respiration

When you breathe in or inhale, these changes happen:

1. The muscles in the diaphragm contract. This pulls the diaphragm downwards.

2. The intercostal muscles contract. This pulls the ribs upwards and outwards.

3. The lungs expand. When the volume increases, the pressure decreases in the lungs.

4. Air moves into the lungs from the nose/mouth.

When you breathe out or exhale, these changes occur:

1. The diaphragm muscles relax. This allows the diaphragm to become normal, domed shape.

2. The intercostal muscles relax. This allows the ribs to move downwards and inwards.

3. The lungs are compressed. When the volume decreases, the pressure increases in the lungs.

4. Air is forced out from the lungs to the surrounding air.

General Principles:

• Muscle Action:
  Muscles can only pull, not push. This is why relaxation is needed for opposite movement.

• Inhalation (Synergistic Action):
  Different muscles work together (diaphragm and intercostal muscles contract at the same time).

• Exhalation (Antagonistic Action):
  Muscles work in opposite directions (relaxation of muscles brings about exhalation).

3.4 Diseases Related to Respiratory System

The most common respiratory disorders include Bronchitis, Emphysema, Pneumonia, Asthma, and Lung Cancer.

3.4.1 Bronchitis (Reversible)

• Definition:
  Bronchitis is the inflammation of the inner lining of the air passages — including the trachea, bronchi, and bronchioles.

• Symptoms:

  • Overproduction of mucus by goblet cells.

  • Persistent and repeated coughing.

  • Breathlessness which worsens as the disease progresses.

  • In acute bronchitis, mucus may be yellow, green, or white.

• Types of Bronchitis:

  • Acute bronchitis: Short-term inflammation of the bronchi of the lungs, usually lasting a few days, often a side effect of viral infections like the flu. (Due to pathogens).

  • Chronic bronchitis: Long-term inflammation and irritation of the bronchi, most commonly caused by smoking and to a lesser extent by air pollution. It may last for months. The sensation of breathlessness occurs due to reduced gas exchange. (Due to the environment you're living in)

• Treatment:

  • Usually resolves in a week if it's acute.

  • Avoid smoking.

  • Drink plenty of fluids and take rest.

  • Use of inhalers for relief.

  • Antibiotics may be given if there's a secondary bacterial infection.

3.4.2 Emphysema (Not Reversible)

• Definition:
  Emphysema is a respiratory disease involving over-inflammation of the alveoli in the lungs, leading to a decrease in lung function.

• Symptoms:

  • Persistent breathlessness that increases over time.

  • Difficulty exhaling due to loss of lung elasticity.

  • In advanced cases, the patient finds it difficult to walk.

  • Narrowing of small bronchioles also occurs.

• Cause:

  • Long-term irritation of lungs caused mainly by cigarette smoke.

  • Other causes include air pollution and industrial dust.

  • Damage involves breakdown of alveolar walls, leading to poor gas exchange.

• Treatment:

  • Damage cannot be reversed.

  • Avoiding smoking is the best prevention.

  • Medications may help ease breathing but not cure the disease.

3.4.3 Pneumonia

• Definition:
  Pneumonia is defined as an inflammation of alveoli of lungs caused by acute infection. When both lungs are affected, it's called double pneumonia.

• Symptoms:

  • Fever and chills

  • Chest pain and cough

  • Headache and sore throat

  • Nausea and diarrhoea

• Cause:

  • Most commonly caused by Streptococcus pneumoniae (bacteria).

  • Other causes may include viruses and fungi.

• Treatment:

  • Antibiotics are used if the pneumonia is bacterial.

3.4.4 Asthma

• Definition:
  Asthma is a chronic inflammatory disease of the airways in the lungs.

• Symptoms:

  • Difficulty breathing out more than in.

  • A whistling sound (wheezing) is caused during breathing.

  • Mucus over-secretion and swelling of air passage lining.

• Cause:

  • Allergic reaction to allergens like pollen, dust, certain foods, cold air, smoke, or exercise.

  • Emotional stress can also trigger an attack.

• Treatment:

  • Bronchodilators are used for mild attacks.

  • Inhalers to dilate airways and ease breathing.

  • Asthma has no permanent cure but can be managed with two types of medicines:

    • Long-term control medications

    • Quick-relief medications

3.4.5 Lung Cancer

• Definition:
  Lung cancer involves uncontrolled cell division that forms tumours in the lungs.
  It usually begins in the epithelial lining of bronchioles and spreads throughout the lungs.

• Symptoms:

  • Thickening and callusing of bronchiole lining cells.

  • Loss of cilia, making it hard to remove dust and dirt from lungs.

  • Appearance of tumours with abnormal nuclei.

  • Tumours can block bronchi, cutting air supply to lung areas.

  • Cancer may spread (metastasis) to other parts.

• Cause:

  • Tobacco smoke is the leading cause.

  • Air pollution, especially car exhaust, asbestos, and arsenic, also increase the risk.

• Treatment:

  • Main treatment is pneumonectomy (removal of lung or lobe).

  • In some cases, radiation therapy is used to destroy cancerous tissue.

Bad Effects of Smoking:

• Increases risk of lung cancer, chronic bronchitis, emphysema, and pneumonia

• Causes morning cough, worsens asthma and allergies

• Makes breathing difficult and reduces lung efficiency