| what are the features of an alveolus? | pneumocytes 1 and 2
pulmonary surfactant
wall of alveolus
spherical
rich capillary network
wall of capillary |
| How is the alveolus adapted for diffusion (4)? | fluid makes it easier for gases to dissolve into
1 cell thick wall
spherical = maximises SA
rich capillary network = increases gas exchange |
| What are pneumocytes? | cell that lines alveoli |
| what does type 1 pneumocytes do? (3) | gas exchange bw alveoli and capillary
flattened = less distance for gases
amitotic = divides without mitosis |
| What does type 2 pneumocytes?(4) | secretes pulmonary surfactant = decreases surface tension + easier to diffuse when gases are dissolved
cuboidal + many granules
less than type 1 |
| why is surface tension needed in alveoli? (2) | They can collapse and resist inflation
elastic force decreases surface area without cohesion |
| How is surface tension affected with type 2 pneumocytes? (3) | as alveoli expands = surfactant spreads out which increases surface tension
slows expansion rate so all alveoli inflates at the same rate
= equal pressure |
| What happens in inspiration? what muscles and bones are involved? (6) | diaphragm contracts
volume increases
external intercostal muscles contract
ribs up and out
sternocleidomastoid = elevates sternum
pectoralis minor = pulls rib out |
| What happens in expiration? what muscles and bones are involved? (6) | diaphragm relaxes
volume decreases
internal intercostal muscles contract
ribs in and down
abdominals contract
quadratus lumborum contracts = pulls ribs down |
| what is the difference between ventilation, gas exchange and cell respiration? | ventilation: air exchanged bw atmosphere and lungs by breathing
gas exchange: exchange of O2 and CO2 bw alveoli and blood (passive)
cell respiration: ATP released from organic molecules |
| What is Boyle's law? | P = 1/v
gases move from a high pressure region to low pressure region |
| Why is it harder to breathe at higher altitudes? | atmosphere pressure is lower so greater volume is needed to breathe in |
| what are the features of lung cancer? (5) | uncontrolled growth in lung cells form tumor
can be benign (still) or malignant (spreads)
spreads quickly (metastasis)
symptoms = coughing blood, weight loss
causes = tobacco, aging, radiation |
| What are the features of emphysema? (5) | alveoli walls lose elasticity bec of damage to alveolar walls
abnormal enlargement from holes= - SA huge spaces
cause: smoking
damages cell elastase
symptoms: shortness of breath, chest infections |
| How does ventilation because of exercise? (3) | more ATP production to remove carbon dioxide
changes in CO2 detected by chromosensors in artery wall
sent to brainstem to increase ventilation for more gas exchange and increased tidal volume |
| What is tidal volume? | volume of air taken in and out |
| How can ventilation be measured? (3) | observation - counting number of breaths
chest belt and pressure meter (rise and fall)
spirometer (records volume of air being taken in and removed) |
| What does the spirometer do? | records volume of air being taken in and removed |
