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
What modified cardiac muscle cells of the intrinsic conduction systems are found in the SA and AV nodes, are smaller than surrounding atrial contractile cardiac cells and contain fewer myofibrils and lack intercalated discs?
nodal cardiac cells
Purkinje fibers are found in AV bundle, bundle branches and subendothelial branches. They are ___ than surrounding ventricular contractile cells and contain ___ at their periphery. They have ___ ___ and are positive for ___ staining because of large amounts of glycogen. With ___ stain their center appears homogenous and stains pale.
larger; myofibrils; intercalated discs; PAS; H&E
What are the three layers or tunics of blood vessels?
tunica interna/intima
tunica media
tunica externa/adventitia
What are the three parts of the tunica interna layer?
endothelium, basal lamina, subendothelial layer
The tunica ___ layer contains rings of smooth muscle responsible for vasoconstriction and vasodilation. It also contains sheets or lamellae or laminae of elastin.
media
In larger vessels this tunic contains a vasa vasorum and nervi vascularis.
tunica externa
In cross section, ___ will appear more open and ___ more collapsed. Additionally, the lumen of a ___ is much larger than that of the comparable ___.
arteries; veins; vein; artery
What is the thickest layer of arteries?
tunica media
What is the thickest layer in veins?
tunica externa
What are the four types of arteries?
elastic/conducting/large
muscular/distributing/medium
small
arterioles
Which type of artery is important in helping to propel blood onward while ventricles are relaxing and contain elastic fibers that function as pressure reserves?
elastic/conducting/large arteries
Which type of artery is responsible for vasoconstriction and vasodilation?
muscular/distributing/medium arteries
Which type of artery has as many as 8 layers of smooth muscle in their tunica media? 1 or 2 layers?
small arteries
arterioles
T/F. Elastic aorta and arteries ___ during ventricular contraction and ___ during ventricular relaxation.
stretch; recoil
Which artery may or may not have an internal elastic membrane?
arterioles
Which blood vessel has the smallest diameter of blood vessels (4um - 10um) and has a thin wall of only endothelial cells and its basal lamina?
capillaries
What are the three types of capillaries?
continous, fenestrated, and discontinuous capillaries
Continuous capillaries are found in muscle, lung and CNS. It has uninterrupted endothelial cell lining with ___ or ___ junctions. It may have pericytes.
tight; occluding
Fenestrated capillaries are found in ___ glands and at the sites of fluid and metabolite absorption. They have oval pores called ___.
endocrine; fenestrations
___ capillaries are found in the liver, spleen and bone marrow. They have a large diameter and are more irregularly shaped than other capillaries.
Discontinuous
Define microcirculation.
The flow of blood from an arteriole through a capillary network to a postcapillary venule
What makes up the funcitonal unit called the microcirculatory bed or microvascular bed?
- arteriole
- capillary network
- postcapillary venule
What are the two types of vessels in the capillary network?
true capillaries
ateriovenous (AV) anatomoses or shunts (also known as Metarteriole-Thoroughfare Channel)
The more the precapillary sphincters ___ (and the smooth muscle of the AV shunt ___) the more blood will pass through the true capillaries in the capillary beds.
relax; contract
The more the precapillary sphnicters ___(and the smooth muscle of the AV shunt ___) the more blood will pass through the arteriovenous anastomoses and bypass the true capillaries.
contract; relax
What are the four types of veins?
- venule
- smal veins
- medium veins
- large veins
Of the two types of venules, which one has endothelial cell with basal lamina and pericytes but no tunica media or adventitia?
postcapillary venule
Which type of vein receives blood from muscular venules?
small veins
Which type of venule posses a tunica media with one or two layers of smooth muscle and a thin tunica adventitia but no pericytes?
Muscular venule
Which two veins have all three layers present?
medium and large veins
Most veins in limbs have ___ which prevent backflow of blood.
valves
___ are thin folds of tunica ___ that contain endothelial cells over a thin layer of connective tissue.
Valves; initima
