Exam1Lec8Baroreceptor&ChemoreceptorRegulation

Question 1

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?

Answer 1

low venous return> decr in pre-load >decr in contractility >decr in SV=>Decr in MBP>decr blood to brain

O2 not in brain

Question 2

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?

Answer 2

baroreceptor detects arterial BP
low Ca=compliance which decr w/ age affecting baroreceptors

Question 3

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?

Answer 3

rapid changes in BP due to changes in blood flow due to change in gravity

Incr blood flow to extremities

Question 4

What do vascular reflexes sense?

Answer 4

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

Question 5

How do vascular reflexes respond?

Answer 5

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

Question 6

Vascualr refelxes work to maintian and optimize what?

Answer 6

cardiovascular performance in rapidly changing physiological situations.

rapidly changing physiological situations.: posture change, exercise

Question 7

What are the type of vascular reflexes?

Answer 7

Peripheral Baroreceptors
Peripheral Chemoreceptors
Central Chemoreceptors
Pulmonary stretch receptors
Hypothalamus (temperature sensors)

Question 8

Arterial baroreceptros play a key role in what?

Answer 8

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)

Question 9

Arterial Baroreceptors are located where?

Answer 9

Stretch (mechanoreceptrs) receptors located in the carotid sinuses and the aortic arch.

Question 10

What do Arterial Baroreceptors detect

Answer 10

These stretch receptors detect physical deformations in the vessel wall due to blood pressure changes.

Question 11

For Arterial Baroreceptors how are changes relayed?

Answer 11

Changes are relayed to the nucleus tractus solitarius (NTS) in the medulla via afferent nerve fibers.

Question 12

The carotid barorectrpr afferent travels where

Answer 12

the sinus nerve to the glossopharyngeal nerve to the NTS

located at carotid sinus

Question 13

The Aortic baroreceptor afferent travels where

Answer 13

afferents travel along the vagus nerve to the NTS

located at aortic arch

Question 14

Carotid Sinus afferent firing increases
with ____ blood pressure

Answer 14

increased

Question 15

At normal arterial pressures, carotid sinus afferent firing occurs mainly during what?

Answer 15

systole

Question 16

At normal arterial pressures carotid aferent firing rate decreases during what?

Answer 16

late systole and diastole

Question 17

Barareceptor stimulation ____ sympathetic activity and ____ parasymp activity

Answer 17

decr, incr

Question 18

An increased baroreceptor firing rate leads to what?

Answer 18

leads to vasodilation and bradycardia.

Question 19

What must work in conjunction to slow the heart rate?

Answer 19

The reduction in sympathetic firing is paralleled by an increase in parasympathetic outflow that slows the heart rate.

vagus decr hr

Question 20

Explain sypmathetic negative feeback

Answer 20

1. incr BP
2. incr baroreceptor firing
3. decr sympt discharge
4. decr vasoconstriction
5. decr BP back to set value

1. and vice versa

Question 21

Explain parasym neg feedback pathway

Answer 21

1. Incr bp
2. incr barorecp firing
3. incr vagal discharge
4. decr hr
5. decr blood pressure

and vice versa

Question 22

Adaption of barorecptors occurs when?

Answer 22

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)

Question 23

Where are the “low pressure” baroreceptors located?

Answer 23

Mechanoreceptors located in
Atria
Pulmonary vessels

where bood is reterning in the heart
they also sense mechanical changes

Question 24

What do low pressure baroreceptors detect?

Answer 24

Detects blood volume changes (pre-load)

sense filling/fullness (this will make is fire more)

Question 25

For atrial mechanoreceptors , how do the afferent fibers run?

Answer 25

They run the vagus to the medulla

Question 26

For atrial baroreceptors, increased stimulation (stretc) incr stimulation of the medullary centets causing what 2 things

Answer 26

decreased parasympathetic output to the heart
(increasing heart rate)
increased sympathetic output to the heart
(increasing heart rate)

Negative Feedback to reduce preload by increasing cardiac output

Question 27

Peripheral chemoreceptors are organized into what 2 locations?

Answer 27

aortic and carotid bodies

Question 28

What are aortic bodies and carotid bodies?

Answer 28

Highly vascularized cells (lots of cap, perfusing them) in the aortic arch and carotid sinus that are sensitive to blood O2, CO2, and pH .

they are more tunesd to O2 changes

Question 29

Aortic bodies and carotid bodies are monstly involved in what?

Answer 29

Mostly involved in respiratory regulation, but they have some minor affect on the vasomotor centers in the medulla

incr cardiac out , incr perih resistance and shunt it toward pulm circuit

Question 30

What is the primary role of central chemoreceptors?

Answer 30

respiratory regulation but also some Cardiovascular effects

Question 31

What stimulates the central chemoreceptors and where?
What does this cause?

Answer 31

Incr blood CO2 that the signal is sent to the medulla

causes incr sympathetic outflow and vasoconstriction(shut blood to lungs) to increase venous return(o2)

Central more tuned to CO2 and ph changes

Question 32

What reduces stimulates the central chemoreceptors and
What does this cause?

Answer 32

Increased ventilation causes decreased blood CO2 levels
causes reduced sympa outflow resulting in vasodilation

Question 33

Does O2 tension have an effect on the central chemorecptors?

Answer 33

NO

Question 34

Long term control of BP (hours to days) involved regualting what?

Answer 34

Systemic blood volume by the kidneys

Question 35

What are the main hormonal mechanisms involved in long term BP regulation?

Answer 35

• ADH secretions
• renin-angiotensin-aldsosterone sysyem
• atrial natriuretic peptides

Question 36

How do the hormones affect blood volume for long term BP regulation

Answer 36

volume by regulating salt and water retention/excretion from the kidneys.

this is how we control circulatory volume

Question 37

90 -95% of hypertension cases are called? What does this mean?

Answer 37

Essential hypertension. No known origins or causes. some genetic influences are known.

Question 38

What are the characteristics that we see with someone with essential hypertension?
mean BP?
CO?
TPR?
Renal resistance?

Answer 38

Mean blood pressure is increased 40-60%
Cardiac Output is near normal
TPR is increased 40-60%
Renal resistance is increased 2-4X

Question 39

What is needed in someone with essential hypertension to excrete normal amounts of salt and water?

Answer 39

High blood pressure

Question 40

Explain the pathway of response to posture change

slide 33/34

Answer 40