Ch 19- Circulatory System: Heart Flashcards
Two divisions of the cardiovascular system and what they do
Pulmonary- carries blood to the lungs for gas exchange and returns it to heart , supplied by right side of the heart
Systemic- supplies blood to the body including some parts of the lung, supplied by left side of the heart
pulmonary and systemic veins vs artery
artery- away from heart, P is deoxygenated, S is oxygenated
Veins- toward to the heart, P is oxygenated and S is deoxygenated
location of the heart and its structure
-located in the mediastinum
-base (wider where large vessels are attched)
-apex (tapered, pointy, tilts to left)
the pericardium layers of the heart
pericardium- double wall sac that encloses the heart- two layer below
fibrous pericardium- outer wall not attached to heart
serous pericardium two layers:
-parietal- lines fibrous pericardium
-visceral (epicardium)- covers heart surface
the heart layers
-epicardium (apart of pericardium visceral)
-myocardium (middle)
-endocardium (inner)
the spiral orientation that cause the ventricles to contract and enhance blood is
vortex of the heart
heart chambers
two upper:
left and right atria- receive the blood returning to the heart
Two lower-
left and right ventricles- RV wraps around LV in c shaped and they “pump” that eject blood
are the left and right ventricles the same in volume?
yes
Atrioventricular valves (av valves)
regulate the openings between atria and ventricles
R AV valve- tricuspid (three cusps)
L AV valve- mitral valve (two cusps)
chordae tendineae
- strings on the valves which prevent bulging when ventricles contract
semilunar valves
-regulate blood flow from ventricles into arteries, both have three cusps:
-aortic: controls openings from L ventricle to aorta
and pulmonary valves -controls openings from R ventricle to the pulmonary trunk
blood flow through chamber system
- blood enters the right atrium from superior and inferior venae cavae
-blood in right atrium flows in the right AV valve into the right ventricle
-contraction opens pulmonary valves and blood flows to the pulmonary trunk
-blood is released from right and left pulmonary arteries to the lungs where it unloads CO2 then loads O2
-blood returns from lungs into pulmonary veins and into the left atrium
-blood in left atrium flows into left ventricle by the AV valve
-contraction of ventricle forces aortic valve to open
-blood flows through aortic valve into aorta
-blood in aorta is distributed to the body where it unloads CO2 and loads CO2
-blood returns to right atrium from venae cavae
the coronary circulation (outside heart):
-branches off the ascending aorta
-supplies blood to both ventricles
angina pectoris
chest pain from blood flow obstruction
myocardial infarction
-sudden death of a patch of myocardium from long term circulation obstruction
structure of a cardiac muscle
-broad band
-filaments anchored to plasma membrane
-desmosomes to link cardiomyocytes together
-gap junctions for cells to flow through
what does the conduction system do?
-coordinates the heartbeat
conduction system
-SA node fires (pacemaker cells)
-excitation spreads through myocardium
-AV node fires (delay in signal conduction so ventricles can fill)
-excitation spread to AV bundle
-Subendothelial (fibres spread throughout ventricular myocardium)
cycles of events in the heart
-systole- contraction
-diastole- relaxation
Cardiac action potential
-Na inflow and channels open
-depolarization
-Na channels closes once depolarized and volatge peaks
-Ca2+ enters and prolongs depolarization of membrane creating a plateau
-Ca closes and K channels open with rapid outflow returns membrane to resting potention
Cardiac action potential vs skeletal muscle action potential
-longer depolarization
-longer action potential
-creates a plateau
-longer refrac period
order of ECG letter cycle
PQRST
(P , PR, QRS, QT, ST, T Wave is a noral ECG)
P Wave and PR interval
P wave- SA node firing, atrial systole begins
PR interval- conduction through AV node because ventricle activation
QRS complex and QT interval
QRS- ventricular depolarization, spike due to different thickness and shape of two ventricles
QT interval- duration of ventricular depolarization, shorter during exercise
