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2727425
The lungs and lung disease
Description
Revision of lung structure and lung diseases from 4.5 of Nelson Thornes AS Biology book plus extra information (in square boxes)
No tags specified
lungs
tb
pulmonary
pulmonary tuberculosis
tuberculosis
pulmonary fibrosis
asthma
aqa
biology
as level
emphysema
alpha-1 antitrypsin deficiency
Mind Map by
charharrison
, updated more than 1 year ago
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Created by
charharrison
over 9 years ago
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Resource summary
The lungs and lung disease
Structure of human lungs
Trachea
Supported by rings of cartilage to prevent collapse when breathing in
Walls made up of muscle and ciliated epithelium
Goblet cells produce mucus that traps dirt/pathogens
Bronchi
2 subdivisions of trachea
Lined with cilia
Supported by rings of cartilage, amount reduces are bronchi get smaller
Bronchioles
Subdivisions of the bronchi
Lined with muscle
Allows them to constrict and control airflow
Alveoli
Air sacs at the end of bronchioles
Contain collagen and elastin
Fibrous proteins, collagen - high tensile strength, elastin is elastic!
Mixed to prevent elastin overstretch
Squamous epithelium
Thin cells - short diffusion pathway
Large sa:v ratio
Partially permeable
Rich supply of capillaries
Narrow so red blood cells are flattened against them
Shorter diffusion distance
Slows rbc's allowing more time for diffusion
Endothelium is one cell thick
Equations
Pulmonary ventilation = tidal volume (dm^3) x ventilation rate (min^-1)
Fick's Law
Diffusion is proportional to
Surface area x conc. gradient / length of diffusion pathway
Pulmonary Tuberculosis
Caused by 2 species of rod-shaped bacteria
Mycobacterium tuberculosis
Mycobacterium bovis
Symptoms
Persistent cough
Tiredness
Loss of appetite
Weightloss
Development can lead to coughing up blood and fever
Transmission
Airborne droplets
Close contact over long period of time
Infected cows milk
People with reduced immunity more susceptible, eg:
HIV/AIDS
Very young and old
Immunosuppressant drugs
Course of infection
1. The bacteria grow and divide in the upper regions of the lungs
2. The body's immune system responds with white blood cells accumulating in the area
3. This causes inflammation, enlargement of lymph nodes - PRIMARY INFECTION
4. Some bacteria remain in tubercules surrounded by white blood cells with the bacteria and infected phagocytes in the middle
5. POST-PRIMARY INFECTION can occur years later when the immune system is weakened
6. The bacteria reproduce quickly, destroying the lungs and causing cavities
Hence, sufferers cough up damaged tissue and bacteria, and scar tissue develops
7. The bacteria may spread to other regions if they reach blood supply
Pulmonary fibrosis
Scar tissue on epithlium
Irreversibly thickens the alveoli walls
Longer diffusion pathway
Less efficient gas exchange
Smaller lung volume
Reduces elasticity
Lack of elastic recoil
Makes breathing more difficult
Difficult to maintain conc. gradient
Effects
Shortness of breath
Chronic, dry cough
Pain and discomfort in chest
Weakness and fatigue
Causes
Microscopic injury (asbestosis)
Unknown (idopathic)
Damage to alveoli resulting in overproduction of fibroblasts
Asthma
Causes
Genetic predisposition
Allergens
Anxiety, cold air, exercise can worsen or trigger asthma
1. Allergens cause white blood cells on the linings in the bronchi and bronchioles to produce histamine
2. Histamine causes the following effects in the airways
Inflammation
Increased mucus secretion
Fluid leaving capillaries and entering airways
Contraction of smooth muscle surronding bronchioles constricting airways
Effects
Greater resistance to the flow of air
Difficult to ventilate lungs and maintain conc. gradient
Difficulty breathing
Wheezing
Tigh-chest feeling
Coughing
Emphysema
Usually a result of long term smoking
Particles from smoke cause immune response, over a long time of smoking the enzymes released by white blood cells breaks down elastin
Lack of elastic recoil
Alveoli burst
Reduced surface area
Alpha-1 Antitrypsin Deficiency
Mutation to the gene coding for the enzyme alpha-1 antitrypsin,gets stuck in the liver
Enzyme protects the lungs from neutophil elastane which breaks down elastin
Often looks like emphysema
Injection of alpha-1 antitrypsin and gene therapy is promising
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