CVS 3: Vasculature, Smooth Muscle, Blood Flow & Pressure

Question 1

3 layers of blood vessel wall

Answer 1

1. tunica externa
2. tunica media
3. tunica interna

Question 2

T/F?: tunica externa composed of connective tissue

Answer 2

True

Question 3

T/F?: tunica media composed of connective tissue

Answer 3

False
Tunica media composed of smooth muscle

Question 4

T/F?: Tunica interna composed of smooth muscle

Answer 4

False.
composed of elastin

Question 5

when do the elastin fibers in aorta & other large arteries expand

Answer 5

when the pressure of the blood rises during ventricular systole & recoils when ventricles relax

Question 6

T/F?: smooth muscle regulates the diameter of the lumen

Answer 6

true

Question 7

what are capillaries composed of

Answer 7

single layer of endothelium & a basement membrane

Question 8

capillary function

Answer 8

permits exchange of nutrients & wastes between blood & tissue fluid

Question 9

difference between walls of arteries and veins

Answer 9

walls of veins contain smooth muscle & elastin like arteries
BUT are much thinner

Question 10

why are veins much thinner than arteries

Answer 10

pressure on venous system much lower than arterial system

Question 11

purpose of smooth muscle in vascular tissue

Answer 11

contraction/relaxation of vascular smooth muscle regulates blood flow

Question 12

T/F?: smooth muscle sontains sarcomeres

Answer 12

False.
smooth muscle does not contain sarcomeres (not striated)
Forms a lattice structure around the cell periphery.

Question 13

does smooth muscle contain more actin or myosin?

Answer 13

more actin than myosin (ratio of 16:1)

Question 14

SM contraction

what is smooth muscle contraction dependent on

Answer 14

dependent on inward diffusion of extracellular Ca2+ through voltage gated Ca2+ channels.
opening of Ca2+ channels graded by amount of depolarisation

Question 15

SM contraction

what does Ca2+ bind to in smooth muscle cells

Answer 15

calmodulin

Question 16

SM contraction

T/F?: Ca2+ binds to troponin C in smooth muscle cells

Answer 16

False.
Troponin C not expressed in smooth muscle cells so Ca2+ binds to calmodulin

Question 17

SM contraction

what does the Ca2+/calmodulin complex join & activate

Answer 17

joins & activates myosin light chain kinase (kinase enzymes phosphorylate a substrate) MLCK

Question 18

SM contraction

what does MLCK do

Answer 18

myosin heads are phosphorylated
myosin heads bind w actin & contraction occurs

Question 19

SM contraction

what enhances myosin ATPase activity, driving contraction

Answer 19

MLCK phosphorylates light chains in the myosin head.
this enhances myosin ATPase activity & drives contraction

Question 20

SM contraction

T/F?: myosin ATPase activity in smooth muscle is slower than skeletal muscle leading to a slower & more sustained contraction

Answer 20

true

Question 21

steps in smooth muscle relaxation

Answer 21

• relaxation occurs when Ca2+ conc decreases
• Ca2+ ATPase pumps Ca2+ out of the cytoplasm
• Ca2+ dissociates from calmodulin & MLCK inactivates
• myosin heads become dephosphorylated
• myosin ATPase activity decreases & slow relaxation occurs

Question 22

T/F?: smooth muscle relaxation occurs when Ca2+ increases

Answer 22

False
occurs when Ca2+ decreases

Question 23

what is the generation of action potentials & opening of Ca2+ channels in vascular smooth muscle regulated by

Answer 23

autonomic nerves - mainly sympathetic nerves

Question 24

T/F?: generation of APs & opening of Ca2+ channels in SM is regulated maily by parasympathetic nerves

Answer 24

False
Mainly be sympathetic nerves

Question 25

What is rate of blood flow directly proportional to

Answer 25

rate of blood flow (F) directky proportional to delta P (delta P = P1 - P2 -> blood flowing from region of high pressure to region of low pressure)

Question 26

what causes resistance to blood flow (2)

Answer 26

1. friction between blood & walls of blood vessels 2. friction from blood cells rubbing against each other

Question 27

what is the relationship between rate of blood flow and resistance

Answer 27

rate of blood flow (F) is inversely proportional to resistance, R

Question 28

what does the resistance to blood flow depend on

Answer 28

the length (L) and radius (r) of the blood vessels and the viscosity of the blood (greek letter that looks like n)

Question 29

T/F?: the resistance to blood flow depends on length & radius of vessel & viscosity of blood & is shown by formula: F= deltaPr^4(pi) / Ln(8)

Answer 29

true

Question 30

what are the major regulators of blood flow (3)

Answer 30

1. mean arterial pressure 2. blood vessel diameter 3. blood viscosity (HCT)

Question 31

T/F?: large veins & systemic arteries contain the highest % of blood

Answer 31

false. venules/small veins in tissues contain highest % of blood (capacitance vessels)

Question 32

why do venules/small veins contain the highest % of blood (2)

Answer 32

1. due to low venous pressure 2. consequent slow rate of venous return

Question 33

what is arterial blood pressure caused by

Answer 33

left ventricular contraction (systole) the driving force for blood flow through the systemic circulation

Question 34

the effect of stroke volume on wall of aorta

Answer 34

stroke vol ejected into aorta, elastic wall of aorta & downstream arteries expand

Question 35

when do arterial walls recoil

Answer 35

during ventricula diastole, the arterial walls recoil, pushing the blood forward into arteries

Question 36

explain systolic blood pressure

Answer 36

as stroke volume is ejected into the aorta, pressure in the aorta increases to almost that of the contracting ventricle

Question 37

explain diastolic BP

Answer 37

one semilunar valves close, recoil in aortic wall pushes blood into the vasculature & pressure falls back

Question 38

T/F?: normal systolic BP is 120 mmHg

Answer 38

true

Question 39

T/F?: normal diastolic BP is 60 mmHg

Answer 39

false normal is 80 mmHg

Question 40

formula for calculating mean arterial pressure (MAP)

Answer 40

MAP = diastolic pressure + 1/3 (systolic - diastolic pressure)

Question 41

T/F?: MAP value is closer to diastolic pressure than systolic

Answer 41

true as diastole lasts twice as long

Question 42

formula for calculating pulse pressure

Answer 42

pulse pressure = systolic pressure - diastolic pressure

Question 43

explain pulse pressure

Answer 43

* each left ventricular contraction creates a pulse of systolic pressure as blood is ejected into arteries * this pressure wave is transmitted through the elastic walls of the large arteries