Blood vessels 1

Question 1

The large or conducting arteries allow

Answer 1

rapid blood flow and their elastic laminae help to smooth out pressure differences with distance from the heart.

Question 2

The medium or distributing arteries

Answer 2

have a slower blood flow and the flow can be controlled by regulatory factors such as chemical or neural input to regulate flow to various organs.

Question 3

What are the three concentric layers or tunics surrounding the lumens of blood vessels above precapillaries?

Answer 3

Tunica intima, tunica media, tunica adventitia

Question 4

Tunica intima:

Answer 4

The intima consists of the endothelium, basal lamina, and a subendothelial layer of loose connective tissue that may contain an occasional smooth muscle cell.

Question 5

Internal elastic lamina

Answer 5

In arteries an internal elastic lamina (sometimes considered part of the media) borders the media. This is a fenestrated layer of elastin.

Question 6

Tunica media:

Answer 6

The media is composed of smooth muscle and variable amounts of elastic fibers and lamellae, reticular fibers, and proteoglycans.

Question 7

The extracellular matrix of the tunica media is synthesized by?

Answer 7

the smooth muscle cells. External elastic lamina Larger vessels have an external elastic lamina.

Question 8

What replaces the media in capillaries and postcapillary venules?

Answer 8

Pericytes

Question 9

Tunica adventitia:

Answer 9

The outermost layer is composed of fibroblasts and longitudinally oriented type I collagen and elastic fibers.

Question 10

Larger blood vessels have a

Answer 10

vasa vasorum (?vessels of the vessel?) in the adventitia and a portion of the media that provides nutrients via small vessels to the vessel wall.

Question 11

Which has a more extensive vasa vorum; veins or arteries? Why?

Answer 11

Veins have a more extensive vasa vasorum because of the low nutrient and oxygen content of venous blood.

Question 12

What is the function of the intima?

Answer 12

The intima forms a permeable or semipermeable barrier.

Question 13

What is the function of the media?

Answer 13

the media controls diameter and blood pressure and movement.

Question 14

What is the function of the adventitia?

Answer 14

The adventitia provides physical support, attaches vessels to tissue, and carries vessels and nerves.

Question 15

Endocardium: Homology? Location? Composition?

Answer 15

it is homologous to the intima of blood vessels. The endocardium lines the atria and ventricles. It is composed of an endothelium and a subendothelial layer of connective tissue.

Question 16

Myocardium Homology? Composition?

Answer 16

is homologous to the media of blood vessels. It is the thickest layer of the heart wall and composed of cardiac muscle that is thicker in the ventricles than in the atria.

Question 17

Epicardium Homology? Location? Composition?

Answer 17

is homologous to the adventitia of blood vessels. It forms the surface of the heart and is anatomically defined as the visceral layer of the pericardium. The epicardium is composed of a mesothelium and the subepicardial layer of loose connective tissue that contains nerves, adipose tissue, and the coronary blood vessels.

Question 18

Where are large, elastic, conducting arteries located?

Answer 18

1. The aorta and its main branches, common carotid, brachiocephalic, subclavian, and pulmonary arteries are elastic arteries.

Question 19

Funtion of large, elastic, conducting arteries?

Answer 19

Systole distends the elastic arteries and they recoil and contract during diastole. This produces a more uniform flow and pressure.

Question 20

Intima of elastic arteries (size, composition)

Answer 20

is about 150 microns thick in adults (1/6th of wall thickness). There are scattered smooth muscles in the subendothelial layer. The endothelial cells contain Weibel-Palade bodies

Question 21

Weibel-Palade bodies

Answer 21

that are membrane-bound inclusions (0.1 by 3 microns) that have a dense matrix containing von Willebrand factor.

Question 22

Describe the endothelial cells of the intima of large, elastic, conducting arteries?

Answer 22

they are slightly elongated polygons with their long axes oriented with the blood flow and the cells are connected by occluding junctions.

Question 23

Media of large, elastic, conducting arteries (size, composition, vaso vasorum)

Answer 23

is about 2 millimeters thick and is made of 40-70 layers of fenestrated elastic lamellae with smooth muscle cells interspersed between. There is a thin external elastic lamina and the vasa vasorum of the adventitia penetrates the outer third to half of the media.

Question 24

Adventitia

Answer 24

is relatively thin with nerve fibers, lymphatics, and vasa vasorum in the loose connective tissue.

Question 25

Mixed, Musculo-Elastic Arteries location

Answer 25

Forms parts of terminal abdominal aorta, the iliac arteries, external carotids, axillary arteries and others.

Question 26

Mixed, Musculo-Elastic Arteries function

Answer 26

These are transitional segments between large and medium arteries.

Question 27

Compare the tunica media and adventitia

Answer 27

they are about the same thickness. The media has fewer elastic lamellae and there is a more obvious internal elastic membrane.

Question 28

Medium, Muscular, Distributing Arteries location

Answer 28

Most named arteries are of this type such as coronary, renal, mesenteric, brachial femoral and others.

Question 29

Medium, Muscular, Distributing Arteries function

Answer 29

The muscular arteries distribute blood to tissues and organs regulated by autonomic nervous system control of the media.

Question 30

Intima of Medium, Muscular, Distributing Arteries

Answer 30

is relatively thin and includes a prominent internal elastic lamina (IEL) that undulates.

Question 31

Media of Medium, Muscular, Distributing Arteries

Answer 31

it is relatively thick and is composed of many concentric layers of smooth muscle cells bounded in larger muscular arteries by an external elastic lamina (EEL) that gets thinner and disappears in smaller diameter specimens.

Question 32

Adventitia of Medium, Muscular, Distributing Arteries

Answer 32

may be as thick as the media. The vasa vasorum and lymphatics are poorly developed.

Question 33

What are the General Features and Functions of arterioles?

Answer 33

1. 100 microns or less in diameter. 2. Invisible to the naked eye. 3. Function to maintain normal blood pressure in the arterial system and to reduce the pressure of the blood entering the capillaries.

Question 34

Intima of arterioles

Answer 34

has only a thin subendothelial layer of reticular fibers and the internal elastic membrane is absent in the smallest arterioles.

Question 35

Media of arterioles

Answer 35

is composed of one to five layers of smooth muscle.

Question 36

Adventitia of arterioles

Answer 36

is moderate to scant.

Question 37

Metarteriole

Answer 37

The terminal segment before a capillary bed forms a metarteriole or precapillary sphincter that regulates blood flow into capillaries.

Question 38

Structural Changes in Arteries with Age

Answer 38

1. The three tunics are complete during the fourth month in utero. 2. The largest arteries continue to grow until about age 25. 3. The aging process involves the intima and media. 4. After age 30, the media becomes stiffer due to an increase in elastic lamellae and deposition of collagen and proteoglycans.

Question 39

Which arteries show greater change with age?

Answer 39

Large elastic arteries show greater change than muscular arteries.

Question 40

What happens to the media with age?

Answer 40

elastic tissue can develop irregular thickenings and elastic fibers can fragment.

Question 41

Atherosclerotic plaques form in the

Answer 41

intima as a consequence of noncellular lipid material accumulation in the subendothelial layer.

Question 42

Muscular arteries of the media?

Answer 42

undergo calcification. Large muscular arteries like the coronaries develop atherosclerotic plaques in their intima that can reduce the luminal diameter appreciably even by age 25.