Flashcards in Resp Deck (126)
What is the total adult lung volume?
What is the hilum?
root of the lungs
What is the difference between visceral pleura and parietal pleura?
visceral adheres to the lungs, pleural lines thoracic cavity
What is the main muscle of inspiration?
diaphragm. 80% of inspiration, controlled by the medulla via the phrenic nerve.
Where does the phrenic nerve exit?
C3, 4, 5
Describe the mechanical process of inspiration.
diaphragm contracts and flattens, pulls down the parietal pleura which decreases pressure and draws air into lungs. 80% of the work. the remaining 20% is done by accessory muscles such as external intercostals, actively moving rib cage up and out
Describe the process of expiration.
Not a passive process diaphragm relaxes, elastic recoil of the lungs, chest wall, and abdominal structures compress the lungs, exhalation longer than inspiration intercostals assist with inward movement of the ribs
What are the accessory muscles?
Scalene from neck to first two ribs, Sternoclediomastoid raises the sternum, and pectoral is major and minor
What are the conducting airways?
nasal cavity, nasopharynx, oropharynx (soft palate to hyoid), laryngopharynx
Characteristics of the trachea
smooth muscles, 11cm long, c shaped cartilagenous rings
Characteristics of the carina
Tracheal bifurcation site, right main stem bronchus, important anatomical landmark 2-3 cm above carina for ett placement
Characteristics of alveoli
primary site of gas exchange
Type 1 alveolar epithelial cells
90% functioning alveoli, gas exchange
type 2 alveolar epithelial cells
greater number vs type 1 cells, a supporting cell, produce , store and secrete surfactant
functions of surfactant
decrease surface tension, stabilizes alveoli, prevents collapse, increases lung compliance, eases WOB
What are the two vascular systems of the pulmonary alveoli.
pulmonary (pulmonary arteries, divides into right and left branches, receives venous blood from the right side of the heart) and bronchial( no gas exchange)
functions to distribute blood to the airways, does not participate in gas exchange
Alveolar capillary membrane
5 layers thick
no air in the blood
no blood in the alveoli
diffusion of oxygen and carbon dioxide
Co2 is 20x faster than o2
What is the maximum peak pressure
The rate of diffusion is influenced by
thickness of the alveolar capillary membrane
surface area of the alveolar capillary membrane
diffusion coefficient of the gas
Why is CO2 faster than O2 to perfuse?
because it is more soluble
What can impair diffusion through AC membrane?
pulmonary edema, ARDS, pulmonary fibrosis Thickens alveolar membrane
Function of pulmonary lymphatic circulation
removal of foreign matter, cell debris, remove fluid to help keep alveoli clear, produce antibody and cell mediated immune response
eventually drains into the primary lymph nodes located at the hila
two forms of oxygen
bound to hemoglobin 97% oxyhemoglobin, 4 oxygen molecules, SaO2
plasma oxygen PaO2diffuses to the cellular level, which the stimulates haemoglobin to offload its oxygen.
What determines o2 delivery?
cardiac output 4-8l/min
oxygen binding capacity of the hemoglobin
ount of oxygen int he blood SaO2
how much oxygen is extracted every minute?
25% arterial oxygen every minute
what changes hemoglobin binding capacity
hypoxemia, altered rbc morphology
describe the relationship between extraction an consumption
once maximum extraction is reached, further increase in demand or decrease in supply leads to hypoxia
then anerobic metabolism and lactic acidosis
what are the three forms of CO2 in the blood
bicarbonate 60% can accept or reject components to maintain acid base balance