L10 Flashcards

1
Q

Too little perfusion - sympa or para activation?

A

Sympa

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2
Q

Too much perfusion - sympa or para activation?

A

Para

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3
Q

What are baroreceptors? Where are high pressure ones located?

A

Stretch receptors
Carotid sinus
Aortic arch

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4
Q

Where are low pressure baroreceptors located?

A

RA: cavo-atrial jxn
LA: jxn of all 4 pulm veins
Low P as in venous system

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5
Q

What is the Bezold Jarisch reflex?

A
Stimulation of chemoreceptors with vagal afferents 
Causes potent vagal tone
- Bradycardia
- Hypotension
- Brief apnea
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6
Q

What are arterial baroreceptors most sensitive to?

A

Changes in pulse pressure
↑PP - ↑rate baroreceptor firing
Inhibits sympa discharge + vagal stimulation of heart
Net ↓HR

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7
Q

What type of drug is phenylephrine? What is the effect on HR?

A
  1. ↑BP
    Alpha agonist - vasocontriction
    Only affects vasculature - ↑P
  2. ↓HR via more baroreceptor firing
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8
Q

How does sympa innervation impact the heart?

A
↑HR
↑Rate conduction
↑Contractility 
↑Rate relaxation 
While inhibiting parasympa
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9
Q

How does para innervation impart the heart?

A

↓HR

↓Contractility

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10
Q

How does sympa innervate vasculature?

A

Constrict arteries
Mild venous constriction
Net ↑BP
DILATION of skeletal muscle only

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11
Q

How does parasympa innervate vasculature?

A

IT DOESN’T YOU DUMMY

Vasodilation is due to sympa withdraw

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12
Q

↑baroreceptor discharge leads to…

A
Sympa withdraw
- Arteries dilate
- Veins dilate
- Net ↓BP 
Vagal dominance
- ↓HR
- ↓CO
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13
Q

What is the pressor response?

A

HEMORRHAGE
Baroreceptors see ↓BP
↑CO and TPR together via SYMPA

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14
Q

What is the response during exercise?

A

Net ↓TPR
- Local metabolic vasodilators + cholinergic dilation > sympa vasocontriction at skeletal muscle
Sympa ↑HR
Baroreceptors NOT triggered b/c adequate flow through the system - no competing vagal tone to ↑BP

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15
Q

Describe Valsalva effects during strain

A
  1. ↑BP + ↓HR

2. ↓MAP –> ↓baroreceptor firing –> ↑sympa –> ↑HR & vasoconstriction

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16
Q

Describe Valsalva effects during strain release

A
  1. Transient ↓BP, restored CO

2. ↑MAP –> ↑baroreceptor firing –> ↓HR

17
Q

3 presentations of neurocardiogenic syncope

A
1. Cardioinhibitory
↑para --> bradycardia
Could progress to asystole
2. Vasodepressor
↓Sympa --> hypotension 
HR unchanged 
3. Mixed 
↓HR & BP
18
Q

What exacerbates syncope?

A

Dehydration - adds to sympa hypotension

Isoproterenol

19
Q

Describe the tilt table test

A

Pt on table
Horizontal –> 70/80 degrees
No syncope + isoproterenol
Nothing after 40 mins, test = negative