Human Anatomy Quiz: Larynx and Respiration

Respiratory System

• The respiratory system facilitates oxygen and carbon dioxide exchange with the blood.
• It includes the lungs and a branching system of bronchial tubes.

Alveoli

• Alveoli are small, sac-like structures within the lungs.
• They are the sites of gas exchange between inspired air and blood.
• Alveoli are lined with simple squamous epithelium for efficient gas diffusion.

Conducting Portion

• The conducting portion includes the nasal cavities, pharynx, larynx, trachea, bronchi, and bronchioles.
• Its role is to clean, humidify, and warm inspired air.
• It provides passageways for air to and from the alveoli.

Alveolar Ducts

• Alveolar ducts are small airways connecting bronchioles to alveolar sacs and alveoli.
• They facilitate air flow to the alveolar regions for gas exchange.
• They are lined with simple cuboidal epithelium in some areas and simple squamous epithelium where alveoli open directly into the ducts.

Respiratory Epithelium

• Respiratory epithelium is ciliated pseudostratified columnar.
• This epithelium lines most of the nasal cavities and the conducting portion of the respiratory system.
• The epithelium consists of ciliated columnar cells, goblet cells, brush cells, small granule cells, and basal cells.

Types of Alveolar Cells

• Type I Alveolar Cells (Pneumocytes): Thin, flat cells that cover a majority of the alveolar surface, facilitating gas exchange.
• Type II Alveolar Cells (Pneumocytes): Cuboidal cells producing surfactant which prevents alveolar collapse. They also act as progenitor cells (regenerating damage).
• Alveolar Macrophages (Dust Cells): Immune cells found within alveoli that phagocytose debris and pathogens.

Nasal Cavities Functions and Epithelium

• Vestibule of nasal cavity (entrance): stratified squamous epithelium (keratinized near opening and non-keratinized as it progresses inward)
• Nasopharynx: pseudostratified columnar epithelium
• Oropharynx: non-keratinized stratified squamous epithelium
• Laryngopharynx: non-keratinized stratified squamous epithelium.

Olfactory Epithelium

• Specialised mucous membrane found in superior nasal conchae.
• Contains olfactory neurons, supporting cells and basal cells.
• Lamina propria in olfactory epithelium includes olfactory glands which produce fluid surrounding olfactory cilia to aid odour detection.

Paranasal Sinuses

• Air-filled spaces within frontal, maxillary, ethmoid, and sphenoid bones.
• Lined with thin respiratory epithelium.
• Functions in lightening the skull and voice resonance.

The Pharynx

• The pharynx is a passageway for air and food.
• It links the nasal cavity/oral cavity to the esophagus and larynx.
• It is composed of the nasopharynx, oropharynx, and laryngopharynx, with each section having different functions.
• The nasopharynx connects to the nasal cavity and auditory tubes, oropharynx connects to the oral cavity and has tonsils, and laryngopharynx connects to the larynx and esophagus.

The Larynx

• Also known as the voice box.
• Its role is in protecting the airway during swallowing and sound production.
• Framework of hyaline and elastic cartilages.

The Trachea

• A tube leading from the larynx to the bronchi, providing air passage to the lungs.
• Supported by C-shaped hyaline cartilage rings to prevent collapse.
• Pseudostratified columnar epithelium lines the trachea with goblet cells producing mucus to trap inhaled particles.

The Pleura

• The lung is the outer surface and the internal wall of the thoracic cavity is covered by a serous membrane called the pleura.
• It consists of parietal pleura (lining the thoracic wall) and visceral pleura (attached to the lung tissue).
• Pleural fluid within the pleural cavity acts as a lubricant during respiratory movements, reducing friction during breathing.