CPR 5.03 Histology of Vessels Flashcards
Describe the characteristics of the Tunica Intima of blood vessels.
Endothelium
Subendothelial layer: thin loose CT. May have smooth muscle.
Internal elastic lamina: prominent limiting layer found in arteries and some large veins. Has elastic fibers.
Describe the characteristics of the tunica media of blood vessels.
Tunica Media: Middle layer. Thickest layer in arteries.
Concentric layers of smooth muscle: helically arranged. Regulate BP.
CT: Elastic lamellae. Provides resiliency.
External elastic lamina: separates tinuca media from tunica adventitia.
Describe the characteristics of tunica adventitia of blood vessels.
outermost layer. Thickest layer in veins.
CT: Type I collagen (dense or loose based on vessel location). Elastic fibers. Vasomotor nerves in large vessels.
Vasa Vasorum: Vessels of the vessel seen in large vessels because their walls are too thick to be nourished soley by diffusion.
What are the main histological differences between arteries and veins
Arteries: Narrow circular lumen. Thick tunica media.
Veins: Large lumen. Thick adventitia. Valves from intima.
Identify and describe fxn and characteristics of elastic arteries.
conduct from heart with elastic recoil.
Ex: Aorta, pulmonary aa.
Tunica intima: well developed. Many smooth muscle cells. Internal elastic lamina hard to distinguish from elastic lamellae of tunica media.
Tunica media: thick. Well developed, fenestrated elastic lamellae which permit diffusion from lumen.
Tunica adentitia: CT, thinner than media. Vasa vasorum abundant.
Glomus bodies: ganglion like structures in carotid sinuses detect change in blood concentrations. Tunica media thinner and tunica adventita has CN IX sensory nerve endings
Identify and describe fxn and characteristics of muscular arteries.
distinct tunics. Distribute blood to organs and maintain steady pressure and flow.
Ex: Radial and Femoral aa.
Tunica Intima: thin. Prominent internal elastic lamina with squiggly appearance.
Media: Many Smooth muscle layers. Less elastic material. Fenestrated external elastic lamina.
Adentitia: CT. Vasa vasorum may or may not be present.
Identify and describe fxn and characteristics of arterioles.
Regulate flow into capillaries. Usually round. Lumen is about the size of the wall thickness
Intima: only endothelium.
Media: 1-2 layers of smooth muscle. No external lamina.
Adventitia: very thin.
Identify and decribe the fxn and characteristics of capillaries
Capillaries: permit and regulate exchange between blood and surrounding tissues.
Intima: endothelium only. Curved nucleus. Basal lamina.
Media: pericytes present (mesenchymal cells with developed networks of myosin, actin, and tropomysin, contractililty facilitates flow of blood cells, proliferate after damage and differentiate to smooth muscle.
Identify and describe the fxn and characteristics of post-capillary veinules
Postcapllary:
Intima only
Media: Primary site for WBC’s to leave circulation.
Identify and describe the characteristics of collecting venules.
Slightly larger, more contractile cells. Irregular shape of lumen.
What is now visible once you get up to the level of muscular veins?
Larger diameter. 3 layers.
Identify and describe characteristics of small veins.
Small Veins
Role: Collect blood from venules.
Intima: CT with scattered smooth m.
Media: thin, 2-3 layers of smooth muscle.
Adventitia: thicker than media.
Identify and describe the fxn and characteristics of medium veins
Medium Veins
Role: Carry blood to larger veins, prevent backflow.
Intima: valves present.
Media: 3-5 layers of Smooth muscle.
Adventitia thicker than media/ Longitudinal smooth m may be present.
Identify and describe the fxn and characteristics of large veins
Large Veins
Role: return blood to heart.
Intima: Prominent valves.
Media: >5 layers of smooth muscle, with much collagen.
Adventitia: thickest, bundles of longitudinal smooth muscle
Identify and describe the fxn and characteristcs of lymphatic capillaries (Intima only)
Lymphatic Capillaries
Role: drain interstitial fluid
Description: no RBC’s in lymph, lightly staining proteins. Closed-ended vessels.
Intima: Large endothelial cells. Incomplete lamina. Anchoring filaments contain elastin.
Recognize in EM, and describe the characteristics of continuous capillaries.
Continuous
Endothelial cells overlap.
Basal lamina complete and intact (light halo around entire capillary).
Pericytes present.
Muscle, CT, lungs, exocrine glands, nervous tissue.
Recognize in EM, and describe the characteristics of Fenestrated capillaries
Fenestrations covered by basal lamina.
Specialized for uptake or outflow of molecules. Kidneys, intestine, choroid plexus, endocrine glands, pancreas
Recognize in EM, and describe the characteristics of Discontinous Capillaries (Sinusoids)
Discontinuous(Sinusoids)
Large lumen. Thin endothelial cells.
Large fenestrations with no diaphragmà Leaky.
Discontinuous basal lamina.
Allow maximal exchange of macromolecules. Liver spleen, endocrine organs, bone marrow.
