Chapter 4 ( Respiratory ) Flashcards
Physiologic dead space equation ?
Physiologic dead space =
tidal volume x ( (Pco2 of alveoli - Pco2 of expired air) / Pco2 of alveoli )
Alveolar ventilation equation ?
Alveolar ventilation =
tidal volume - physiologic dead space
LaPlace’s law ?
Pressure = 2 x surface tension / radius
Surfactant source and molecular structure ?
Type ll pneumocytes
Dipalmitoylphosphatidylcholine
Indicator of mature levels of surfactant in fetus lung ?
Lecithin : sphingomyelin > 2:1
In amniotic fluid
Major site of airway resistance ?
Medium-sized bronchi
Causes of constriction of airways ?
Parasympathetic stimulation
Irritants
Slow reacting substances of anaphylaxis ( asthma )
Dalton’s law of partial pressures ?
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
Dissolved gas equation
Dissolved gas = partial pressure of that gas in blood x solubility of that gas in blood
Examples for perfusion limited exchange and diffusion limited exchange ?
Perfusion limited : N2O CO2 O2 in normal conditions Diffusion limited CO O2 in emphysema , fibrosis , strenuous exercise
Adult Hb and fetal Hb ?
Adult Hb : alpha 2 beta 2
Fetal Hb : alpha 2 gamma 2
Blood O2 content equation ?
O2 content =
( Hb concentration x O2 binding capacity x percentage of saturation ) + dissolved O2
Causes of shift to the right of O2-Hb dissociation curve ?
1- Increased Pco2
2- decreased PH
3- increased temperature
4- increased 2,3-DPG
Causes pf shift to the left of Hb-O2 dissociation curve ?
1- decreased Pco2 2- increased PH 3- decreased temperature 4- decreased 2,3-DPG 5- HbF 6- CO poisoning
Definition and Causes of Hypoxemia ?
Def : decrease in arterial Po2 Causes : Decreased PAo2 Diffusion defect V/Q defect Right to left shunt
Alveolar gas equation ?
PAo2 = Pio2 - ( PAco2/R )
R : respiratory exchange ration =
CO2 production / O2 consumption
Hypoxia definition and causes ?
Decreased O2 delivery to the tissues Causes : Decreased cardiac output Anemia Hypoxemia CO poisoning Cyanide poisoning
Oxygen delivery equation ?
O2 delivery = cardiac output x O2 content of blood
Response of the kidney to hypoxia ?
Increase hypoxia-inducible factor alpha
Which directs the synthesis of EPO mRNA and ultimately promotes development of mature RBCs
Forms of CO2 in blood ?
1- dissolved CO2 5%
2- Carbaminohemoglobin 5%
3- HCO3- 90%
Medullary respiratory center location ? Groups ? Their function ?their Input and output ?
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
Apneustic center location and function ?
Lower pons
Stimulates inspiration
Pneumotaxic center location and function ?
Upper pons
Inhibits inspiration
Types of receptors for control of breathing ?
1- peripheral and central Chemoreceptors 2- Lung stretch receptors 3- Irritant receptors 4- J ( juxtacapillary ) receptors 5- Joint and muscle receptors
