Gas Exchange (in humans) Flashcards
(23 cards)
Describe the path which air enters the human body
Trachea (windpipe)
Two bronchi (one bronchus leading to each lung)
Bronchioles (smaller tubes)
Alveoli (air sacks)
What is ventilation?
Breathing in and out (inspiration and expiration)
Describe the process of inspiration
Intercostal and diaphragm muscles contract
Causes ribcage to move up and outwards Diaphragm to flattens
Lung pressure decreases below atmospheric pressure
Air flows into lungs
Describe the process of normal expiration
Intercostal and diaphragm muscles relax Ribcage moves down and inwards Diaphragm becomes curved again Volume of thorax decreases and case air pressure to increase Air forced out of lungs
Is inspiration active or passive?
Active
Is normal expiration active or passive?
Passive
Describe the process of forced expiration (e.g. Blowing out candle)
External intercostal muscles relax
Internal intercostal muscles contract
Movement of intercostal muscles is antagonistic (opposing)
Where does gas exchange happen in the lungs?
Alveoli
How are alveoli adapted for gas exchange?
Large surface area
One cell thick
Next to blood capillary
What is tidal volume?
Volume of air in each breath
What is ventilation rate?
Number of breaths per minute
What is forced expiration volume?
The maximum volume of air that can be breathed out in 1 second
What is forced vital capacity?
The maximum volume of air that is forcefully breathed out after a deep breath
What is TB?
Tuberculosis bacteria
How does TB form tubercles? (Small, hard lumps in lungs)
Immune system builds a wall around the tuberculosis bacteria
Infected tissue within tubercle dies and damages gas exchange surfaces
What are the symptoms of TB?
Coughing blood and mucus, shortness of breath, chest pains, fatigue
What is fibrosis?
The formation of scar tissue in the lungs
What is residual volume?
The volume of air remaining in the lungs after expiration
How does fibrosis prevent gas exchange?
Scar tissue is thicker and less elastic - lungs can’t expand as much
What is asthma?
A respiratory condition where the airways become inflamed and irritated (result of allergy to pollen/dust)
What happens during an asthma attack?
The muscle lining the bronchioles contract and lots of mucus produced- causes constriction of the airways
What is emphysema?
Lung disease caused by smoking or long term exposure to air pollution
Explain how emphysema causes shortness of breath
Particles become trapped in alveoli Causes inflammation Phagocytes attracted to area Produce enzyme which breaks down elastin Leads to destruction of alveoli walls
