3 (19) The Cardiovascular System: Blood Vessels

Question 1

What is an artery?

Answer 1

carries blood away from the heart

Question 2

What is the lumen?

Answer 2

the hole in the middle of the artery

Question 3

What are the three layers or tunics of an artery?

Answer 3

tunica interna, tunica media, tunica externa

Question 4

Which tunic is the thickest?

Answer 4

tunica media

Question 5

What makes up each layer of an artery?

Answer 5

TUNICA INTERNA - simple squamous epithelium called “endothelium”
TUNICA MEDIA - smooth muscle fibers
TUNICA EXTERNA - thin connective tissue

Question 6

What are the vasa vasorum?

Answer 6

tiny vessels in the tunica externa that form capillaries and provide blood to external cells of the vessel

Question 7

How do the elastic arteries act as a pressure reservoir?

Answer 7

redistributing the pulsatile input over time by expansion and recoil

Question 8

How do arterioles differ in structure from arteries?

Answer 8

they have all three layers, but thin as they divide

Question 9

What are arteriovenous shunts?

Answer 9

abnormal connections between coronary arteries and a compartment of the venous side of the heart

Question 10

What is the structure of a capillary wall?

Answer 10

only a single layer of endothelium and a basement membrane

Question 11

What structure is always found at the start of a true capillary?

Answer 11

pre-capillary sphincter

Question 12

What do capillaries do for the cardiovascular system?

Answer 12

functional part of system for exchange of gases, wastes, and nutrient

Question 13

What makes up a capillary?

Answer 13

single layer of endothelium and basement membrane

Question 14

What is the difference in structure between continuous capillaries, fenestrated capillaries, sinusoids, and the capillaries found in the brain?

Answer 14

CONTINUOUS - intercellular clefts, but otherwise uninterrupted; “garden variety” common capillaries
FENESTRATED - have “windows” or pores (act in filtration) (window in French = fenetre)
SINUSOIDS - (discontinuous capillaries) have spaces b/w cells; basement membrane is incomplete or absent
BRAIN - form a barrier (blood-brain barrier)

Question 15

What are venules?

Answer 15

a small blood vessel in the microcirculation that allows deoxygenated blood to return from capillary beds to larger blood vessels called veins

Question 16

What is the structure of a vein, and how does it differ from an artery?

Answer 16

OUTER - connective tissue, “tunica adventitia” / “tunica externa”
MIDDLE - smooth muscle, “tunica media” (thinner than artery)
INNER - lined with endothelial cells, “tunica intima”

Question 17

What internal structures do veins contain that arteries do not?

Answer 17

VALVES that ensure blood flows in only one direction

Question 18

Why are systemic veins called blood reservoirs? What can happen if you lock your knees, as when standing at attention?

Answer 18

• because it can be mobilized to boost cardiac output and in turn systemic arterial pressure when physiological demands require so (nearly 60% of the total volume of blood in the human body is present within the veins)
• squeezes your veins shut in your legs, that leads to you losing blood supply to the rest of your body causing you to faint

Question 19

What is blood pressure?

Answer 19

pressure on the walls of a vessel

Question 20

What is meant by systolic blood pressure and what would you expect the values for this to be?

Answer 20

the amount of pressure in your arteries during the contraction of ventricle (~120 mm Hg)

Question 21

What is meant by diastolic blood pressure, and what would you expect the values for this to be?

Answer 21

blood pressure generated by ventricular relaxation (~80 mm Hg)

Question 22

What is the mean arterial pressure?

Answer 22

93 mm Hg

Question 23

In what vessels does blood travel the fastest?

Answer 23

arteries

Question 24

In what vessels does blood travel the slowest?

Answer 24

capillaries

Question 25

What is a normal systolic blood pressure? Diastolic blood pressure?

Answer 25

120

80

Question 26

What factors influence arterial blood pressure?

Answer 26

cardiac output
blood volume
peripheral resistance (BP = CO * PR)
viscosity
blood vessel diameter

Question 27

What is a pulse, and how can it be used to determine the health of an individual?

Answer 27

PULSE: pressure wave generated by the alternating expansion and recoil of arteries during each cardiac cycle
- can be used to determine extent of injury, effects of activity, postural changes, emotions on heart rate, arrhythmias

Question 28

What is the normal central venous pressure and where is it measured?

Answer 28

2-6 mm Hg

measured in thoracic vena cava

Question 29

What part of the nervous system controls blood vessel diameter, and why is this unusual?

Answer 29

sympathetic nervous system

Question 30

Look over fetal circulation again.

Answer 30

• obtains oxygen/nutrients from maternal circulation

- ductus

Question 31

What is the hepatic portal system? Why is it important?

Answer 31

• drains spleen, stomach, pancreas, gallbladder, and small/large intestines
• 2nd capillary bed in liver
• glucose is removed and stored as glycogen
• blood is detoxified
• leaves through hepatic vein and goes to inferior vena cava

Question 32

What is the Circle of Willis or cerebrovascular circle? What does it do for the brain?

Answer 32

• the joining area of several arteries at the bottom (inferior) side of the brain
• the internal carotid arteries branch into smaller arteries that supply oxygenated blood to over 80% of the cerebrum