Vessels and Circulation #1 Flashcards
Circulation that consists of left atrium, left ventricle, and all named arteries and veins blood travels through until it comes back to the heart (not including right atrium)
Systemic Circulation
high pressure circulation system
systemic
Circulation that consists of right atrium, right ventricle, and all named arteries and veins that blood travels through until it comes back to the heart (not including left atrium)
Pulmonary Circulation
low pressure circulation system
pulmonary
3 classes of blood vessels
Arteries, Capillaries, and Veins
carry blood from heart and become progressively smaller as they travel farther from heart
Arteries
Arteries branch into these smaller vessels
Arterioles
where gas and nutrient exchange occurs between tissue cells and blood
Capillaries
carry blood to heart and become progressively larger as they merge and travel closer to heart
Veins
Veins receive blood from these small branches of vessels
Venules
site where two or more arteries or veins merge to supply the same body region
Anastomosis
provide alternate blood supply routes to body tissues or organs
Arterial Anastomoses
Which type of vessel forms many more anastomoses than the other?
Veins form more
When there is only one pathway through which blood can reach an organ.
End Arteries
Two examples of end arteries
Renal Artery and Splenic artery
Arteries that do not form and anastomoses
End Arteries
When an artery will travel with the corresponding vein because they service the same body region and tend to lie next one another
Companion vessels
Both arteries and veins walls have three layers called what
Tunics
The tunics surround this inside space of the blood vessel through which blood flows
Lumen
The innermost layer of a blood vessel wall
Tunica intima
What layer of a blood vessel wall has structural differences between veins and arteries? What is the structural difference?
The Tunica intima in the veins has one-way valves which are not seen in arteries
What is the tunica intima composed of?
Endothelium and a subendothelial layer (thin layer of connective tissue)
The middle layer of the blood vessel wall
Tunica media
What is that tunica media composed of?
Circularly arranged layers of smooth muscle cells
In the blood vessel tunics what causes the smooth muscles to contract, resulting in narrowing of the blood vessel lumen? What is the term for this action?
Sympathetic innervation causes vasoconstriction
What is the term or when the smooth muscle fibers relax in the blood vessel tunics and result in widening the blood vessel lumen?
Vasodilation
The vasomotor center, responsible for vasoconstriction and vasodilation, resides where the brain?
Medulla oblongata
The outermost layer of a blood vessel wall
Tunica externa
What is the tunica externa composed of?
Connective tissue that contains elastic and collagen fibers
Which is the thickest tunic in arteries? In veins?
Arteries= tunica media, veins= tunica externa
Very large blood vessels require their own blood supply to and through which Tunica in the form of a network of small arteries?
Tunica externa
This is narrower in an artery than in a vein of the same size
The lumen
Arteries tend to have more what in all their tunics? What does this mean?
They have more elastic and collagen fibers which means that artery walls remain open (patent) and can spring back to shape
Vein walls tend to do what if there’s no blood in them?
Collapse
Capillaries contain only which tunic?
Tunica intima
The tunica intima of capillaries consist of what?
A basement membrane and endothelium only
Capillaries containing only the tunica intima allow for easier what?
Exchange of materials between the blood in the vessels and the interstitial fluid
What is the scientific name for tissue fluid?
Interstitial fluid
What is the primary function of capillaries?
Exchange of materials
If the veins collapsed and there is severe hypotension, what life-saving procedure can be done?
Intraosseous infusion (IO)
In general, as an artery’s diameter decreases, there is a corresponding decrease in what? And a relative increase in what?
A decrease in the amount of elastic fibers and a relative increase in the amount of smooth muscle
What are the three basic types of arteries?
Elastic arteries, muscular arteries, and arterioles
Which type of artery is the largest, with diameters ranging from 2.5 to 1 cm?
Elastic arteries
Elastic arteries have a large proportion of what throughout all three tunics, especially in this layer?
Elastic fibers, especially in the Tunica media
The abundant elastic fibers within elastic arteries allow them to do what?
Stretch when a heart to ventricle ejects blood into it
What is responsible for the forwarding propulsion of your arterial blood?
Ventricular systole and the elastic recoil of the arterial walls
Name six elastic arteries
Aorta, pulmonary, brachiocephalic, common carotid, subclavian, and common iliac arteries
Elastic arteries branch into what?
Muscular arteries
This type of artery typically has diameters ranging from 1cm-3mm
Muscular arteries
Unlike elastic arteries, how are the elastic fibers within muscular arteries arranged?
They are confined to 2 laminar rings (one ring between the tunica intima and media, and the second between the Tunica media and externa)
Most of the named arteries belong to which category?
Muscular arteries
Muscular arteries branch into what?
Arterioles
These are the smallest arteries, what diameters ranging from 3 mm to 10 µm
Arterioles
Which layer of muscular arteries are proportionately thicker, with multiple layers of smooth muscle? This results in a better ability do what?
thicker tunica media gives them a better ability to vasoconstrict and vasodilate
How do larger arterioles and smaller arterioles differ?
Larger arterioles have all three tunics, whereas the smallest arterioles have fewer
What do arterioles regulate by vasoconstricting or vasodilating?
Arterial blood pressure AND blood flow through capillaries
What connects arterioles to venules?
Capillaries, the smallest blood vessels
The average capillary diameter is just slightly larger than what? What does this mean?
The diameter of a single erythrocyte; erythrocytes must travel single file through each capillary
What causes blockages and infarctions in body organs, such as the spleen and brain, due to narrow vessel diameter?
Sickle cell disease