Histology 2 Flashcards
Functions of cardiovascular system
Nutrient transport.
Gas exchange.
Waste removal.
Hormone distribution.
Distribute immune cells.
Clotting mechanisms.
Body temp regulation.
pH regulation.
Pressure regulation.
3 main components of vessel walls
1) tunica intima
2) tunica media
3) tunica adventitia
tunica intima
Endothelial cells.
Underlying CT.
Inner elastic lamina - made by smooth muscle cells (not always present).
tunica media
Smooth muscle.
Elastic lamina*
Elastic fibers*
External elastic lamina*
- not always present
- made by smooth muscle cells
tunica adventitia
CT.
Blood vessels*
Nerves*
*not always present
elastic arteries
Thick tunica media.
Lots of elastic fibers in media.
Expand during systole to reduce pulatile flow.
Fenestrated elastic lamina in tunica media –> communication.
Have own blood/nerve supply.
muscular arteries
Thin inner elastic lamina.
Tunica media has some elastic fibers.
External elastic lamina present.
Expand some during systole to reduce pulsatile flow.
small arteries
May not have inner elastic lamina.
3-10 layers of smooth muscle.
arterioles
No elastic lamina.
< 3 layers of smooth muscle.
Part of “microcirculation.
capillaries
Just endothelial cells + basal lamina.
No tunica media/adventitia.
4-10 um diameter – RBCs can barely pass through.
1) Continuous
2) Fenestrated
3) Discontinuous
Continuous capillary
1 cell wraps around.
Connected via tight junction.
Located in: nervous system, muscle, CT.
Fenestrated capillary
Pores allow small molecules to escape.
Located in: endocrine glands, kidney glomerulus
discontinuous capillary
Large openings between cells.
Blood cells can exit.
In lymphoid organs, liver.
pericytes
Within basal lamina.
Regulate capillary permeability (blood-brain barrier, phagocytic).
Contractile –> control lumen size.
Control endothelial proliferation.
venules
Lined by endothelium.
No tunica media/adventitia.
Leaky –> most lymph and WBC cells exit here.
Histamine sensitive.
small/medium veins
Lined by endothelium.
Tunica media w/ smooth muscle.
Thick tunica adventitia.
Valves in extremities.
varicose veins
Valves fail.
Blood return is inefficient.
large vein
Brachiocephalic, vena cava. Very thick. Endothelial cell lining. Thin tunica media. Tunica adventitia has lots of smooth muscle (longitudinal). Elastic fibers
portal system
capillary bed –> vessel –> capillary bed
heart wall
Epicardium.
Myocardium.
Endocardium.
Pericardium (visceral/parietal).
epicardium
Outer layer.
Mesothelium, CT, fat, blood vessels.
Equivalent to tunica adventitia.
myocardium
Middle layer.
Cardiac muscle.
Equivalent to tunica media.
endocardium
Inner layer.
Endothelium.
Equivalent to tunica intima.
pericardium
Pericardial sac.
Mesothelium.
Visceral: inner surface (lines organ).
Parietal: outer surface (lines cavity).
perkinje fibers
In subenocardial CT.
Specialized for conduction.
Contain lots of glycogen stores (increase resistance to hypoxia).
atherosclerosis
Thickening of tunica intima. ECM build up. Smooth muscle with lipid. Macrophages with lipid (foam cells). Cholesterol deposits. Prone to clotting.
Complications: myocardial infarct, angina, arrhythmias.
myocardial infarct
Damaged cardiac muscle.
Replaced by fibrous tissue.
edema
fluid accumulates in interstitial spaces
lymph circulation
Blind ended capillaries.
Pick up interstitial fluid.
Return fluid toward general circulation via subclavian vein.
elephantitis
Lymph malfunction.
Fluid accumulates.
Extremely swollen extremities.
lymph vessels
look like large capillary but with no blood in it
neurovascular bundle
Blood vessels, nerves, lymphatics travel together.
components of cardiovascular system
Blood vascular system: heart, arteries, capillaries, veins.
Lymphatic vascular system: capillaries, increasingly larger vessels, termination in vascular system.
Raynoud’s disease
Vasospasm involving dermal capillary beds.
abdominal aortic aneurism
Due to weakening of the vessel wall (infections, inflammation, genetic).
vasa vasorum
small blood vessels supplying large vessels
lymphedema
Caused by lymphatic blockage/ damage, or lymphadenectomy.
Swollen limbs.
lymphoid tissues
Masses of lymphocytes and associated cells required to mount an immune response.
Either a discrete organ or a mass of cells within various organs.
general appearance of lymphoid tissues
Little CT.
High number of cells/nuclei per area.
Large nuclear size.
Little cytoplasm.
primary lymphoid tissues
Bone marrow (development of immunocompetent B-cells).
Thymus (development of immunocompetent T-cells).
secondary lymphoid organs
Lymph nodes, spleen, MALT.
Populated by immunocompetent B/T-cells.
All have nodular/diffuse lymphoid tissue
development of immunocompetent cells
Thymocyte/C-cell precursor is produced.
Developing cells create receptors against anything.
Weed out the cells with receptors against “self.”
cytoreticulum
Formed from thymic epithelial cells.
Becomes infiltrated by T-cell precursors.
Epithelioreticular cells connected by desmosomes.
epithelioreticular cells release:
Hormones.
Ex: thymotaxin recruits thymocytes from bone marrow which mature into immunocompetent cells.
Epithelioreticular cells
Cytokeratin positive.
Support thymocytes.
Surround capillaries.
Contribute to blood-thymus barrier.
Hassall’s Corpuscles
Unsure of function.
Only in thymic medulla.
Whorls of epithelioreticular cells.
lymphoid nodules
B-lymphocytes.
Germinal center is lighter area.
