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Spring 2020 - Physiology 1 > Shock & Exercise - Quiz 11 > Flashcards

Shock & Exercise - Quiz 11 Flashcards

1
Q

What is Circlatory Shock?

A

Not enough blood flow in the body to where tissues are damange d/t lack of oxygen & nutrient delivery - gets worse once it begins

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2
Q

What is the “Last-Ditch Stand”

A

When the brain lacks O2 & increased CO2, it activates extreme stimulation of SNS as last effort to keep the MAP from falling too low

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3
Q

What Causes Shock?

A
  • Shock is from inadequate Cardiac Output
    • Cardiac Abrnomalities effecting pump
    • Factors decreasing venous return
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4
Q

How can you have Circulatory Shock even with Normal Cardiac Output?

A

Excessive Metabolic Rate

&

Abnormal Tissue Perfusion

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5
Q

How much blood can be loss before going into Hemorrhagic/Hypovolemic shock?

A

> 10% will causes decreases in Cardiac Output & MAP

40-45% Total blood Loss = Cardiac Output & Map of Zero

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6
Q

What happens during the Sympathetic Reflex to shock?

A
  1. Arterioles constrict = Increased PVR
  2. Veins constrict = adequate venous return
  3. Increased HR
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7
Q

How is blood flow to the Brain & Heart affected by the Sympathetic Reflex during shock?

A

No Constriction in Brain or Heart

Autoregulation maintains Blood flow as long as MAP > 70 mmHg

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8
Q

What are the Compensatory Mechanisms in Hemorrhage?

A
  • Baroreceptors
  • Chemoreceptors
  • Cerebral Ischemic Response
  • Endogenous Vasoconstrictors
  • Reabsorption of Tissue Fluids
  • Salt and Water Conservation
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9
Q

How do Baroreceptors work?

A

Located in Carotid Sinus & Aortic Arch

Senses pressure changes and alters CNS, HR & Contractility accordingly.

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10
Q

How do the Peripheral Chemoreceptors respond to Severe Hypotension?

A

Decreased organ blood flow leads to acidosis activating the chemoreceptors.

Further increases SNS response & respiration to increase BP

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11
Q

How does the Reabsorption of Tissue Fluids happen in shock?

A

Hypotension & Vasoconstriction causes a drop in Hydrostatic Pressure and net fluid reabsorption from interstitium into capillaries up to 1L/hr

Can cause Hemodilution = ↓Hct

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12
Q

How does the Kidney come into play during Shock?

A
  • Kidneys release more
    • Angiotensin II - Vasoconstriction
    • Aldersterone - Salt & Water Reabsorption to increase blood volume
    • Stimulates Vasopressin Release
    • Important for long-term recovery
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13
Q

What is Circulatory Decompensation or Progressive Shock?

A

When the body’s compensation mechanisms is not enough to maintain a sufficent MAP to perfuse organs and leads to irreversible shock where everything fails.

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14
Q

What is Cardiogenic Shock?

A

Poor blood flow to the heart from hypotension causes myocardial hypoxia & acidosis, which depress its function & cause arrythmias

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15
Q

What is Symptathetic Escape?

A

Buildup of tissue metabolic vasodilators impairs sympathetic vasoconstriction causing more hypotension & hypoperfusion

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16
Q

How does progressive shock affect the brain?

A

Cerebral Ischemia/Hypoxia

Loss of Sympathetic outflow = more vasodilation, hypotension, and poor cerebral perfusion

17
Q

What are the Rheological (flow) effects of Progressive Shock?

A

Increased blood viscosity, reducing perfusion

&

Intravascular Coagulation

18
Q

What are the Stages of Shock?

A
  • Non-Progressive/Compensated
    • ​Body can compensate to full recovery
  • Progressive
    • W/o therapy, shock gets worse til death
  • Irreversible
    • Nothing you can do, patient will die
19
Q

What are treatments for Hypotension?

A

Give Blood

Epi/Norepi

Head Down Position

Oxygen

Glucocorticoids

20
Q

In shock, where is Vasoconstriction most prominent?

A

Skin, Skeletal Muscle, and Splanchnic Vascular Beds

21
Q

Blood flow is preferentially redistributed to which body organs in shock states?

A

Brain and Heart

22
Q

What are the Decompensatory Mechanisms?

A

Cardiac & CNS Depression
Acidosis
Vasomotor Failure
Abnormal Clotting
Reticulo-Endothelial System
Cellular Deterioration
Low Flow States

23
Q

What are the Positive Feedback Decompensatory Mechanisms?

A

↓CO & Contractility

↓MAP & O2 Transport

Vasodilation

Tissue Hypoxia

24
Q

What happens on the Cellular Level that leads to Irreversible Shock?

A

Depletion of high-energy phosphates

25
Q

What is the normal Rate of Blood flow through muscles?

A

3-4 mL/min/100g of muscle

26
Q

What is the Rate of Blood Flow through muscles during Excercise for a nonathlete and an athelete?

A

Non Athelete: 4-5x normal blood flow

Athelete: 6-7x normal blood flow
(50-80 mL/min/100g of muscle)

27
Q

What causes Low Blood flow to muscles during muscle contraction?

A

Muscle contraction compresses blood vessels

Can stop blood flow, but also rapidly weakens contraction

28
Q

What is the status of some Muscle Capillaries at rest vs. during exercise?

A

At Rest: Some Capillaries have no flow

During Exercise: All capillaries open, increases surface area 2-3x & enhances o2 diffusion

29
Q

What causes the tremendous amount of blood flow to the muscles during exercise?

A
  • Vasodilation d/t release of
    • Adenosine (ATP)
    • Lactic Acid
    • Potassium
  • Blood flow can increase 20x
30
Q

What factors helps oxygen unloading from Hgb to muscle tissues during excercise?

A

Right OxyHgb shift

Acidosis

Increased Temperature

31
Q

What factor Greatly enhances blood flow to the muscle?

A

Decreased Oxygen in Muscle

32
Q

How does Epi and Norepi play a role in Blood Flow to the Muscles?

A
  • Epinephrine
    • Alpha: Vasoconscriction in Non-Active Muscles, Renal & Splanchnic vessels
    • Beta-2: Mild Vasodilation
  • Norepinephrine
    • Alpha: Vasoconstriction in Non-Active Muscles, Renal & Splancnic vessels
33
Q

How much is Oxygen Consumption increased during Exercise?

A

60x

34
Q

How is the Heart affected during exercise?

A

↑Sympathetic & ↓Parasympathetic

↑Cardiac Output: ↑HR, ↑Inotropy, ↑CVP, ↑Lusitropy

↓SVR

35
Q

How does the change in Cardiac Output correlate to Heart Rate during exercise?

A

Stroke Volume only increases 10-35% durign exercise

Cardiac Output needs increase via Increase in Heart Rate durign exercise to keep up with oxygen demand

36
Q

How does the Heart maintain its stroke volume at the high Heart Rates of exercise?

A
  • Abdominothoracic & Skeletal muscles increase venous return to maintain CVP & Preload
  • Venous Constriction/Decreased Venous Compliance
  • Increased Atrial Inotropy for atrial filling
  • Increased Ventricle Inotropy to squeeze out more blood
  • Enhanced Ventricle Relaxation for better filling
37
Q

What factors enhance Venous Return during Exercise?

A
  • Sympathetically-mediated constriction of Capicitance Vessels
  • ↓SVR in Muscles
  • Contracting Muscles help pump venous blood back to heart
  • Deeper & Faster breathing decreases intrathoracic pressure to enhance cardiac blood flow
38
Q

How is the Mean Arterial Pressure affected by Exercise?

A

Increase in Cardiac Output is more than the decrease in SVR

MAP increases even though SVR decreases

39
Q

What is the importance of an Increased MAP during Exercise?

A

Increased Pressure stretches vessel walls to increase blood flow up to 20x

&

Increased pressure also increases Perfusion Pressure

Spring 2020 - Physiology 1 (24 decks)

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