blood pressure 2

Question 1

nucleus tractus solitarius

Answer 1

• receives inputs from peripheral (sensory) receptors and sends projections to cardio inhibitory center in the vasomotor center

Question 2

describe the vasomotor area of the vasomotor center.

Answer 2

• it has bilateral structures
  -RVLM- vasoconstrictor center-last site before spinal cord for Sym. Nerv system
• CVLM- (caudal) vasodilatory center- actually inhibits RVLM
  THEREFORE, IF EXCITE RVLM WE EXCITE SYMPATHETIC VASOCONSTRICTION; IF WE EXCITE CVLM, WE INHIBIT RVLM AND CAUSE VASODILATION

Question 3

what regulates the parasympathetics in the vasomotor center?

Answer 3

the cardioinhibitory center of the vasomotor center that consists of:

1) nucleus ambiguous (cardioinhibitory)
2) -dorsal motor nucleus of the vagus (cardioinhib)

= receive input from sensory neurons to the NTS (nucleus tractus solitaries) and that sends a signal to the nucleus ambiguous and the dorsal motor nucleus which end the message along the vagus to heart that causes decrease in HR

Question 4

where are the three places we have sensory receptors that are significant to the heart? what do they sense? because of the type of sensing, what are they referred to as?

Answer 4

at the aorta,external carotid and the internal carotid- measure oxygen and pressure
-called chemoreceptors

Question 5

what do baroreceptors measure

Answer 5

sense pressure

Question 6

what are arterial baroreflexes:
how activated?
where are they?
what are they sensitive to?

Answer 6

how activated? high pressure
where are they? aortic arch and carotid sinus
what are they sensitive to? mechanoreceptive (pressure)
short term

Question 7

cardiopulmonary baroreflex
how activated?
where are they?
what are they sensitive to?

Answer 7

how activated? low pressure (volume)
where are they? atria, pulmonary vessels
what are they sensitive to? mechanoreceptive

Question 8

chemoreflex

Answer 8

how activated? O2, CO2, pH
where are they? centrally and peripherally
what are they sensitive to? chemosensitive
peripherally- change sympathetic tone and vasoconstrict
centrally- local dilation and change in sympathetic tone causing vasoconst

Question 9

walk thru what occurs when there is an increase in pressure of the aorta or carotid

Answer 9

• baroreceptors sense a change in the pressure of the vessel wall
• they fire
• send signal to NTS (nucleus tractus solitaries) thru vagus. 2 things occur:

1) Parasympatheitics- activates nucleus ambiguous and dorsal motor nucleus of the vagus to get a decrease in heart rate
2) Sympatheitics - causes inhibition of vasoconstrictor center (via activating NVLM and thus decreasing RVLM)
- get decrease in HR and vasodilation and decrease strength in contraction

Question 10

what’s important to note about pt with htn and the prescribing of vasodilators?

Answer 10

• be very conservative about vasodilator dose
• pt with htn operate at a new pressure normal so if the vasodilator drops the pressure to a “normal” pressure for most people, it could make them pass out

Question 11

what exactly do chemoreceptors respond to? they are in the peripheral as well as the central areas of the body but where are they located in terms of the heart. what pressure activates them?

Answer 11

• they are seen in the carotid bodies and aortic bodies
• respond to higher H ions (low pH), increased CO2, and decreased O2
• pressure 80

Question 12

lets say there was a decrease in arterial pressure. what happens?

Answer 12

• there is a decrease in O2, increase in Co2 and decrease in pH
• this causes the chemoreceptors to fire and send the signal to the CNS
• this causes activation in the vasoconstrictor center and there is vasoconstriction in the vessels increasing arterial pressure
• > activate SNS and PNS

Question 13

what is the central nervous system response to hypoxia?

Answer 13

• brain can do 2 chemoreceptive things
  1) can have peripheral effect via sympathetics (increase BP to flush co2 and deliver o2)
  2) vasodil, vasoconst

Question 14

*describe the cardiopulmonary reflex; walk thru a whole response

Answer 14

• responds to decrease in pressure
• decrease in blood volume causes a decrease in pressure of the atria where the receptor are located
• 2 things occur
  1) Increase in firing of the CNS- increases renal sympatheiic nerve activity, increases vasoconst, increases vasopressin/increases antidiuretic hormone release to keep pee in and keep BP up

2) cause decrease in atrial naturetic peptide which decreases naturesis

Question 15

atrial naturetic peptide

Answer 15

causes peeing

Question 16

what occurs to CO and AP when we breathe in? why?

Answer 16

• when we breathe in, the thoracic pressure decreases and causes the blood vessles to expand causing less blood to return back to the heart
• this causes a momentaty decrease in CO and AP
• during this time, vascular and atrial sensory receptors can be activated

Question 17

what do the kidneys use to alter the salt and water balance

Answer 17

renin-angiotensin-aldosterone system

Question 18

if you increase pressure, what occurs with the urine

Answer 18

increased

Question 19

what are two mechanisms by which the renal system can increase bp

Answer 19

• decrease urine output

- alter the water salt intake

Question 20

summarize blood pressure regulation for
short term
mid term
long term

Answer 20

short term- baroreceptors, chemorecepots, ischemic response
mid- renin angiotensis, stress relax, capillary fluid shift
long- renal changes