Lungs and Lung Disease

Expiration/Exhalation

1. Internal intercostal muscles contract. 2. External intercostal muscles relax. 3. Ribs are pulled downwards and inwards. 4. This decreases the volume in the thorax. 5. Diaphragm muscles relax, causing it to returns to its upwardly domed position. 6. This further decreases the volume in the thorax. 7. The decrease volume of the thorax increases the pressure in the lung. 8. Pulmonary pressre is now greater than atmospheric pressure. 9. AIR MOVES FROM HIGHER TO LOWER PRESSURE, DOWN A PRESSURE GRADIENT. 10. As a result, air is forced out the lungs.

Why is the percentage of nitrogen lower in exhaled air rather than inhaled air

1. Its volume is the same 2. BUT its percentage decreases because due to greater volume of water vapour in exhaled air = increase in percentage of water vapour

How does one get PF?

1. Lung tissues tries to repair itself, e.g. when there are cavities. 2. Arises when scars from on the epithelium of the lungs. 3. Causes them to become irreversibly thickened. (to diffusion respiratory gases, linings of alveoli need to be thin).

The concentration of water vapour is higher in the alveolus than in the atmospheric air

1. (Lining of) alveoli moist/surface film of fluid/water; 2. Evaporates; 3. Due to warm body temperature

What is asthma?

1. A respiratory condition where the airways become inflamed and irritated = a localised allergic reaction. 2. Reaction to substances like pollen, dust, animal, fur, faeces of house dust mites, air pollutants, exercise, anxiety, stress, infection, genetics.

Air when first exhaled as same oxygen percentage as atmospheric air

1. Air is from nose/trachea 2. Has not been in the alveoli 3. GAS EXCHANGE ONLY IN ALVEOLI, NOT IN THESE STRUCTURES

Passage of molecule from alveolus to the blood

1. Alveolar epithelium 2. Capillary endothelium

Structure of the alveoli.

1. Alveoli = large surface area of volume ratio = fast diffusion. 2. There are MANY alveoli = large surface area for gas exchange = fast diffusion. 3. MANY capillaries = provide a large SA = fast diffusion. 4. Constant blood flow through pulmonary capillaries/circulation = maintains concentration gradient = fast diffusion. 5. Ventilation = maintains concentration gradient = fast diffusion. 6. Alveolar epithelium, single layer of thin flat cells/ flattened, squamous epithelium = short diffusion pathway between alveoli + blood = fast diffusion. 7. Capillary endothelium, 1 cell layer = short diffusion pathway = fast diffusion. 8. Partially permeable membrane = allows oxygen molecules to diffuse through. 9. Red blood cells are flattend against capillary walls = shorter diffusion distance between alveolar air and RBCs. 10. Red blood cells slowed as they pass through pulmonary capillaries = more time for diffusion.

The alveoli

1. Are surrounded by a network of capillaries. 2. High conc of CO2 in blood and low conc of O2 in blood. 2. Breathing movements constantly ventilate the lungs.

How does one get pulmonary TB?

1. Bacteria inhaled. 2. Bacteria engulfed/ingested by phagocytes/macrohages. 3. Bacteria encased in tubercle. 4. Bacteria are dormant/inactive. 5. If immunosuppressed, bacteria active, replicate + are released. 6. Bacteria destroy alveoli, produces cavities 7. Leads to fibrosis, cavities where lungs repairs itself. 8. Damage leads to less diffusion because: - Less surface area - Increase diffusion distance - Reduced concentration gradient as tidal volume, poor ventilation, elasticity. 9. Damage allows bacteria to enter the blood. 10. Spreads to other organs via bloodstream.

Why is the volume of oxygen and carbon dioxide large?

1. Because mammals are relatively large organisms. 2. Have a large volume of cells. 3. Maintain a high body temp. 4. Therefore have high metabolic, and thus high respiratory rates.

How does oxygen move into the blood?

1. By diffusion. 2. Across alveolar epithelium/capillary endothelium.

All aerobic organisms require:

1. Constant supply of ocygen to release energy in the form of ATP during respiration. 2. Carbon dioxide which is produced in the process to be removed = build up can be harmful to the body.

Describe the part played by the diaphragm

1. Contracts 2. Flattens 3. Increase volume in chest 4. Reduces pressure allowing air to entr

Effects of TB

1. Cough up damaged lung tissue containing bacteria + blood. 2. Chest pains. 3. Shortness of breath. 4. Fatigue. 5. Reduction in appetite = weight loss.

Emphysema is a disease which affects the lungs It causes a decrease in the number of alveoli. It may also cause the alveolar walls to become thickened. Explain why people with emphysema may need to use oxygen masks to help with their breathing.

1. Decreases surface area; 2. (Thick wall) slows down diffusion rate / increases diffusionpathway 3. Mask increases concentration gradient / difference!

What happens when you have asthma?

1. Difficulty breathing: - Constriction of bronchi/bronchioles, inflamed linings, fluid and additional mucus within them. 2. Wheezing sound: - Air passing through very constricted bronchi/bronchioles. 3. Tight feeling in chest: - Not be able to ventilate lungs adequately. 4. Coughing: - Reflex response to obstructed bronchi and bronchioles in an effort to clear them.

Inspiration/Inhalation

1. External intercostal muscles contract. 2. While internal intercostal muscles relax. 3. Ribs are thus pulled upwards and outwards. 4. This increases the volume of the thorax. 5. Diaphragm muscles contract, causing it to flatten. 6. Further increases volume of thorax. 7. Increased volume of thorax results in the reduction of pressure in the lungs. 8. Atmospheric pressure is now GREATER than pulmonary pressure. 9. AIR MOVES FROM HIGHER TO LOWER PRESSURE, DOWN A PRESSURE GRADIENT. 10. As a result, air is forced into the lungs.

Effects of emphysema

1. Feel weak: -Increase diffusion pathway, decreased surface area, reduced concentration gradient. - Less diffusion = less oxygen enters blood. - Tissues recieve less oxygen. - Less respiration/lower rate. - Less energy released/less ATP produced = feel weak. 2. Shortness of breath: - If lungs cannot be emptied, difficult to inhale fresh air. - Difficulty ventilating lungs. - Less oxygen entering the blood. - Reduced levels of oxygen in blood means patient tries to increase oxygen supply by breathing more rapidly to replenish O2. 3. Chronic cough: - Consequence of lung damage. - Body's effort to remove damaged tissue and mucus that cannot be removed naturally because... - Cilia on bronchi/bronchioles are also destroyed. 4. Blueish colour: - Due to lowish levels of oxygen in the blood due to poor gas diffusion in the lungs.

The lungs of a mammal are adapted for gas exchange. Use your knowledge of Fick's law to explain how.

1. Fick's law as (Rate of) diffusion proportional to SA x diff in conc/conc grad ...DIVIDED BY: Thickness of (exchange surface/membrane/distance) 2. Many (small) alveoli; 3. Many capillaries; 4. Exchange surface consists of squamous/pavement epithelium/epithelial cells flat; = Short diffusion pathway (between lumen and blood)/thin for diffusion; 5. (Concentration difference maintained by) circulating blood; 65. (Concentration difference maintained by) ventilation/breathing;

What happens when you have emphysema?

1. Foreign (smoke) particles trapped in alveoli. 2. Causes inflammation, thickens alveolar walls, increase diffusion pathway, less diffusion. 3. Attracts phagocytes to the area. 4. They produce an enzyme which breaks down protein elastin. 5. Loss of elastin means alveoli can't recoil to expel air as well. 6. Air remains trapped in alveoli = stagnant, high in CO2 concentration = lungs cannot be emptied, more difficult to inhale fresh air, thus air is not replenished 7. Makes it more difficult to ventilate the lungs. 8. Causes a reduced diffusion/concentration gradient, less diffusion. 9. Stretched and damaged alveoli sometimes rupture/burst. 10. Destruction of alveoli reduces surface area of alveoli. 11. Less diffusion. 12. Rate of gaseous exchange decreases.

Problems with prevention and control

1. Increase in HIV infection = people with impaired immune systems = vaccination less effective at stimulating immunity =more likely to contract TB. 2. Mobile populations, global, tourism, refugees = difficult to ensure majority of individuals are vaccinated. 3. Proportion of elderly people in population increasing = less effective immune systems = vaccination is less effective at stimulating immunity.

How does PV increase during exercise

1. Increase in amount of air breathed in and out 2. Increase in number of breaths per minute

How does one get pulmonary TB?

1. M.TB bacteria inhaled. 2. Bacteria grow + divide in upper regions of lungs, where there is plenty of oxygen. 3. TB bacterium engulfed by phagocytes. 4. White blood cells accumulate at site of infection. 5. They build a wall around the bacteria in the lungs. 6. This encases the bacteria in small hard lumps called tubercles. 7. Leads to inflammation. 8. This is the primary infection = few symptoms, if any, and the reaction is controlled within a few weeks. 9. Some bacteria remain, dormant/not active. 10. Post-primary TB = immunosuppressed = bacteria activated +released. 11. Bacteria destroy the alveoli = reduced surface area. 12. Results in cavities, and where lung repairs itself = FIBROSIS/SCAR TISSUE. 13. Increased thickness of gas exchange, reduced tidal volume, poor ventilation. 14. Increased diffusion pathway/reduced concentration gradient. 15. Slow diffusion. 16. If bacteria enter bloodstream = spead to other parts of the body.

Prevention and control

1. Main measure = vaccination. 2.Vaccine is weakened/attenuated strain of M.bovis = TB in cattle. 3. Better and more housing = less crowiding. 4. Improved health facilities. 5. Better nutrition to ensure immune systems are not weakened by pure diet. 6. Drugs treatment= but some M.TB strains no longer respond to drugs.

Give two other ways in which the composition of the air in the alveolus differs from that of atmospheric air

1. More carbon dioxide 2. Less oxygen

How is asthma caused?

1. One or more of these allergens present. 2. Causes white blood cells in linings of bronchi/bronchioles to release a chemical called histamine, which has the following effects. 3. Lining of airways become inflamed. 4. Cells of epithelial lining secrete large quantities of mucus than normal. 5. Fluid leaves the capillaries and enters the airways also. 6. Muscles surrounding bronchioles/bronchi contract and so constrict airways. 7. Greater resistance to air flow in and out of the alveoli. = more difficult for air to pass through. 8. Air flow in and out of the lungs is severely reduced. 9. More difficult to ventilate the lungs. 10. Less oxygen enters the alveoli. 11. Makes it more difficult to maintain a concentration gradient across the exchange surface. 12. Less diffusion. 13. Less oxygen enters the blood. 14. Body cells recieve less oxygen. 15. Rate of aerobic respiration reduced. 16. Attacks can be relieved by drugs, in inhalers, that cause the muscle in the bronchioles to relax.

During exercise

1. PV increases

Ratio of height:breadth of an alveolus EPITHELIAL CELL

1. Ratio is SMALL 2. Because cell is thin, has a large surface area = adapted for diffusion

Describe how muscles in thorax/chest cause air to enter lungs

1. Refer to intercostal AND DIAPHRAGM

Cause of pulmonary fibrosis?

1. Result of an infection (TB) 2. Exposure to substances like asbestos/dust

How is emphysema caused?

1. Smoking = foreign particle in spoke. 2. Long term exposure to air pollution.

Where is the site of gas exchange in mammals?

1. The epithelium of the alveoli. 2. To ensure a constant supply of oxygen to the body, a diffusion graident must be maintained at the alveolar surface.

What happens during normal quiet breathing?

1. The recoil of the elastic lungs in the main cause of air being forced out. 2. Only more strenuous conditions such as exercise do the various muscles play a part.

How come fibrosis means oxygen diffuse into the blood as efficiently?

1. Thickened epithelium of alveoli = diffusion pathway considerably lengthened = less/slower diffusion. 2. Fibrous tissue takes up air space = volume of air in lungs reduced = reduces concentration gradient = slower diffusion. 3. Scar tissue is thicker, reduces elasticity of lungs = - Lungs cannot recoil. - Stagnant air, high in CO2 conc left in lungs. - Lungs are less able to expand. - Can't hold as much air as normal. - Difficulty ventilating the lungs. - Less air/oxygen taken into lungs at ea breath = tidal volume reduced. - Higher CO2 conc in alveoli. = Harder to maintain diffusion gradient, reduced concentration gradient = slower diffusion.

How is pulmonary TB spread?

1. Transmitted by droplet infection. 2. Droplets expelled via coughing/sneezing. 3. Droplets contain the bacteria. 4. Droplets are taking in through gas exchange system/nose/lungs. 5. TB is much more widespread in areas where: - Hygiene levels are poor. - People live in crowded conditions. - Also spread from cows to humans, milk may contain bacteria.

Effects of PF:

1. Weakness and fatigue: - Slower/less diffusion. - Reduced intake of oxygen into the blood. - Body cells recieve less oxygen. - Rate of respiration in cells reduced. - Less energy released. 2. Shortness of breath: - Diffusion of oxygen into blood is very slow. - Sufferers have faster breathing rate than normal to get enough air into their lungs to oxygenate their blood. 3. Chronic dry cough: - Fibrous tissue creates obstruction of airways lungs. - Body's reflex reaction is to remove obstruction via coughing. - Tissue is immovable. - Nothing expelled = cough is dry. 4. Chest pain and discomfort: - Pressure and damage from mass of fibrous tissue in lungs. - Further damage due to coughing/scarring.

Highlight distinction between a correlation and causal relationship

1. correlation indicates link between number of cigarettes smoked and incidence of emphysema; 2. does not show that smoking is the direct cause of emphysema;

Three differences between emphysema and asthma

1. emphysema is not an allergic reaction, asthma is. 2. Emphysema affects alveoli, asthma affects bronchi/bronchioles 3. asthma involves INFLAMMATION.

What could cause increase in the number of TB cases?

1. mutation 2. immigration 3. reduced vaccination 4. increase in social deprivation

Main emphysema points:

1. smoking 2. infection/bronchitis 3. heredity 4. inhalation of pollution particles

What is emphysema?

A condition in which the air sacs of the lungs are damaged and enlarged, causing breathlessness.

What is breathing out?

A largely passive process - does not require much energy.

What is ventilation

Air must be constantly moved in and out of the lings = in order to maintain diffusion of gases across alveolar epithelium.

What is breathing in?

An active process - it requires energy.

MUST ALWAYS

DESCRIBE SHAPE OF DIAPHRAGM = FLAT/DOMED

Transmission

DROPLETS IN THE AIR!!

TB more likely in crowded conditions

Droplet infection; Droplets (of mucus/saliva/fluid containing bacteria/TB) inhaled; More likely to occur when people are close together/reduced ventilation/explained;

What is pulmonary fibrosis?

Formation of scar tissue in the lungs.

What is pulmonary TB?

Lung disease caused by the bacterium: mycobacterium TB + bovis.

Explain what causes the concentration of carbon dioxide in the blood to increase during a period of exercise

Increased respiration; Carbon dioxide from muscles

Explain how you would calculate the volume of air taken into the lungs in one minute.

Multiply A / tidal volume / volume of breath by number of breaths per minute

Suggest why carbon monoxide is used for this test

Not normally present / needed; Any detected must have come from this testxplain what causes the concentration

Ventilation rate

Number of breaths PER MINUTE

all =

REDUCED GASEOUS EXCHANGE

Ventilation is important

Removes carbon dioxide; Supplies oxygen; Maintains concentration gradient; For diffusion;

Emphysema is a condition in which the walls between the alveoli break down and enlarge the air spaces. The blood of a person with emphysema contains a higher concentration of carbon dioxide than the blood of a healthy person.

Smaller surface area; For diffusion of carbon dioxide from blood / into lungs / diffusion slower.

Tidal volume

Volume of air in EACH BREATH

Pulmonary ventilation

Volume of air taken into the lungs in one minute, dm3min-1

Main factors for an investigation

large number in sample; equal number of males and females in each group; similar age; similar life style linked to other risks; healthy/no medical problems;

Symptoms of TB

persistent cough; fatigue; weight loss; coughing up blood;

Pulmonary fibrosis

reduces elasticity of the lungs; reduces exhalation/ventilation; epithelium thickened/scar tissue lining alveoli; increases diffusion pathway; reduced gaseous exchange;