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<3 > Regulation Of Arterial Pressure > Flashcards

Regulation Of Arterial Pressure Flashcards

1
Q

How does the baroreceptor reflex occur?

A

Using classical reflex arc

  1. Detector
  2. Afferent neural pathway
  3. Coordinator center
  4. Efferent neural pathway
  5. Effectors
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2
Q

What is the Baroreceptor reflex?

A

‣ Fast, neural mediated reflexes that attempt to keep arterial pressure constant via changes in the output of the SNS and PNS to the heart and blood vessels

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3
Q

What can alter the sensitivity of baroreceptors?

A

Disease

I.e. chronic hypertension - will reset them to a higher set point

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4
Q

Where are baroreceptors located?

Where wil they lead to?

A
  • carotid sinus
  • aortic sinus

Lead to Nucleus tractus solitaries (NTS)

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5
Q

What types of detectors are present in baroreceptors?

A

Mechanoreceptors - changes in pressure

Chemoreceptors - reponse to PO2, PCO2, pH

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6
Q

How will firign rate change iwth increased stretch on vessel wall?

A

Increased firing rate

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7
Q

How will firing rate change with decreased stretch on vessel wall?

A

Decreased firing rate

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8
Q

What are the baroreceptors most responsive to?

A

Rate of change in pressure

Not just the magnitude of change

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9
Q

What 3 systems regulate MAP?

A
  1. Baroreceptor reflex
  2. Endocrine wise via RAAS
  3. Input from ADH & ANP
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10
Q

What does “decreased firing rate” refer to?

A

Refers to firing rate of afferent neurons

-decreased when decrased stretch

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11
Q

Where will efferent from the Baroreceptor pathway go to?

A

To cerebral cortex and hypothalamus

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12
Q

What is the region associated with PNS activity in the Nucleus of Tractus solitarius (NTS) ?

A

Dorsal motor nucleus of CN 10 and Nucleus ambiguus

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13
Q

What is the region associated with SNS activity in the Nucleus of Tractus solitarius (NTS) ?

A

Rostral ventrolateral medulla

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14
Q

How does the aortic sinus differ from the carotid?

A

‣ Aortic sinus = high threshold for activation
• Will continue to respond above saturation
• Less sensitive to rate
• Less affected by decreases

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15
Q

What effects does the SNS have on the CV system? (4)

A

‣ 1. SA node = increase HR (beta-1)
‣ 2. cardaic muscle = increase Contractility and SV
‣ 3. Arterioles to produce vasoconstriction = increase TPR (alpha-1)
‣ 4. veins to produce venoconstriction = decrease unstressed volume

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16
Q

How does the SNS influence the kidney for the CV system?

A

Goes to adrenal gland via splanchnic n.

-fluid retention by kidney du to afferent arteriole constriction and RENIN SECRETION

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17
Q

What is the influence of the PNS on CV system?

A
  • SA node via CN 10 = decrease HR (Musc. Rs.)
  • increased baroreceptor firing rate
  • INDIRECT vasoDILATION via NO release stimulation
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18
Q

How does decreased symapthetic influence affect tone of blood vessels?

A
  • decreased A. Constriction = decrased TPR

- decreased V. Constriction = incr. compliance = increased unstressed volume

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19
Q

What can cause a decrease in blood volume?

A

Hemorrhage
Dehydration
Loss of body fluids

20
Q

What will happen with decreased blood volume?

VR, preload, SV, CO, MAP, vascular function curve?

A

Decrease in VR, SV, CO, and MAP

-vascular function curve will shift left

21
Q

What will the compensatory response be to decreased blood volume?

A
  • decrease in carotid sinus nerve firing
  • decreased afferents
  • decreases HR, contractility, Cardiac Output
  • decreased unstressed (want more stressed to bring up pressure)
  • increased TPR
  • increased Epi, ADH, Renin, Angiotensin II, aldosterone
22
Q

How does a hemorrhage affect the body?

A
  • decreases Partery (bc BV and stressed volume =decreased)
  • Baroreceptor reflex activated by acute decr.
  • decreased stretch = decr. Firing rate
  • will increase SNS, decrease PNS
23
Q

How is blood pushed upward?

A

Normal upright movement initiates muscle pumps which push blood upward toward heart past valves in limb

24
Q

What happens to blood if there is no movement?

A
  • VR accumulates in lower limbs
  • increases venous and capillary hydrostatic pressure
  • venous pooling —> edema & HYPOtension
  • reflexes to bring BP back up (increase SNS)
25
Q

What is orthostatic hypotension?

A

Decrease in arterial BP upon standing

26
Q

Why does orthostatic hypotension occur?

A

-going from supine to standing —> blood pools in veins of LEs

-decreases VR —> decreases CO
—> decreased MAP

  • edema also occurs bc increased hydrostatic pressure =increased filtration
  • if decrease in Partery is dramatic, then cerebral BP may decrease and cause fainting
27
Q

What can cause long term adjustments of arterial pressure?

A

Hormonal responses can begin w/in minutes and build over a period of days

28
Q

How does the Renin-Angiotensin II aldosterone system affect BP?

What other system does it overlap with?

A

Controls BP by regulating BV and TPR

Overlaps w/ SNS

29
Q

What is renin?

A

‣ Enzyme secreted by kidney into blood in response to DROP in BP
• If BP is high - less renin secreted

30
Q

When is renin secreted and by what?

A

Secreted when BP is LOW
Or
in response to SNS stimulation

By juxtaglomerular cells in walls of renal afferent arterioles

31
Q

What r. Is activated to release renin?

A

Beta 1 adrenergic r.

32
Q

What effect does renin have on NaCl?

A

NaCl will decrease at macula dense

33
Q

What is the downstream effect of renin?

A

Renin —>
angiotensin —>
angiotensin I (inactive) —>
angiotensin II (active, converted in lungs/kidneys) —>

aldosterone

34
Q

What is the effect of ANgiotensin II?

A

‣ Causes secretion of aldosterone from adrenal cortex

35
Q

What are the effects of Aldosterone?

A
  • na and H2O retention by kidney
  • increases BV, SV, CO

—> increases BP

36
Q

Where does ADH/vasopressin act?

A

At V1 receptors (sm. M.) and V2 receptors (collecting ducts)

37
Q

What is ADH secreted in response to? (4)

A

‣ 1. Angiotensin II

‣ 2. Atrial receptors in presence of low preload - decreased atrial receptor firing

‣ 3. Increased osmolality of blood - hyperosmolarity

‣ 4. Sympathetic stimulation

38
Q

What is effect of ADH?

A

Increases TPR and water retention

39
Q

What will increase the secretion of ANP/BNP?

A

When there is Excessive Preload of atria and ventricles (high BP)

40
Q

What effect does ANP have?

A

‣ Arteriolar dilation - decreases TPR

‣ Increases fluid loss - decreases preload

‣ Inhibits renin- decreases both TPR and preload

‣ Will decrease Blood Volume and BP

41
Q

What does ANP protect against?

A

Protects against overdilation or over stretching of cardiac chambers

42
Q

What is the central command response during exercise?

A

Increase SNS

  • increase HR, contractility, CO
  • constricts Arterioles (constricts skin, splanchnic regions, kidneys, inactive m.)
  • constricts veins (decreasing unstressed volume and increasing VR)

Decrease PNS (to HR only)

43
Q

What is the local response during exercise?

A

Increase vasodilator metabolites

-increased release of lactate, K+, adenosine

—> dilation of skeletal msucle arterioles —> decrased TPR

44
Q

How do the cardaic function curve and vascular function curve change w/ exercise?

A

Both increase slope

45
Q

How is TPR during exercise?

A

Decreased

Even though there is a bunch of constriction bc of SNS, local dilation allows for overall TPR decrease

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