chapter 12

External Respiration
- The exchange of air in the lungs and between capillaries:
- Process: Oxygen is inhaled into the air sacs of the lungs, where it is approximately 21% O2.
- Gas Exchange: Oxygen immediately passes into the capillaries, while carbon dioxide passes from the capillaries into the air sacs to be exhaled.
- Composition of Exhaled Air: Exhaled air contains about 16% O2.
Internal Respiration
- The exchange of gases at the cellular level:
- Occurs simultaneously between cells and capillaries.
- Oxygen Movement: Oxygen passes out of the bloodstream (from capillaries) into the tissues.
- Carbon Dioxide Movement: Carbon dioxide moves from the tissues back into the bloodstream to travel to the lungs.

Mediastinum
- Defined as the middle part of the chest.
- Where the trachea divides into two bronchi.
- The space is located outside and between the two lungs.
Hilum of the Lung
- Contains:
- Blood vessels
- Nerves
- Lymphatic tissues
- Bronchial tubes (entering and exiting the lung)
Lungs Anatomy
- Lobes Structure:
- Right Lung: Larger with 3 lobes.
- Left Lung: Smaller with 2 lobes.
Bronchi
- Bifurcate from the trachea, leading to each lung.
Bronchioles
- Smaller branches that end in the alveoli.
Alveolus
- Site of gas exchange.

Cava
- Meaning "hollow".
- Pulmonary Artery: Carries O2-poor blood from the heart to the lungs.
- Pulmonary Vein: Carries O2-rich blood from the lungs to the heart.
Vena Cava: Comprises left vein and is referred to as hollow.

Epistaxis:
- Common bleeding from the nose, noticed when blood drains through the nostrils.
Asthma:
- Characterized by reversible airflow obstruction and bronchospasm. Thought to stem from genetic and environmental factors.
Bronchiectasis:
- Involves permanent enlargement (dilation) of airway parts. Bronchi become dilated, inflamed, and easily collapse. Can arise from conditions like pneumonia, tuberculosis, or cystic fibrosis.
Emphysema:
- Characterized by hyperinflation of alveoli due to loss of elasticity.
- Involves narrowed small airways and breakdown of lung tissue.
Chronic Obstructive Pulmonary Disease (COPD):
- Encompasses conditions leading to long-term breathing issues and poor airflow, with shortness of breath and productive cough as major symptoms.
Lung Cancer:
- Malignant growth characterized by uncontrolled cell growth in lung tissues.
- Symptoms include coughing (possibly with blood), weight loss, shortness of breath, and chest pains.
Pneumonia:
- Inflammatory condition primarily affecting alveoli, typically caused by viral or bacterial infection. Symptoms include cough, fever, and chest pain.
Pulmonary Embolism:
- Occurs when a blood clot travels to the lungs, blocking major blood vessels and causing difficulty in breathing and chest pain.

CPAP (Continuous Positive Airway Pressure):
- A method of applying mild air pressure to open airways, often used in premature infants and for sleep apnea treatment.
Bronchoscopy:
- Involves the insertion of a flexible endoscope into bronchial tubes for viewing, diagnosis, or biopsy purposes.
Endotracheal Intubation:
- Placement of a tube from mouth to trachea to secure airway.
Thoracentesis:
- Surgical puncture to remove excess fluid from the pleural space.
Tracheostomy:
- A surgical procedure creating an opening through the neck into the trachea for secure airway access and secretion drainage.
Spirometry:
- Common pulmonary function test measuring lung abilities in terms of air volume and speed during inhalation and exhalation.

Adenoids: Lymphatic tissue in the nasopharynx.
Alveoli: Air sacs in the lungs responsible for gas exchange.
Carbon Dioxide (CO2): Waste gas produced by body cells; exhaled via the lungs.
Diaphragm: Muscle below the lungs aiding in breathing, separating the chest from the abdomen.
Epiglottis: Lid-like cartilage covering the larynx.
Parietal Pleura: Outer fold of pleura lying closer to the chest wall.
Visceral Pleura: Inner fold of pleura neighboring lung tissue.