Chapter 4 ( Respiratory )

Question 1

Physiologic dead space equation ?

Answer 1

Physiologic dead space =

tidal volume x ( (Pco2 of alveoli - Pco2 of expired air) / Pco2 of alveoli )

Question 2

Alveolar ventilation equation ?

Answer 2

Alveolar ventilation =

tidal volume - physiologic dead space

Question 3

LaPlace’s law ?

Answer 3

Pressure = 2 x surface tension / radius

Question 4

Surfactant source and molecular structure ?

Answer 4

Type ll pneumocytes

Dipalmitoylphosphatidylcholine

Question 5

Indicator of mature levels of surfactant in fetus lung ?

Answer 5

Lecithin : sphingomyelin > 2:1

In amniotic fluid

Question 6

Major site of airway resistance ?

Answer 6

Medium-sized bronchi

Question 7

Causes of constriction of airways ?

Answer 7

Parasympathetic stimulation
Irritants
Slow reacting substances of anaphylaxis ( asthma )

Question 8

Dalton’s law of partial pressures ?

Answer 8

In dry air
Partial pressure = total pressure x fractional gas concentration
In humidified tracheal air
Partial pressure =( total pressure - partial pressure of H2O ) x fractional gas concentration

Question 9

Dissolved gas equation

Answer 9

Dissolved gas = partial pressure of that gas in blood x solubility of that gas in blood

Question 10

Examples for perfusion limited exchange and diffusion limited exchange ?

Answer 10

Perfusion limited :
N2O
CO2
O2 in normal conditions 
Diffusion limited 
CO
O2 in emphysema , fibrosis , strenuous exercise

Question 11

Adult Hb and fetal Hb ?

Answer 11

Adult Hb : alpha 2 beta 2

Fetal Hb : alpha 2 gamma 2

Question 12

Blood O2 content equation ?

Answer 12

O2 content =

( Hb concentration x O2 binding capacity x percentage of saturation ) + dissolved O2

Question 13

Causes of shift to the right of O2-Hb dissociation curve ?

Answer 13

1- Increased Pco2
2- decreased PH
3- increased temperature
4- increased 2,3-DPG

Question 14

Causes pf shift to the left of Hb-O2 dissociation curve ?

Answer 14

1- decreased Pco2
2- increased PH
3- decreased temperature
4- decreased 2,3-DPG
5- HbF
6- CO poisoning

Question 15

Definition and Causes of Hypoxemia ?

Answer 15

Def : decrease in arterial Po2
Causes :
Decreased PAo2
Diffusion defect 
V/Q defect 
Right to left shunt

Question 16

Alveolar gas equation ?

Answer 16

PAo2 = Pio2 - ( PAco2/R )
R : respiratory exchange ration =
CO2 production / O2 consumption

Question 17

Hypoxia definition and causes ?

Answer 17

Decreased O2 delivery to the tissues 
Causes :
Decreased cardiac output
Anemia 
Hypoxemia 
CO poisoning 
Cyanide poisoning

Question 18

Oxygen delivery equation ?

Answer 18

O2 delivery = cardiac output x O2 content of blood

Question 19

Response of the kidney to hypoxia ?

Answer 19

Increase hypoxia-inducible factor alpha

Which directs the synthesis of EPO mRNA and ultimately promotes development of mature RBCs

Question 20

Forms of CO2 in blood ?

Answer 20

1- dissolved CO2 5%
2- Carbaminohemoglobin 5%
3- HCO3- 90%

Question 21

Medullary respiratory center location ? Groups ? Their function ?their Input and output ?

Answer 21

Location : the reticular formation
Groups :
1- Dorsal respiratory group
Responsible for inspiration and basic rhythm of breathing
Input : Vagus nerve which relays information from peripheral chemoreceptors and mechanoreceptors in the lung
and Glossopharyngeal nerve which relays information from peripheral chemoreceptors
Output vis the Phrenic nerve to the diaphragm

2- Ventral respiratory group
Responsible for expiration only activated when expiration becomes an active process and nor passive

Question 22

Apneustic center location and function ?

Answer 22

Lower pons

Stimulates inspiration

Question 23

Pneumotaxic center location and function ?

Answer 23

Upper pons

Inhibits inspiration

Question 24

Types of receptors for control of breathing ?

Answer 24

1- peripheral and central Chemoreceptors 
2- Lung stretch receptors 
3- Irritant receptors 
4- J ( juxtacapillary ) receptors 
5- Joint and muscle receptors