Cardiovascular Histology Flashcards
metarteriole
narrow vessel surrounded by large, isolated bundles of smooth muscle initial portion surrounded by additional smooth muscle cells, which form a precapillary sphincter that regulates the blood flow through the capillary bed
thoroughfare channel
central channel in the arteriolar system
endocardium
-inner layer of the heart -lines the ventricles and atria completely and covers the cardiac valves and associated structures -continuous with the tunica interna of the large blood vessels entering and leaving
myocardium
- middle and thickest layer of the heart
- composed of bundles of cardiac muscle cells, branches of cardiac conduction fibers, an extensive capillary network, and the cardiac skeleton
epicardium
- outer surface of heart (visceral serous pericardium)
- covers myocardium externally
- outermost layer is mesothelial cells, which line the pericardial cavity and secrete serous fluid
- supported by dense connective-tissue layer rich in elastic fibers and adipocytes with blood vessels
subendocardial layer
-loosely arranged collagen and elastic fibers -adipose cells may be present, along with a rich supply of blood and lymph vessels and connective tissue that is continuous with that of the myocardium -in some locations, modified cardiac muscle cells of the cardiac impulse conduction system are present
fibrous cardiac skeleton
three parts
1) the fibrous rings (annuli fibrosi)
- composed of intermingling bundles of collagen and a few elastic fibers that surround the atrioventricular, aortic, and pulmonary trunk openings
2) the fibrous triangles (trigona fibrosa cordis)
- small areas of connective tissue that fill the spaces between the atrioventricular openings and the base of the aorta
3) the fibrous (or membranous) part of the interventricular septum
- collagen fiber bundles
intercalated disks
connects individual cardiomyocytes through junctions like gap, anchoring and desmosomes
support synchronised contraction of cardiac tissue
6 microscopic features of the myocardium
- cross striated
- central single nucleus
- intercalated disks
- lipofuscin
- sarcoplasmic reticulum
- many mitochondria
Os Cordis
from fibrous trigone area undergoing osseous differentiation
primarily seen in cattle
tunica intima
Innermost endothelium of vessels
has an internal elastic membrane and subendothelial connective tissue
tunica media
middle smooth muscle layer of vessels
contains elastic lamellae/fibers
tunica adventitia (externa)
outermost connective tissue layer of vessels
principally collagen
may contain blood vessels, nerves, and capillaries
What does the vascular endothelium do besides act as a barrier?
it is an important mediator of fluid distribution, hemostasis, inflammation, and healing
Tunica media
Veins vs Arteries
muscular tunica media of veins is thinner than that of arteries
smooth muscle fibers have an irregular orientation, approximately circular