Vessel Structure

Question 1

What are the 3 classes of blood vessels?

Answer 1

• arteries
• capillaries
• veins

Question 2

Arteries carry blood _______ the heart and become progressively __(size)___ as they_________.

Answer 2

• away from
• smaller
• branch and finally result in capillaries

Question 3

Veins carry blood _______ the heart and become progressively ___(size)____ as they_________.

Answer 3

• towards
• larger
• merge and are closer to the heart

Question 4

What are the layers in artery and vein walls called?

Answer 4

• tunics

Question 5

Name the layers of tunic from inner to outer.

Answer 5

• tunica intima
• tunica media
• tunica externa

Question 6

What is the endothelium?

Answer 6

simple squamous epithelium lining the blood vessel lumen

Question 7

Describe the tunica intima.

Answer 7

composed of endothelium and a subendothelial layer of areola connective tissue

Question 8

Describe the tunica media.

Answer 8

• comprised of circularly arranged smooth muscle
• sympathetic input causes this smooth muscle to contract resulting in vasoconstriction
• parasympathetic input results in vasodilation

Question 9

Describe the tunica externa.

Answer 9

• connective tissue that help anchor the blood vessel to an organ
• vasa vasorum run through the tunica externa

Question 10

What is the vasa vasorum?

Answer 10

small arteries that supply the larger arteries

Question 11

Do arteries or veins have thicker walls?

Answer 11

arteries

Question 12

What is the thickest tunic in arteries?

Answer 12

tunica media

Question 13

What is the thickest tunic in veins?

Answer 13

tunica externa

Question 14

Do arteries or veins have valves?

Answer 14

veins

Question 15

Do arteries or veins have higher blood pressure?

Answer 15

arteries

Question 16

Describe blood oxygen levels in arteries.

Answer 16

• systemic arteries transport blood high in O2

- pulmonary arteries transport blood low in O2

Question 17

Describe blood oxygen levels in veins.

Answer 17

• systemic veins transport blood low in O2

- pulmonary veins transport blood high in O2

Question 18

What are the 3 types of arteries?

Answer 18

• elastic arteries
• muscular arteries
• arterioles

Question 19

Which type of arteries are the largest?

Answer 19

elastic arteries

Question 20

Name some elastic arteries near the heart.

Answer 20

• aorta
• pulmonary artery
• brachiocephalic artery
• common carotid arteries
• subclavian arteries

Question 21

What do the elastic fibres in elastic arteries allow for?

Answer 21

in all 3 tunics. Allow for stretching under increased pressure generated by blood ejected from the heart

Question 22

Elastic arteries branch into ______ arteries.

Answer 22

muscular

Question 23

Name the elastic fibres in muscular arteries.

Answer 23

• internal elastic lamina: separates tunica intima and tunica media
• external elastic lamina: separates tunica media and tunica externa

Question 24

Which type of arteries are the smallest?

Answer 24

arterioles

Question 25

Describe vasoconstriction in the arterioles.

Answer 25

sympathetic innervation to the muscle fibre cells of the tunica media causes vasoconstriction resulting in elevation of blood pressure

Question 26

Describe vasodilation in the arterioles.

Answer 26

parasympathetic innervation to the muscle fibre cells of the tunica media causes vasodilation resulting in lowering of blood pressure

Question 27

What is the only type of blood vessel where metabolic exchange can occur between blood and tissues?

Answer 27

capillaries

Question 28

Describe capillaries

Answer 28

- smallest blood vessels - diameter only slightly larger than an erythrocyte - wall consists solely of the tunica intima (single layer of endothelial cells)

Question 29

Each capillary bed is fed by a _______.

Answer 29

metarteriole

Question 30

What are true capillaries?

Answer 30

branches from the metarteriole that begin with a ring of smooth muscle on their walls

Question 31

What are the 3 types of capillaries?

Answer 31

- continuous - fenestrated - sinusoids

Question 32

Describe continuous capillaries.

Answer 32

- most common - endothelial cells - continuous, complete lining aided by the presence of tight junctions

Question 33

Describe fenestrated capillaries.

Answer 33

- contain pores called fenestrations | - allows fluid exchange between blood and interstitial fluid

Question 34

Describe sinusoid capillaries.

Answer 34

- have large gaps between endothelial cells - allows transport of large molecules and cells to and from the blood - basement membrane is discontinuous or absent

Question 35

The body's veins hold about __% of the body's blood.

Answer 35

- 60% | - veins function as blood reservoirs

Question 36

What are the smallest veins?

Answer 36

venules

Question 37

What are the smallest venules?

Answer 37

postcapillary venules

Question 38

What occurs through the walls of postcapillary venules?

Answer 38

diapedesis: leukocyte travel to damage/infection

Question 39

Venules merge to form ____.

Answer 39

veins

Question 40

What are companion vessels with arterioles?

Answer 40

venules

Question 41

Smaller and medium sized _____ travel with muscular arteries, while large ____ travel with elastic arteries.

Answer 41

veins

Question 42

Why do valves exist in veins, and where are they formed from?

Answer 42

- blood pressure in veins is low, have valves to prevent pooling - formed from the tunica intima

Question 43

What 2 pumps assist with venous return (along with valves)?

Answer 43

- skeletal muscle pump | - respiratory pump

Question 44

Describe the skeletal muscle pump.

Answer 44

- skeletal muscles contract - the first valve closes - the pressure build up causes the second valve to open

Question 45

Describe the respiratory pump.

Answer 45

INHALATION - increases blood flow into thoracic veins through decreased intrathoracic pressure, diaphragm contracting, increased intra-abdominal pressure EXHALATION - increases blood flow into heart and abdominal veins though increased intrathoracic pressure, diaphragm relaxing, decreased intra-abdominal pressure