Short Term Blood Pressure Control

Question 1

what is the driving force pushing blood through the circulation?

Answer 1

mean arterial pressure

which is affected by cardiac output and total peripheral resistance

Question 2

what happens if blood pressure is too low?

Answer 2

there is fainting, syncope

Question 3

what happens if blood pressure is too high?

Answer 3

hypertension

Question 4

where are the arterial baroreceptors receptors found?

Answer 4

in the internal carotid arteries and the aortic arch.

Question 5

what do baroreceptors respond to?

Answer 5

they are stretch receptors and fire when the vessel they are in is stretched

Question 6

what do the parasympathetic nerves innervate in the arterial baroreflex?

Answer 6

they innervate the pacemaker cells at the sinoatrial node. muscarinic receptors are acted on by acetylcholine reducing the heart rate.

Question 7

what four things do the sympathetic nerves innervate in the arterial baroreflex?

Answer 7

> pacemaker cells in the sinoatrial reflex
the adrenal medulla
venoconstriction
arteriolar constriction

Question 8

how does the sympathetic nerves increase heart rate at the sinoatrial node?

Answer 8

it releases noradrenaline that act of beta1 receptors at the sinoatrial node depolarising it faster and increasing the heart rate.

Question 9

how does innervation of the adrenal medulla increase stroke volume?

Answer 9

adrenaline released increases the amount of calcium that is released making a stronger contraction and increasing stroke volume.

Question 10

what is the effect of the sympathetic vasoconstriction?

Answer 10

> venoconstriction increases preload and stroke volume

> arteriolar constriction increases the mean arteriolar pressure

Question 11

name other inputs to the medullary cardiovascular centres

Answer 11

> cardiopulmonary baroreceptors
> central chemoreceptors
> chemoreceptors in muscle
> joint receptors
> higher centres

Question 12

what activates chemoreceptors in the muscle?

Answer 12

increasing concentration of metabolites

Question 13

what do the higher receptors respond to?

Answer 13

If you know you are about to do exercise or if there is food. this is to prepare you for what you are about to do

Question 14

what are the effects of satnding?

Answer 14

> there is increased hydrostatic pressure causing pooling at the feet
> decrease in venous return
> decrease in end diastolic volume
> decrease in preload
> decrease in stroke volume
> decrease in cardiac output
> decrease in mean arterial pressure
> decrease in baroreceptor firing rate

Question 15

what is the Valsalva manoeuvre?

Answer 15

this is forced expiration against a closed glottis

Question 16

what is the effect on the increased thoracic pressure during the Valsalva manoeuvre?

Answer 16

decrease in:
> venous return
> end diastolic volume
> stroke volume
> cardiac output
> mean arterial pressure

Question 17

how is the blood pressure brought back to normal in the Valsalva manoeuvre?

Answer 17

the decrease in mean arterial pressure is detected by baroreceptors which initiate the reflex and increase cardiac output and increase total peripheral pressure

Question 18

why is there in increase in pressure after the Valsalva manoeuvre has stopped?

Answer 18

because the reflex effects have not worn off and the venous return is higher