Week 4 Mean Arterial Pressure

Question 1

normal blood pressure

Answer 1

120/80 mmHg

Question 2

hypertension

Answer 2

140/90 mmHg

Question 3

hypotension

Answer 3

100/60 mmHg

Question 4

Mean Arterial Pressure (MAP) =

Answer 4

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

Question 5

Pulse Pressure =

Answer 5

systolic pressure - diastolic pressure

Question 6

on pressure time axis - SP and DP are

Answer 6

SP - peak
DP - lower point

Question 7

systolic pressure

Answer 7

beginning of sounds

Question 8

diastolic pressure

Answer 8

end of sounds

Question 9

in terms of CO and TPR, Mean Arterial Pressure =

Answer 9

= cardiac output x total peripheral resistance

Question 10

total peripheral resistance

Answer 10

the force needed to maintain blood flow from the aorta root to the venous exit

Question 11

Cardiac Output =

Answer 11

= heart rate x stroke volume

Question 12

what controls the heart rate, other than the heart itself

Answer 12

autonomic input

Question 13

intrinsic firing rate of the heart

Answer 13

100 bpm

Question 14

firing rate at rest + dominating system

Answer 14

parasympathetic dominates

75 bpm

Question 15

firing rate during excitement + dominating system

Answer 15

sympathetic dominates

HR increases

Question 16

what NT is used by the ANS to affect the SAN/AVN

Answer 16

• ACh is used by parasympathetic and sympathetic nerves
• in the final cardiac accelerator nerve - norepinephrine (NT) used

Question 17

how does norepinephrine (NT) affect cardiomyocytes

Answer 17

• cardiomyocytes are stimulated
• they conduct APs faster
• so rate of contraction can match rate of AP wave stimulation

Question 18

chronotropic agents

Answer 18

affects heart rate by targeting the conduction system

Question 19

in paraS - how does ACh act

Answer 19

ACh binds to a cholinergic receptor

different type of G proteins directly affect T type Ca channels

Question 20

what is the difference between positive and negative chronotropic effect

Answer 20

positive - funny channels open much quicker, putting pressure on T type calcium channels to open

L type Ca channels are unaffected

Question 21

what is the baroreceptor reflex

Answer 21

a rapid homeostatic mechanism

maintains blood pressure by change of heart rate

Question 22

what is the structure of arterioles

Answer 22

• thinner walls
• lack a tunica externa

Question 23

larger arterioles

Answer 23

extensive tunica media
thick layers of smooth muscle

Question 24

smaller arterioles

Answer 24

tunica media has a single layer of smooth muscle
arranged spirally around endothelium

Question 25

what is vascular tone

Answer 25

degree of constriction relative to dilated vessel

Question 26

why is control of radius of a vessel important to blood flow

Answer 26

radius strongly influences resistance which controls blood flow

Question 27

effect of vasoconstriction

Answer 27

more contraction, smaller radius increased resistance, decreased flow

Question 28

effect of vasodilation

Answer 28

less contraction, bigger radius low contraction, increased flow

Question 29

what factors determine resistance to blood flow in a single vessel

Answer 29

vessel diameter, length and viscosity of blood

Question 30

Poi*Seuille’s law

Answer 30

volume flow rate is directly proportional to the pressure gradient and to the fourth power of its internal resistance

Question 31

what is the effect of norepinephrine and epinephrine on adrenergic receptors

Answer 31

alpha receptors - affected more by norepinephrine - leads to smooth muscle contraction beta receptors - more epinephrine - leads to smooth muscle relaxation

Question 32

increased blood flow effect on temp

Answer 32

increased BF = heat - vasodilation

Question 33

decreased blood flow effect on temp

Answer 33

decreased BF = cold - vasoconstriction

Question 34

metabolite changes in endothelial cells causing vasodilation

Answer 34

increase in adenosine from AMP, CO2, H+, K+

Question 35

metabolite changes in endothelial cells causing vasoconstriction

Answer 35

increase in O2

Question 36

example of vasodilator substances

Answer 36

nitric oxide histamine - inflammation/allergy

Question 37

examples of vasoconstrictor substances

Answer 37

endothelin

Question 38

what is vasopressin

Answer 38

ADH from the posterior pituitary gland maintain BP

Question 39

angiotensin II

Answer 39

from the kidney by the RAAS system increases blood pressure

Question 40

structure of veins

Answer 40

large diameter small amount of smooth muscle thin walls

Question 41

what is venous return

Answer 41

volume of blood that returns to the atria from veins

Question 42

effect of increased blood volume on venous return

Answer 42

increased BV = increased VR

Question 43

what is venomotor tone

Answer 43

constant excitatory influence on smooth muscle in veins

Question 44

effect of venomotor tone of venous return

Answer 44

norepinephrine stimulates contraction of smooth muscle causing venous constriction increases central venous pressure decreases venous compliance increases venous return

Question 45

how does norepinephrine increase MAP

Answer 45

increasing vascular tone (constriction) and heart rate

Question 46

why increase total peripheral resistance during exercise

Answer 46

increased TPR - local areas dilate - blood moves through arterioles faster

Question 47

during inspiration

Answer 47

diaphragm contracts increased intrapleural volume = decreased pressure in the chest cavity blood is squeezed from lower veins to chest veins = increased central venous pressure + VR