SOMS1913 WK 2 - Lower respiratory system

Function of C-shaped hyaline cartilage in the trachea

Ensures airways remain patent (open) while allowing the oesophagus to expand anteriorly into the trachea during swallowing.

Histological layers of the trachea (internal to external)

1. Mucosa (Respiratory Epithelium)

2. Submucosa (contains tracheal glands)

3. Cartilage layer

4. Adventitia

Respiratory Epithelium type

Ciliated Pseudostratified Columnar Epithelium (containing goblet cells).

Structural differences: Right vs. Left Main Bronchus

The Right main bronchus is wider, shorter, and more vertical than the Left.

Components of the Respiratory Zone

Respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli

Type II Pneumocyte function

Cuboidal cells that secrete surfactant to reduce surface tension in the alveoli

Layers of the Pleura  

Parietal pleura (lines thoracic wall) and Visceral pleura (covers lung surface), separated by the pleural cavity

Primary muscles of quiet inhalation

The Diaphragm (main muscle) and the External Intercostal muscles

Pump-handle mechanism

Movement of ribs 2–6 that increases the anterior-posterior dimension of the thoracic cavity

Bucket-handle mechanism

Movement of ribs 7–10 that increases the transverse (lateral) dimension of the thoracic cavity.

Definition of Dalton's Law

In a mixture of gases, the total pressure is the sum of the partial pressures exerted by each gas if it were present alone

Formula for Henry's Law

Cx = Sol * Px (Concentration depends on solubility and partial pressure)

External vs. Internal Respiration  

External: Exchange between alveoli and pulmonary capillaries. Internal: Exchange between systemic capillaries and tissues.

Cooperative Binding of Hemoglobin

When one O2 binds, Hb changes shape (Tense to Relaxed), making it easier for more O2 to bind.

Factors shifting Oxygen-Hemoglobin Curve to the RIGHT

Increased Temp, Increased PCO2, Increased H+ (lower pH), Increased 2,3-DPG.

The Bohr Effect

Decrease in Hb affinity for O2 due to high CO2 or low pH (helps unload O2 at tissues).

The Haldane Effect  

Deoxygenated blood has a higher affinity for CO2.

The Chloride Shift

Exchange where HCO3- diffuses OUT of RBCs and Cl- diffuses IN to maintain electrical balance.

Carbonic Anhydrase function

Enzyme in RBCs that catalyzes: CO2 + H2O <-> H2CO3.

Primary method of CO2 transport

As Bicarbonate ions (HCO3-) (approx 70%).

Lobes of the Lungs

Right: 3 lobes (Upper, Middle, Lower). Left: 2 lobes (Upper, Lower).

The Carina

Internal ridge where trachea bifurcates (T4/T5); highly sensitive cough reflex site.

Nerve supply to the Diaphragm

Phrenic nerve (C3, C4, C5).

P50 Value

Partial pressure where Hb is 50% saturated. Higher P50 = Lower affinity.

Bronchopulmonary Segments  

Functionally independent units (10 per lung) each supplied by its own bronchus and artery.

Hilum of the lung 

• Roots where vessels leave the lung. 

• Bronchi are posterior 

• Pulmonary arteries are superior to the pulmonary veins

• Pulmonary veins are most inferior.