Ch 19 Flashcards

1
Q

What are the two primary determinants of long-term arterial pressure level?

A
  1. degree of pressure shift of the renal output curve for water and salt
  2. The level of salt and water intake
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2
Q

Briefly, what is the effect of increased arterial pressure on the sympathetic nervous system?

A

SNS activity decreases (as does Angiotensin II and aldosterone

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3
Q

What is the basic equation for arterial pressure?

A

Arterial pressure = cardiac output x total peripheral resistance

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4
Q

Where is pro-renin produced and activated?

A

The juxtaglomerular cells of the kidney in the walls of the afferent arterioles proximal to the glomeruli

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5
Q

The juxtaglomerular cells are modified ______ cells

A

smooth muscle

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6
Q

Renin causes catalyzes formation of which substance?

A

Angiotensin I (from angiotensinogen)

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7
Q

what is the action of angiotensin I

A

-mild vasoconstrictor
-used to form angiotensin II

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8
Q

where is angiotensin II produced?

A

The lungs’ blood vessels, and to a lesser extent, the kidneys and other blood vessels

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9
Q

What are the functions of Angiotensin II?

A
  1. Rapid, multifocal vasoconstriction to increase venous return
  2. Decreased salt and water excretion by the kidneys (more powerful method)
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10
Q

How long does it take the RAAS to become fully active?

A

About 20 minutes

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11
Q

How does angiotensin II cause renal salt and water retention?

A
  1. acts directly on the kidneys
  2. causes aldosterone secretion by the adrenal glands, which acts at the kidney to save salt and water
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12
Q

How does angiotensin act directly on the kidneys?

A
  1. renal arteriolar constriction to reduce blood flow, reducing pressure in the peritubular capillaries to stimulate fluid reabsorption from tubules
  2. acts on tubular cells to increase sodium and water reabsorption
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13
Q

which mechanisms show responses to changes in arterial pressure within minutes to seconds?

A
  1. Baroreceptor feedback mechanism
  2. The central nervous system ischemic mechanism
  3. The chemoreceptor mechanism
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14
Q

In a patient with acute severe hemorrhage, what three main results do the nervous mechanisms cause to maintain blood pressure?

A
  1. Venous constriction and transfer of blood to the heart
  2. Increased heart rate and cardiac contractility to improve pumping
  3. Peripheral arteriolar constriction to impede blood flow out of arteries
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15
Q

What three pressure control mechanisms take minutes-hours to fully activate?

A
  1. Renin-angiotensin vasoconstrictor mechanism
  2. Stress-relaxation of the vasculature
  3. Shift of fluid through tissue capillary walls in and out of circulation
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16
Q

Which pressure-regulating mechanism acts over the longest expanse of time?

A

The renal body fluid mechanism