Cardiac Histology II

Question 1

The 3 tunics

Answer 1

Tunica intima
Tunica media
Tunica adventitia

Question 2

Endothelium of tunica intima

Answer 2

Single layer of squamous cells.

Question 3

Layers of the tunica intima

Answer 3

Endothelium
Basal lamina
Subendothelial cells (loose CT) w/ internal elastic membrane

Question 4

Internal elastic membrane

Answer 4

Sheet-like layer of fenestrated elastic material in arteries and arterioles.

Question 5

Tunica media

Answer 5

Thick in arteries.
Extends from internal elastic membrane to external elastic membrane (which separates tunica media from tunica adventitia).

Question 6

Tunica adventitia

Answer 6

Merges w/ surrounding loose CT.

Thin in arteries and thick in veins.

Question 7

Vasa vasorum

Answer 7

Vessels of tunica adventitia of large arteries and veins.

Supplies the vasculature itself.

Question 8

Nervi vasorum

Answer 8

ANS input that controls contraction of vascular smooth muscle.

Question 9

In large vessels, elastin forms:

Answer 9

Lamellae (sheets) between smooth muscle.

No fibroblasts.

Question 10

Distribution of muscle and elastin in medium sized arteries (4):

Answer 10

More smooth muscle, less elastin.
The internal elastic membrane becomes very apparent.
External elastic membrane also apparent.
Thick tunic adventitia.

Question 11

Small arteries have how many layers of SM?

Answer 11

Up to 8

Question 12

Arterioles have how many layers of SM?

Answer 12

1-2 layers and internal elastic membrane may or may not be present.

Question 13

Pericytes

Answer 13

Perivascular contractile cells w/ branching cytoplasmic processes.
Controlled by NO.
Promotes stability of capillaries and postcapillary venules

Question 14

Continuous capillaries

Answer 14

Have complete endothelial cells and pericytes.

Found in many places in the body. Most common.

Question 15

Fenestrated capillaries

Answer 15

Have fenestrated endothelial cells.

Found in sites of fluid/metabolite absorption (gallbladder, kidneys).

Question 16

Discontinuous/sinusoidal capillaries

Answer 16

Discontinuous basal lamina and fenestrations.

Found in spleen, liver, bone marrow.

Question 17

Metarterioles

Answer 17

First branch off of arteriole supplying tissues.

Question 18

True capillaries

Answer 18

Branch from metarteriole.
No smooth muscle.
May or may not have pericytes.

Question 19

Thoroughfare channel

Answer 19

Distal end of metarteriole.
No smooth muscle.
Connects arterioles to venules.

Question 20

Diameters of veins (small, medium, large)

Answer 20

Less than 1 mm
10 mm or less
Greater than 10 mm

Question 21

Veins vs. arteries

Answer 21

Veins have thinner walls. The lumen is larger, but can be collapsed.

Question 22

Postcapillary venules

Answer 22

Drain capillaries , no true tunica media.

Question 23

Muscular venules

Answer 23

Have 1-2 layers of SM in tunica media.

Thin tunica advventitia.

Question 24

Small veins

Answer 24

Have 3 tunics.
Thicker tunica adventitia.
Tunica media has 2-3 layers.

Question 25

Hierarchy of veins (5)

Answer 25

Postcapillary venules -> muscular venules -> small vein -> medium vein -> large vein

Question 26

Medium veins

Answer 26

Thicker tunica media and adventitia.

Contains valves.

Question 27

Large veins

Answer 27

Very thick tunica adventitia.
Tunia media and tunica intima both thin.
Has circumferentially arranged SM cells.

Question 28

Lymphatic capillaries

Answer 28

Overlapping endothlial cells make valves.

Has incomplete basal lamina which increases permeability.

Question 29

Anchoring filaments

Answer 29

Hold the openings open in the endothelial cells.

Question 30

Lymphatic vessels have:

Answer 30

All tunics and valves.