Long Term Control Of Blood Pressure Flashcards

1
Q

What is sensed in the control of ECF volume?

A

Effective Circulating Volume (ECV)

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2
Q

What sensors are used to control of ECf volume?

A

Carotid sinus, aortic arch, renal afferent arteriole, atria

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3
Q

Hormonal Transducers used in control of ECF volume?

A
  1. Renin-Angiotensin-Aldosterone System (RAAS)
  2. Sympathetic Nervous System
  3. Atrial Natriuretic Peptide (ANP)
  4. Arginine Vasopressin (AVP)
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4
Q

Effectors of Control of ECF Volume - Long term? Short term?

A

Long term - Kidney

Short term - Heart and blood vessels

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5
Q

What is affected in control of ECF volume - short term? long term?

A

Short term - blood pressure

Long term - Na+ excretion

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6
Q

Main osmotic constituent of the ECF?

A

Na+

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7
Q

What is sensed in control of ECF osmolality?

A

Plasma osmolality

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8
Q

What sensors help control ECF osmolality?

A

Hypothalamic Osmoreceptors

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9
Q

Hormonal Transducers which help control of ECF osmolality?

A

AVP and thirst

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10
Q

Effectors which help control of ECF osmolality?

A

Kidney and Brain (drinking behaviour)

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11
Q

What is affected by effectors of ECF osmolality?

A

Renal H2O excretion and H2O intake.

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11
Q

What is affected by effectors of ECF osmolality?

A

Renal H2O excretion and H2O intake.

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11
Q

What is affected by effectors of ECF osmolality?

A

Renal H2O excretion and H2O intake.

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12
Q

Effecting Circulating Volume (ECV)

A
  • Critical parameter for regulating Na+ excretion is the effective circulation volume.
  • Can be distorted in disease - no longer parallel to ECF volume, ECF increased but ECV is low (which increases Na+ retention) - Congestive Heart Failure, Nephrotic Syndrome and Liver Cirrhosis.
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13
Q

Volume Expansion

A

When Na+ intake persists in the face of impaired Na+ excretion. Body retains isosmotic fluid. Expansion of plasma fluid volume and of the interstitial fluid compartment. When severe, interstitial volume increase so severe that subepidermal tissues swell (e.g. ankles) - pitting oedema.

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13
Q

Volume Contraction

A

Excessive loss of Na+ into the urine. Dramatic shrinkage of the ECF volume, e.g. hypovolaemic shock. Prolonged use of diuretics. Osmotic diuresis in poorly controlled diabetes mellitus. Adrenal insufficiency. Recovery phase after AKI/urinary obstruction.

14
Q

Renal Sympathetic Nervous System

A
  • Enhanced activity of the renal sympathetic nerves has 2 direct effects on Na+ reabsorption from the ultrafiltrate (thereby reducing excretion). - Increased vascular resistance. Increased Na+ reabsorption by tubule cells.
  • Indirect effect: Enhancing renin release from granular cells.
  • Together these reduce GFR and enhance Na+ reabsorption. - Increasing Na+ retention and ECV.
  • However, in an unstressed state - role of sympathetic nerve activity in kidney function appears to be modest.
15
Q

Total Body Na+

A

ECF volume X [Na+]ECF (with osmolality ~constant)

16
Q

Oral Na+ Intake

A

Renal Na+ Output + Extrarenal Na+ Output