Heart and Circulation Flashcards
Pericardium
fibrous protective sac enclosing the heart
Epicardium
inner layer of pericardium
Myocardium
heart muscle
major portion of the heart
Endocardium
smooth lining of the inner surface and cavities of the heart
Right atrium receives blood from
systemic circulation
from SVC and IVC
Right ventricle receives blood from
RA and pumps blood via pulmonary artery to the lungs for oxygenation
low pressure pulmonary pump
Left atrium receives blood from
oxygenated blood from lungs and four pulmonary veins
Left ventricle receives blood from
LA and pumps blood via aorta throughout the entire systemic circulation
high pressure system pump
Valves provide
one way flow of blood
AV valves prevent
backflow of blood into atria during ventricular systole
anchored by chordae tendinae to papillary mm
valves close when ventricular walls contract
AV valves are what
Tricuspid - RIGHT
Mitral or Bicuspid - LEFT
Semilunar valves are what
Pulmonary valve - prevents RIGHT backflow
Aortic valve - prevents LEFT backflor
Semilunar valves prevent
backflow of blood from aorta and pulmonary arteries into ventricles during diastole
Systole is the period of
ventricular contraction
Systolic volume is the amount of blood in
the ventricles after systole
about 50 mL
Diastole is the period of
ventricular relaxation and filling of blood
End diastolic volume is the amount of blood in
the ventricles after diasole
about 120 mL
Atrial contraction (atrial kick) happens when
during the last third of diastole and completes ventricular filling
comprising last 20-30% of end diastolic volume
Arteries - arise from
directly from aorta near aortic valve
blood circulates to myocardium during diastole
Right coronary artery supplies what
right atrium most of right ventricle inferior wall of the left ventricle AV node and bundle of his SA node 60% of the time
Left coronary artery supplies what
most of left ventricle
TWO MAIN DIVISIONS - left anterior descending and circumflex
LCA - Left anterior descending supplies
left ventricle
IV septum
Inferior areas of apex
LCA - circumflex supplies blood to the
lateral and inferior wall of left ventricle
portions of left atrium
SA node 40$ of time
Veins - the coronary sinus receives venous blood from ___ and empties into ___
Receives from heart
Empties into RA
SA node is located where
at junction of SVC and RA
Main pacemaker of the heart is what
SA node
initiates the impulse at rate of 60-100 bpm
SA node has what kind of innervation
sympathetic and parasympathetic
affecting both HR and strength of contraction
AV node is located where
at junction of RA and RV
AV node innervation
sympathetic and parasympathetic
AV node - intrinsic firing rate of
40-60 bpm
AV nodes merges with what
Bundle of His
Right and left bundle branches of the AV node are located
on either side of interventricular septum
Terminate in purkinje fibers
Intrinsic firing of 20-40 bpm
Myocardial muscle tissue is
striated mm fibers with numerous mitochondria
rhythmicity of contraction
fibers contract as a functional unit
Myocardial metabolism is
aerobic sustained by continuous O2 delivery from coronary arteries
Stroke volume
the amount of blood ejected with each myocardial contraction
55-100 mL/beat
Stroke volume is influenced by
Left ventricular end diastolic volume
Contractility
Afterload
Stroke volume is influenced by - Left ventricular end diastolic volume
the amount of blood left in the ventricle at the end of diastole (AKA preload)
Stroke volume is influenced by - contractility
the ability of the ventricle to contract
Stroke volume is influenced by - afterload
the force the LV must generate during systole to overcome aortic pressure to open the aortic valve
Cardiac output
the amount of blood discharged from the left or right ventricle per minute
4-5 L per minute
CO is determined by
HR x SV
Cardiac index is
CO divided by body surface area
2.5-3.5 L/min
Left ventricular end diastolic volume
pressure in the LV during diastole
5-12 mmHg
Ejection fraction
percentage of blood emptied from ventricle during systole
Useful measure of LV function
Calculating EF
SV/left ventricular end diastolic volume
EF norm
more than 55%
the lower it is, the more impaired the LV
Atrial filling pressure
the difference between the venous and arterial pressures
Right atrial filling pressure is affected by
changes in intrathoracic pressure
Decreased with inspiration
Increased with forced expiration
Right atrial filling pressure is decreased during
strong ventricular contraction and atrial filling is enhanced
Venous return increases when ___ and decreases with what
Increases when blood volume expands
Decreases during hypovolemic shock
Diastolic filling time decreases with
increased HR and with heart disease
Myocardial oxygen demand (MVO2) represents
the energy cost to the myocardium
Myocardial oxygen demand is clinically measured how
HR x SBP
Known as rate pressure produce (RPP)
Myocardial oxygen demand increases with
activity and with HR and/or BP