Histology Cardiovascular System

Front 1

What are the three layers of blood vessels?

Back 1

Tunica Intima
Tunica Media
Tunica Adventitia

Front 2

Tunica Intima
Structure?

Back 2

This is the innermost layer.
It has a lining of endothelial cells resting on a basal lamina/basement membrane. The endothelium is simple sqaumous epithelium.

Front 3

The endothelium of Tunica Intima is made of what type of cells?

Back 3

Simple Squamous Epithelium

Front 4

The Endothelium of the Tunica Intima plays a role in?

Back 4

1) Transporting substances to and from the blood.
2) Vascular smooth muscle tone.
3) Control of blood clotting.
4) Attachment of WBC's to the vessel wall.

Front 5

Subendothelial Layer

Back 5

A layer of CT that may be present under the endothelium of the Tunica Intima.

Front 6

Tunica Media
Structure?

Back 6

Middle layer.
Varies in thickness and composition depending on the vessel. It contains smooth muscle, elastic fibers, and type III Collagen fibers in varying ratios.

Front 7

What is the purpose of having Type III Collagen in the Tunica Media?

Back 7

Recoil

Front 8

Tunica Adventitia

Back 8

Outer layer
Collagen and elastic fibers blend with the surround CT.

Front 9

What are Vasa Vasorum and where are they found?

Back 9

"Vessels of Vessels"
Found in the Tunica Adventitia and outer part of the Tunica Media of large vessels.

Front 10

What is the function of Vasa Vasorum?

Back 10

Provide nutrients and carry away wastes from the media and adventitia.

Front 11

What provides nutrients to the Tunica Intima and the inner part of the Tunica Media?

Back 11

Provided for by diffusion from and to the blood in the lumen of the vessel.

Front 12

Nerves that are part of the ________ nervous system innervate smooth muscle in the Tunica ______, causing vasoconstriction. The neurotransmitter here is _______.

Back 12

Sympathetic NS
Tunica Media
Norepinephrine.

Front 13

What makes blood vessels dilate?

Back 13

NT (such as ACh) binds to endothelial cells of Tunica Intima causing the release of NO, which travels to adjacent muscle cells and causes them to relax.

Front 14

The nerves leading to dilation of blood vessels are part of the _____ NS.

Back 14

Parasympathetic.

Front 15

Large Elastic Arteries (examples)

Back 15

Conducting arteries
Include the aorta and its branches (femoral, posterior tibial, brachial, etc...)

Front 16

What are arteries classified as?

Back 16

Elastic
Muscular
Arterioles

Front 17

Large Elastic Arteries conduct blood to ?

Back 17

Muscular Arteries

Front 18

In large elastic arteries, what makes up the Tunica Intima?

Back 18

Consists of the endothelium and its basal lamina and a thick subendothelial layer

Front 19

In large elastic arteries, what separates the Tunica Intima from the Tunica Media?

Back 19

An internal elastic lamina separates them but it is usually difficult to distinguish from the adjacent elastic laminae in the Tunica Media under the microscope.

Front 20

Large Elastic Arteries
Structure of-
Tunica Intima
Tunica Media
Tunica Adventitia

Back 20

Tunica Intima- Endothelium plus basal lamina plus a thick subendothelial layer

Tunica Media- Extremely thick layer of concentric layers of elastic tissue, collagen fibers, and smooth muscle cells.

Tunica Adventitia- Relatively thin layer of CT. Has Vasa Vasorum, lymphatics, and nerves.

Front 21

With age, the ratio of elastic to collagen fibers ___?

Back 21

decreases

Front 22

Vasa Vasorum are present in what part of large elastic arteries?

Back 22

Outer third of Tunica Media and all of the Tunica Adventitia

Front 23

Tunica Adventitia of Large Elastic Arteries.

Back 23

relatively thin layer of CT.
Vasa vasorum, lymphatics and nerves are present here.

Front 24

Muscular Arteries
Which ones?
Function?

Back 24

Distributing Arteries.
Include most of the named arteries of the body.
The function of these arteries is to distribute blood under high pressure to body regions.

Front 25

A prominent internal elastic lamina separates the Tunica Intima from the Tunica Media in these vessels.

Back 25

Muscular Arteries

Front 26

Structure of the Tunica Intima of Muscular Arteries.

Back 26

relatively thin layer of endothelium and its basal lamina and a thin subendothelial layer

Front 27

Structure of the Tunica Media of Muscular Arteries.

Back 27

Relatively thick layer of smooth muscle with some collagen and elastic fibers. There may be as many as 40 concentric layers of smooth muscle.

Front 28

Do Muscular Arteries have elastic laminas?

Back 28

Yes- two. The external separates the media from the adventitia but is not as prominent as the internal.

Front 29

Structure of the Tunica Adventitia of Muscular Arteries

Back 29

layer of CT that may have vasa vasorum, lymphatics and nerves

Front 30

Aneurysm
What is it?
Why does it happen?

Back 30

An aneurysm is a weakness in the wall of an artery that causes dilation in that area. It may result in the rupture of the artery. The weakness may be due to a developmental defect of, or damage to, the TUNCIA MEDIA.

Front 31

A weakness in what part of an artery could lead to an aneurysm?

Back 31

Tunica Media

Front 32

Arteriosclerosis

Back 32

Hardening of the arteries

Front 33

What is the most common type of Arteriosclerosis?

Back 33

Atherosclerosis

Front 34

What is atherosclerosis?
What causes it?

Back 34

Fibrolipid plaques form in the Tunica Intima.
Though that an inflammatory response caused by LDL cholesterol in the intima of the vessel causes most of these plaques.

Front 35

When do most MI's occur?

Back 35

When a plaque in a coronary artery ruptures and a clot forms, blocking the flow of blood to the heart.

Front 36

Arterioles
Size?
Function?

Back 36

Vessels of less than 0.5 mm diameter.
Functions-
1) slow down blood pressure before it reaches the terminal vascular bed (capillaries)
2) regulate blood flow through the capillary beds.

Front 37

The tonus in arterioles has a marked effect on ____?

Back 37

blood pressure

Front 38

Arterioles
Structure of-
Tunica Intima
Tunica Media
Tunica Adventitia

Back 38

Tunica Intima- endothelial cells plus basal lamina plus a thin subendothelial layer

Tunica Media- the thickest layer, made of smooth muscle.

Tunica Adventitia- thin layer of collagen and elastic fibers

Front 39

Structure of the Tunica Media of Arterioles?

Back 39

The thickest layer.
Consists of smooth muscle (1-5 layers).

Front 40

Structure of the Tunica Adventitia of Arterioles?

Back 40

thin layer of collagen and elastic fibers

Front 41

Metarterioles
What are they?
Structure?
Where do they go?

Back 41

Small vessels that branch off arterioles.
They have a lining of endothelium and its basal lamina and a discontinuous layer of smooth muscle in the Tunica Media.
They branch into capillary bed.

Front 42

Constriction of the smooth muscle in _____ helps to regulate blood flow through the capillary beds.

Back 42

Metarterioles

Front 43

Precapillary sphincters

Back 43

Smooth muscle at the point where capillaries branch off metarterioles and arterioles.

Front 44

What would be the result of constriction of the precapillary sphincter?

Back 44

Can stop blood flow through a capillary bed

Front 45

Capillaries
Size?
Site of?

Back 45

Vessels of very small diameter (7 um).
Site of interchange between blood and tissue fluid.

Front 46

What are the three types of capillaries?

Back 46

Fenestrated Capillaries
Continuous Capillaries
Sinusoidal Capillaries

Front 47

Fenestrated Capillaries

Back 47

Large openings in the wall that allow for exchange of molecules.

Front 48

Where would you find Fenestrated Capillaries?

Back 48

Examples are found in the kidney, intestine, endocrine glands and other tissues where exchange between the circulatory system and the tissues is significant.

Front 49

Continuous Capillaries

Back 49

No openings in the wall, limiting exchange of molecules.

Front 50

Where would you find continuous capillaries?

Back 50

Examples include muscle, CT, and nervous tissue.

Front 51

Sinusoidal Capillaries

Back 51

Large diameter. They have fenestrations and a discontinuous basal lamina.

Front 52

Phagocytic cells are often associated with the wall of ?

Back 52

Sinusoidal Capillaries

Front 53

Arteriovenous (A-V) Anastomosis

Back 53

This is a direct communication between arterial and venous circulation. These vessels have thick muscular walls proximally, and a wider lumen distally.

Front 54

These collect blood from capillaries.

Back 54

Venules

Front 55

Structure of the Tunica Intima of Venules?

Back 55

Made only of endothelium and its basal lamina. The endothelial cell attachment is weak, making venules leakier than other vessels.

Front 56

What makes venules leaky? Why is this important?

Back 56

The endothelial cell attachment of the Tunica Initima is weak.
Leukocytes can escape here during the acute inflammatory reaction.

Front 57

Structure of the Tunica Media of Venules?

Back 57

One layer of smooth muscle. May be absent.

Front 58

Structure of the Tunica Adventitia of Venules?

Back 58

Made of collagen fibers

Front 59

These conduct blood toward the heart under low pressure.

Back 59

Small to medium muscular veins.

Front 60

Structure of the Tunica Intima of Small to Medium Veins?

Back 60

Consists of the endothelium and its basal lamina. There may be a subendothelial layer.

Front 61

Valves are folds of the _____ that project into the _____ facing ____, to prevent backflow of blood. They may be found in veins located ___.

Back 61

Tunica Intima
Lumen
Downstream
Below the heart

Front 62

Structure of the Tuncia Media of Small to Medium Veins?

Back 62

thin layer of smooth muscle, collagen fibers, and elastic fibers

Front 63

Structure of the Tunica Adventitia of Small to Medium Veins?

Back 63

Relatively thick layer of CT.

Front 64

What structural changes would you see in varicose veins?

Back 64

Larger diameter. Elongated. Thickening of walls due to increase in CT in the intima and more smooth muscle cells in the media.

Front 65

What causes varicose veins?

Back 65

Due to prolonged increase in venous pressure

Front 66

Where are you most likely to have varicose veins?

Back 66

superficial veins of the lower extremity, the lower esophagus, and the anal canal (hemorrhoids)

Front 67

Large veins

Back 67

Return blood to the heart under low pressure

Front 68

Structure of the Tunica Intima of Large Veins?

Back 68

Relatively thin layer consisting of the endothelium and its basal lamina and a subendothelial layer

Front 69

Structure of the Tunica Media of Large Veins?

Back 69

relatively thin layer of CT and smooth muscle

Front 70

Large Veins
Structure of-
Tunica Intima
Tunica Media
Tunica Adventitia

Back 70

Tunica Intima- relatively thin. endothelium plus basal lamina plus subendothelial layer.

Tunica Media- relatively thin. CT and smooth muscle.

Tunica Adventitia- thick layer of CT. Also has Vasa Vasorum and lymphatics.

Front 71

What is the inner layer of the heart called?

Back 71

Endocardium

Front 72

What makes up the Endocardium?

Back 72

The inner layer of the heart consists of the endothelium plus its basal lamina and a subendothelial layer of CT.

Front 73

Subendocardial Layer

Back 73

This is a CT layer between the endocardium and the myocardium.

Front 74

What is contained in the Subendocardial Layer of the heart?

Back 74

Veins, Nerves of the ANS, and Purkinje Fibers.

Front 75

The ____ of the ____ Layer make up the Atrioventricular (AV) Bundle.

Back 75

Purkinje Fibers
Subendochondrial

Front 76

The AV Bundle divides into ____ which are located ____.

Back 76

Right and left branches.
on either side of the ventricular septum and extending toward the apex of the heart. The right and left bundle branches spread around each ventricle and back toward the base of the heart.

Front 77

What is the result of failure of the AV Bundle to conduct the normal cardiac impulse?

Back 77

arrhythmias or, if there is a complete bundle block, complete dissociation between the atrial and ventricular rates of contraction.

Front 78

Myocardium

Back 78

the middle layer of the heart
thick layer of cardiac muscle cells

Front 79

Epicardium
Layers and Structures?

Back 79

Mesothelium- lying on a CT layer
Subepicardial- layer of CT that separates the epicardium and the myocardium.

Front 80

What are the layers of the heart from outside in?

Back 80

Pericardium
Epicardium
Myocardium
Endocardium

Front 81

What is contained in the subepicardial portion of the Epicardium of the heart?

Back 81

blood vessels, nerves, ganglia of the parasympathetic NS and adipose tissue

Front 82

Skeleton of the heart-
Made of?
Function?
Limits?

Back 82

The dense CT rings that surround the cardiac valves.
Provides attachment for the cardiac muscle fibers of the atria and ventricles and for the cusps of the AV valves.
It limits the diameter of the AV and arterial orifices during the different phases of the cardiac cycle.

Front 83

Cardiac Valves are made out of what?

Back 83

Dense fibrous CT lined by endothelium.

Front 84

What attaches the cusps of the tricupsid and mitral valves to the papillary muscles?

Back 84

Chordae Tendinae

Front 85

Lymphatic Capillares
Structure?
Function?

Back 85

Blind-ended vessels that look very much like blood capillaries. They may have a fenestrated endothelium that has a discontinuous basal lamina to allow large molecules and cells to enter.
The function is to collect surplus tissue fluid.

Front 86

Lymphatic Vessels
Structure?
Function?

Back 86

Resemble veins or venules, although their wall may be thinner. They have valves to prevent backflow.
Convey lymph collected by lymphatic capillaries to the lymphatic ducts.

Front 87

Lymphatic Ducts
Structure?
Function?

Back 87

Their structure is similar to that of veins.
Return lymph to the blood circulatory system. (thoracic duct and right lymphatic duct)