What are the three tunics that make up the wall of a blood vessel (from inner to outer)?
1) Tunica Intima
2) Tunica Media
3) Tunica Adventitia
The network of small blood vessels that supply nutrients to wall of large blood vessels is called?
Neural innervation of blood vessels is responsible for what action(s)
Vasoconstriction (sympathetic) and vasodilatation (parasympathetic)
What makes for the easy exchange of gases and molecules in capillaries?
Single-layered, permeable wall of endothelium and fenestrae (windows)
What are the characteristics and permeability of a continuous capillary?
No fenestrae, Low permeability.
What are the characteristics and permeability of a fenestrated capillary?
Contain fenestrae, usually with diaphragm. Highly permeable
What are the characteristics and permeability of a sinusoidal capillary?
Larger in diameter. Contain large fenestrae with no diaphragm. Highly permeable to larger molecules
What is the use of sinusoid in the thyroid and anterior pituitary gland?
Large holes allows for movement of hormones to blood
What are the smooth muscle cells that regulate blood flow through the capillaries?
Path of blood flow through a capillary bed (starting with arteriole)
Arteriole → Metarteriole → Thoroughfare channel → Precapillary sphincter → Arterial capillaries → Venous capillaries → Thoroughfare channel → Venule
What happens to path of blood when precapillary sphincters close?
Blood passes directly from arteriole to venule, through thoroughfare channel, by-passing the capillary network/tissues.
Direct connections between arterioles and venules which allow blood to bypass capillary beds
Describe the portal system.
Blood passes through two capillary networks before returning to the heart (i.e., hepatic portal system, for filtration of blood)
What are the characteristics of elastic arteries (diameter, vessel wall)?
Largest in diameter (1 - 2.5 cm); walls contain less smooth muscle but more elastic fibers
ex. aorta, subclavian
What are the characteristics of muscular arteries (diameter, vessel wall)?
Include medium and small arteries; walls are comprised of thicker smooth muscle layer and thick internal elastic membrane
How is an elastic artery different from a muscular artery?
Has larger amount of elastic tissue and less smooth muscle
What are the characteristics of arterioles (diameter, vessel wall)?
Smallest in diameter (9-40 μm); all three tunics observable but no internal elastic membrane
What are the characteristics of venules and small veins (diameter, vessel wall)?
Diameter of 50 μm up to 0.3mm; vessel wall structure similar to capillaries
What is the function of venules?
Collect deoxygenated blood from the capillaries and transport it to the small veins; some nutrient exchange occurs in smallest venules
Which veins are also known as capacitance vessels and why?
medium veins; because they contain 65% of blood volume, as blood is held here while waiting to be transported back to the heart (via vasoconstriction)
What happens when a vein's walls are stretched to the point that the valves fail?
Varicose veins can develop
In arteriosclerosis, what happens to the: 1) tunica intima, and 2) tunica media and what does it lead to?
Tunica intima thickens and permeability is compromised; tunica media loses elasticity; leads to calcium buildup in vessel wall and increased resistance to blood flow
What is the condition in which fatty deposits called plaque build up on the inner walls of the arteries?
What arteries branch off the aortic arch?
1) brachiocephalic artery
2) left common carotid artery
3) left subclavian artery
What two arterial branches does the abdominal aorta give rise to?
1) left common iliac artery
2) right common iliac artery
What tributaries drain directly into the superior vena cava?
1) Right brachiocephalic vein
2) Left brachiocephalic vein
3) Azygos vein
What tributaries drain directly into the right brachiocephalic vein?
1) Right internal jugular vein
2) Right subclavian vein
3) Right internal thoracic vein
Path of pulmonary blood circulation
Heart (right side) → Pulmonary trunk → Pulmonary arteries → (Lungs) → Pulmonary vein → Heart (left side)