CV System Structure Flashcards
describe 2 primary roles of the CV system
- distribution of essential substances to the tissues (dissolved gases, molecules for nutrition, growth, repair)
- removal of by products of metabolism
describe 3 secondary roles of the CV system
- circulation of hormones and neurotransmitters that allow for chemical signaling among cells (humoral communication)
- heat dissipation: by transfer from core to body surface
- mediation of defense responses against invading microorganisms (immunity!)
what are the 2 pumps of the heart? how are they arranged?
- right heart: propels oxygen-poor blood through the lungs (pulmonary circulation)
- left heart: propels oxygen-rich blood to all other tissues (systemic/peripheral circulation)
these pumps are arranged end to end or in series
describe flow of blood through the heart (direction)
unidirectional thanks to the presence of one way valves
describe cardiac output generation
pulsatile; with each heartbeat the ventricles generate pressure pulses that drive blood through a system of tubes (vascular system)
what is found on each side of the heart?
- a thin walled atrium (the receiving chamber and primer pump)
- a thick walled ventricle (main pumping chamber)
list and describe the 2 cells of the heart
- contractile cells: atrial and ventricular myocytes; the work horses and majority of heart cells
- myoconductive cells: in nodal and purkinji fibers; specialized excitatory/conductive cells that spontaneously generate or conduct electrical signals through the heart so that it beats rhythmically; contain only a few contractile elements so contract weakly
describe arrangement of cardiac muscle (3)
- arranged in a lattice that behaves LIKE a syncytium
- cells are short, branches, and interconnected
- connected by intercalated discs
describe intercalated discs (2)
- connect cardiac cells end to end; specialized junctions that fuse neighboring cells via
- desmosomes: provide physical connection/mechanical coupling
- gap junctions: provide electrical connection/coupling
what doesn’t work in dilated cardiomyopathy?
desmosomes of intercalated discs
why is interconnectedness of myocytes important?
myocytes can be activated almost instantaneously by a wave of electrical stimulation and contract as one to generate a coordinated heartbeat
what is syncytium? are cardiac fibers a true anatomical syncytium?
a syncytium is a single, large, multinucleated cell formed from many fused cells; cardiac muscle is not a true syncytium because the cells are separated by sarcolemma; so considered a functional syncytium instead
what are the 2 functional syncytia of the heart?
atrial syncytium: right and left atria
ventricular syncytium: right and left ventricles
what physically and electrically separates atrial and ventricular muscle?
a fibrous skeleton
describe the fibrous skeleton of the heart (3)
- a tough CT sheet that encircles the valves
- lies along the plane of the atrioventricular/coronary groove
- blocks electrical communication between atria and ventricles except at AV bundle/bindle of His
what does the electrical insulation of the fibrous skeleton of the heart allow for?
electrical insulation allows atrial and ventricular syncytia to be activated separately and sequentially with a time delay between
what are the 2 one-way valves of the right side of the heart?
- tricuspid/right AV valve
- pulmonary/pulmonic/right semilunar valve
what are the 2 one-way valves of the left side of the heart?
- mitral/left AV/bicuspid valve
- aortic/left semilunar valve
what separates the right and left sides of the heart?
two septa:
interventricular septum
interarterial septum
at what locations of the heart do NO valves exist?
- between the cranial and caudal vena cavae and the right atrium
- between the pulmonary veins (4-6 of them) and the left atrium
define the cardiac valves
thin flaps of flexible endothelium-covered fibrous tissue that open and close to maintain unidirectional blood flow
is valve motion passive or active? explain
passive: moved by pressure exerted by flowing blood
what is closure of heart valves associated with?
events that produce the typical heart sounds heard by stethoscope
describe the AV valves
separate each atrium from its corresponding ventricle