SG Ch: 41 - Oxygenation

Question 1

Define “Work of Breathing”

Answer 1

Effort required to expand and contract the lungs

Question 2

Define respiratory “Compliance”

Answer 2

Ability of the lungs to distend or to expand in response to increased
intraalveolar pressure

Question 3

What is “Airway Resistance”?

Answer 3

Pressure difference between the mouth and the alveoli in relation to the
rate of flow of inspired gas

Question 4

What is “Deoxyhemoglobin”?

Answer 4

Hemoglobin with reduced or no oxygen

Question 5

Explain “Pre-load”

Answer 5

• Also known as End Dyastolc Volume (EDV)
• Refers to the blood volume in the ventricle after diastolic contraction
• The greater the volume, the greater the tension of the ventricle pre-systole
• The greater the volume and tension, the greater the stroke volume (blood output upon contraction)

Question 6

Define “cardiac output”

Answer 6

Amount of blood ejected from the left ventricle each minute

(SV x HR) = Cardiac Output

Question 7

Describe “afterload”

Answer 7

• Systemic vascular resistance that the heart must work against to eject blood during systole (ventricular contraction).
• Determined primarly by diameter of blood vessels
• As aortic and pulmonary pressures increase, the afterload increases on the left and right ventricles respectively.

Question 8

What are the three comonents to Stroke Volume?

Answer 8

1. Preload
2. Contractility
3. Afterload

Question 9

What is cardiac “contractility”?

Answer 9

• The inherent strength of myocardial contraction
• The tension developed and velocity of shortening (i.e., the “strength” of contraction) of myocardial fibers at a given preload and afterload.
• It represents a unique and intrinsic ability of cardiac muscle to generate a force that is independent of any load or stretch applied.