Regulation of blood pressure

Question 1

cardiac output?

Answer 1

blood flow in volume/time

Question 2

CO = (equation)

Answer 2

heart rate (bpm) X stroke volume (volume of blood per beat)

Question 3

systole?

Answer 3

contraction

Question 4

diastole?

Answer 4

relaxation

Question 5

end systolic volume? (ESV)

Answer 5

volume of ventricle at end of contraction

Question 6

end diastolic volume (EDV)?

Answer 6

volume of ventricle just before contraction (i.e. end of filling)

Question 7

stoke volume = (equation)

Answer 7

EDV - ESV

Question 8

mean blood pressure is controlled by?

Answer 8

controlled by changing total peripheral resistance and or cardiac output

Question 9

cardiac output is controlled by?

Answer 9

by sympathetic and para sympathetic nerves which effect heart rate and force of contraction

Question 10

TPR controlled by?

Answer 10

by nervous and chemical means to effect constriction/dilation of arterioles and venules due to elasticity

Question 11

TPR?

Answer 11

total peripheral resistance

Question 12

P = (blood pressure equation)

Answer 12

= CO x TPR
cardiac output X total peripheral resistance

Question 13

arterial blood pressure measured in?

Answer 13

in mm Hg

Question 14

Systolic blood pressure (SBP)

Answer 14

maximum arterial blood pressure during heart contraction (i.e. systole)
Average 90-120 mm Hg in humans

Question 15

Diastolic blood pressure (DBP)?

Answer 15

minimum arterial blood pressure during heart relaxation (i.e. diastole)
Average 60-80 mm Hg in humans

Question 16

mean arterial pressure?

Answer 16

the mean pressure over the entire cardiac cycle
it usually is not equal to the mean of the SBP and DBP as the systolic and diastolic phases of the cardiac cycle are not the same duration
Average: 95mm Hg in humans

Question 17

the vessels of small mammals are very small so…

Answer 17

so they have high resistances
As a result, their heart rates are much higher than large mammals (hamster HR = 400 beats/min, whale = 20)

Question 18

the smaller the animal … the larger the animal…

Answer 18

smaller = higher HR
larger = lower HR

Question 19

why is it important to maintain blood pressure within a range?

Answer 19

ensure adequate perfusion of vital organs

Question 20

why is the process of balancing blood pressure required?

Answer 20

daily activities, physiological situations, food - they all cause changes in the body

Question 21

what types of regulation is there for blood pressure?

Answer 21

short term regulation
long term regulation

Question 22

baroreceptors?

Answer 22

found in arterial wall increase their AP firing rate in response to increased stretch (as by increased pressure)
thus a decrease in pressure actually decreases baroreceptor firing, which in turn increases contraction force

Question 23

the most important baroreceptors are found where?

Answer 23

in the carotid artery (in the carotid bodies) and the aortic arch (in the aortic bodies)

Question 24

the net results of baroreceptors is?

Answer 24

response to mechanical stress
net result is vasodilation, decrease HR, decrease contractility etc. all of which tend to restore arterial pressure to normal

Question 25

carotid sinus baroreceptors detect?

Answer 25

detect changes in pressure to the brain

Question 26

aortic arch baroreceptor detect?

Answer 26

detect changes in pressure to the body

Question 27

what are the sensors if the blood pressure falls?

Answer 27

aortic arch and carotid sinus due to baroreceptors present here

Question 28

effectors of baroreceptor reflex?

Answer 28

constriction of veins and arterioles increased stroke volume increased heart rate THEREFORE increased peripheral resistance and cardiac output and thus increased blood pressure

Question 29

neural integration of baroreceptor reflex?

Answer 29

nucleus tractus solitarius vasoconstriction, cardiac stimulation, cardiac inhibition

Question 30

postral hypertension?

Answer 30

sitting down too long and stand up and feel dizzy so when sitting - blood circulating in body is the same as when standing up however when sitting down for prolonged amounts of time, the venous return (how much blood goes back into heart) is quicker when sitting Stand up to quickly - so venous return decreases therefore cardiac output decreases as does blood flow and blood pressure so baroreceptors react - feel dizzy

Question 31

what is nucleus tractus solitarius?

Answer 31

relay centre in brain and receives information to do with heart

Question 32

what are peripheral chemoreceptors?

Answer 32

(found in carotid and aortic bodies) and central chemoreceptors (in medulla oblongata) are stimulated by low arterial 02, high arterial co2 and low arterial pH

Question 33

activation of chemoreceptors produces?

Answer 33

peripheral vasoconstriction increased lung ventilation (except when under water) in some cases, decreased HR

Question 34

coronary artery baroreceptors respond to?

Answer 34

to arterial pressure but more sensitive than carotid and aortic ones

Question 35

veno-atrial mechanoreceptors?

Answer 35

respond to changes in central blood volume - lie down, lift your legs and cause peripheral vasodilation

Question 36

unmyelinated mechanoreceptors?

Answer 36

respond to distension of heart ventricular ones during systole; atrial ones during inspiration

Question 37

apart from chemo and baro - what are the other stretch receptors?

Answer 37

coronary artery baroreceptors veno-atrial mechanoreceptors unmyelinated mechanoreceptors

Question 38

if decline in blood pressure last more than a few mins - what gets involved and why?

Answer 38

THE KIDNEY rechannelling of blood occurs to vital organs and kidneys give up blood supply for other organs When this takes longer than expected, the drop in pressure is sensed by specialised cells in the kidneys Activation of the RAAS occurs

Question 39

decrease in perfusion is sensed by?

Answer 39

JGA in the macula densa (modified cells in glomerular capillary) AIMED AT INCREASING BP

Question 40

renin is?

Answer 40

it is released by JG cells it is Renin cleaves Angiotensinogen - Angiotensin I AIMED AT INCREASING BP

Question 41

what does ACE do?

Answer 41

converts angiotensin I to angiotensin II by angiotensin converting enzyme in the lungs AIMED AT INCREASING BP

Question 42

angiotensin II is a major vasoactive product and what does it result in?

Answer 42

causes vasoconstriction stimulates release of aldosterone from adrenal gland Stimulate release of ADH pituitary gland AIMED AT INCREASING BP

Question 43

Clinical value of knowing RAAS system?

Answer 43

ACE inhibitors - managing hypertension feline hypertension very common