Chapter 19

Question 1

Name 3 vessels in the delivery system that carries blood to and from the heart and describe what they do

Answer 1

arteries, capillaries, veins

Question 2

Name the 3 layers in the arteries and veins

Answer 2

tunica externa
tunica media
tunica intima

Question 3

Which layer does the capillaries have?

Answer 3

tunica intima

Question 4

What is the fluid filled cavity in the centre of the vessels?

Answer 4

lumen

Question 5

What lines the tunica intima and what is its function?

Answer 5

endothelium simple squamous epithelium; friction free surface

Question 6

What is the tunica media made of and what is its function?

Answer 6

circular smooth muscle and sheets of elastin; controls diameter of vessel

Question 7

What controls the vasoconstriction and vasodilation of vessels?

Answer 7

vasomotor nerve fibers

Question 8

What is the tunica externa made of and what is its function?

Answer 8

loose network of collage fibers; anchors and reinforces vessel

Question 9

What additionally does the tunica externa contain and what does large veins have and for what purpose?

Answer 9

nerves, lymph vessles and blood vessels; elastin fibers to allow stretch

Question 10

Name 3 types of arteries

Answer 10

elastic arteries

muscular arteries

arterioles

Question 11

What is the function of the elastic arteries and where are they located?

Answer 11

provides low resistance pathway; expand and recoil as blood is ejected from the heart

closest to the heart

Question 12

Where are muscular arteries located and what is their function?

Answer 12

located distal to elastic arteries; vasoconstriction, control blood flow to different parts of the body

deliver blood to body organs

Question 13

What are the smallest arteries and what is their function?

Answer 13

arterioles; control flow into capillary beds by dilating or constricting

Question 14

Name the two types of arterioles

Answer 14

terminal arteriole and metarteriole

Question 15

What are the microscopic bloods vessels that only allow a single RBC to pass?

Answer 15

capillaries

Question 16

How many layers do the capillaries have and describe? What is the main function of the capillary

Answer 16

one layer of simple squamous epithelial cells

exchanges with tissue cells

Question 17

What are the smooth muscle like cells that reinforce capillary walls and what is their function?

Answer 17

pericytes; regulate permeability

Question 18

Name the 3 types of capillaries

Answer 18

continuous capillaries
fenestrated capillaries
sinusoidal capillaries

Question 19

Where are continuous capillaries most abundant and what allows the passage of fluids and small solutes? What connects the endothelial cells?

Answer 19

skin and muscles; intercellular clefts

tight junctions

Question 20

What is the difference between fenestrated capillaries and continuous capillaries?

Answer 20

they are more permeable

Question 21

What is the function of fenestrated capillaries? Where are they located?

Answer 21

absorption of filtrate formation

located: small intestines, endocrine glands and kidneys

Question 22

Where are sinusoidal capillaries located and what is their function?

Answer 22

found in liver, bone marrow and spleen

blood cells and large molecules to pass

Question 23

What are capillary beds and what do they do?

Answer 23

interwoven networks of capillaries form the circulation between arterioles and venules

Question 24

What are the two types of vessels in a capillary bed?

Answer 24

true capillaries

vascular shunt (metarteriole / thoroughfare channel)

Question 25

What is the function of the precapillary sphincters?

Answer 25

regulate blood flow into true capillaries

Question 26

What is blood flow regulated by in the capillary beds and why is the blood flow slow?

Answer 26

regulated by local chemicals and vasomotor nerves slow to allow exchanges of materials with tissue cells (more efficient exchange due to slowness)

Question 27

What is the function of the arteriovenous shunts?

Answer 27

bypass capillary beds, direct blood to where it is needed

Question 28

What happens the the size of the vein as blood travels towards the heart?

Answer 28

the diameter growsq

Question 29

What is the function of the venule?

Answer 29

collect blood from capillary beds

Question 30

Describe the venule.

Answer 30

very porous: allow fluids and WBC's into tissues post capillary venules consist of endothelium and a few pericytes larger venules have one or two layers of smooth muscle cells

Question 31

What is the function of the vein?

Answer 31

acts as blood reservoirs; collect blood from venules and carry to heart contain up to 65% of blood supply

Question 32

What are the venous valves function and where are they most abundant?

Answer 32

prevent backflow of blood; most abundant in veins of the limbs

Question 33

What causes varicose veins?

Answer 33

leaky valves

Question 34

What is the venous sinus?

Answer 34

flattened veins with extremely thin walls of only endothelium

Question 35

Name the two venous sinus' and what is their function?

Answer 35

coronary sinus: collects deoxygenated blood from cardiac veins dural sinus: collects blood draining from brain

Question 36

What are vascular anastomoses and what do they do?

Answer 36

interconnections of blood vessels arterial anastomoses provide alternate pathways to a given region (common at joints, abdominal organs, brain, heart)

Question 37

What are the alternated pathways called formed by anastomoses?

Answer 37

collateral channels

Question 38

What happens the the size of the vein as blood travels towards the heart?

Answer 38

the diameter growsq

Question 39

What is the function of the venule?

Answer 39

collect blood from capillary beds

Question 40

Describe the venule.

Answer 40

very porous: allow fluids and WBC's into tissues post capillary venules consist of endothelium and a few pericytes larger venules have one or two layers of smooth muscle cells

Question 41

What is the function of the vein?

Answer 41

acts as blood reservoirs; collect blood from venules and carry to heart contain up to 65% of blood supply

Question 42

What are the venous valves function and where are they most abundant?

Answer 42

prevent backflow of blood; most abundant in veins of the limbs

Question 43

What causes varicose veins?

Answer 43

leaky valves

Question 44

What is the venous sinus?

Answer 44

flattened veins with extremely thin walls of only endothelium

Question 45

Name the two venous sinus' and what is their function?

Answer 45

coronary sinus: collects deoxygenated blood from cardiac veins dural sinus: collects blood draining from brain

Question 46

What are vascular anastomoses and what do they do?

Answer 46

interconnections of blood vessels arterial anastomoses provide alternate pathways to a given region (common at joints, abdominal organs, brain, heart)

Question 47

What are the alternated pathways called formed by anastomoses?

Answer 47

collateral channels

Question 48

Define blood flow

Answer 48

volume of blood flowing through a vessel, an organ, or the entire circulation in a given period (usually per minute)

Question 49

How is blood flow measured?

Answer 49

ml/min

Question 50

Define blood pressure

Answer 50

force per unit area exerted on the wall of a blood vessel by the blood

Question 51

How is it measured?

Answer 51

mm Hg

Question 52

What pressure gradient does blood move from?

Answer 52

blood moves from high to low pressure

Question 53

What is resistance?

Answer 53

opposition to flow; is a measure of the amount of friction blood encounters

Question 54

What are the 3 important sources of resistance?

Answer 54

1. blood viscosity 2. total blood vessel length 3. blood vessel diameter

Question 55

What happens if the radius is halved in terms of resistance? What happens to the vessel?

Answer 55

resistance increased by 16 times

Question 56

What are the major determinants of peripheral resistance?

Answer 56

small diameter arterioles

Question 57

Blood flow is directly proportional to pressure gradient...if the pressure gradient increases, blood flow.....

Answer 57

speeds up

Question 58

Blood flow is inversely proportional to resistance - if resistance increases, blood flow.....

Answer 58

decreases

Question 59

Where is systemic pressure the highest?

Answer 59

in the aorta

Question 60

Systemic pressure is lowest in which vessels?

Answer 60

the veins

Question 61

Where does the steepest drop occur with systemic pressure?

Answer 61

arterioles

Question 62

What does systemic pressure measure as in the right atrium?

Answer 62

0 mm Hg

Question 63

Where is arterial blood pressure measured?

Answer 63

in the aorta

Question 64

What is systolic pressure?

Answer 64

pressure exerted during ventricular contraction

Question 65

What is diastolic pressure?

Answer 65

pressure exerted during ventricular diastole

Question 66

What is pulse pressure?

Answer 66

systolic pressure minus diastolic pressure

Question 67

What is mean arterial pressure (MAP)?

Answer 67

average pressure that propels the blood through the body

Question 68

What is the forumla for MAP?

Answer 68

systolic - diastolic / 3 then... plus diastolic = MAP

Question 69

Name 3 main factors influencing blood pressure

Answer 69

1. cardiac output (CO = HRxSV) 2. blood viscosity and volume 3. peripheral resistance

Question 70

What is the resting heart rate maintained by?

Answer 70

cardioinhibitory center via parasympathetic vagus nerves

Question 71

What is the function of the neural controls and how do they accomplish this?

Answer 71

controls of peripheral resistance 1. maintain MAP by altering blood vessel diameter 2. alter blood distribution in response to specific demands (ie. fight or flight response)

Question 72

What is the function of the vasomotor centre?

Answer 72

cluster of sympathetic neurons in the medulla that oversea changes in vessel diameter

Question 73

What is vasomotor tone?

Answer 73

moderate constriction of arterioles