How much would the heart contract during a lifespan?
Around 3 billion times
What are cardiac muscles highly dependent on?
Aerobic respiration
How much blood does each beat eject?
70mL
How much does the heart weigh?
325g (male)
275g (female)
Where is the base of the heart?
The superior surface
The level of the third costal cartilage
Where is the apex of the heart located?
Just left of the sternum between the junction of the fourth and fifth ribs
What structure separates the right and left halves of the heart
The interatrial and interventricular septums
Through which structure is blood pumped from atrium to the ventricles?
Tricuspid valve, bicuspid valve
Where is blood pumped through from the r. ventricle into the pulmonary trunk?
Semilunar valve
What is the difference in the volume pumped from each side of the heart?
They are the same
What causes the valves of the heart to open and close?
Pressure changes as the heart contracts and relaxes
Where are chordae tendineae tethered?
To the ventricular endothelium via papillary muscles
When do tri and bi valves prevent backflow?
During ventricular contraction
Where do semilunar valves prevent backflow?
From the circuits back into the ventricles
How is oxygenated blood and nutrients delivered to the myocardium?
Through the coronary arteries
Where do coronary viens converge?
The coronary sinus
What are 3 characteristics of cardiac muscles
Branch freely
Intercalated discs bound by desmosomes
Gap junctions
What is autorhythmicity
They have the ability to initiate their own electrical potential at a fixed rate which are able to spread through the gap junctions
What is the cardiac muscles primarily modulated by?
Endocrine and nervous systems
What is the first type of myocardial cells? (and %)
99%
Myocardial contractile cells
Responsible for contractions that pump blood through body
What is the second type of myocardial cells? (and %)
1%
From conduction system of the heart initiate and propagate the action potential which travel throughout the heart
What are the 5 components of the cardiac conduction system?
Sinoatrial node
Atrioventricular node
Atrioventricular bundle
Atrioventricular bundle branches
Purkinje cells
What is the cardiac rhythm established by?
The sinoatrial node
What is the SA node known as? What does it do?
The pacemaker, with highest inherent rate of depolarization
Initiated the sinus rhythm
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