| Alveoli | - Air sacs at the end of bronchioles
- Covered in network of capillaries
- Each alveolus is made from a single layer of thin, flat cells - alveolar epithelium |
| Adaptations of alveoli for gas exchange | - LSA, lots of alveoli
- Thin surface, alveolar epithelium, one cell thick, shorter diffusion path
- Steep concen.gradi. of O2 + CO2 between alveoli + capillaries, increasing diffusion |
| Capillary endothelium | - A type of epithelium that forms the capillary wall |
| Gas exchange with alveoli | - O2 diffuses out of the alveoli
- Across the alveolar epithelium + the capillary endothelium into the capillaries
- Into haemoglobin in the blood
- CO2 diffuses into the alveoli from the blood, and is breathed out |
| Gas exchange summary | - O2 from air moves down the trachea, bronchi + bronchioles into alveoli
- Down pressure gradient
- Once in alveoli, O2 diffuses across alveolar epithelium, then capillary endothelium, into capillary
- This happens down diffusion gradient |
| Lung disease | - Affects ventilation and gas exchange |
| Tidal volume | - The volume of air in each breath
- Usually between 0.4dm3 - 0.5dm3 in adults |
| Pulmonary Ventilation rate (PVR) | - The number of breaths per minute
- Healthy person at rest = 15 breaths |
| Calculating the pulmonary ventilation rate (PVR) | PV R = tidal volume × breathing rate |
| Forced expiratory volume | - FEV1
- Maximum volume of air that can be breathed out in 1 sec |
| Forced vital capacity | - FVC1
- The maximum volume of air that can be forcefully breathed out, after really deep breath in |
| Pulmonary tuberculosis (TB) | - Infected with tuberculosis bacteria
- Immune system cells build wall around bacteria
- Forms hard small lumps, tubercles
- Tissues die, gas exchange system damaged
- Reduces tidal volume, less air inhaled,breath faster
- Coughing blood + mucus, chest pains |
| Fibrosis | - Scar tissue in lungs
- Cause by asbestos or dust
- Less elastic + thicker
- Less able to expand, holds less air
- Reduces tidal volume + FVC + increase PVR
- Reduction of gas exchange, diffusion slower
- Shortness of breath, chest pain |
| Emphysema (em-fu-see-muh) | - Caused by smoking or air pollution
- Particles trapped in alveoli
- Causes inflammation
- Attracts phagocytes, produces enzymes, breaks down elastin, protein in walls of alveoli
- Alveoli cannot recoil + expel air
- Alveoli die, reducing SA, reducing gas exchange
- Increases PVR
- Shortness of breath, wheezing |
| COPD meaning | - Chronic obstructive pulmonary disease |
| Risk factors for lung disease | - Smoking, 90% with COPD are smokers
- Air pollution
- Genetic make-up
- Frequently getting chest infections
- Occupation, environment with harmful substances |
| Asthma | - Airways become inflamed + irritated
- Allergic reaction to pollen + dust
- During asthma attack, smooth muscle lining bronchioles contract, lots of mucus produced
- Constricts airways
- Cannot breath properly
- Reducing FEV
- Wheezing, tightness of chest, shortness of breath |
