Circulatory System - Histo Flashcards
The left side of the heart pumps for the ___ circuit and the right side of heart pumps for the ___ circuit.
systemic; pulmonary
The fibrous skeleton of the heart contains ___ fibrous rings surrounding valve orifices, two fibrous ___ connecting rings and a ___ portion of interventricular and interatrial septa.
four; trigones; membranous
What are the three layers of the heart from inner to outer?
endocardium; myocardium; epicardium
What layer of the heart wall contains the fibrous skeleton of the heart?
myocardium
Which heart wall layer is also the visceral layer of serous pericardium?
epicardium
What are the three layers of the endocardium?
inner layer - endothelial cells
middle layer - dense connective tissue and smooth muscle cells
deeper layer - contains the intrinsic conduction system
What two valves prevent backflow into the atria?
tricuspid and biscuspid/mitral valves
What two valves prevent backflow into the ventricles?
aortic semilunar and pulmonary semilunar valve
Heart valves enforce one way blood flow through the heart and open/close in response to ___ changes.
pressure
T/F. There are no valves associated with entrances of venae cavae, coronary sinus and pulmonary veins into the heart.
True.
Heart valves are composed of connective tissue with overlying ___.
endocardium
What are the three layers of the heart valves?
spongiosa; fibrosa; ventricularis
The ___ is a loose connective tissue covered in endothelium and located on atrial or blood vessels side of valve with loosely arranged collagen and elastic fibers infiltrated with proteoglycans to serve as a shock absorber.
spongiosa
Which heart valve layer contains fibrous extensions from the dense irregular connective tissue of skeletal rings of heart?
fibrosa layer
Which heart valve layer contains dense connective tissue with layers of elastic fibers covered in endothelium adjacent to the ventricular side of the valve?
ventricularis layer
Why is the cardiac muscle of the heart able to depolarize and contract without impulses from the nervous system?
because of the intrinsic cardiac conduction system that contains 1% noncontractile cardiac cells called cardiac conducting cells that are self-excitable and can generate an action potential without nervous system input.
Cells of the intrinsic conducting systems are organized into nodes and highly specialized conducting fibers/tracts called ___ fibers that are responsible for the initiation and distribution of impulses throughout the heart.
Purkinje
What factors impact the intrinsic rate?
pacemaker cells (purkinje)
sympathetic (accelerates heartbeat)
parasympathetic (decelerates heartbeat)
hormones
What is the excitation sequence that takes place in collections of autorhythmic cardiac cells?
- SA node
- AV node
- AV bundle/Bundle of His
- Right and Left bundle branches
- Purkinje Fibers
Which autorhytmic cardiac cell is the only electrical connection between the atria and ventricles?
AV bundle/Bundle of His
The impulse travels to the AV node via the ___ pathway or tracts where the impulse is delayed to allow for the ___ to contract.
internodal; atria