Respiratory concepts Flashcards
Why is the pO2 in the left atrium lower than in the pulmonary veins (where the blood just came from)?
b/c deoxygenated blood originating from the bronchial arteries mixes with the oxy blood (“venous admixture”)
secreted from the lamellar bodies of type 2 pneumocytes
Surfactant
the main components of surfactant
phosphatidylcholine (Lethicin) & sphingomyelin (L:S ratio > 2 means lungs are mature)
What kind of transmembrane protein is the CFTR protein (responsible for Cystic Fibrosis)
- an ATP-gated ion transporter - pumps Cl- out against a gradient using ATP for energy
Normal arterial blood gas values
-pH —> 7.35-7.45 -PaO2—> 80-95 -PaCO2 —> 35-45 -HCO3- —> 22-26
How can you tell an absolute erythrocytosis from a relative erythrocytosis?
(Erythrocytosis/ Polycythemia is defined as HEMATOCRIT > 52% in men and >48% in women)
you measure the RBC mass
- if it is increased, they have an absolute erythrocytosis
- if it is normal, they have a relative erythrocytosis (ie: relative to decrs in plasma volume)

DIff bwtween Minute Ventilation & Alveolar Ventilation?
Dead Space
- Minute Ventilation = Tidal Volume (L) x breaths/min
- Alveolar Ventilation = (Tidal volume - dead space) x breaths/min
-Alveolar ventilation only measures the vol of air participating in gas exchange per minute
___________ lung diseases are associated with decreased lung volumes & increased expiratory flow rates (due to decreased lung compliance/ increased recoil and increased radial traction on the airways by the lung)
Restrictive diseases (fibrosis)
Heroin overdose causes what kind of metabolic disturbance?
-Suppresses respiratory centers and causes hypoventiliation, retaining of CO2 –> Respiratory Acidosis
blood flow (Q) is greatest at the _____ of the lung
at the BASE
- Ventilation (V) is also greatest at the base
- but the perfusion (Q) is MUCH GREATER than the Ventilation at the base ((so the V/Q ratio is actually lower at the base ))
Where is the correct place to perform a thoracentesis along the midclavicular line, midaxillary and paravertebral line?
Midclavicular –> btw ribs 5- 7
Midaxillary –> btw ribs 7-9
Paravertebral –> btw ribs 9-11
- The pleural border is usually 2 intercostal spaces below the lung border
- you must go in the space past the lung border but within the pleura.. so you must stay within these rib margins
- remember: Needle goes on TOP of rib
Fetal lung Lethicin (dipalmitoyl phosphatidylcholine) increases production at ___ weeks gestation
increases sharply at 30 weeks
Airway resistance is lowest at the ______________
terminal bronchioles (the smallest )
- Why? – b/c they have the largest total cross sectional area
- most resistance is in the medium and small sized bronchi
At what point on a spirometry reading is the total pulmonary vascular resistance lowest?
at the end of a regular (vital capacity) expiration
- Not at the end of a forced expiration (b/c then the vessles would be compressed and have higher resistance)
In patients with longstanding COPD, what is their main stimulator of respiratory drive??
- CO2?
- O2?
- -Hypoxia (low paO2) sensed at the peripheral chemoreceptors (ie: carotid bodies)* is their only stimulation of resp drive
- their prolonged hypercapnia has caused CO2 to no longer stimulate the medullay resp center
T or F?
Blood flow per minute is always the same in systemic and pulmonary circulations?
TRUE
- the rate of flow through the lungs must equal the flow rate in systemic circulation at all times ( or else the chambers of the heart wouldn’t fill adequately)
Oxygenated blood from the mother flows into the fetus by the Umbilical __________ –> then to the fetal IVC
Umbilical Vein
- 1 vein (oxy)
- 2 arteries (deoxy)
What is the main mechanism for clearing small particles (< 2 microns) from the lungs?
PHAGOCYTOSIS
- largest dust particles are sneezed / coughed out
- particles 10-15 microns are trapped in the UR tract
- particles 2.5 - 10 microns are cleared by mucociliaryelevator
- smallest are phagocytized
What is a normal A-a gradient ?
Normally the Alveolar -arterial gradient is not more than 10-15 mmHg
(the A-a gradient is the difference btw Alveolar and arterial Oxygen)
dV / dP =
**Compliance **
- volume for a given pressure
- reduced in Restrictive lung dz
- increased in Obstructive lung dz
Which lung volume is increased in a person w/ COPD?
Residual Volume
What can decrease lung compliance?
- pulmonary fibrosis
- insufficiant surfactant
- pulmonary edema / congestion (ie: Left sided heart failure)
which nerve mediates the afferent limb of the cough reflex ?
Internal laryngeal nerve
- located in the pharynx in the piriform recess
- fish bones stuck in the piriform recess can damage this nerve and affect the cough reflex
High altitude exposure lasting more than a few days results in hypoxemia and a chronic ________ _____________, that is compensated by increased renal excretion of bicarb
Respiratory alkalosis (hyperventilate , blow off CO2)