CV Histology Flashcards
What are the layers of the wall of the heart? (name outside to inside)
epicardium (aka serous pericardium)
myocardium
endocardium
What is the principal/largest cardiac muscle layer?
myocardium
Describe the composition of the epicardium
single layer of mesothelial cells, CT, and adipose tissues
Describe the composition of endocardium
inner layer of endothelium and subendo CT
middle layer of CT and smooth muscle
deeper CT layer (subendocardial) that contains Purkinje fibers and nuclei
Describe the tissue composition of the heart valves.
connective tissue with overlying endocardium
What layer of the heart wall contains the Purkinje fibers?
endocardium
What structural feature do the purkinje fibers contain?
intercalated disks
In what layer of the heart wall are the cardiac muscle fibers found
myocardium
Which is larger, purkinje fibers or cardiac muscle fibers?
purkinje fibers
**nuclei are larger too
What color do the purkinje fiber nuclei stain in H&E? Why?
pale pink bc they are glycogen rich
What is sarcoplasm?
cytoplasm of muscle cells
What are the structural features found in slides of cardiac muscle
intercalated disks
sarcoplasm (where nuclei are found)
What pigment will cardiac muscle frequently contain?
lipofuscin
What is a portal system? What are the 2 portal systems called
a vein or arteriole is interposed between 2 capillary networks
- hepatic portal system
- hypothalamic-hypophyseal portal system
What is a portal vein?
a vessel that connects 2 capillary beds
What is are tunics?
layers of the walls of arteries and veins
What is the innermost layer of vessel wall called?
middle?
outermost?
tunica intima
tunical media
tunica adventitia
Describe the composition of the tunica intima
- endothelium with BM
- subendothelial layer of CT and internal elastic lamina
- *FENESTRATED
Describe the composition of the tunica media
circularly arranged layers of smooth muscle cells, elastic and collagen fibers, and sometimes an external elastic membrane
*thickest
Describe the composition of the tunica adventitia
CT layer (mostly collagen) that contains vasa vasorum and nervi vasorum
What supplies blood to the tunica adventitia and media?
vasa vasorum
What supplies blood to the tunica intima?
the blood vessel itself
*also supplies part of media
Where is the vasa vasorum found? What is it/does it do?
adventitia of large arteria and veins
it is in tunica adventitia and supplies blood to tunica adventitia and media
What is the nervi vascularis?
What does it do?
Where is it found?
What is another name for it
network of automatic nerves
controls contraction and relaxation of smooth muscle
in T. adventitia
aka nervi vasorum
What causes vasodialtion?
NO
EDRF (endothelial derived relaxing factor)
What are 5 roles/functions of vascular endothelial cells?
- maintain blood homeostasis
- maintain selective permiabilty barrier
- modulate Q and R
- hormone synthesis
- oxidation of lipoproteins
What are the extracellular components of the T media? What makes these?
elastin
reticular fibers
proteoglycans
*made by smooth muscle cells are are found in between layers of sm muscle
Large arteries are also known as
elastic arteries
i.e aorta
Describe the variations on the 3 layers in large arteries.
- T intima is thick and contains collagen and elastic fibers
- internal elastic lamina is hard to find
- T media is thicker than adventitia
- T media contains multiple fenestrated sheets of elastic lamellae
What does collagen in T media and adventita do? (in large arteries)
prevents excessive distention during systole
What maintains BP during diastole? (in large arteries)
recoil of the elastic, distended fibers
Medium arteries are also known as
muscular arteries
How are medium arteries different than large arteries?
- T media has more smooth muscle
- prominent internal elastic lamina
- thinner subendothelial layer
- less elastic material in T media
- T adventia is the same size as T media (in large arteries media is thicker adventitia)
What kind of artery has prominent internal AND external elastic membranes
medium (large only have prominent external)
Describe the walls of arterioles (small arteries)
- 1-5 layers of smooth muscle in T media
- may or may not have internal elastic lamina
- tunica adventitia is thin and ill defined
How can you distinguish between small and medium arteries?
count the layers of smooth muscle
1-5 = small
> 5 = medium
Describe the vascular wall of capillaries
they have a single layer of endothelium and basal lamina
*note: pericyte covering the basal lamina does not count as a layer
What are the 3 types of capillaries?
continuous
fenestrated
discontinuous
Where are continuous capillaries found?
muscle, CNS, lung
In continuous capillaries, what is found between endothelial cells?
occluding junctions
What are unspecialized cells that give rise to endothelial cells and smooth muscle cells?
pericytes (Rouget cells)
**assc with some continuous capillaries
Where are fenestrated capillaries found?
endocrine glands
What types of capillaries have a continuous basal lamina?
continuous and fenestrated
What separates the fenestrations in fenestrated capillaries?
thin diaphragms
Where are sinusoid capillaries found?
liver, spleen, bone
T or F: the diameter of sinusoid capillaries are smaller then continuous and fenestrated
F: they are larger
What are between the endothelial cells in sinusoid capillaries?
gaps
In liver, what can be found in sinusoidal spaces?
macrophages (kupffer cells)
Richness of capillary network is related to ____
metabolic activity of the tissue
What is a slight thickening of the smooth muscle at the origin of the capillaries from an arteriole called?
pre-capillary sphincter
What are the 3 categories of veins?
venules, small-medium veins, and large veins
What are the 2 subtypes of venules?
post capillary and muscular
What is the difference between postcapillary venules and muscular venules?
postcapillary receive blood from capillaries while muscular venules lie distal to postcapillary venules
postcapillary venules has endothelium resting on basal lamina and pericytes there is no T media or T adventitia
muscular venules have 1-3 layers of smooth muscle in T media and a thin adventitia
What kind of vessel is the principal site of action for histamine and serotonin?
postcapillary venules
Do veins or arteries have a larger lumen?
veins
Where in the body do our veins have valves? What is the function of these valves?
in the extremities to make sure the blood flows in one direction
Describe the 3 layers of the walls of medium sized veins.
T intima: endothelium, BM, subendothelial layer, and sometimes an internal elastic membrane
T media: circularly arranged smooth muscle
T adventitia: thicker than the T media and consists of collagen and elastic fibers
How are medium sized arteries different than medium sized veins?
T media is much larger in a medium sized artery and the T adventitia is much larger in a medium sized vein
Describe the layers large veins
T initma: sub endothelium, BM, and thin sub endothelial layer (NO internal elastic lamina)
T media:is thin and has circularly arranged muscle fibers
T adventitia: thickest layer and has bundles of longitudinally arranged smooth muscle
How are large arteries and veins different?
wall of veins are much thinner
veins may have a much larger lumen
How can you compare and contrast arteries and veins of the same size?
- both a and v have 3 layers
- arteries have thicker walls due to inc thicknessof T media
- in histological sections, veins are more collapsed than arteries after fixation
What sized veins have valves
medium and large
What is the function of arteriovenous shunts?
regulate blood flow
How do AV shunts regulate blood flow?
contraction of arteriole smooth muscle sends blood to capillaries (inc P)
relaxation of arterioles sends blood directly to venules (bypassing capillaries0
How do the walls of lymphatic vessels compare to venules?
much thinner
Is the flow in lymphatic vessels uni or bi directional? How?
uni
**valves
where are lymphatic vessels most numerous?
in loose CT under the epithelium of
- skin
- mucous membranes
lymphatic vessels ultimatly end up as 2 large trunks…
- thoracic duct
2. right lymphatic duct
