chapter 18 Flashcards
where are cardiac centers in the brain located?
medulla oblongata
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?
ventricular repolarization
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?
T wave
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
Bainbridge reflex
what is an Atrial reflex?
Sympathetic reflex initiated by increased venous return that increases the heart rate
effect of epinephrine on heart rate?
increases it
effect of thyroxine on heart rate?
increases heart rate and enhances the effects of norepinephrine and epinephrine
abnormally fast heart rate
Tachycardia
abnormally slow heart rate
Bradycardia
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?
90-95
how many action potentials does the AV node produce per minute?
40-60
The only electrical connection between the atria and the ventricles
the atrioventricular bundle or
bundle of His
final leg of the intrinsic conduction system of the heart
Purkinje fibers
irregular heart beat
arrhythmia
the 2 cardiac centers in the medulla oblongata
cardioacceletory center
cardioinhibitory center
stenosis
when a valve does not close properly
regurgitation
when a valve does not open properly
best point to listen for the aortic valve
second intercoastal space to the right of the sternum
best point to listen for the pulmonary valve
second intercoastal space to the left of the sternum
best point to listen for the mitral valve
fifth intercoastal space to the left of the sternum
best point to listen for the tricuspid valve
fifth intercoastal space the right of the sternum
what is contraction of the heart called?
systole
what is relaxation of the heart called?
diastole
factors the reduce contractility of cardiac muscles
negative inotropic
the phase of the cardiac cycle when all 4 heart valves are closed again and no blood flows into or out of the ventricles
isovolumetric relaxation
where the bundle of His is located
interventricular septum
when atrial repolarization occurs as seen on an EKG
QRS complex
The entire ventricular myocardium is depolarized during this time on an EKG
S-T segment
directly supplies the papillary muscles with nerve impulses
Purkinje fibers.
what are the lub-dup heart sounds heard during auscultation of the heart associated with?
the heart valves closing
what is blood flow during ventricular filling most dependent on?
pressure changes
stimulation of this nerve reduces heart rate
vagus nerve
this electrical event causes contraction of the atria
p wave
3 factors that affect the size of the stroke volume
preload
contractility
Afterload
what are factors that increase heart rate called?
positive chronotropic
effect of parasympathetic nervous system on heart rate
slows heart rate
effect that the sympathetic nervous system has on heart rate
positive chronotropic and inotropic
what the heart exhibits at rest
vagal tone
where is the first lub heard
at isovolumetric contraction
what is isovolumetric contraction?
the phase when both the AV and SL valves are both closed
the short-lived drop in aortic pressure when SL valves close
dicrotic notch
