Ch. 10

Question 1

Primary purpose of respiratory system is to

Answer 1

provide a means of gas exchange between atmosphere and cells of body

Question 2

What is the blood flow to the lungs?

Answer 2

1. pulmonary circulation begins at the pulmonary artery which receives venous blood from right ventricle
2. mixed venous blood is circulated through capillaries where gas exchange occurs
3. this oxygenated blood is returned to the left atrium via pulmonary vein to be circulated throughout body

Question 3

T/F rates of blood flow in pulmonary and systemic circulation are equal

Answer 3

TRUE

Question 4

In a healthy adult, L and R ventricles of the heart have an output of what approx

Answer 4

5 L/min

Question 5

T/F Pressures in pulmonary circulation are higher when compared to those in systemic circulation

Answer 5

FALSE; lower

Question 6

Why is pressure lower in pulmonary circulation?

Answer 6

due to low vascular resistance in pulmonary circulation

Question 7

What causes resistance in pulmonary system to fall during exercise? and what does it result in

Answer 7

• caused by distension of vessels and recruitment of previously unused capillaries
• results in increased lung blood flow during exercise with small increases in pulmonary arterial pressure

Question 8

When we are standing, what happens to to blood flow to lungs?

Answer 8

it is distributed to the base of the lung due to gravitational force

Question 9

During low intensity exercise, blood flow to the top of lung is

Answer 9

increased

Question 10

Normal gas exchange requires a matching of what?

Answer 10

ventilation to blow flow (perfusion, Q)

Question 11

What is the ideal ventilation to perfusion ratio (V/Q)

Answer 11

1.0 or slightly greater

Question 12

Ventilation to blood flow ratio in apex of lung and base of lung

Answer 12

apex: 3.43
base: 0.64

Question 13

what does a large V/Q ratio represent?

Answer 13

disproportionately high ventilation relative to blood flow which results in poor gas exchange

Question 14

What effect does exercise have on V/Q ratio?

Answer 14

• light to moderate exercise IMPROVES V/Q relationship

- heavy exercise may result in SMALL V/Q inequality and thus minor impairment

Question 15

what is hemoglobin?

Answer 15

approx. 99% of O2 transported in blood is bound to hemoglobin which is a protein contained in RBC

Question 16

Each molecule of hemoglobin can transport how many O2 molecules?

Answer 16

four

Question 17

What does the binding of O2 to hemoglobin form?

Answer 17

Oxyhemoglobin

Question 18

The amount of O2 that can be transported per unit of volume of blood is dependent on

Answer 18

[] of hemoglobin

Question 19

when completely saturated with O2, each gram of hemoglobin can transport how much O2

Answer 19

1.34 ml

Question 20

What is the oxygen hemoglobin disassociation curve?

Answer 20

relationship between partial pressure of O2 and binding of O2 to hemoglobin in blood

Question 21

What is loading?

Answer 21

combination of O2 with hemoglobin in the lungs

Question 22

what is unloading?

Answer 22

release of O2 from hemoglobin at the tissues

Question 23

Factors that determine the direction of the loading and unloading reaction is dependent on:

Answer 23

1. PO2 of blood

2. affinity or bond strength between hemoglobin and O2

Question 24

What drives the reaction to the right?

Answer 24

1. high PO2 (loading)

high PO2 in lungs results in increase in arterial PO2 and formation of oxyhemoglobin

vs low PO2 in peripheral tissue results in decrease of PO2 in systemic capillaries thus O2 is released from hemoglobin to be used by tissues

Question 25

The sigmoidal (s shaped) curve has interesting features

Answer 25

1. percent hemoglobin saturated with O2 increases sharply up to arterial Po2 of 40 mm Hg
2. At Po2 values above 40 slowly plateau around 90

Question 26

The relatively flat portion of curve allows

Answer 26

arterial Po2 to oscillate from 90 to 100 without large drop in %oxyhemoglobin