Overview

The respiratory system is vital to the survival of mammals. It ensures that an organism has enough oxygenated blood.  All organisms require oxygen to survive thus the respiratory system is essential to survival.  The respiratory system is responsible for delivering oxygen to the blood for it to be distributed around the body.  The respiratory system is also responsible for removing Carbon Dioxide from the blood.  The respiratory system works closely with the circulatory system.     

Structural Features

The major parts of the respiratory system are the lungs, trachea, larynx, nose, mouth, bronchi, bronchioles and alveoli. Air travels through the nose or mouth and passes into the pharynx (throat). The air then moves down the trachea (windpipe) and separates into two tubes known as bronchi. Epithelial cells that line the bronchi and trachea secrete mucus. Cilia is found on many epithelial cells, they filter out foreign materials and move mucus. The bronchi branch out into many bronchioles. Each bronchiole separates in to a number of alveoli; small sacs of air designed to accommodate gas exchange. 

Breathing

The diaphragm, a powerful muscle located beneath the lungs, causes the lungs to inflate.  This inflation draws air into the alveoli through the trachea, bronchi and bronchioles.  The diaphragm then causes the lungs to deflate, pushing deoxygenated air out of the lungs. Breathing is characterised by two processes: inhalation (breathing in) and exhalation (breathing out).  It is important to note that breathing is not the same as respiration, but merely a part of the system.

Gas Exchange

Gas exchange is the process by which oxygen enters an organism and Carbon dioxide is removed from an organism.  Not all organisms use gas exchange.  During the process of gas exchange, newly inhaled air is drawn into the alveoli of the lungs alveoli.  Alveoli are small sacs of tissue lined with many capillaries (small blood vessels). As the air enters them, the process of diffusion occurs. Because there is a high concentration of oxygen in the air and a lower concentration in the blood, some of the oxygen in the air transfers through a membrane to the blood.  Carbon dioxide diffuses also through the membrane form the blood into the air.

Respiratory System in Other Animals

The respiratory system of most animals differs considerably from that of humans. For instance, birds do not possess a diaphragm. They instead boast numerous air sacs which store oxygen-rich and oxygen-deprived air in separate regions. These air sacs open and close rhythmically, flushing out air deprived of useful gases, and sucking in fresh air. This method is much more efficient than that of humans, because it ensures a constant supply of oxygen, rather than an intermittent one. Another example of an animal with a different respiratory system is a fish. They have a specialized structure for respiration know as ‘gills’. Gills consist of many layers of folded tissue, stacked in two lung-shaped adjacent piles. The gill tissue is folded and stacked to increase the surface area of water contacting tissue. This adaptation is in place because water generally has a low oxygen content compared to air, so in order to sustain a large organism, lots of water contacting tissue is required. Many blood vessels are interspersed in the tissue; the oxygen in the water is transferred to the blood through the process of diffusion.

Diseases of the Respiratory System

Tuberculosis is an infectious disease that is easily passed between people when bacteria enter one’s body through breathing. The bacteria population grow inside a person’s lungs and can spread to other parts of the body. Some symptoms of Tuberculosis are chest pain, fever, coughing and weight loss.  Tuberculosis can be fatal if not treated in time.

Lung cancer is the most common cancer in both males and females.  Tobacco smoke contains carcinogens that can cause cancer of not only the lungs but also the mouth, bladder, larynx and pancreas.

Severe Acute Respiratory Syndrome (SARS) originated in China, but has spread to over 35 countries across the world. In Canada, around 440 people are infected and roughly 10% die each year. To identify SARS, a chest x-ray is taken to look for pneumonia.  Symptoms of SARS are high fevers, influenza symptoms, dry coughing, sore throat, muscle pain, exhaustion, and short breathing.

Bibliography

Wikipedia (For numerous articles)

mynelsonscience.com

Google images (Diagrams and backgrounds)

Quiz

1. Which is not a part of the Respiratory system, Larynx, Trachea, Tibia or Cilia?
2. Epithelial cells are inside the bronchi and trachea. Name is one of their functions?
3. What specialized structure do fish have in their respiratory system?
4. What is the name of the process by which blood becomes oxygenated?
5. What specialized structure does a bird have in their respiratory system?
6. What muscle allows the intake of oxygen?
7. Which cancers other then lung can be caused by carcinogens in tobacco smoke?
8. What was the fatality rate of SARS in Canada?
9. What is the primary function of the respiratory system?
10. What is another function of the respiratory system?
11. Is breathing the same as respiration?
12. What is the technical term for breathing out?


Answers
1. Tibia
2. Produces mucus to line the bronchi and trachea
3. They have gills
4. Diffusion
5. More air sacks then a human, no lungs
6. Diaphragm
7. Mouth, bladder, larynx and pancreas
8. roughly 10%
9. To oxygenate the blood
10. Remove CO2 from the blood
11. No, breathing is a part of respiration
12. Exhalation