Autonomic Control of the CV System Flashcards
What does the dicrotic notch on the arterial blood pressure graph below represent?
Relaxation of the left ventricle; blood falls back against the aortic valve before the aortic pressure decreases.
What is the equation for mean arterial pressure (MAP)?
MAP = diastolic pressure + 1/3 pulse pressure
OR
MAP = diastolic pressure - 1/3 (systolic-diastolic)
What is pulse pressure?
The difference between systolic & diastolic pressures.
What’s a normal systolic blood pressure?
120 mmHg
What’s a normal mean arterial blood pressure?
93.3 mmHg
(80 + 40/3)
What’s a normal diastolic blood pressure?
80 mmHg
What’s a normal pulse pressure? (Systolic - Diastolic)
40 mmHg
(120 - 80 mmHg)
What are the bodies 4 major mechanisms to maintain blood pressure within normal limits?
What is the S2 or “Dub” heart sound?
Aortic valve opening in left ventricle
What is the S1 or “Lub” heart sound?
Mitral/bicuspid valve opening in left ventricle
What factors will cause vasodilation?
What are the two categories of vascular diameter regulation?
- Intrinsic - local control
- Extrinsic - autonomic & endocrine control
What factors will cause vasoconstriction?
What are neural control inputs & outputs for maintaining blood pressure homeostasis?
Parasympathetic innervation & it’s neurotransmitter acetylcholine (ACh) have what affect on blood vessels?
Vasodilation
Sympathetic innervation & it’s neurotransmitters norepinephrine & epinephrine have what affect on blood vessels?
Depends on the receptor.
Sympathetic alpha receptors (both 1 & 2) & beta 1 receptor will cause vasoconstriction.
Sympathetic beta 2 receptor will cause vasodilation.
Both receptor types can bind either epinephrine or norepinephrine
Which catecholamine is most abundant in the blood stream?
Epinephrine ( 80%).
Norepinephrine only 20 %
What afftects on the heart function do inotropy, chronotropy, & dromotropy have?
Inotropy – contractility
Chronotropy – heart rate
Dromotropy – conduction velocity in the AV node
How des norepinephrine & epinephrine affect the mean arterial pressure & heart rate?
At low or medium plasma epinephrine concentrations, what is the dominant receptor & the effect of blood vessels?
Low/Medium epinephrine concentrations = beta2 receptor dominance = vasodilation
At high plasma epinephrine concentrations, what is the dominant receptor & the effect of blood vessels?
High epinephrine concentrations = alpha receptor dominance = vasoconstriction
How is mean arterial pressure regulated?
Where are the chemoreceptors for the CV system located?
CV system chemoreceptors detect oxygen levels in the blood.
Chemoreceptors are located in bodies.
What is the single most important mechanism for providing short-term regulation of arterial pressure?
Arterial baroreceptors
Where are the baroreceptors for the CV system located?
Baroreceptors detect pressure changes in the blood.
Baroreceptor are located in the sinuses
What maneuvers can affect the baroreceptor reflex?
Describe the effects of the baroreceptor reflex response to increased blood pressure.
Describe the effects of the baroreceptor reflex response to increased blood pressure.
What ions do peripheral chemoreceptors respond to? What about central chemoreceptors?
What is the response of chemoreceptor stimulation?
What are the two central chemoreceptor reflexes?
Cerebral Ischemcic response ‘Last ditch response” - triggered by brain ischemia (decreased blood flow, BP less than 60 mmHg); causes increased sympathetic outflow, & intense vasoconstriction & cardiac stimulation
Cushing Reflex - triggere by an increase in intracranial pressure (like an intracranial bleed); also causes increases in sympathetic outflow, MAP, bradycardia (low HR), high BP, & irregular respiration (cushing’s triad)
What is the brainbridge reflex?
Lecture Summary
