Lecture 22: Regulation of Arterial BP and CPR Endocrinology Flashcards Preview

CPR I (Cardiopulmonary and Renal I) Midterm > Lecture 22: Regulation of Arterial BP and CPR Endocrinology > Flashcards

Flashcards in Lecture 22: Regulation of Arterial BP and CPR Endocrinology Deck (16)
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1
Q

Mean Arterial Pressure Equation

A

MAP = CO x TPR = HR x SV x TPR

normally = 93.3 mmHg

MAP = 2/3 (DBP) + 1/3 (SBP)

2
Q

What three systems regulate Mean Arterial Pressure?

A
  1. Baroreceptor Reflex (rapid)
  2. Renin-Angiotensin-Aldosterone System (RAAS)
    • slower
  3. ADH (vasopressin) and ANP (slower)
3
Q

Baroreceptor Classic Reflex Arc

A

Detector –> Afferent Neural Pathway –> Brain Stem –> Efferent Neural Pathway –> Effectors

  • effectors correct deviation from set point
4
Q

What are the two major baroreceptors and their nerves? What do they feed into?

A
  1. Carotid Sinus (Glossopharyngeal N./Sinus N. of Hering)
  2. Aortic Sinus (Vagus N./Aortic N.)
  • lead to nucleus tractus solitarius (NTS)
    • afferent neurons use GLUTAMATE
5
Q

How do baroreceptors respond to changes in pressure?

A

Mechanoreceptors: respond to arterial stretch/relaxation
Chemoreceptors: respond to oxygen, carbon dioxide, and hydrogen

  • inc. firing rate from inc. stretch
  • dec. firing rate from dec. stretch
6
Q

What are the 3 major control centers in the Brain for Arterial Pressure?

A
  1. Nucleus of Tractus Solitarius (NTS)
    • receive/coordinate peripheral signals
  2. Dorsal Motor Nucleus and Nucleus Ambiguus
    • parasympathetic activity
  3. Rostral Ventrolateral Medulla
    • sympathetic activity
7
Q

Which baroreceptor, and why, has a higher threshold for activation?

A
  • Aortic Arch
  • brain has lower threshold to protect it from brain damage if pressure becomes to high
  • carotid sinus more sensitive to rate
8
Q

Sympathetic Response to BP and 3 effects

A
  • triggered by DECREASED baroreceptor firing
  • influences heart muscles and SA node directly

Constrict arterioles/veins (alpha receptors)
Inc. HR and Contractility (beta1 receptors)
Kidney fluid retention and renin secretion

9
Q

Parasympathetic Response to BP and 2 effects

A
  • triggered by INCREASED baroreceptor firing
Decreased HR (Vagus N. to SA node: muscarinic)
Indirect vasodilation of BVs (stimulate NO release)
10
Q

Baroreceptor Adaptation

A
  • baroreceptors able to adjust set-point to different conditions, such as Hypertension

EX: hypertension resets receptors to regulate pressure at a higher set point

“Getting Used to It”

11
Q

Renin Role in RAAS (Renin-Angiotensin-Aldosterone System)

A
  • renin (from kidney) released in response to LOW BP
    • stimulated by B1 adrenergic receptors/SNS
    • dec. salt at macula densa
  • causes angiotensinogen –> angiotensin I
  • angiotensin I –> angiotensin II (in lungs)
  • secreted from Juxtaglomerular Cells in walls of renal afferent arterioles
12
Q

Angiotensin II Role in RAAS (Renin-Angiotensin-Aldosterone System)

A
  • causes aldosterone secretion from adrenal cortex
    • sodium/water retention
    • inc. blood vol., preload, stroke volume, CO, and BP
  • stimulates secretion of antidiuretic hormone
    • VASOPRESSIN (reduced urine production)
  • global arteriole vasoconstriction
13
Q

Antidiuretic Hormone (ADH)

A

aka “Vasopressin”

V1 = BV constriction, V2 = kidney fluid resorption

  • increases TPR and water retention
14
Q

Natriuretic Peptides (3) and their function

A

ANP (atrial), BNP (brain), CNP (C-type)

  • increased secretion by excessive preload of atria and ventricles (too much blood volume)
  • caused by arteriolar dilation; increases fluid loss and inhibits renin
  • protects against overdilation or overstretching of cardiac chambers
15
Q

Response to Hemorrhage (Dec. Blood Volume)

A
  • dec. venous return, preload, stroke, volume, CO, MAP
  • vascular function curve shifts left

Compensatory Response:

  • dec. carotid firing = inc. HR, contractility, CO
  • inc. TPR
  • inc. epinephrine, ADH, renin, angiotensin II, aldost.
16
Q

Posture Changes

A
  • upright movement initiates muscle pumps that push blood upwards towards heart past valves in the limb

When no movement is occuring:

  • venous return accumulates in lower limbs
  • inc. venous/capillary hydrostatic pressure
  • potential edema/hypotension

Reflexes will attempt to bring BP back to normal