BP Regulation I, II Flashcards
Baroreceptors are?
mechanoreceptors that respond to passive stretch w/ a generator potential
Baroreceptor reflex is?
rapid, neg feedback pathway,
controls mean arterial pressure (Pa) around a setpoint for Pa
Baroreceptor reflex follows what type of NS pathway?
afferent (toward CNS)
Baroreceptor reflex sends signals from aortic baroreceptors to brain via what CN?
CN X (vagus)
Baroreceptor reflex sends signals from carotid sinus baroreceptors to brain via what CN?
CN IX (glossopharyngeal)
Baroreceptor reflex mechanism?
Setpoint Pa compared to actual Pa,
feedback signal proportional to difference,
brain responds until difference = 0
Interruption in efferent branch of baroreceptor reflex results in what?
↓ Pa
which indicates ↑ resting symp tone and basal (resting) activity of C1, A1 vasomotor area of medulla
Valsalva Maneuver?
“pop your ears”
causes ↓ Pa ->
kicks off baroreceptor reflex
Glomus cells play what role in control of Pa?
respond to ↓ in Po2 and pH or ↑ Pco2 with APs
Baroreceptor setpoint resets if what?
long term ∆s in Pa
Glomus cells are?
chemsensitive cells in aortic arch and carotid bodies
Primary action of aortic/carotid chemoreceptors and central chemoreceptors working together under normal circumstances is?
enhancement of respiratory ventilation
How does enhanced respiratory ventilation cause increased heart rate?
↑ resp ventilation ->
↓ Pco2 ->
inhibit cardioinhibitory center ->
↑ HR
Glomus cells APs travel where?
Result in?
up CN IX and X to NTS of medulla
vasoconstriction (↓ HR)
Overall response to ↓ Po2
or ↓ pH
or ↑ Pco2
is what?
reflex tachycardia
2 types of Low Pressure Atrial Receptors?
A Fibers
B Fibers
A Fibers found where?
entry to R atrium
A Fibers do what?
signal pressure ↑ associated w/ atrial contraction
B Fibers found where?
superior and inferior vena cavae
B Fibers do what?
signal pressure ↑ associated w/ vent contraction
↑ pressure in vena cavae indicates what?
Produces what?
↑ venous return to R heart
reflex ↑ HR,
renal vasodilation,
↓ in AVP (antidiuretic hormone)
What is Brainbridge Reflex?
reflexive ↑ in HR
Purpose of renal vasodilation?
↑ renal bloodflow and urine output
causing ↓ circulating volume
Purpose of reducing AVP release?
↓ AVP = ↓ H2O reabsorption from kidney
causing ↓ circulating volume
Summary: when high pressure baroreceptors (arterial side) sense ↑P, reflex response does what?
↓ BP
Summary: when low pressure receptors (venous side) sense ↑P, reflex response does what?
↓ blood volume
Compliance eqn
C = V/P
typically, ↓ V means ↓ P and ↑ V means ↑ P
Atrial Natriuretic Peptide (ANP) promotes what?
Na+ and H2O excretion in kidney ->
reduces effective circulating volume
↑ venous return causes ↑ what?
atrial stretch
↑ atrial stretch affects release of ANP how?
↑ release of ANP
Summary:
High Pressure Baroreceptors’ primary output variable is?
Control what end of circulation?
Type of control?
Pa (mean arterial pressure)
arterial end
short term control
Renin-Angiotensin System for interm/long term BP control fxns primarily by regulating what?
effective circulating volume
Summary:
Chemoreceptor Integrated Response involves control of what?
ventilation and secondary effects on HR
Summary:
Low Pressure Receptors response is to do what?
Controls what end of circulation?
Output Variable is?
↑ HR (thru Bainbridge reflex)
venous end
↑ in effective circulating volume
Summary:
Renin-Angiotensin activated by?
Controls what end of circulation?
Primary output variable is?
Sympathetic NS
renal perfusion
effective circulating volume
Pa eqn
CO x TPR
TPR = total peripheral resistance
Which receptors are more sensitive to pressure changes, aortic or carotid sinus?
carotid sinus
Ѧ ∆ in carotid sinus P causes > compensatory effect on Pa than a ∆ in aortic pressure
5 kinds of Vasoconstrictors?
1) Epi (α1)
2) Serotonin
3) Ang II
4) AVP
5) Endothelin
5 kinds of Vasodilators?
1) Epi (β2)
2) Histamine
3) ANP
4) Bradykinins
5) PGE2, PGI2, NO
Flow charts to review in lecture
slide 14 and 15
