Gas Exchange Flashcards
what is the gas concentration gradient in alveoli and capillaries?
the gases move down concentration gradients by diffusion and the concentration gradients are the same as pressure gradients
what structures are involved in the conducting airways?
bronchi containing cartilage and non respiratory bronchioles
what structures are involved in the respiratory unit?
respiratory bronchioles and alveolar ducts
as the airway divides from trachea - bronchioles - alveoli what occurs in each division
an increase in number, a decrease in diameter and an increase in surface area
what forms the anatomic dead space?
conducting airways (bronchi and non-respiratory bronchioles)
what structures do not take part in gas exchange?
conducting airways (bronchi and non-respiratory bronchioles)
what is the approximate volume of the respiratory airways?
2500ml
what is the approximate volume of the conducting airways?
150ml
what is a respiratory unit?
gas exchanging unit, basic physiological unit of the lug consisting of respiratory bronchioles, alveolar ducts and alveoli
what are the type 1 epithelial cells in the alveoli and what do they do?
occupy 97% of alveoli and are the primary site of gas exchange
what are the type 2 epithelial cells in the alveoli and what do they do?
occupy 3% of the surface area and produce pulmonary surfactant
what does surfactant do?
reduce surface tension
what do alveolar macrophages do?
removal of debris
what are the characteristics of alveoli which make it perfectly designed for gas exchange ?
large surface area, very thin walls, good diffusion characteristics
what is the function of the pulmonary circulation?
brings deoxygenated blood from heart to lung and oxygenated blood from lung to heart and then rest of the body
what is the function of the bronchial circulation?
brings oxygenated blood to lung parenchyma
what does the lymphatic system do?
defence and removal of lymph fluid
what are the two types of blood circulation in the lungs?
pulmonary circulation and bronchial circulation
what is the total blood volume in the pulmonary circulation?
500ml
at rest what is the volume of blood in the alveolar-capillary network?
75mls
what happens to the volume of blood in the alveolar-capillary network during exercise?
increases to 150-200mls due to recruitment of new capillaries secondary to an increase in pressure and flow
what is the difference between pulmonary arteries and systemic arteries?
pulmonary arteries are thin walled, highly compliant, large diameter and have low resistance
what is the distance between the alveoli and a red blood cell
1-2upm
what lies between an alveoli and a red blood cell?
alveolar epithelial cell, capillary endothelial cell and basement membrane
in the pulmonary circuit what is the change in O2 and CO2?
O2 enters blood and CO2 leaves blood
in the systemic circuit what is the change in O2 and CO2?
O2 leaves blood and CO2 enters
what gradient do gases move down?
pressure gradients
what is the difference between the O2 and CO2 pressure gradients?
the pressure gradient for O2 is much bigger and CO2 is more diffusible
describe the pulmonary circulation in terms of volume and pressure
carries large volumes of blood at low pressures
what exchange happens between the alveoli and the capillary in the pulmonary circulation?
CO2 moves from capillary to alveoli and O2 moves from alveoli to capillary
