Heart Physiology Flashcards
intrinsic conduction
ability to depolarizes and contract on its own
autorhythmic cells
Autorhythmic cells have unstable resting membrane potentials
noncontractile cells in contractile muscle that initiate and propagate impulse
Leaky
Na+ moves in easily to depolarie
Self generate AP
SA node
coronary sinus, in right atrium; main controller “pacemaker”
AV node
in interventricular space, top of septum
Bundle of his
splits to R+L
Bundle branches
in walls
Purkinje fibers
electrical stimulation to muscle tissue in papillary muscle
extrinsic innervation
nervous connection
cardioacceleratory and cardioinhibitory
Cardioacceleratory center
sympathetic; NE causes quicker depolarization; faster heart rate
Cardioinhibitory center
parasympathetic; ACh causes the slower heart rate
vagal tone
reduction of contraction from vagus nerve stimulation
Allows us to increase heart rate
Parasympathetic hyperpolarize SA causing decrease in heart rate from medulla
P wave
SA
depolarization of atria
QRS complex
depolarization of ventricles (masked is the repolarization of atria)
T wave
repolarization of ventricles
what causes lab sound
AV valves close
what causes dup sound
SL valves close
murmur
malfunctioning of the valve
cardiac cycle
Systole and diastole of both atria plus systole and diastole of both ventricles
cardiac output
SV x HR
stroke volume
blood leaving heart per beat
Difference between amount of blood in ventricles before and after systole
End diastolic volume-end systolic volume
cardiac reserve
difference between maximum CO and minimum CO
factors affecting stroke volume
Stretch of cardiac muscle
Contract with more force after stretch
Starling law of the heart
More blood in ventricles= more pressure in contract
preload= blood in ventricles prior to contraction
Contraction strength not due to stretch
NE moves more Ca 2+ into the heart, increases force of contraction
Arterial pressure
After load= artery pressure not as much blood leaves
factors affecting heart rate
Sympathetic nervous system activation
NE
Corresponding increase in contractility
Parasympathetic nervous system activation
ACh
Adrenal medulla production of epinephrine
Thyroid production of thyroxine
Heart rate increases
Gradual and sustained
Blood pressure changes (baroreceptors)
Ionic balances
Age
Heart rate decreases
Sex
Females have higher heart rate
Exercise
Heart rate decreases as you are more efficient (LT)
Temperature
Increase temperature increases heart rate
tachycardia
inability to slow heart rate
