lung anatomy, ventilation and disease Flashcards
alveoli adaptations
- many alveoli = large surface area
- lots of capillaries = good blood supply, maintaining concentration gradient
- thin exchange surface =alveolar squamous epithelium (one cell thick) gives a short diffusion distance
what is the mechanism for breathing called
ventilation
what happens when you inhale
- air moves into lungs down a pressure gradient
- thoracic cavity volume increases
- pressure in lungs is lower than atmospheric pressure
- external intercostal muscles contract , pulling rib cage up and out
- diaphragm contracts and pulls down
gas exchange surface features
- large SA
- permeable
- thin walls
- moist (gases diffuse more readily in solutions)
- efficient transport system (maintains concentration gradient)
what happens when you exhale
- air moves out of lungs down a pressure gradient
-thoracic cavity volume decreases - pressure in lungs is greater than atmospheric pressure
-external intercostal muscles relax
-diaphragm relaxes and moves up
how does O2 get into the blood
- O2 moves through trachea, bronchus, bronchioles
- diffuses across alveolar squamous cells of alveoli
-diffuses across endothelial wall of the capillary - combines with haemoglobin to form oxyhaemoglobin
- pulmonary arteriole carries deoxygenated blood to alveoli
- pulmonary venule carries oxygenated blood to heart
breathing definition
result of the difference in pressure between lungs and air outside body
pressure inside the lungs is changed by changes in lung volume
risk factors for asthma
- air pollution
- smoking
- occupation
-genetics
risk factors of emphysema
- smoking
- occupation
risk factors of tuberculosis
- infection
risk factors of fibrosis
- occupation
- genetics
how can all 4 lung diseases affect breathing
asthma = diffusion gradient cannot be maintained with air in lungs
tuberculosis= scarring - increases diffusion distance
fibrosis= scarring - increases diffusion distance
emphysema = scarring - increases diffusion distance, less alveoli - lower SA
pulmonary ventilation rate calculation and measurements
pulmonary ventilation rate (dm3 min-1) =
tidal volume (dm3) x breathing rate (min-1)
tidal volume definition
natural breathing rate (eg at rest)
inspiratory/ expiratory reserve definition
extra volume needed for a deep breath
vital capacity definition
maximum amount of air a person can expel from the lungs
residual definition
air that remains in lungs (cannot be accessed)
to prevent collapse of alveoli
