Exam 3: Lecture 13 Flashcards
T/F: For cardiac failure, the heart must completely stop.
False, the heart must be unable to keep up with demands, not necessarily stop
Define cardiac failure
Failure of the heart to pump enough blood to satisfy the needs of the body
What are the 3 compensatory mechanisms by the ANS for acute cardiac failure?
1) Baroreceptor reflex
2) Chemoreceptor reflex
3) CNS ischemic response
If all ventricular musculature is diffusely damaged but is still functional, ___________________.
The SNS strengthens this damaged musculature
If part of the musculature is nonfunctional and part is still normal, ___________________.
The normal muscle is strongly stimulated
During chronic compensation of moderate heart attacks, the maximum pumping ability of the partly recovered heart is still depressed _____.
To less than 1/2 normal
T/F: An increase in right atrial pressure can maintain the cardiac output at a near normal level despite continued weakness of the heart.
True
What causes pulmonary edema?
Loss of function to left side of heart results in blood from lungs not being pumped into heart. Hydrostatic pressure of capillaries rises in lungs as blood volume increases and fluid is pushed out.
What are the two major problems associated with left heart failure?
Pulmonary edema
Pulmonary vascular congestion
Arteriovenous fistula leads to high output cardiac failure. What is Arteriovenous fistula?
Heart overloads because of excessive venous return
Venous return curve rotates upward
Beriberi leads to high output cardiac failure. What is beriberi?
Weakening of heart due to thiamin deficiency
Decreases blood flow to kidneys-> fluid retention
Venous return curve shifts right
What makes the “lub” sound of the heart beat?
AV valves closing at onset of ventricular systole
What makes the “dub” sound of the heart beat?
Semilunar valves closing at end of systole
What is an example of a left-right shunt and what does it cause?
Patent ductus arteriosus
Causes blood to flow backward into heat and not flow through circulation
What is an example of right-left shunt and what does it cause?
Tetralogy of fallot
Causes blood to flow from right to left side of heart, bypassing lungs
Define circulatory shock.
Inadequate blood flow through the body, to the extent that the body tissues are damaged
What two factors can severely reduce cardiac output?
Decreased ability of heart to pump blood
Decreased venous return
T/F: Circulatory shock that results from diminished cardiac pumping ability is called cardiogenic shock.
True
What causes decreased venous return?
Diminished blood volume
Decreased vascular tone
Obstruction of blood flow
What causes decreased ability of heat to pump blood?
MI
Toxic state
Valve dysfunction
Heart arrhythmias
Return of cardiac output to normal after cardiac shock is due to powerful sympathetic reflexes which cause…
Decrease in arterial pressure after hemorrhage
Decrease in pressure in the pulmonary arteries and veins in thorax
The sympathetic reflexes result in what 3 effects?
1) Arterioles constrict
2) Veins/venous reservoirs constrict
3) heart activity increases markedly
T/F: Autoregulation maintains normal levels in cerebral and cardiac vessels as long as arterial pressure is above 100 mmHg.
False, as long as arterial pressure is above 70 mmHgq
Explain the baroreceptor reflexes in shock recovery.
Powerful sympathetic stimulation
Explain the CNS ischemic response in shock recovery.
Powerful sympathetic stimulation
Not activated until under 50 mmHg arterial pressure
Explain the reverse stress-relaxation of circulatory system in shock recovery.
Blood vessels contract around diminished blood volume so blood volume that is available more adequately fills circulation
Explain the increased secretion of renin by kidneys & formation of angiotensin II in shock recovery.
Decreases water output
Explain the increased secretion by posterior pituitary of ADH in shock recovery.
Increases water retention
Explain the increased secretion by adrenal medullae of epinephrine/norepinephrine in shock recovery.
Increases HR
What are the 4 compensatory mechanisms from shock?
Absorption of large quantities of intestinal fluid
Absorption of fluid into blood capillaries
Conservation of water/salt
Increased thirst/appetite for salt
What is non-progressive shock?
Sympathetic reflexes and other factors work enough to prevent further deterioration of circulation
*Negative feedback mechanism
What is progressive shock?
When arterial pressure falls too low, myocardium become weak and can’t pump, decreasing cardiac output even more
*Positive feedback mechanism
What is neurogenic shock?
When vascular capacity increases so much that normal amount of blood becomes incapable of filing circulatory system
- May occur without loss of blood volume
- Major cause is loss of vasomotor tone
What are the 3 causes of neurogenic shock?
Deep general anesthesia
Spinal anesthesia
Brain damage
How does deep general anesthesia cause neurogenic shock?
Causes vasomotor paralysis
How does spinal anesthesia cause neurogenic shock?
Blocks sympathetic nervous outflow
How does brain damage cause neurogenic shock?
Causes vasomotor paralysis
