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Medical Physiology > CV Controls/reflexes > Flashcards

CV Controls/reflexes Flashcards

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USMLE® Step 1 flashcards
1
Q

How are reflexes activated?

A
  1. Mechanoreceptors by stretch

2. Chemoreceptors by metabolic products

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2
Q

How does Mild to moderate exercise lead to increased cardia output?

A

Anticipation of activity —> inhibits vagus nerve to heart and increases sympathetic discharge. —> Increased HR and Contractility —> Increased Heart rate

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3
Q

What is the action of isoproterenol?

A
  • Increaess signal to aquaporin
  • Increases contractility of the heart
  • Beta agonist Only
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4
Q

How does the preoptic anterior hypothalamus affect CV system?

A

Temperature center of the heart: Temperature changes alter HR and TPR

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5
Q

How does the Parahypogloassal area of the medulla affect the CV system?

A

Reciprocally activates Sympathetic and inhibits parasympathetic activity

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6
Q

What nucleus is the first to receive information from baroreceptors?

A

NTS: Nuceus of the tracts solitarius

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7
Q

What is the effect of the stimulation of NTS?

A

Inhibits sympathetic nerve outflow to peripheral blood vessels

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8
Q

What are the two locations of baroreceptors, and which are more sensitive?

A

Aortic

Carotid - More sensitive

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9
Q

How does NE affect Carotid Sinus sensitivity?

A

Enhances sensitivity; Increase in intravenous pressure produces greater depressor response

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10
Q

What are the two types of cardiopulmonary receptors? How are they activated?

A
  1. Type A: Tension activated during systole

2. Type B: Stretch activated during diastole

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11
Q

How to CP receptors modulate BP?

A

Initiated a reflex which lowers BP by inhibiting vasoconstrictor center in the cerebral medulla:

Inhibits:

  • Angiotensin
  • Aldosterone
  • Vasopressin/ADH
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12
Q

Describe the relationship of change in Heart rate and Blood pressure reflex at different values.

A
  • Inverse relationship btwn HR and BP is most pronounced at intermediate ranges
  • At High and low values, HR is constant
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13
Q

What is the Bainbridge reflex?

A

Heart rate increases when Central venous pressure rises following right heart distention

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14
Q

Ho does the hypothalamus affect cardiovascular ulnar reflexes?

A
  • Hypothalamus is responsible for behavioral and emotional control of CVS

Anterior: DEC BP and Bradycardia

Posterolateral: INC BP and HR

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15
Q

What is Cushing’s Phemomenon?

A
  • Elevation in intracranial pressure caused by brain tumor results in increase in systemic blood pressure
  • Ischemic stim of vasomotor regions in medulla
  • Helps maintain cerebral blood flow in certain conditions such as expanding intracranial tumors
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16
Q

What are the pulmonary CV reflexes?

A

Lung Inflation —> Systemic vasodilation and DEC in BP

Lung collapse —> Systemic Vasoconstriction

  • Fibers in Vagus nerve and sympathetic nerves
  • Stretch receptors which inhibit vasomotor areas
  • Magnitude Of depressor response directly related to degree of inflation
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17
Q

What is the response of central chemoreceptors to changes in blood chemistry?

A
  • INC in PCO2 —> Vasoconstriction and INC Preiperal resistance
  • DEC in PO2 —> Decrease tonic activity and decrease peripheral resistance

Lowering pH stimulates cerebral areas, ties in pH inhibits them

18
Q

Where are the peripheral chemoreceptors located? What is their action?

A

On aortic arch just medial to carotid sinuses.

Stimulate vasoconstrictor regions in response to changes in PO2, PCO2, and pH

19
Q

What is the primary reflex caused by peripheral chemoreceptors?

A

Activate medullary vagal center —> DEC HR

20
Q

What are the secondary reflex responses to chemoreceptors?

A

Peripheral chemoreceptors —> Respiratory activity —> Hypocapnea + Increased Lungstretch —> Inhibits medullary vagal center

21
Q

What is Coronary perfusion pressure?

A

Difference between aortic diastolic pressure and LVEDP

22
Q

How does Left coronary artery physic pressure differ from Aortic and right coronary artery physic pressure?

A
  • Dramatic downstroke at at end of of Diastole/beginning of systole
  • Dramatic upswing after systole
23
Q

What is Angina Pectoris?

A

Chest pains associated with myocardial ischemia

24
Q

What are the most common treatments for Angina Pectoris?

A

Organic Nitrates —> Metabolized to NO which is a vasodilator

Calcium channel antagonist —> Cause Vasodilation

B-adrenergic antagonists

25
Q

What is the common suffix for calcium channel blockers?

A
  • dipine

* Think DHP channels

26
Q

What is Coronary Steal?

A

Reduced pressure on the narrowed vessel further compromises blood flow to the ischemic myocardium

27
Q

What is the action of Dipyridamole?

A
  • Vasodilator

- Full dilate normal vessel branches which are parallel to narrowed segments and reduce pressure to occluded vessels

28
Q

What is counterpulsation?

A
  • Inflatable balloon inserted into thoracic aorta via femoral artery
  • Balloon inflated during each ventricular diastole and deflated during systole
  • Enhances coronary blood flow by raising diastolic pressure at a time when coronary extravascular resistance is lowest.
29
Q

Which arteries come together to form the circle of Willis?

A
  • Vertebral arteries come together to form Basilar arteries

- Basilar arteries and internal carotids form circle of Willis

30
Q

How does innervation differ between pial and parenchyma arteries?

A

Pial Arteries —> External —> Sup Cervical Ganglion, Sphenopalpatine, and trigeminal nerve

Parenchymal—> Intrinisic —> Cerebral Neurons

31
Q

What is the rate of cerebral blood flow?

A

55 ml/min/100g of brain tissue

32
Q

What are the protective mechanisms for blood flow to the brain?

A
  • Blood brain barrier
  • Extrinsic regulation of CV centers
  • Intrinsic control of autoregulation of circulation
  • Funcitonal hyperemia
33
Q

What is the effects of angiopoeitin?

A
  • Growth factor

- Stimulates expression of occludins in endothelial cells of pericytes

34
Q

What are circumventricular organs?

A

Places of the brain along the 3/4th ventricles where there are fenestrated capillaries and no BBB

35
Q

What is the area postrema?

A

Circumventricular area of the brain which induces vomiting - Susceptible to chemotoxic agents

36
Q

What provides the parasympathetic stimulation to cerebral vessels?

A

Facial nerve

37
Q

What local factors adjust cerebral blood flow to metabolic activity?

A
  • pH: Dilates cerebral vessels
  • K+
  • Adenosine
38
Q

What is the pressure range for normal cerebral circulation?

A

60 - 160 mm Hg

39
Q

What are neural factors which regulate blood flow in the brain?

A
  • Extrinsic innervation: Cervical Sympathetic ganglion accompany carotid and vertebral arteries into cranial cavity and innervates cerebral arteries *Sympathetic exerts MOST PROMINENT effect during pathophysiological conditions
  • Glu or Ach: Activate Astrocytes IP3 pathway —> Released K+ —> hyperpolarization —> Vasodilation
40
Q

How does CO2 regulate cerebral blood flow?

A
  • Increases in PaCO2 —> vasodilation
  • Inhalation increases CO2 2X or 7%
  • DEC in CO@f rom hyperventilation —> DEC cerebral blood flow
  • CO2 works by altering arteriolar resistance by altering perivascular pH
41
Q

Where’s are arteriovenous anastomoses located and what are their functions?

A
  • Bypass Capillaries
  • Palms, fingertips, Toes, Soles, ear, nose, and lips
  • Respond to reflexes to regulate blood flow for temperature control
42
Q

What is characteristic of Sefer exercise on the CV system?

A
  • max 180 BP And SV
  • Compensatory chaises start to fail
  • Heat loss decreased
  • Reduced pH

Medical Physiology (43 decks)

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