Chapter 18- The Blood Vessels

Question 1

What are the two circuits that that carry blood through the body?

Answer 1

Systemic and pulmonary circuits

Question 2

Describe arteries

Answer 2

Distribution functions

Carry blood away from the heart to the lungs and other extremities to distribute oxygenated and deoxygenated blood

Question 3

Describe capillaries

Answer 3

Smallest vessels act as an exchange system in tissues for oxygen and CO2

Branching networks called capillary beds

Question 4

Describe veins

Answer 4

Collect blood from the lungs and other tissues to return it to the heart

Drain blood from capillary beds

Become larger as they approach the heart

Question 5

What is the lumen?

Answer 5

Central space within blood vessels

Question 6

What are the three tunics of blood vessel walls?

Answer 6

Tunica intima
Tunica media
Tunica externa

Question 7

What is the tunica intima composed of?

Answer 7

Endothelium

Question 8

What are the two layers of the tunica media?

Answer 8

Smooth muscle

External elastic lamina

Question 9

What does the smooth muscle of the blood vessels control?

Answer 9

Vessel diameter and therefore the amount of blood flowing to the organs

Question 10

What innervate the smooth muscle of the vessel walls?

Answer 10

Sympathetic nervous system

Vasomotor nerves

Question 11

What is vasoconstriction?

Answer 11

When the smooth muscle contracts to narrow the opening of the lumen and restrict blood flow

Raises BP

Question 12

What is vasodilation?

Answer 12

When the smooth muscles relax and the lumen diameter widens allowing blood to flow freely

Lowers BP

Question 13

What is the tunica externa composed of?

Answer 13

Dense irregular collagenous connective tissue

Supports vessel and prevents overstretching

Question 14

What are the two big differences between a typical artery wall and the wall of a typical vein?

Answer 14

Arteries have a thicker tunica media

Internal and external lamina are more extensive in arteries

Question 15

What are the different size arteries in order from largest to smallest in diameter?

Answer 15

Elastic arteries
Muscular arteries
Arterioles
Metarterioles

Question 16

Which vessels directly feed the capillary beds?

Answer 16

Metarterioles

Question 17

What do baroreceptors do?

Answer 17

Detect blood oxygen, CO2 and hydrogen ion concentration in the aorta and common carotid artery

Question 18

Characteristics of veins

Answer 18

Outnumber arteries

Larger lumens

Function as blood reservoirs

Can be diverted to other parts of the body because they have thinner walls, fewer elastic fibers, less smooth muscle

Question 19

What are the smallest veins called?

Answer 19

Venules

Thin tunica media

Question 20

What prevents blood from flowing backward in the venous circuit?

Answer 20

Venous valves

Question 21

What are vascular anastomoses?

Answer 21

Locations where vessels connect via pathways called collateral vessels

Question 22

What is hemodynamics?

Answer 22

Physiology of blood flow in the cardiovascular system

Question 23

What is blood pressure and in which vessels is it highest and lowest?

Answer 23

The outward force exerted by blood on the walls of blood vessels

Highest in the large systemic arteries and lowest in the large systemic veins

Question 24

What is the main factor that determines blood flow?

Answer 24

The magnitude of the blood pressure gradient

Question 25

What is blood flow?

Answer 25

The volume of blood that flows per minute Matches cardiac output Directly proportionate to the pressure gradient: blood flow increases when the pressure gradient increases and vice versa

Question 26

What is resistance?

Answer 26

Any impedance to blood flow Blood flow is inversely proportionate to resistance: when resistance increases, blood flow decreases

Question 27

What effect does cross sectional area have on blood flow? Where is it highest?

Answer 27

Cross sectional area is highest in the small vessel branches as they split off from the larger vessels As this area increases, the velocity of blood flow decreases. Blood flow is fastest in the aorta and slowest in the capillaries

Question 28

Factors that determine blood pressure

Answer 28

Resistance Cardiac output Blood volume

Question 29

What is peripheral resistance?

Answer 29

Any factors that slow blood flow through the vessels As resistance increases, BP increases

Question 30

Variables that contribute to resistance

Answer 30

Vessel radius Viscosity Vessel length

Question 31

What is cardiac output?

Answer 31

The amount of blood the heart pumps through the circulatory system in one minute

Question 32

What is cardiac output the result of?

Answer 32

Stroke volume X heart rate

Question 33

2 factors that determine the pressure gradient that drives circulation

Answer 33

Cardiac output Peripheral resistance DeltaP= CO x PR

Question 34

Final major factor that determines overall blood pressure

Answer 34

Volume of blood in circulation

Question 35

What is total blood volume directly linked to?

Answer 35

The amount of water in the blood More water= higher blood volume

Question 36

What is compliance? Which vessels are most compliant?

Answer 36

Ability of vessels to stretch due to small increases of blood volume Veins

Question 37

What are the average blood pressures in the pulmonary and systemic circuits?

Answer 37

``` Pulmonary= 15mmHg Systemic= 95mmHg ```

Question 38

What is ventricular systole? | What is average systolic pressure?

Answer 38

Period of contraction in the heart 120 mmHg

Question 39

What is ventricular diastole? What is average diastolic pressure?

Answer 39

Period of relaxation in the heart 80mmHg

Question 40

What is pulse pressure?

Answer 40

The different between the systolic and diastolic pressure, about 40mmHg

Question 41

What is the name of the tool used to take blood pressure?

Answer 41

Sphygmomanometer

Question 42

What is mean arterial pressure (MAP)? How is it measured?

Answer 42

Average pressure on a patients arteries during one cardiac cycle MAP= diastolic pressure+1/3(pulse pressure) Typically maintained at 95mmHg

Question 43

What is systemic capillary pressure? Why does it happen?

Answer 43

The drop in pressure between the arteriolar and ventilate ends of the capillary beds. About 35mmHg to 15mmHg Reduction in blood volume from fluid loss

Question 44

What accounts for the extremely low pressure in the inferior vena cava and right atrium?

Answer 44

The high compliance of veins and reduction in pressure as the veins grow larger as they get nearer the heart

Question 45

Ways in which the rate of venous return is increased

Answer 45

Skeletal muscle pump Respiratory pump Valves

Question 46

What immediate effects does the sympathetic nervous system have on blood pressure? How?

Answer 46

Releases epinephrine and norepinephrine onto cardiac cells to increase heart rate and cardiac output as well as vasoconstriction which increases resistance

Question 47

What immediate effects does the parasympathetic nervous system have on blood pressure? How?

Answer 47

Acetylcholine released onto pacemaker cells decreases heart rate which decreases cardiac output

Question 48

What is the baroreceptor reflex?

Answer 48

Negative feedback loop that senses increase and decreases in blood pressure Stretch receptors that respond to the pressure induced stretching of the vessels in which they are found

Question 49

What do we call abnormally high blood pressure?

Answer 49

Hypertension