Microanatomy of the Circulatory System

Question 1

Blood Vessels

Answer 1

arteries, veins, and capillaries

Question 2

Layers of Blood Vessels

Answer 2

1. tunica intima
2. tunica media
3. tunica adventitia

Question 3

Tunica Intima

Answer 3

composed of epithelium and internal elastic lamina. Endothelium is simple squamous composed in contact with blood.

Question 4

Tunica Media

Answer 4

mostly smooth muscle, thickness varies with type of vessel. May have elastic fibers, may have external elastic lamina.

Question 5

Tunica Adventitia

Answer 5

outer layer. Connective tissue (collagen) that is blue on trichrome stain. Blends with and anchors to surrounding tissue.

Question 6

Components of the Tunica Adventitia

Answer 6

vasa vasorum, nervi vasorum, adipose tissue

Question 7

Vasa Vasorum

Answer 7

small vessels that supply large vessels

Question 8

Nervi Vasorum

Answer 8

nerve supply to large blood vessels.

Question 9

Arteries

Answer 9

high pressure vessels that take blood away from the heart

Question 10

Types of Arteries

Answer 10

elastic arteries, muscular arteries, and arterioles

Question 11

Elastic Arteries

Answer 11

aorta and largest branches. Tunica media contains lots of elastic fibers that are squiggly bright pink fibers. Cells between elastic fibers are smooth muscle

Question 12

Muscular Arteries

Answer 12

medium-sized arteries. Tunica media is muscular. Very common

Question 13

Arterioles

Answer 13

less than 3 layers of smooth muscle cells. Small diameter. Innervated by sympathetic nervous system. Regulate blood flow into capillaries via capillary sphincter

Question 14

Capillaries

Answer 14

consist of endothelium and basement membrane only. No muscle. almost every cell in the body has a capillary nearby. Erythrocytes are often single file

Question 15

What happens at capillaries?

Answer 15

oxygen, nutrients, and carbon dioxide diffuse.

Question 16

What is the most numerous type of vessel?

Answer 16

capillary

Question 17

Types of Capillary

Answer 17

continuous, fenestrated, and discontinuous.

Question 18

How to identify type of capillary

Answer 18

by location

Question 19

Continuous Capillary

Answer 19

complete basement membrane. Complete endothelial cells joined by tight junctions. Allows gas transport. Found in muscle, brain, lung

Question 20

Fenestrated Capillary

Answer 20

complete basement membrane. Holes in endothelial cells allow for substantial transport of fluid, ions, hormones, and nutrients. Found in intestine, glomeruli, endocrine glands

Question 21

Discontinuous Capillary

Answer 21

incomplete basement membrane and endothelial cells. Large molecules and cells can pass through gaps. Liver (sinusoids), spleen (sinuses), lymph nodes (sinuses), bone marrow, placenta

Question 22

Veins

Answer 22

low pressure vessels that take blood towards the heart

Question 23

Types of Veins

Answer 23

venules, medium-sized veins, large veins

Question 24

Venules

Answer 24

thin walled, lack a tunica media.

Question 25

How to differentiate a venule from a capillary

Answer 25

by diameter

Question 26

Medium-Sized Veins

Answer 26

thin muscular tunica media. Valves for one-way flow. More irregularly shaped than artery.

Question 27

Large Veins

Answer 27

thin muscular tunica media. Valves to prevent blood from flowing back into capillaries.

Question 28

What is the venous partner to the arteriole?

Answer 28

venule

Question 29

What is the venous partner to the muscular artery?

Answer 29

medium-shaped vein

Question 30

Intimal Bodies

Answer 30

small mineralizations of the intima of the submucosal intestinal vessels in horses. Significance is unknown

Question 31

What is the endocardium made of?

Answer 31

simple squamous epithelium

Question 32

Hemangiosarcoma

Answer 32

malignant tumor of endothelial cells that tends to occur in the right atrium of dogs

Question 33

Valves

Answer 33

thin connective tissue core. Covered with endothelial/endocardial cells.

Question 34

Myocardium

Answer 34

cardiac muscles- striated with central nuclei and branching myocytes. Purkinje fibers

Question 35

Cardiac Skeleton

Answer 35

four fibrous rings. May be partly cartilagenous (cats) or osseus (cattle)

Question 36

os cordis

Answer 36

heart bone in cattle

Question 37

Epicardium

Answer 37

Has adipose tissue, coronary arteries, and is covered in mesothelium

Question 38

How are flat mesothelial cells distinguished from endothelial cells?

Answer 38

by location

Question 39

Pericardial Sac

Answer 39

thin collagen layer with mesothelium on both sides. may contain adipose tissue

Question 40

Layers of the pericadrium

Answer 40

parietal layer and visceral layer.

Question 41

Lymphatic Vessels

Answer 41

contain lymph fluid and lymphocytes

Question 42

Characteristics of lymphatic vessels

Answer 42

thin-walled and have valves. Look similar to veins

Question 43

Lymphatic Capillaries Direction of Flow

Answer 43

fluid flows toward heart only.

Question 44

Components of Lymphatic Capillaries

Answer 44

discontinuous endothelial cells and basement membrane

Question 45

Main function of lymphatic capillaries

Answer 45

constantly pick up fluid, protein, and cells from interstitium and return it to the circulatory system

Question 46

What uses lymphatic vessels to metastasize?

Answer 46

carcinomas

Question 47

Larger lymphatic vessels

Answer 47

pass through lymph nodes and empty lymph into large veins.

Question 48

Largest lymphatic vessel

Answer 48

thoracic duct (left lymphatic duct)