Lecture 15

Question 1

Cardiac Failure

Answer 1

Failure of the heart to pump enough blood to satisfy the needs of the body

Question 2

How Does the Heart Compensate for Acute Cardiac Failure

Answer 2

Increases sympathetic innervation and decreases parasympathetic innervation; increased sympathetic innervation strengthens muscle contractions in damaged and undamaged areas and increases the tone of vessels (especially veins) which increases mean systemic filling pressure

Question 3

Compensatory Mechanisms by ANS for Acute Cardiac Failure

Answer 3

Baroreceptor Reflex
Chemoreceptor Reflex
CNS Ischemic Response

Question 4

Acute Effects following Acute Heart Attack

Answer 4

Reduced cardiac output and damming of blood in the veins which increases venous pressure

Question 5

Chronic Compensations following Acute Heart Attack (Compensated Heart Failure)

Answer 5

Partial heart recovery and renal retention of fluid; maximum pumping ability of the partly recovered heart is still depressed to less than 1/2 normal; any attempt to perform heavy exercise usually causes immediate return of symptoms of acute failure because heart can’t increase its pumping capacity to the levels required for exercise; an increase in right atrial pressure can maintain the cardiac output at a near normal level despite continued weakness of the heart

Question 6

Pulmonary Edema

Answer 6

Left side of the heart fails without concomitant failure of the right side; blood continues to be pumped into the lungs but is NOT pumped adequately out of the lungs; this causes the mean pulmonary filling pressure to rise because of the shift of large volumes of blood from the systemic circulation into pulmonary circulation; pulmonary capillary pressure then increases; if this rises above colloid osmotic pressure, fluid begins to filter out of the capillaries into the lung interstitial spaces and alveoli

Question 7

2 Major Problems of Left Heart Failure

Answer 7

Pulmonary Vascular Congestion and Pulmonary Edema

Question 8

Arteriovenous Fistula

Answer 8

Overloads heart because of excessive venous return

Question 9

Beriberi

Answer 9

Thiamin deficiency and weakening of the heart; decreased blood flow to the kidney results in fluid retention; this increases mean filling pressure

Question 10

First Sound of a Heart

Answer 10

AV valves close at the onset of ventricular systole

Question 11

Second Sound of a Heart

Answer 11

Semilunar valves close at the end of systole

Question 12

Valvular Defects

Answer 12

Valvular lesions
Rheumatic valvular lesions
Heart murmurs
Aortic stenosis
Aortic regurgitation
Mitral regurgitation
Mitral stenosis

Question 13

Left-to-Right Shunt

Answer 13

Blood flows backward and fails to flow through systemic circulation (Patent Ductus Arteriosus)

Question 14

Right-to-Left Shunt

Answer 14

Blood flows from right to left side of the heart, bypassing the lungs (Tetralogy of Fallot)

Question 15

Circulatory Shock

Answer 15

Generalized inadequate blood flow through the body, to the extent that the body tissues are damaged, especially because of too little oxygen and other nutrients delivered to the tissue cells

Question 16

Cardiac Abnormalities that Decrease the Ability of the Heart to Pump Blood

Answer 16

Myocardial infarction
Toxic state of the heart
Severe heart valve dysfunction
Heart arrhythmias
Cardiogenic shock

Question 17

Cardiogenic Shock

Answer 17

Circulatory shock that results from diminished cardiac pumping ability

Question 18

Factors that Decrease Venous Return

Answer 18

Diminished blood volume
Decreased vascular tone (especially of venous reservoirs)
Obstruction of blood flow

Question 19

What causes powerful sympathetic reflexes?

Answer 19

Decrease in arterial pressure after a hemorrhage and decreases in pressures in the pulmonary arteries and veins in the thorax

Question 20

What do sympathetic reflexes result in?

Answer 20

Arterioles to constrict in most parts of the systemic circulation, veins and venous reservoirs constrict, and heart activity increases markedly

Question 21

After a shock, what compensatory mechanisms return blood volume back to normal?

Answer 21

Absorption of large quantities of fluid from the intestinal tract, absorption of fluids into the blood capillaries from the interstitial spaces of the body, conservation of water and salt by the kidneys, and increased thirst and increased appetite for salt

Question 22

Non-Progressive Shock

Answer 22

Sympathetic reflexes and other factors compensate enough to prevent further deterioration of the circulation; all of these factors are negative feedback mechanisms that attempt to return cardiac output and arterial pressure back to normal

Question 23

Progressive Shock

Answer 23

Positive feedbacks; when arterial pressure falls low enough, coronary blood flow decreases below that required for adequate nutrition of the myocardium; this weakens the heart muscle and decreases cardiac output even more

Important factor in progressive shock is whether it is hemorrhagic in origin or not

Question 24

Factors in the Final Lethal Progression of Shock

Answer 24

Vasomotor failure, blockage of small vessels, increased vascular permeability, release of toxins by necrotic tissue, cardiac depression caused by endotoxin, and generalized cellular deterioration

Question 25

Neurogenic Shock

Answer 25

May occur with/without any loss of blood volume; vascular capacity increases so much that even the normal amount of blood becomes incapable of filling circulatory system adequately; loss of vasomotor tone resulting in massive dilation of the veins

Question 26

Causes of Neurogenic Shock

Answer 26

Deep general anesthesia (depresses vasomotor center enough to cause vasomotor paralysis), spinal anesthesia (blocks sympathetic nervous outflow), and brain damage (causes vasomotor paralysis)