respiration gas exchange Flashcards
how do gases move?
down concentration gradients by diffusion
what does partial pressure/tensions need to be equal to?
total pressure
how is partial pressure of a gas calculated?
fraction of gas in gas mixture x barometric pressure
- once breathes into body its humidified so PlO2= FractionO2(Pb-PH2O)
what is barometric pressure at sea level?
760 mmHg
what is the unit of pressure?
mmHg
what is the partial pressure of water at body temperature?
47mmHg
what is the smallest branch of the respiratory tree?
alveolar ducts
what are conducting airways?
bronchi containing cartilage and non-respiratory bronchioles
- anatomic dead space, not involved in gas exchange
what is the volume of the conducting airways?
150ml (30% of average breath)
what is the alveoli volume?
2500ml
what is another name for the respiratory unit?
gas exchange unit
how many alveolar sacs are in an adult?
300-400 million
- polygonal shape
- type 1 and 2 epithelial cells
what occupies 97% of surface area of alveoli?
type 1 epithelial cells- primary site of gas exchange
what occupies 3% of surface area of alveoli?
type 2 epithelial cells- produce pulmonary surfactant which reduces surface tension (common problem in premature babies which cant produce this)
what is the function of alveolar macrophages?
removal of debris
what are characteristics of alveoli which make them good for gas exchange?
- large surface area
- thin walls
what are the two separate blood supplies of the lungs?
- pulmonary circulation
- bronchial circulation
what is the pulmonary circulation blood supply to the lungs?
brings deoxygenated blood from the heart to lung and oxygenated blood from lung to heart and then rest of body
what is the bronchial circulation blood supply to the lungs?
brings oxygenated blood to lung parenchyma (lung cells and tissues)
what is the total blood volume in the pulmonary circulation?
500ml
what happens to the pulmonary circulation during exercise?
alveolar capillary network volume increases due to recruitment of new capillaries
what is different about the arteries in the pulmonary system?
- thinner walls
- larger diameter
- lower resistance
(than systemic system arteries)
what is the distance between the alveoli and blood?
very small- ideal for gas exchange
what happens to CO2 and O2 in the pulmonary circuit?
O2 enters blood, CO2 leaves
what happens to CO2 and O2 in the systemic circuit?
CO2 enters blood, O2 leaves
does CO2 or O2 have a larger pressure gradient?
O2
is CO2 or O2 more diffusible?
CO2
