Histo Block I: Arteries

Question 1

Mention the types of arteries?

Answer 1

1. Elastic arteries (conducting arteries)
2. Muscular arteries (distributing vessels)
3. Arterioles & metarterioles (microvasculature)

Question 2

Identify

Answer 2

Elastic artery

Question 3

identify

Answer 3

Muscular artery - elastic stain

Question 4

identify

Answer 4

arteriole

Question 5

What are some of the elastic arteries int he body?

Answer 5

the aorta and pulmonary arteries and their major branches: brachiocephalic, common carotid, subclavian, and common iliac.

Question 6

Which arteries are the major conduits from the heart for the blood?

Answer 6

Elastic arteries

Question 7

Explain how the elastic arteries maintain blood pressure and propelling blood?

Answer 7

Distension of the elastic lamellae during systole is followed by elastic recoil during diastole

Question 8

Where do muscular arteries branch from and what do they do?

Answer 8

Branch from the elastic arteries and through their smooth muscle in tunica media regulate blood flow to organs

Question 9

How do arterioles distribute and regulate blood flow?

Answer 9

through smooth muscle in tunica media distribute and regulate blood flow at microvascular level to the tissues and cells

Question 10

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

Answer 10

high; media; thickest

Question 11

What is the major characteristic of elastic arteries in the tunica media?

Answer 11

A very thick tunica media characterized by alternating concentric layers of fenestrated elastic lamellae

Question 12

How many elastic lamellae are in the adult in the tunica media of elastic artery?

Answer 12

~70

Question 13

What cells are present in elastic lamellae?

Answer 13

Smooth muscle cells are present between the elastic lamellae and make both the elastic lamellae as well as reticular fibers and a ground substance

Question 14

Describe the tunica intima in elastic arteries

Answer 14

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

Question 15

Is there Vasa vasorum in elastic arteries? explain

Answer 15

present in tunica adventitia along with nerves. Vasa vasorum supply oxygen and nutrients to vessel wall

Question 16

identify

Answer 16

aorta; elastic stain

Question 17

identify

Answer 17

Elastic artery (aorta) at lower magnification showing layers

Question 18

identify

Answer 18

Fenestrated elastic lamellae in aorta artery (aorta) with smooth muscles

Question 19

Explain Ehlers-Dnlos syndrome and Marfan’s syndrome

Answer 19

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.)

Question 20

What is the distinguished characteristic of muscular arteries tunica intima?

Answer 20

1. Tunica Intima with a prominent internal elastic membrane
2. Thinner than in elastic arteries and consists of endothelium with its basal lamina, a sparse subendothelial CT layer, and a prominent internal elastic membrane
3. Often appears wavy due to contraction of smooth muscle in tunic media.

Question 21

What is the tunica media in muscular arteries composed of?

Answer 21

multiple layers of smooth muscle with very little elastic material.

Question 22

Describe the tunica media of muscular arteries

Answer 22

1. thickest layer.
2. The smooth muscle layers are circumferential or spirally oriented.
3. The smooth muscle cells synthesize all the collagen, elastic material, and ground substance.

Question 23

WHat membrane is typically present in the tunica media of muscular arteries?

Answer 23

A distinguishable external elastic membrane composed of multiple thinner elastic fibers/sheets

Question 24

identify

Answer 24

muscular-artery elastic stain

Question 25

is there vasa vasorum in muscular arteries?

Answer 25

SOMETIMES IN LARGE ONES

Question 26

identify

Answer 26

muscular artery

Question 27

identify

Answer 27

muscular artery

Question 28

What components are included in the microvasculature system?

Answer 28

• Arterioles
• Metarterioles
• Precapillary sphincters
• Capillaries
• Venules

Question 29

WHat is the microvasculature system and its function?

Answer 29

(only visible in microscope)
1. vessels which control distribution and removal of blood at the tissue level in the capillary beds

2. Functions in the exchange of gases, metabolites, waste products with the tissues; and in control of blood pressure

Question 30

Smoot muscle present in the arterioles, metarterioles and precapillary sphincters is important for what?

Answer 30

important for regulating the flow of blood to capillary bed

Question 31

identify

Answer 31

macrovasculature system

Question 32

WHich layer is the thickest in an arteriole?

Answer 32

Tunica media is thickest layer with 1-3 layers of smooth muscle. 30-100 microns

Question 33

How is th etunica intima in arterioles?

Answer 33

Tunica intima is very thin consisting mainly of endothelia cells with minimal subendothelial CT. Internal elastic membrane is typically absent.

Question 34

Describe the tunica adventitia in arterioles

Answer 34

Tunia adventitia is thin and blends with surrounding CT, so often hard to distinguish

Question 35

identify

Answer 35

LM of arteriole

Question 36

identify

Answer 36

EM of arteriole

Question 37

How is the wall of the arterioles?

Answer 37

Wall of arteriole is about ½ of lumen diameter and thus arterioles have a high wall thickness to lumen diameter ratio

Question 38

are arterioles high pressure vessels?

Answer 38

yes, with significant amount of smooth muscle

Question 39

How do arterioles regulate blood flow to capillary bed and who are they typically paired with?

Answer 39

by contraction/ dialation of smooth muscle. Frequently paired with venule.

Question 40

identify

Answer 40

Arteriole (A), venule (V) and small nerve

Question 41

identify

Answer 41

Arteriole cut in longitudinal section

Question 42

How is the tunica media in metarterioles?

Answer 42

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

Question 43

Where do metarterioles branch off?

Answer 43

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

Question 44

main function of metarterioles?

Answer 44

regulate flow of blood through capillary bed, to allow blood flow into capillaries or block by contraction of smooth muscle

Question 45

what is the clinical consideration of arterioles and blood pressure?

Answer 45

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.