Heart lecture 3 Flashcards
Period between start of heartbeat and the next
Cardiac cycle
Phases of cardiac cycle step 1
Cycle begins, everything relaxed (diastole)
atrial systole
Atrial systole, atria contracts, fills ventricles
How atrial systole works?
SA node fires, atriums contract
End of atrial systole/ventricular diastole measurement
End diastolic volume (EDV)
Phases of cardiac cycle step 3: Atrial diastole
atria relax, signal continue thru heart
Phases of cardiac cycle step 4/5:
Ventricular systole (2phases)
Ventricular systole phase 1
Ventricular contraction - prior to semilunar valves
Contraction with no volume change
Isovolumetric contraction
Ventricular systole phase 2
Ventricular ejection - semilunar valves open, blood leaves
Pressure needed to open semilunar valves
LV: >80mmHg
RV: >20mmHg
Remaining volume in each ventricle after systole
End systolic volume
Phases of Cardiac cycle step 6: Ventricular diastole
Ventricular diastole - ventricles relax, pressure drops, valve closing
Isovolumetric relaxation
valves closed, blood passively fill atria
Phases of cardiac cycle step 8: late ventricular diastole
Ventricular diastole- late - chambers relaxed - ventricles passively fill ~70%
Ventricular diastole how long?
400msec
State of ventricles and atria during ventricular diastole
Relaxed
pressure aortic valve closes
100mmHg
What happens when ventricular pressure drop below atrial
AV valves open
How does aortic valve open
Pressure changes in aorta
aortic valve closing causes what?
short pressure rise
What is dicrotic notch
Valley in pressure tracing by short pressure rise
What is the process of listening to body sounds? What tool used for it
Auscultation
Stethoscope
How heart sounds produced
blood turbulance from closing valves
Heart sounds s1 , s2 , s3, s4
S1 - av valve close, start contraction
s2 - semilunar valves close
s3 - very feint
s4 - pathologic
Abnormal heart sound name
Heart murmurs
What could heart murmurs indicate
valve insufficiency
What’s cardiac output
total blood ejected from left ventricle per min
Cardiac output (CO) formula
CO = Heart rate x Stroke volume
Stroke volume formula
End-diastolic volume - End-systolic volume
What is cardiac reserve
different between max CO and CO at rest
How much average cardiac reserve?
4-5 times resting value
where autonomic regulation occurs
cardiovascular center of the medulla oblongata
How autonomic regulation works
Uses signals from sensory receptors - increase or decrease nerve receptors
baroreceptors input signals from
pressure changes
Chemoreceptors input signals from
chemical changes in blood
proprioceptors input signals from
sensory from limbs/extremities
Cardiac centers of medulla oblongata
Cardioinhibitory center
Cardioacceleratory center
Cardioinhibitory center
slows heart rate via vagus nerve
Cardioacceleratory center
controls sympathetic neurons. increase heart rate
Where cardiac accelerator nerves located? What travels through it
Thoracic spine. Sympathetics
What travels thru Vagus nerve
parasympathetics
What is released during sympathetic influence to increase heart rate
Norepinephrine
what is released during parasympathetic influence to decrease heart rate
Acetylcholine
Chemical factor affecting HR
Electrolyte imbalance, hormones
3 main factors regulating stroke volume
Preload
Contractility
Afterload
What is preload
Degree of heart stretch before contract
Frank starling law
higher volume blood = more stretch and greater contraction
Contractility
strength of fiber contraction
What substances affect contractility
positive (increase contraction) and negative (decrease contraction) ionotropic agents
Afterload
pressure needed for semilunar valves to open
Loss of pumping efficiency called
Congestive heart failure
Abnormal rhythm of heart pathology
Arrhythmia
Arrhythmia cause
Defect in heart conduction system
Accumulation of atherosclerotic plaque causes
Coronary Artery disease
Defects present from birth called
Congenital heart defects
Segment of aorta narrowed
Coarctation of aorta
Ductus arteriosus remains open rather than closing
Patent Ductus Arteriosus
Fetal foramen ovale fail to close
Atrial Septal defect
Incomplete development of septum
Ventricular Septal Defect