Lecture 20

Question 1

List the three layers (tunics) of the heart wall

Answer 1

Endocardium

Myocardium

Epicardium

Question 2

Describe the Endocardium in terms of where it is found, its components, and it’s association with the tunica intima

Answer 2

Endocardium: the innermost layer, lining the atria and the ventricles

Components are endothelium and subendothelial CT

It is continuous with the tunica intima of the blood vessels entering and leaving the heart

Question 3

Describe the Myocardium in terms of it’s location, and what it consists of

Answer 3

Myocardium: middle layer that consists of cardiac muscle cells

Question 4

Describe the Epicardium in terms of it’s location, the tissue it is covered with and what it is composed of

Answer 4

Epicardium: most external layer

it’s external surface is covered by simple squamous epithelium (mesothelium)

Mesothelium overlies fibroelastic CT that contains adipose cells, nerves, and coronary vessels

Question 5

Describe the location of the subendocardium and what it contains

Answer 5

The “subendocardium” is found between the endocardium and the myocardium and contains nerves and Purkinje fibers (subendothelial fibers)

Question 6

State the 3 tunics of blood vessels

Answer 6

Tunica Intima

Tunica Media

Tunica Adventitia

Question 7

Describe the tunica intima in terms of what blood vessels it is found in, what it is composed of and what it’s endothelial cells produce.

Answer 7

Tunica Intima: found in all arteries and arterioles and is composed of endothelium and basal lamina

It’s endothelial cells produce von Willebrand’s facto VIII

Question 8

Describe the tunica media in terms of what it is composed of and what types of fibers it contains

Answer 8

Tunica Media: contains collagen and elastic fibers

Made up of circular smooth muscle tissue and fibroblasts

Question 9

Describe the tunica adventitia in terms of it’s location compared to the other tunics, what it is composed of, and how it receives blood supply/innervation.

Answer 9

Tunica Adventitia: the outermost layer that is lacking in arterioles

Composed of loose areolar tissue and contains irregular fibroelastic tissue with adipocytes

Has small vessels (vasa vasorum) and nerves (nervi vasorum)

Question 10

What blood vessel tunic is present in capillaries that are so small that they are only a single layer of cells?

Answer 10

Tunica intima

Question 11

Describe Elastic arteries in terms of their behavior during systole/diastole, what their tunica media consists of, and give examples of where these can be found in the body (be sure to include another name for them)

Answer 11

Elastic arteries: aka “conducting arteries” stretch during systole and recoil during diastole

Tunica media consists of layers of elastic fibers organized into elastic laminae (with CT interspersed between the elastic laminae
40 layers in newborn and 70 layers in adult

Ex. Aorta, pulmonary trunk, and large branches of the aorta

Question 12

Describe Muscular arteries in terms of what their tunica media consists of, what it responds to, changes in this layer as vessels get smaller, and examples of where to find these types of vessels (include another name for them)

Answer 12

Muscular Arteries: aka “distributing arteries” tunica media consists of smooth muscle that responds to autonomic stimulation and hormones

The thickness of the smooth muscle layer decreases as the vessel gets smaller, while there is also a gradual transition from elastic artery to muscular artery

Ex. All named arteries of the body except elastic arteries

Question 13

Define arterioles, describe their tunica media, what they give rise to, and changes that occur as vessels get smaller.

Answer 13

Arterioles: basically just small arteries with a tunica media that consists of 2-3 layers of smooth muscle cells

Arterioles give rise to metarterioles which have a discontinuous layer of smooth muscle tissue

Same as arteries, the thickness of the smooth muscle layer decreases as the diameter becomes smaller

Question 14

The mean arterial pressure depends on the ___ ____ __ ___ _____ _____ in the arterioles (peripheral resistance arterioles)

Answer 14

proper tone of the smooth muscles

Question 15

Describe veins in terms of their structure and include a characteristic of their tunica adventitia (in larger veins)

Answer 15

Veins: compared to arteries, they have a larger lumen, thinner wall, and valves are present in them

Larger veins have a layer of longitudinal smooth muscle in the inner aspect of the tunica adventitia

Question 16

Describe Pericytes

Answer 16

Pericytes: undifferentiated mesenchymal cells that may serve as stem cells to differentiate into fibroblasts

may also be contractile

Question 17

What type of capillary can be found in the brain, muscle, thymus, bone, and lung?

Answer 17

continuous capillaries

Question 18

What type of capillary can be found in the intestinal villi, choroid plexus, and ciliary processes of the eyes?

Answer 18

fenestrated capillaries

Question 19

What type of capillary can be found in the gaps in the venous sinusoids in the liver, and in the spleen?

Answer 19

Discontinuous capillaries (sinusoid)

Question 20

What type of cell is found in the glomerulus, supported by a significantly thickened basal lamina?

Answer 20

a fenestrated endothelial cell