Histo Block I: Arteries Flashcards
Mention the types of arteries?
- Elastic arteries (conducting arteries)
- Muscular arteries (distributing vessels)
- Arterioles & metarterioles (microvasculature)
Identify
Elastic artery
identify
Muscular artery - elastic stain
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arteriole
What are some of the elastic arteries int he body?
the aorta and pulmonary arteries and their major branches: brachiocephalic, common carotid, subclavian, and common iliac.
Which arteries are the major conduits from the heart for the blood?
Elastic arteries
Explain how the elastic arteries maintain blood pressure and propelling blood?
Distension of the elastic lamellae during systole is followed by elastic recoil during diastole
Where do muscular arteries branch from and what do they do?
Branch from the elastic arteries and through their smooth muscle in tunica media regulate blood flow to organs
How do arterioles distribute and regulate blood flow?
through smooth muscle in tunica media distribute and regulate blood flow at microvascular level to the tissues and cells
Arteries are ______ pressure vessels characterized by very thick walls with the tunica ______ being the ________ layer with smooth muscle that allows the arteries to regulate blood flow in the body
high; media; thickest
What is the major characteristic of elastic arteries in the tunica media?
A very thick tunica media characterized by alternating concentric layers of fenestrated elastic lamellae
How many elastic lamellae are in the adult in the tunica media of elastic artery?
~70
What cells are present in elastic lamellae?
Smooth muscle cells are present between the elastic lamellae and make both the elastic lamellae as well as reticular fibers and a ground substance
Describe the tunica intima in elastic arteries
is relatively thick with the endothelium, its basal lamina, and subendothelial CT. A distinct internal elastic membrane is not clear because of the large number of elastic lamella present in tunica media
Is there Vasa vasorum in elastic arteries? explain
present in tunica adventitia along with nerves. Vasa vasorum supply oxygen and nutrients to vessel wall
identify
aorta; elastic stain
identify
Elastic artery (aorta) at lower magnification showing layers
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Fenestrated elastic lamellae in aorta artery (aorta) with smooth muscles
Explain Ehlers-Dnlos syndrome and Marfan’s syndrome
Genetic Pathologies Involving Elastic Arteries:
Ehlers-Danlos Vascular Type Syndrome (Type 3 & 4 older terminology)- resulting from defects in collagen type III. Characterized by hyperextensibility of skin & joints, easy bruising, poor wound healing, and ruptures of walls of major tubes in vascular and gastrointestinal tract. Is inheritable condition. The vascular effects involving dissection and rupture of the aorta or other large arteries often results in early death (~ 50 yrs or younger)
Marfan’s syndrome - mutation in the fibrillin-1 gene. Typically seen in very tall thin individuals who have abnormally long fingers, and lax joints, pulmonary problems, dislocations of the lens, valve defects, and fragile vascular walls. Although patients can live a long life if they avoid stress, patients are prone to death by their mid-forties because of dissection and catastrophic ruptures in the wall of the aorta. (Note that both the long fingers and frequent dislocations of the lens may suggest the possibility of Marfan’s.)
What is the distinguished characteristic of muscular arteries tunica intima?
- Tunica Intima with a prominent internal elastic membrane
- Thinner than in elastic arteries and consists of endothelium with its basal lamina, a sparse subendothelial CT layer, and a prominent internal elastic membrane
- Often appears wavy due to contraction of smooth muscle in tunic media.
What is the tunica media in muscular arteries composed of?
multiple layers of smooth muscle with very little elastic material.
Describe the tunica media of muscular arteries
- thickest layer.
- The smooth muscle layers are circumferential or spirally oriented.
- The smooth muscle cells synthesize all the collagen, elastic material, and ground substance.
WHat membrane is typically present in the tunica media of muscular arteries?
A distinguishable external elastic membrane composed of multiple thinner elastic fibers/sheets
identify
muscular-artery elastic stain
is there vasa vasorum in muscular arteries?
SOMETIMES IN LARGE ONES
identify
muscular artery
identify
muscular artery
What components are included in the microvasculature system?
- Arterioles
- Metarterioles
- Precapillary sphincters
- Capillaries
- Venules
WHat is the microvasculature system and its function?
(only visible in microscope)
1. vessels which control distribution and removal of blood at the tissue level in the capillary beds
- Functions in the exchange of gases, metabolites, waste products with the tissues; and in control of blood pressure
Smoot muscle present in the arterioles, metarterioles and precapillary sphincters is important for what?
important for regulating the flow of blood to capillary bed
identify
macrovasculature system
WHich layer is the thickest in an arteriole?
Tunica media is thickest layer with 1-3 layers of smooth muscle. 30-100 microns
How is th etunica intima in arterioles?
Tunica intima is very thin consisting mainly of endothelia cells with minimal subendothelial CT. Internal elastic membrane is typically absent.
Describe the tunica adventitia in arterioles
Tunia adventitia is thin and blends with surrounding CT, so often hard to distinguish
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LM of arteriole
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EM of arteriole
How is the wall of the arterioles?
Wall of arteriole is about ½ of lumen diameter and thus arterioles have a high wall thickness to lumen diameter ratio
are arterioles high pressure vessels?
yes, with significant amount of smooth muscle
How do arterioles regulate blood flow to capillary bed and who are they typically paired with?
by contraction/ dialation of smooth muscle. Frequently paired with venule.
identify
Arteriole (A), venule (V) and small nerve
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Arteriole cut in longitudinal section
How is the tunica media in metarterioles?
They have only scattered smooth muscle cells in their tunic media, unlike the relatively regular continuous layers of smooth muscle in the media of arterioles
Where do metarterioles branch off?
branch off of arterioles to form the proximal part of channels called thoroughfare channels which allow direct flow from an arteriole to a venule, thus potentially bypassing parts of the capillary bed. Like arterioles they can also have capillaries branch off
main function of metarterioles?
regulate flow of blood through capillary bed, to allow blood flow into capillaries or block by contraction of smooth muscle
what is the clinical consideration of arterioles and blood pressure?
Arteriolesplay a key role in controlling blood flow and blood pressure throughout your body. They are responsible for approximately 80% of the vascular resistance (peripheral resistance) and constantly regulate the flow rate of blood to the various tissues and cells through a combination of vasocontriction and vasodilation controlled by the autonomic nervous system and hormones such as angiotensin II.
