Why are lungs situated inside the body? (2)
-Air is not dense enough to support and protect delicate structures -They would lose a great deal of water and dry out
What do the rings of cartilage supporting the trachea do?
Prevent trachea collapsing as air pressure inside falls when breathing in.
What are the tracheal walls made up of and what is the function of these things.
Muscle lined with: ciliated epithelium and goblet cells- goblet cells produce mucus that traps dirt particles and bacteria from the air breathed in. The cilia move the mucus full of dirt and microorganisms, up the throat, from where it passes down the oesophagus into the stomach.
What are the bronchi?
Two divisions of the trachea, each leading to one lung. Supported by cartilage. Produce mucus to trap dirt particles and have cilia to move it up throat and down oesophagus.
What are the bronchioles and what allows them to do their job?
Series of branching subdivisions of bronchi. Walls made up of muscle lined with epithelial cells. Muscles allow them to constrict so they can control the flow of air in and out of the alveoli.
What are the alveoli?
Minute air-sacs at the end of the bronchioles.
What do the alveoli contain and what do these allow them to do?
They contain COLLAGEN and ELASTIC FIBRES, they are lined with EPITHELIUM.
The elastic fibres allow them to stretch as they fill with air when breathing in.
They then spring back during breathing outin order to expel CO2 rich air.
ALVEOLAR MEMBRANE IS THE GAS EXCHANGE SURFACE.
Air constantly moving in and out of lungs to maintain diffusion across the alveolar epithelium.
When the air pressure of the atmosphere is greater than the air pressure inside the lungs, air is forced into the alveoli. INHALING
When the air pressure inside the lungs is greater than that of the atmosphere, air is forced out of the lungs. EXHALATION
What is the diaphragm?
A sheet of muscle that separated the thorax from the abdomen.
Where are the intercostal muscles?
Between the ribs.
Explain the PROCESS of inspiration.
ACTIVE PROCESS (Uses energy) -External intercostals contract, while internal relax. -Ribs pull upwards and outwards, increasing volume of thorax. -Diaphragm muscles contract, causing it to flatten, increasing vol. of thorax. -Increased vol. of thorax results in reduction of pressure in lungs. -Atmospheric pressure>pulmonary pressure. AIR FORCED IN.
Explain the PROCESS of expiration.
Largely PASSIVE PROCESS(not much energy needed) - Internal intercostal muscles contract, while external relax. -Ribs move downwards and inwards, decreasing volume of thorax. -Diaphragm muscles relax (return to domed position), decreasing vol. of thorax. -Increased pressure in lungs. -Pulmonary pressure>atmosphere AIR FORCED OUT
What is PULMONARY VENTILATION?
The total volume of air that is moved into the lungs in one minute. Tidal volume- air normally taken in at each breath at rest. Ventilation- number of breaths taken in one minute PV(dm3min-1)=tidal vol.(dm3)xventilation rate(min-1
What are the essential feature of gas exchange surfaces? (5)
-Large SA:Volume ratio (speed up rate of exchange)
-V. thin (short diffusion pathway, speed)
-Partially permeable- selected materials diffuse easily.
-Movement of environmental medium(eg. air)- maintain diffusion gradient.
-Movement of internal medium (eg. blood)- Maintain diffusion gradient.
Diffusion is proportional to: SA x difference in concentration/length of diffusion path
Why is diffusion of blood across the alveoli very quick? (5)
-Red blood cells slowed as pass through pulmonary capillaries (v. narrow), allowing more time for diffusion.
-Red blood cells pressed against capillary walls, reduced distance.
-V. thin walls of capillaried and alveoli, short diffusion pathway.
-Alveoli and capillaries have v. large total SA.
-Breathing movements constantly ventilate the lungs, heart constantly circulates blood. Ensure steep conc. gradient of gases maintained.
Causes (2) and Symptoms (5) of PULMONARY TUBERCULOSIS.
CAUSE: 2 species of rod- shaped bacteria: MYCOBACTERIUM TB. MYCOBACTERIUM BOVIS SYMPTOMS: -Persistant cough -Tiredness -Loss of appetite/ weight loss -Fever -Coughing up blood
How is TB transmitted?
THROUGH AIR BY DROPLETS -Coughing/ Sneezing/Laughing/Talking. USUALLY TAKES PROLONGED CONTACT (Family/friends/colleagues/etc.) COWS-HUMANS (M. BOVIS)
Who is at a greater risk of contracting TB? (4)
-Close contact with infected
-Live/work in long term care facility
-From a country where TB is common
-Reduced immunity (eg.AIDs)
What is the course of PRIMARY INFECTION of TB?
-Bacteria grow & divide within upper regions of lungs (PLENTY O2).
-IMMUNE SYSTEM RESPONSE-white blood cells accumulate at site of infection and ingest bacteria.
-Leads to INFLAMATION/ ENLARGEMENT of LYMPH NODES, that drain that are of the lung.
FEW SYMPTOMS, INFECTION USUALLY CONTROLLED WITHIN A FEW WEEKS. SOME BACTERIA USUALLY REMAIN
Course of POST-PRIMARY TB.
-Years after PRIMARY, bacteria may re-emerge to cause 2nd infection.
-Also arises in upper lung but is not so easily controlled. BACTERIUM DESTROY TISSUE OF LUNG. Results in CAVITIES and scar tissue.
-Damaged lung coughed up with blood.
-WITHOUT TREATMENT CAN SPREAD TO THE REST OF BODY AND BECOME FATAL.
When does PULMONARY FIBROSIS arise?
When scars form on epithelium tissue of lungs, causing them to become irreversibly thickened.
Why does PULMONARY FIBROSIS reduce the efficiency of gas exchange?
Diffusion pathway lengthened by scar tissue and volume of air lungs can contain has been reduced. Reduces elasticity so difficult to breathe out and therefore ventilate lungs.
What are the symptoms of P. Fibrosis and how are the causes? (4)
-SHORTNESS OF BREATH, (espec. when exercising)- Air space in lungs being taken up by fibrous tissue. Increased diffusion path. Difficult ventilation.
-CHRONIC, DRY COUGH- fibrous tissue creates obstruction of airways. Reflex.
-CHEST PAIN- Pressure and damage from mass of fibrous tissue and damage and scarring from coughing.
-WEAKNESS AND FATIGUE- Reduced O2 intake, less release of energy from cellular resp.
What is ASTHMA?
A localised allergic reaction.
What are some examples of allergens and triggers?(ASTHMA)
Pollen, animal fur, faeces of house dust mites. Air pollutants, exercise, cold air, infection, anxiety, stress.
What is the affect of the chemical histamine, the release of which is triggered by allergens. (RELEASED BY WHITE BLOOD CELLS)
-Lining of airways inflamed
-The cells of epithelial lining secret more mucus.
-Fluid leaves capillaries and enters airways.
-Muscle surrounding bronchioles contracts and constricts airways.
Symptoms and causes of ASTHMA. (4)
DIFFICULTY BREATHING- Constriction of bronchi and bronchioles. (mucus/fluid/inflamation)
WHEEZING-air passing through constricted bronchioles.
TIGHT CHEST- not being able to ventilate lungs properly. -
COUGHING- Reflex to obstructed bronchi(oles).
Cause of ASTHMA
Genetics, increase in air pollution/ stress/ chemicals, cleaner lifestyles.
What is the cause of EMPHYSEMA
What happens to emphysematous lungs?
Elastin has become permanently stretched and lungs are no longer able to force out all the air from the alveoli. SA of alveoli reduced, sometimes burst.
Symptoms of EMPHYSEMA and explanation. (3)
SHORTNESS OF BREATH- difficulty exhaling air, not enough fresh air inhaled, reduced levels of O2.
CHRONIC COUGH- lung damage, reflex to remove damaged tissue and mucus. Can not be removed because of destroyed cilia.
BLUISH SKIN COLOURATION- low levels of O2.
What are the risk factors of lung disease?(5)
-GENETIC MAKE-UP- genetically more/less likely -
INFECTIONS- frequent chest infections, higher risk -
OCCUPATION- Chemicals/ gases/ dusts