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level: 6.8 Exchange of gases in the lungs

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level questions: 6.8 Exchange of gases in the lungs

QuestionAnswer
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