Flashcards in chapter 18 Deck (60)
where are cardiac centers in the brain located?
What is an electrocardiogram?
a composite of all the action potentials generated by nodal and contractile cells at a given time
what is a P wave caused by?
depolarization of SA node
what causes a T wave?
what occurs during the first sound of a heart beat?
AV valves close and signifies beginning of systole
what occurs during the second sound of a heart beat?
SL valves close at the beginning of ventricular diastole
What is End-systolic volume (ESV)?
Volume of blood remaining in each ventricle after the ejection phase
What are murmurs?
abnormal heart sounds
What is end-diastolic volume?
Volume of blood in a ventricle at the end of a filling cycle
Which ECG wave would appear after the 2nd sound?
What is SV or stroke volume?
Volume of blood pumped out by a ventricle with each beat
what is the cardiac output?
Volume of blood pumped by each ventricle in one minute
what is the cardiac reserve?
difference between resting and maximal Cardiac Output
what is preload in relation to heart physiology?
the degree of stretch of cardiac muscle cells during diastole
what do positive inotropic agents do to stroke volume and contractility?
they increase both
what is afterload in regards to cardiac physiology?
the pressure that must be overcome for ventricles to eject blood
Mitral stenosis would have what effect on the preload and stroke volume of the left ventricle?
decrease preload and stroke volume
positive chronotropic factors
increase heart rate
negative chronotropic factors
decrease heart rate
Another word for the Atrial reflex
what is an Atrial reflex?
Sympathetic reflex initiated by increased venous return that increases the heart rate
effect of epinephrine on heart rate?
effect of thyroxine on heart rate?
increases heart rate and enhances the effects of norepinephrine and epinephrine
abnormally fast heart rate
abnormally slow heart rate
what is the physiological pacemaker of the heart?
the sinoatrial node (SA node)
another word for unstable potential
pacemaker potential or prepotential
what is the sinus rhythm?
the rhythm of the contraction of the heart set by the SA node
how many action potential (heart beats) dones the SA node produce per minute?