Breathing system

Objectives

To understand the role of the parts of the breathing system

To know how the breathing system is designed for efficiency

To understand gas exchange in the alveolus

To learn the breathing action

To understand factors that affect the health of the breathing system.

The parts

The parts continued

Parts and roles

Nose and mouth for inhaling, warming and cleaning inspired air and exhaling waste air

Trachea (wind pipe) takes air down to bronchi

Cartilage rings hold open air tubes

Bronchi: tubes leading to each lung (one bronchus)

Bronchioles subdivided air tubes in lungs – get progressively smaller

Alveoli (1 alveolus) microscopic sacs where gas exchange occurs

Associated parts and roles

Epiglottis prevents food entering trachea

Larynx vibrates in exhaled air to produce sound

Ribs protect lungs and have a role in breathing

Intercostal muscles lift ribs up when they contract

Diaphragm – muscular sheet separating thorax from abdomen. Falls when it contracts to allow breathing in.

Breathing

• http://video.about.com/asthma/How-Lungs-Function.htm

Breathing activity

Breathing in (inspiration/inhalation)

Higher pressure outside the body forces air in through the nose

Air pressure in thorax falls

Volume of thorax expands

If deeper breathing is required intercostal muscles contract and lift rib cage up

Diaphragm contracts and drops

Carbon dioxide concentrations rise in the lungs stimulating the breathing response

Breathing out (expiration/exhalation)

Air forced up out of breathing tubes to nose and out to where air pressure is lower.

Air pressure in thoracic cavity rises

Volume of thorax reduced

Diaphragm domes up, rib cage falls

Both sets of muscles relax

Efficiency features of lungs

The lungs must be efficient at exchanging gases to supply sufficient oxygen to the body cells

Large surface area (a tennis court) due to millions of alveoli

Rich blood supply due to millions of capillaries

Thin, moist surface allows rapid diffusion of gases

The lungs can clean themselves

• http://www.youtube.com/watch?v=HiT621PrrO0&feature=related

• http://www.youtube.com/watch?v=miEEluVlemQ

• (both videos cover similar subject matter, i.e. how the lungs clean themselves). It is worth looking at both.

Summary of cleansing features

Hairs in nose trap large particles

Mucus from goblet cells traps smaller particles

Cilia move trapped particles out of lungs and down to stomach

Phagocytes (white blood cells) consume pathogens and other particles on the surface of the lungs

Alveoli

Gas exchange in the alveoli

Chemistry of gas exchange

Summary

Oxygen carried by haemoglobin in red blood cells

Oxygen diffuses across the alveolar and capillary walls to join with haemoglobin in the red blood cells

Carbon dioxide carried as bicarbonate ions in the plasma and released across the capillary and alveoli walls to the alveolus

Smoking

Key toxins

Carbon (soot)

Carbon monoxide

Tar

Nicotine

Carbon/soot

Product of incomplete combustion

Irritates the lung lining

Leads to coughing

Builds up in lungs due to death of cilia

Causes inflammation and damage to bronchioles and alveoli

Leads to prolonged cough – chronic bronchitis

Leads to destruction of alveoli

Leads to COPD Chronic obstructive pulmonary disease (also called emphysema)

Reduces uptake of oxygen from lungs – very debilitating

Carbon monoxide

Product of incomplete combustion of carbon

Preferentially binds to haemoglobin

preventing uptake of oxygen

Reduces the amount of oxygen in the blood

Means heart has to work harder

Raises blood pressure

Increased heart strain

TarA complex mixture

of organic compounds

Many are known carcinogens

Kills cilia in lungs

Stops the cleaning mechanism of the

lungs (see soot)

Stimulates uncontrolled

growth of cells lining lung

Leads to lung cancer

NicotineAddictive stimulant

drug

Increases heart rate thus causing

strain to the heart

Causes thickening of the blood

Leads to deposition of fat in

arteries (called plaques)

Results in blockage of arteries

Prevent supply of oxygen to tissues

Leads to tissue death (in heart to

heart attacks)

In extremities to gangrene

Additional medical issuesReduced blood flow and poor blood oxygen concentration inhibits growth and development of the foetus

Babies born premature and underweight

Reduced survival of babies

Leads to impotence

Ages skin

Particularly dangerous in diabetics due to predisposition for quicker ageing of arteries.

Possible links to a wide range of other cancers

Giving up

Many medical practices and workplaces have smoking cessation sessions (UK)

Save money you would spend on cigarettes and reward yourself

Nicotine patches, lozenges and gums

Special medications Zyban and Chantix (may have side affects)

Hypnotherapy and acupuncture.

Willpower

Nicotine inhalators

Other causes of lung disease

Pathogenic e.g. tuberculosis

Asbestos – asbestosis is a very serious form of lung disease leading to cancer

Silicosis common in coal miners. Small particles of silica lodge in lungs causing scar tissue and destroying lung function

Smoke fires. Many poor people in the developing world cook over wood fires. The smoke slowly kills them.

Homework

Produce an information leaflet to discourage people from smoking/to help them give up

Use clear simple language – this is for the general public not scientists

Explain the risks to health (list main diseases)

Explain what causes it (explain role of main toxins)

Use powerful imagery

Be precise

Don’t preach

Smoking leaflet rubricMarks Information Language presentation

1 1 health risk identified Totally inappropriate Just writing

2 All four toxins identified Scientifically correct but too hard to understand

Some visual material

3 At least 4 health risks identified

Some good explanations but other areas too scientific

Visual material integral to understanding/message

4 At least one health risk linked directly to toxin

No evidence of patronizing attitude

Text well spaced round page

5 Most health risks identified No sense of being lectured Good use of emboldened subheadings to attract attention

6 Most health risks correctly linked to toxins

Very clear and mostly understandable

Some imaginative presentational ideas

7 All health risks fully outlined and linked to poisons in smoke

Clearly explained in lay mans terms – fully understandable to all

Exceptionally professional with innovative techniques of presenting information