15 Circulatory System Histology Flashcards
What 2 systems constitute the circulatory system?
cardiovascular and lymphatic
What is the innermost aspect of the heart wall?
Endocardium
What portion/layer of the endocardium is made of simple squamous epithelial cells?
endothelium
What types of cells make up the sub endothelium?
Loose Irregular CT, elastic fibers and smooth muscle cells
What layer of endocardium contains veins, arteries, and purkinje cells?
subendocardium— loose irregular CT connecting endocardium to myocardium
What is the thickest region of the heart wall?
myocardium
Where is the cardiac muscle the thickest?
left ventricle
Outer layer of the heart wall after opening pericardial sac?
epicardium
What type of tissue makes up the epicardium?
Adipose and loose irregular CT
Purpose of epicardium?
- support/cushion to heart as it beats in pericardial sac
- contains coronary vessels
What is the purpose of pericardial cavity?
contains lubricating fluid and reduces friction/heat
What layer of the heart secretes pericardial fluid into cavity?
parietal layer and visceral layers of the serous pericardium
what tissue type makes up the fibrous pericardium?
thick layer of dense irregular CT
What layer of the great vessels is the fibrous pericardium continuous with superiorly?
tunica adventitia
What layer of pericardium serves as an anchor to the diaphragm and the sternum?
Fibrous pericardium
What tissue type makes up the four fibrous rings surrounding the the heart valves?
Dense irregular CT– attachment for valve leaflets
What connects and holds together the 4 fibrous rings of the heart valves?
2 Fibrous trigones
What portion of the heart is made of dense irregular CT, is devoid of cardiac muscle, and contains branches of the conducting system?
membranous septa
What are the three main functions of the heart’s fibrous skeleton?
support, attachment, insulator (preventing free electrical impulses)
What are the 3 layers of the heart valve?
spongiosa (atrial side), fibrosa (center), ventricularis (ventricle side)
What layer makes the core of the valve leaflet
Fibrosa
What layer of the valve leaflets forms the chord tendinae?
ventricularis
Which layer of the valve leaflets is the shock absorber with numerous elastics?
spongiosa
What causes inflammation of the heart valves that leads to angiogenesis and vascularization of the valves, thickening, and makes the valves inflexible?
Rheumatic Fever
What initiates impulse that spreads along atrial cardiac muscle fibers and internal tracts of modified cardiac muscle fibers?
sino-atrial node– the pacemaker
What function does the AV node perform?
picks up impulse, and delays in order to allow atrial emptying.
What are larger than normal cardiac muscle cells and cause ventricles to contract at paced intervals?
Pukinje Fibers (subendocardium, stain lighter,lack the bulk of striated fibers)
What parasympathetic nerve stimulates the heart and what does it cause it to do?
CNX (Vagus), Decreases heart rate
What sympathetic spinal levels innervate the heart
T1-T6
What are the 3 layers of the tunica intima?
Endothelium, sub endothelium, and internal elastic lamina
What are the two main components of tunica media?
smooth muscle, external elastic lamina (between media and adventitia)
What does the tunica adventitia contain?
vaso vasorum and nervi vascularis (vessels and nerves of the vessel)
What is the main characteristic of the tunica media in large elastic arteries?
sheets of elastin separated my smooth muscle cells (layers on layers)
Besides a much thicker tunica adventitia, what is very prominent in muscular (distributing) arteries?
prominent internal elastic lamina and prominent external elastic lamina (most often)
Do arterioles contain an external elastic lamina?
No–but they have an internal elastic lamina that diminishes as arteriole size gets smaller.
Number of smooth muscle cells in the tunica media of arterioles ?
1-4 cells thick
what type of endothelial capillary junctions are found in muscles, lungs, and CNS?
occluding junctions—tight junctions with complete basal lamina
Where are fenestrated capillaries found?
glomerulus of the kidney
Where are discontinuous capillaries found?
liver, spleen, bone marrow (Gaps between cells and incomplete basal lamina)
What type of cell is contractile and dispersed along capillaries, and proliferate during angiogenesis.
Pericytes
What disease is the unregulated division of pericytes?
hemangiopericytoma
What regulates blood flow through capillary beds, by contraction of extra smooth muscle so blood follows met arteriole through thoroughfare?
pre-capillary sphincters
What type of vessel is characterized by large lumen in comparison to wall size, no internal elastic lamina, no external elastic lamina, 1-2 layers smooth muscle and a distinct layer of CT in the adventitia?
venule
What vessels has thin internal elastic lamina, valves, and a very thick tunica adventitia CT.\?
medium vein
What vessel has thin tunica intima, thin tunica media, and a Tunica adventitia with a thick layer of CT with longitudinally arranged smooth muscle?
Large Vein (vena cava)
Where do atherosclerosis legions most frequently develop?
tunica intima of large arteries following endothelial cell injury
What type of cholesterol is a large problem in atherosclerosis?
LDL
