Exam1Lec8Baroreceptor&ChemoreceptorRegulation Flashcards
Chief Complaint: “I get dizzy and sometimes faint when I get up out of bed”
History of Present Illness:
A 70-year-old female was admitted to the hospital after fainting while getting our of bed, and hitting her head on her nightstand. After regaining consciousness, she has indicated that for the past year or so, she often becomes dizzy when getting out of bed or standing up from her kitchen table and has fainted in the past.
What is the primary cause of the dizziness and fainting spells with getting out of bed?
low venous return> decr in pre-load >decr in contractility >decr in SV=>Decr in MBP>decr blood to brain
O2 not in brain
Chief Complaint: “I get dizzy and sometimes faint when I get up out of bed”
History of Present Illness:
A 70-year-old female was admitted to the hospital after fainting while getting our of bed, and hitting her head on her nightstand. After regaining consciousness, she has indicated that for the past year or so, she often becomes dizzy when getting out of bed or standing up from her kitchen table and has fainted in the past.
What cardiovascular reflex pathway is likely to be dysfunctional?
baroreceptor detects arterial BP
low Ca=compliance which decr w/ age affecting baroreceptors
Chief Complaint: “I get dizzy and sometimes faint when I get up out of bed”
History of Present Illness:
A 70-year-old female was admitted to the hospital after fainting while getting our of bed, and hitting her head on her nightstand. After regaining consciousness, she has indicated that for the past year or so, she often becomes dizzy when getting out of bed or standing up from her kitchen table and has fainted in the past.
How does standing up provoke these episodes?
rapid changes in BP due to changes in blood flow due to change in gravity
Incr blood flow to extremities
What do vascular reflexes sense?
change in Internal sensory-feedback systems that “sense” or detect changes in important circulatory parameters (i.e. blood pressure, O2 and CO2 levels, pH, temperature
How do vascular reflexes respond?
via neg feedback pathways that alter the tonic autonomic control of the heart and vasculature. (involves ANS)
ex: activity of parasymp (heart)/symp (bv) will incr or decr
Vascualr refelxes work to maintian and optimize what?
cardiovascular performance in rapidly changing physiological situations.
rapidly changing physiological situations.: posture change, exercise
What are the type of vascular reflexes?
Peripheral Baroreceptors
Peripheral Chemoreceptors
Central Chemoreceptors
Pulmonary stretch receptors
Hypothalamus (temperature sensors)
Arterial baroreceptros play a key role in what?
short-term (seconds to minute) adjustments of blood pressure when relatively abrupt changes in blood volume, cardiac output, or peripheral resistance occur.
Posture changes
Exercise
Hemorrhage (loss in bv)
Arterial Baroreceptors are located where?
Stretch (mechanoreceptrs) receptors located in the carotid sinuses and the aortic arch.
What do Arterial Baroreceptors detect
These stretch receptors detect physical deformations in the vessel wall due to blood pressure changes.
For Arterial Baroreceptors how are changes relayed?
Changes are relayed to the nucleus tractus solitarius (NTS) in the medulla via afferent nerve fibers.
The carotid barorectrpr afferent travels where
the sinus nerve to the glossopharyngeal nerve to the NTS
located at carotid sinus
The Aortic baroreceptor afferent travels where
afferents travel along the vagus nerve to the NTS
located at aortic arch
Carotid Sinus afferent firing increases
with ____ blood pressure
increased
At normal arterial pressures, carotid sinus afferent firing occurs mainly during what?
systole
At normal arterial pressures carotid aferent firing rate decreases during what?
late systole and diastole
Barareceptor stimulation ____ sympathetic activity and ____ parasymp activity
decr, incr
An increased baroreceptor firing rate leads to what?
leads to vasodilation and bradycardia.
What must work in conjunction to slow the heart rate?
The reduction in sympathetic firing is paralleled by an increase in parasympathetic outflow that slows the heart rate.
vagus decr hr
Explain sypmathetic negative feeback
- incr BP
- incr baroreceptor firing
- decr sympt discharge
- decr vasoconstriction
- decr BP back to set value
- and vice versa
Explain parasym neg feedback pathway
- Incr bp
- incr barorecp firing
- incr vagal discharge
- decr hr
- decr blood pressure
and vice versa
Adaption of barorecptors occurs when?
during long-term changes in mean arterial blood pressure (hypertension), having a decreased sensitivity to pressure changes,
barorector are NOT contantly firirng, they adapt and reset their midpoint to respond to incr and decr (midpt goes up for someone who is hypertensive)
Where are the “low pressure” baroreceptors located?
Mechanoreceptors located in
Atria
Pulmonary vessels
where bood is reterning in the heart
they also sense mechanical changes
What do low pressure baroreceptors detect?
Detects blood volume changes (pre-load)
sense filling/fullness (this will make is fire more)
