Human gas exchange and lung disease and pollutants Flashcards
What does the cartilage do in human gas exchange
- Cartilage is a strong and flexible and found in many places
. One place is in rings along trachea, called tracheal rings they support the trachea and ensures it stays open, while allowing it to move and flex as we breathe
What is a specialised tissue in human gas exchange
Ciliated epithelium - specialised cell along the trachea down to the bronchi. Each cell has small projections of cilia which sweep mucus away from the lungs and the epithelium itself
What is the structure of the humans gas exchange
Air enters the trachea. The trachea splits into 2 bronchi (one bronchus to each lung). They then branch off into bronchioles. The bronchioles end with alveoli’s the sight of gas exchange
What are the intercostal muscles
Muscles found between the ribs
internal intercoastal and external intercoastal
What is the process of inhalation
is this an active or passive process
- External intercostal muscles contract which moves the ribcage up and out
- The diaphragm contracts and flattens
- The volume of the thorax increases and pressure decreases to below atmospheric pressure
- Air will flow in from an area of high pressure to low pressure (down concentration gradient) so it flows down the trachea into the lungs
Active process so requires energy
What happens during exhalation
- The external intercoastal muscles relax and the ribcage moves down and in
- The diaphragm relaxes and becomes dome-shaped
- Volume of the thorax decreases and the pressure inside the thorax increases
- Air is forced out by the recoil of elastic fibres surrounding the alveoli’s
Is exhalation an active or passive process
What happens if it is forced?
Usually a passive process
In forced exhalation (e.g. blowing candles out) the external intercoastal muscles relax and the internal intercoastal muscles contract pulling the ribcage further down and in
Movement of 2 sets of intercoastal muscles is said to be antagonistic (opposite)
How do you work out the PVR
PVR (dm^3/min)=
Tidal volume (dm^3) x Breathing rate (per min)
What is the PVR
Pulmonary ventilation rate
Volume of air breathed (in or out) in one minute
What is gas exchange like in the alveoli
-Surrounded by capillaries
- Diffusion of carbon dioxide out of the capillaries into the alveoli due to there being a high concentration of carbon dioxide in the capillaries (one cell think)
- Diffusion of oxygen out of the alveoli into the capillaries due to there being a higher concentration of oxygen inside the alveoli’s
What are the adaptations of the alveolar epithelium
- Alveoli are tiny air sacks and there are 300 million in each human lung creating a large surface area
-The alveoli epithelium cells are very thin (one cell thick) to minimise diffusion distance - Each alveolus is surrounded by capillaries to remove exchanged gases and they have a constant flow of blood (e.g. to transport oxygenated blood) to maintain a concentration gradient
What is gas exchange like in the Alveoli
- They are surrounded by capillary’s
- There is a simple diffusion of
carbon dioxide into the alveoli due there being a higher concentration in the capillary’s - There is a simple diffusion of oxygen out of the alveoli die to there being a higher concentration of oxygen inside the alveoli
What are the adaptations of the alveoli
- There are a large number of small alveoli (300 million) in each lung creating a large surface area for gas exchange
- The alveoli have very thin walls (one cell thick) to make a short diffusion distance
- Each alveoli is surrounded by capillary’s keeping a constant flow of blood and maintaining a concentration gradient
(capillary’s also one cell think minimising diffusion distance) - Walls of the alveoli also contain a protein called elastin which helps it to return to its normal shape after gas exchange
what are the walls of the alveoli and capillary’s called
Alveoli epithelium and capillary epithelium
What are 2 types of lung disease
- Lung cancer
- COPD
How does lung cancer occur?
- Occurs due to mutations in oncogenes or tumour suppressor genes of the bronchial epithelial cells
- This causes uncontrolled mitosis and develops into a mass of cells in the lumen of the airways
- The tumour becomes larger as it has no method of apoptosis (programmed cell death) and survived due to developing its own blood supply
What does lung cancer do?
What are the symptoms?
- The tumour interferes with normal workings of the lungs, such as squeezing against blood cells or cancer cells entering the lymphatic system
Symptoms - Coughing up blood, Persistent cough, increased mucus, wheezing, breathing difficulties etc
What is the lymphatic system
A group of organs, vessels and tissues that protect you from infections
What is COPD
Chronic obstructive pulmonary disease
also includes chronic bronchitis and emphysema
How does COPD occur
What happens to the cilia and alveoli’s (hint)
- Enlarged goblet cells produce more mucus destroying the cilia in the trachea preventing them sweeping away the mucus
- Mucus narrows bronchioles causing coughing, scar tissue and infection
- Elastase is released which damages the elasticity of alveolar walls decreasing surface area
- Without enough elastin the alveoli breaks down creating large air spaces causing wheezing and breathlessness
What are the symptoms of COPD and what may be required with advanced COPD
Symptoms - shortness of breath, chronic cough, chest tightness, wheezing and difficulty during physical activities
Advanced COPD may require a constant supply of oxygen at all times
What chemicals does smoking cigarettes include and what do they do to the lungs
. Tar - A carcinogen (substance that causes cancer) plus more
. Nicotine - An addictive substance which narrows blood vessels
. Carbon monoxide - Reduces oxygen carrying capacity of the blood
What are the effects of smoking on air passages
Tar destroys the cilia (that carry’s mucus away from the lungs), causing a build up of mucus and potentially leading to bronchitis as the lining of the bronchi becomes irritated
What are the effects of smoking on the alveoli
- Tar continues to break down the walls of the alveoli causing them to merge together
- This creates an insufficient surface area to volume ratio allowing less gas exchange
- This reduces the efficiency of gas exchange causing emphysema where less oxygen is carried in the blood
- Tar can also build up to form a layer on top of the alveolar wall increasing diffusion distance
