Anatomy of the Heart Flashcards
heart responsibility
double sided pump maintaining a constant supply of fresh oxygen and nutrients to the body’s tissues while removing carbon dioxide and waste
right side of heart
receives oxygen-poor blood and and pumps it to the lungs (pulmonary circuit)
left side of heart
receives oxygen-rich blood and pumps it to the body (systemic circuit)
hearts chambers
- two (left and right) atria
- two (left and right) ventricles
2 atria
receiving chambers
- “little hallway”
- right atrium receives blood returning from systemic circuit
- left atrium receives blood returning from the lungs
2 ventricles
pumping chambers
- “little belly”
- right ventricle pumps blood into the pulmonary circuit
- left ventricle pumps blood into the systemic circuit
heart properties
- size of human fist, less than 1 lb
- hollow, cone shaped
- in the mediastinum (midline thoracic cavity
- between sternum and vertebral column
- rests on diaphragm
- 2/3 of heart’s mass is left of the midsternal line
heart base
wide & flat, posterior surface, directed to the right shoulder
apex
points inferiorly to the left hip
pericardium
double walled sac that encloses the heart
fibrous pericardium
loose fitting superficial part of the pericardium
- made of dense connective tissue
- protects the heart, keeps it from overfilling, and anchors it to the mediastinum
serous pericardium
deep to the fibrous pericardium, made of 2 thin layers: parietal + visceral layer
parietal layer of serous pericardium
lines the internal surface of the fibrous pericardium
visceral layer of the serous pericardium
lines the external surface of the heart
pericardial cavity
space between the parietal + visceral layers, filled with serous fluid
- functions to reduce friction
pericarditis
inflammation of the pericardium
- beating of heart rubs against the pericardial sac - audible sound is produced
- causes pain deep to sternum
- can lead to adhesions, impeded cardiac activity
cardiac tamponade
compression of the heart by large amounts of inflammatory fluid in the pericardial cavity
- the heart’s ability to pump blood is reduced
- management: removal of excess fluid by syringe
epicardium
visceral pericardium
- most superficial layerof heart wall
myocardium
middle, muscle layer
- composed of contracting, cardiac muscle; bulk of heart
- cardiac muscle cells are arranged in spiral bundles. they’re tethered to each other by crisscrossing connective tissue fibers
cardiac skeleton of the myocardium
a reinforcing, dense network formed by the connective tissue fibers
- skeleton prevents over stretching from continuous stresses and ensure that action potentials only spread along desired pathways
endocardium
deepest layer, made of endothelium
- lines the heart’s chambers, contiguous with lining of the great vessels
interior partitions
interatrial and interventricular septum
3 external landmarks
- coronary sulcus (atrioventricular groove)
- anterior interventricular sulcus
- posterior interventricular sulcus
auricles
small, wrinkled appendages that sit atop each atrium
- expand the volume capacity of right and left atria as needed
atria
small, receiving chambers; generate only minimal contraction to push blood into ventricles
- anterior wall of the right atrium is covered with bundles of muscles called pectinate muscles
- left atrium’s walls are smooth
fossa ovalis of the atria
a depression in the interatrial septum - marks the spot of the former foramen ovale
foramen ovale of the atria
fetal shunt between the atria - bypasses lungs
blood enters the right atrium via the:
- coronary sinus
- superior vena cava
- inferior vena cava
blood enters the left atrium via the:
pulmonary veins (4)
the ventricles make up _________ and have much _________ than the atria
- most of the volume of the heart
- thicker myocardial walls
the left ventricle’s wall is ____ than the right ventricle’s
3x thicker
Left and right ventricle shapes
- lv: circular
- rv: crescent shaped
trabeculae carneae
irregular ridges of muscle that line the internal walls of the ventricular chambers
papillary muscles
muscles that project into ventricular chambers and play a role in valve function
ventricular contraction
propels blood out of the heart and into circulation
where is blood propelled from the right ventricle?
the pulmonary trunk
where is blood propelled from the left ventricle?
the aorta
valves
ensure that blood flows through the heart in only one direction
- atria > ventricles; ventricles > great arteries
- open/close in response to differences in pressure
atrioventricular (av) valves
located at each atrial ventricular junction, prevent backflow of blood into atria during ventricular contraction
tricuspid valve
atrioventricular valve located between right atrium and ventricle, has 3 flexible cusps (flap of endocardium)
bicuspid / mitral valve
located between the left atrium and ventricle, has 2 flexible cusps
chordae tendineae
tiny white collagen cords attached to AV valves
- anchor the cusps of the valves to the papillary muscles, prevent valve inversion, and force blood into great arteries
semi lunar (sl) valves
aortic + pulmonary
- guard bases of the large arteries emerging from each of the ventricles, prevent back flow from vessel to ventricle
- open and close in response to changes in pressure
SL valves open when…
the ventricles contract and pressure rises
SL valves close when…
blood back flows towards the heart and fills the cusps
locations that lack valves
- between IVC?SVC and right atrium
- between pulmonary veins and left atrium
some, minimal backflow occurs during atrial contraction
valve disease / replacement
- leaking valves reduce efficiency of the pumping heart
- incompetent/insufficient valves force the heart to repump the same blood multiple times
- faulty valves increase the heart’s work load - heart weakens over time
- mitral/aortic valve are most often affected (left side of the heart/more work)
stenotic valves
stiff/narrowed, constrict the heart’s openings
- narrowed openings force the heart to contract more forcefully
valve replacement
