Cardiovascular- Neurohumeral Influences Flashcards

1
Q

Parasympathetic stimulation (cholinergic) and its effect on CV system?

A
  1. control located in medulla oblongata, cardioinhibitory center
  2. via vagus nerve (CN X), cardiac plexus, innervates the SA node, AV node, and sparsely innervates myocardium; releases acetylcholine
  3. slows rate and force of myocardial contraction; decreases myocardial metabolism
  4. Causes coronary artery vasoconstriction
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2
Q

Sympathetic stimulation (adrenergic) and its effect on CV system?

A
  1. control located in medulla oblongata, cardioacceleratory center
  2. via cord segment T1-T4, upper thoracic to superior cervical chain ganglia; innervates SA node, AV node, conduction pathways, and myocytes; releases epinephrine and norepinephrine
  3. causes an increase in the rate and force of myocardial contractions and myocardial metabolism
  4. causes coronary artery vasodilation
  5. The skin and peripheral vasculature receive only postganglionic sympathetic innervation. causes vasoconstriction of cutaneous arteries; sympathetic inhibition must occur for vasodilation.
  6. drugs that increase sympathetic functioning are sympathomimetics; drugs that decrease sympathetic functioning are sympatholytics
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3
Q

What are the additional control mechanisms?

A
  1. baroreceptors (pressure receptors)
  2. chemoreceptors
  3. body temperature
  4. ion concentrations
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4
Q

Baroreceptors- the what, where, why

A
  • main mechanisms controlling heart rate
  • located in walls of aortic arch and carotid sinus via vasomotor center
  • circulatory reflex- responds to changes in blood pressure
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5
Q

How does circulatory reflex in baroreceptors work?

A
  • increased BP results in parasympathetic stimulation, decreased rate and force of cardiac contraction; sympathetic inhabition, decreased peripheral resistance
  • decreased BP results in sympathetic stimulation, increased HR and BP and vasoconstriction of peripheral blood vessels.
  • Increase R atrial pressure causes reflex acceleration of HR
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6
Q

Where are chemoreceptors and what do they do?

A
  1. located in the carotid body
  2. Sensitive to changes in blood chemicals: O2, CO2, lactic acid
    • increased CO2 or decreased O2 or decreased pH (elevated lactic acid) results in an increase in HR
    • increased O2 levels result in a decrease in HR
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7
Q

How does body temperature work as a control mechanism?

A
  • increased body temp causes HR to increase

- decreased body temp causes HR to decrease

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8
Q

What are 6 ion changes that can act as a control mechanism?

A
  1. hyperkalemia
  2. hypokalemia
  3. hypercalcemia
  4. hypocalcemia
  5. hypermagnesemia
  6. hyposmagnesemia
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9
Q

The effect of hyperkalemia

A

increased concentration of potassium ions decreases the HR and force or contraction, produces ECG changes (widened PR interval and QRS, tall T waves)

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10
Q

The effect of hypokalemia

A

decreased concentrations of potassiumions produces ECG changes (flattened T waves, prolonged PR and QT intervals); arrhythmias, may progress to ventricular fibrillation

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11
Q

The effect of hypercalcemia

A

increased calcium = increased heart actions

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12
Q

The effect of hypocalcemia

A

decreased calcium = depressed heart actions

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13
Q

The effect of hypermagnesemia

A

increased magnesium is a calcium blocker which can lead to arrhythmias or cardiac arrest

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14
Q

The effect of hypomagnesemia

A

decreased magnesium causes ventricular arrhthmias, coronary artery vasospasm, and sudden death

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15
Q

3 Things about peripheral resistance

A
  1. increased peripheral resistance increases arterial blood volume and pressure
  2. Decreased peripheral resistance decreases arterial blood volume and pressure.
  3. Influenced by arterial blood volume, viscosity of blood and diameter of arterioles and capillaries.
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