Anatomy of heart Flashcards
Interesting facts
- the adult heart pumps about 5 quarts of blood each minute throughout the body approx 2000 gallons of blood/day
- the heart beats about 100,000 times/day
- size of a closed fist
Location
- posterior to sternum in mediastinum
- 2/3 of heart is left of midline, 1/3 is right o midline
- upper border just below 2nd rib
- lower border on diaphragm around 6th rib
- posteriorly rests on bodies of 5-8th thoracic vertebrae
Coverings of the heart
- pericardium: tough fibrous tissue that holds the heart in place and protects it form overexpansion (fibrous and serous).
1. Fibrous: touch, loose fitting, inelastic sac around the heart
2. Serous: contains 2 layers. (1) parietal layer: lining inside the fibrous pericardium. (2) visceral layer: adhering to the outside of the heart - space between the two serous pericardium layers is called the pericardial cavity
Coverings pic
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Wall of heart pic
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General anatomy of pic
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Epicardium
Shiny, transparent lubricating layer that is an integral part of the heart wall
- the visceral layer of the serous pericardium
Myocardium
- contractile and thick middle layer o cardiac muscle cells
- although it looks striated like skeletal muscle it is autonomic (involuntary) mm
Wall of heart pic
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Endocardium
The lining of the interior of the myocardial wall
- a delicate layer
- it covers the mm and valves
Chambers of the heart
- atria: receive blood from the veins and pump it into the ventricles
- ventricles: receive blood from the atria and pump it to the body and lungs
8both sides of the heart must pump the same amount of blood to avoid blood accumulation in one side of the system (may result in heart failure)
Chambers of heart pic
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Septum
Extension of the heart wall that separates the left and right side chambers
Chambers of the heart pic
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Atria
- two superior chambers of the heart
- receive blood from the veins
- the atria alternately relax and contract to receive blood then push it into the lower chambers
Heart pic
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Ventricles
- the two inferior chambers of the heart
- receive blood from the atria and pump blood out of the heart into arteries
- the myocardium of each ventricle is thicker than the myocardium of either atrium
Valves of the heart pic
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Mitral (bicuspid) valve
- located between the left atrium and left ventricle
- guards the left atroventricular (AV) opening
- has two flaps
- prevents backflow into the atrium during systole (contraction)
Tricuspid valve
- located between the right atrium and the right ventricle
- regulates flow through the right (AV) opening
- has three flaps
- prevents backflow into the atrium during systole
Valve pic
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Aortic semilunar valve
- located between the left ventricle and the entrance of the aorta
- shaped like a half moon
- prevents backflow into the ventricle during diastole (relaxation)
Pulmonary semilunar valve
- located between the right ventricle and the entrance of the pulmonary artery
- prevents backflow from the pulmonary artery into the right ventricle during diastole
Chordae tenineae
Thread-like bands of fibrous tissue that attach on one end to the edges of the tricuspid and mitral valves (AV valves) of the heart and on the other end to papillary muscles within the heart that serve to anchor the valves
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Clinical applications
- damage to the valves of the heart can cause stenosis, insufficiency (inadequate closure), or both
- mitral valve prolapse (a slight insufficiency) is common in young women and is often asymptomatic
Systemic circulation
- arteries carry oxygenated blood from the heart to the rest of the body (thick walls and carry blood away from the heart)
- veins then return the oxygen-depleted blood to the heart (thin walls and return blood to the heart)
Pulmonary circulation
pulmonary arteries carry oxygen-depleted blood to the lungs where it is oxygenated and returned to the heart though pulmonary veins
Right side of heart vs left side
R: Receives deoxygenated blood from the body and delivers it to the lungs
L: Receives oxygenated blood from the lungs and delivers it to the body
- muscles of the left side are 4x thicker and more powerful than those on the right side
Blood flow pic
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Flow of blood
RA: receives deoxygenated blood from body
- blood returns from the body via the superior and inferior vena cava; RA pumps blood into the RV
RV: receives deoxygenated blood from the RA
- it pumps the deoxygenated blood to the lungs via pulmonary artery
- RV is thin-walled, low-pressure chamber
LA: receives oxygenated blood from the lungs via the pulmonary veins.
- it pumps blood into the LV
LV: receives oxygenated blood from the LA
- it pumps blood out to the whole body via the aorta
- thick-walled, high-pressure chamber
Blood supply of heart
2 coronary arteries supply blood to the heart and they are the first branches of the aorta
- Both ventricles get blood from branches of right and left coronary arteries
- Each atrium only receives blood from its corresponding coronary artery
- L ventricle is biggest and gets the most blood
Auto rhythmic cardiac mm fibers
- repeatedly generate action potentials that trigger contraction
- continue to stimulate a heart heat even after the heart has been removed from the body (for several minutes)
- ensures that the cardiac chambers are stimulated to contract in a coordinated manner
Sinoatrial (SA) node
Heart’s primary pacemaker is located high in the right atrium
Atrioventricular (AV) node
Located in the interatrial septum at the base of the right atrium
- conduction system continues into the ventricles via the AV bundle which is located in the superior aspect of the interventricular septum
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Conduction system of heart
- right and left bundle branches: extend through the interventricular septum toward the apex of the heart
- purkinje fibers: conduct the action potential beginning in the apex of the heart upward to the remainder of the ventricular myocardium
Clinical applications
myocardial infarction: cessation of coronary artery flow for more than a few minutes causes death of heart muscle
- CDC says more than 70% of the blood flow must be stopped before tissue damage becomes a problem or any symptoms appear
- 790,000 Americans have a heart attack each year and most are related to coronary artery disease (CAD)
- due to its placement between the sternum and the bodies of the thoracic vertebrae, the heart can be compressed in order to pump blood during cardiac arrest (CPR can be lifesaving)
CPR
Pt’s who suffered out-of-hospital cardiac arrests over a period of one year:
- 36% survival rate CPR + AED
- 9% survival rate CPR alone
