Regulation of BP Flashcards
What are the general classifications of CV regulators?
Neural
Vascular
Hormonal
Local
What are the two general classifications of neural regulators of the CVS?
Autonomic
Reflex
What a reflex mechanisms for neural regulation of the CVS?
Baroreceptor
Bainbridge
Volume
Chemoreceptors
Pulmonary
Somatosympathetic
Where are the baroreceptors?
Carotid sinus
Aortic arch
What are the medullary CV centers?
Nucleus ambiguus
Pressor area
Depressor area
Vasomotor centers
Nucleus of tractus solitarius
What is the CV function of nucleus of tractus solitarius?
Medullary relay center for cardiorespiratory and afferents
What is the CV function of the nucleus ambiguus?
Cardioinhibitory center
Receives afferents from nucleus of tractus solitarius
What is the CV function of the pressor area?
Glutaminergic neurons that exert excitatory effect on spinal sympathetic neurons
What is the CV function of the depressor area?
Stimulate GABA-secreting inhibitory neurons to decrease sympathetic activity
What are the vasomotor centers associated with CVS and their main functions?
Caudal ventrolateral medulla - depressor area
Rostral ventrolateral medulla - pressor area
When is carotid sinus massage used clinically?
To interrupt paroxysmal atrial tachycardia
What will happen to BP if NTS is destroyed bilaterally?
Severe HTN, possibly fatal
How quickly can baroreceptors reset if exposed to a new pressure continuously?
1-2 days
What are atrial stretch receptors and their function?
Low pressure receptors that provide information about circulating blood volume
Type A - during atrial systole only
Type B - during late atrial diastole
What is the Bainbridge relfex?
Initial slow HR or infusion increases venous return which stimulates tachycardia producing stretch receptor to increase HR
What is the volume reflex?
Decreased blood volume in atria decreases atrial stretch which decreases the release of ANP –> decreased secretion in kidney and increased ADH production –> increased ADH increases kidney retention
Main result: increase blood volume to increase BP
What is another name of the coronary chemoreflex?
Bezold-Jarisch reflex
What is the coronary chemoreflex?
Chemical stimulation of afferents in LV baroreceptors stimulates respiratory center and cardiac depressor area –> results in tachypnea, hypotension, and bradycardia which then results in reflex apnea due to CO2 loss in hyperventilation
What are the general distributions of ANS to the heart?
R vagus to SA node
L vagus to AV node
R SyNS trunks to SA node
L SyNS trunks to AV node
What are the results of sympathetic stimulation of heart?
Increased HR/chronotropy
Increased force of contraction/inotropy
Increased conduction/dromotropy
Increased excitability/bathmotropy
What are the results of parasympathetic stimulation of the heart?
Decreased HR
Decreased force of contraction of atria
Decreased conduction
Decreased excitability
What is the result of cutting vagal supply to the heart?
Increased HR to 150-180 bpm
What will occur if both adrenergic and cholinergic systems are blocked to the heart?
HR stabilizes around 100 bpm
What is the response to sympathetic stimulation to the vessels?
Skeletal muscle vessels dilate
Secretion in sweat glands
Release of epinephrine
Skin, renal and GI vessels constrict
What is the effect of arteriolar constriction on BP?
Increase diastolic BP by increasing peripheral resistance
What is the effect of venoconstriction on BP?
Increases systolic BP by increasing venous return and therefore increasing CO
What is the effect of arteriolar dilatation on BP?
Decreases diastolic BP by decreasing peripheral resistance
What is the effect of venodilatation on BP?
Decreases systolic BP by decreasing venous return and therefore decreasing CO
Where are peripheral chemoreceptors located?
Carotid bodies
Aortic bodies
Where are the central chemoreceptors located?
Ventrolateral medullary surface near the exit of CN IX and X
What are Meyer waves?
Slow, regular oscillations in arterial pressure that occur about 1 every 20-40 seconds during hypotension
What are Traube-Hering waves?
Fluctuations in BP synchronized with respiration
What acts as an emergency arterial pressure control system?
CNS ischemic response
What is the Cushing reflex?
Increased intracranial pressure that constricts arterioles causing ischemia results in baroreceptor reflex induced bradycardia
What are the main points that indicate a Cushing reaction?
Triad of HTN, bradycardia, and respiratory depression
What is the general function of pulmonary baroreceptors?
Minimize arterial pressure changes in response to change in blood volume
What is the capillary fluid shift mechanism in relation to BP?
Significant decrease in BP decreases hydrostatic pressure in capillaries drawing more fluid in from interstitial spaces to increase blood volume and thereby increase BP
What is another name for the hormonal mechanism of BP regulation?
Renin-angiotensin-aldosterone system
What is renin?
Production in kidneys stimulated by low BP
Catalyzes the change of angiotensinogen from the liver into angiotensin I
What is angiotensin converting enzyme?
Converts angiotensin I into angiotensin II
What are the functions of angiotensin II?
Vasoconstriction
Increases free fluid to preserve renal function in hypovolemia
Increases aldosterone secretion from adrenal glands
Increases ADH release form posterior pituitary
Increases PCT Na/H exchanger activity
Stimulates hypothalamus to increase thirst
What is pressure natriuresis?
Effect of arterial pressure on renal excretion of sodium
Long-term control of HTN
What are conditions that can trigger renin release?
Coarctation of aorta
Renal A stenosis
CKD
What are the rapid control mechanisms of BP?
Baroreceptors
Chemoreceptors
CNS ischemic response
What are the intermediate control mechanisms of BP?
Capillary fluid shift
Stress relaxation and reverse stress relaxation
What are the long-term control mechanisms of BP?
Hormonal mechanism
Renal mechanisms - changing excretion
What is the Valsalva maneuver?
Forcefully expiring against a closed glottis to change intrathoracic pressure to effect venous return, CO, arterial pressure, and HR
What is phase 1 of the Valsalva maneuver?
Intrathoracic pressure becomes very positive due to compression from contracting rib cage and full lungs
What is the result of phase 1 of the Valsalva maneuver?
Venous compression and increase in RA pressure impedes venous return –> reduces preload
Decrease in CO
Transient increase in aortic pressure
Decrease in HR
What occurs during phase 2 of the Valsalva maneuver?
HR increases
Aortic pressure falls
What occurs during phase 3 of Valsalva maneuver?
Normal breathing resumes
Aortic pressure briefly decreases reflexively
HR briefly increases reflexively
