heart and extends onto the great vessels?
The epicardium
What is the thick muscular layer middle of the heart, and what is it responsible for?
The myocardium and responsible for pumping
Where is the left ventricle’s contraction and thrust result in and where is it felt?
Th apical impulse in the 5th left intercostal space and midclavicular line
What are the order of the valves?
Try Pulling My Arm=
for Tricuspid- Pulmonic- Mitral- Aortic
What is an ECG?
Graphic recording of electrical activity during the cardiac cycle
What is a depolarization?
The spread of stimulus through the heart muscle
What is repolarization?
Return of the stimulated heart to a resting state
What is the P wave?
The spread of stimulus through atria (atrial depolarization)
What is the PR interval?
Time from initial stimulation of the atria to initial stimulation of the ventricles 0.12 to 0.20 second
What is QRS?
The spread of stimulus through the ventricles ( ventricular depolarization) less than 0.12 seconds
What is the ST segment and T wave?
The return of the stimulated ventricular muscle to a resting state ( ventricular repolarization)
How does fetal circulation occur?
The umbilical vessels, compensates for nonfunctional fetal lungs
RA into LA via foremen ovale; right ventricle pumps blood through the patent ductus arterioles rather than into the lungs
When does the ductus arterioles close?
24 -48 hours after birth
Where does the heart lie in infants and why?
The heart lays more horizontally and the apex can be found in the 4th intercostal space, by 7 years old it will reach adult position
