Cardiovascular System: Blood Vessels -NSU
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Transcript of Cardiovascular System: Blood Vessels -NSU
Histology 7a
Gregory Rodocker
NSU
Class Taken: Spring 2009
The Circulatory System
Blood vascular components Heart Arteries Capillaries veins
lymphatic vascular components later
Vessels
Macrovasculature (>0.1 mm) Large arterioles Muscular and elastic arteries Muscular veins
Microvasculature Arterioles Capillaries Post-capillary venules
Capillaries
A single layer of endothelial cells and the basal lamina: (no smooth muscles)
7-9 µm in diameter and 50 µm in length
Walls consist of 1-3 cells with a continuous basal lamina of endothelial origin
Types of Capillaries
Continuous, complete or somatic Fenestrated, or visceral Fenestrated in Kidney Discontinuous sinusoidal
Listed from tightest to leakiest
Fenestrated Capillary in Kidney
Continuous Capillaries
Absence of fenestrae Basal lamina continuous Muscle tissue, CT, exocrine glands
and NT
Fenestrated Capillaries
Large fenestrae covered by diaphragm Thinner than the trilaminar appearing unit
membrane Basal lamina continuous Kidney, intestines and endocrine
glands
Fenestrated Caps. in Kidney
Fenestrated w/o diaphragm Basal lamina continuous and only
barrier for filtration Kidney glomeruli
Discontinuous Sinusoidal Capillaries (sinusoidal so think liver)
Wall and basal lamina discontinuous Tortuous in their path and greatly
enlarged (30-40 µm in diameter) Liver and hematopoietic tissue such as
bone marrow and spleen
1- typical path2- arteriovenous anastomosis3- arterial portal system4- venous portal system
Larger vessels Tunica intima
Endothelium Internal elastic lamina (arteries)
Wrinkled postmortem
Tunica media Smooth muscle External elastic lamina (larger arteries)
Tunica externa CT which is continuous with surrounding
tissues
Larger vessels
Vasa vasorum Vessels supplying blood to walls of larger
blood vessels. Walls too thick to obtain nutrition from large vessel lumen.
“vessels of the vessels”
Muscular vs. elastic artery
Muscular vs. elastic arteries
Media of muscular with up to 40 layers of smooth muscle cells
Elastic arteries include the aorta and its large branches
Elastic arteries have a large lumen and thin walls vs. muscular arteries which have small lumens and thick walls
Elastic vessels recoil with beat of the heart while muscular arteries control blood flow to organs
Veins
Small to medium sized veins (1-9 mm in diameter) Thin intima, thin media and well
developed adventitia Large veins have an obvious intima,
thin media and a prominent adventitia Contain valves to prevent blood back flow
Muscular artery vs. comparable vein