An insight into the respiratory system includes inhaling through the nose and the organs working together, as well as the functions such as the pharynx, oropharynx, and trachea, and down to the lungs and its components. Also the process of preparation through lung inflation, pulmonary ventilation,...
Respiratory system function:
- Air passageway: moves air between external environment and the alveoli of the lungs
- Site of gas exchange: Thin barrier between alveoli and pulmonary capillaries
- Enables Oxygen and carbon dioxide to diffuse across barriers.
- Detects odors: olfactory receptors in the superior region of nasal cavity
- Sound protection: vocal cords of the larynx vibrate as air is passed between them.
Respiratory System Organization:
- Upper Respiratory tract includes the nose, nasal cavity, & pharynx
- Lower respiratory tract includes larynx, trachea, bronchi, bronchioles, alveoli
- Functional Organization:
- Conducting zone: nose to terminal bronchioles
- Respiratory zone: respiratory bronchioles, alveolar ducts, alveoli
Mucosal lining: lining of respiratory tract
- Is ciliated epithelium containing epithelium, basement membrane, & lamina propria
- Gets progressively thinner the deeper the structure
- Changes from pseudostratified ciliated columnar → simple columnar → simple cuboidal
→ simple squamous
- Exceptions:
- Pharynx – passageway for both air and food
- Larynx – includes vocal cords and immediate superior region
- Possess non-keratinized stratified squamous epithelium
Mucus:
- Produced by: Goblet cells and the Lamina propia
- Have mucous and Serous glands
- Compositio:n
- Mucin: a “sticky” protein that increases the viscosity of mucous and entraps dust, dirt,
micro-organisms, pollen, etc.
- Lysozyme: antibacterial enzyme
- Defensins: family of antimicrobial proteins and IgA: Antibodies
Nose: Main conducting passageway for inhaled air
- Formed by bone, hyaline cartilage, dense irregular CT, and covered with skin externally
Nostrils (nares):
- Open into the inferior surface of the nose leading into the nasal cavity
Nasal cavity Anatomy:
- Internal space formed by the nose (anterior) and skull (superior & posterior)
- Oblong-shaped; extends from nostrils to choanae
- Floor is the hard palate
- Roof composed of bones of the skull (nasal, frontal, ethmoid, sphenoid) and some nose cartilage
- Nasal septum
- Formed by nasal septal cartilage and bone (vomer and ethmoid)
- Divides the nose into two chambers
- Lateral walls possess the nasal conchae
- Three paired, bony projections (superior, middle, inferior) referred to as turbinate bones
- Produce turbulence in the inhaled air
, - Nasal meatus: Partitions formed by conchae, immediately inferior to its corresponding conchae
Nasal cavity Functions to Condition the Air:
- Warms the air to body temperature
- Due to extensive vascularization
- Cleanses the air
- Microbes, dust, etc. are trapped by in mucus
- Cilia sweeps “dirty” mucus to pharynx
- Humidifies: Enhanced by conchae which creates turbulence and exposes more air to the mucosal
lining
Pharynx (throat);
- Posterior to the nasal cavity, oral cavity, and larynx
- Conducts air along it’s entire length
- Air and food along the inferior portion
- Lateral walls composed of skeletal muscle
- Flexible and distensible
- Aids in swallowing and propelling food to the esophagus
- Three regions
Nasopharynx: superior region of the pharynx
- Posterior to the nasal cavity and superior to the soft palate
- Lined with pseudostratified ciliated columnar epithelium
- Lateral walls house the openings to the auditory tubes
- Serve to equalize pressure in the middle ear
- Also houses the tubal tonsils
- Posterior wall houses the pharyngeal tonsil, aka adenoids
Oropharynx: middle of pharynx
- Posterior to the oral cavity
- Lined with non-keratinized stratified squamous epithelium
- Lateral walls house the palantine tonsils
- Lingual tonsils located at the base of the tongue
Laryngopharynx: inferior of pharynx
- Posterior to the larynx
- Extends from hyoid bone to larynx and esophagus
- Lined with non-keratinized stratified squamous epithelium
- Serves as common passageway for food and air with oropharynx
Larynx: (voice box)
- Continuous with Laryngopharynx (superior) & trachea (inferior)
- Composed of cartilage and supported by muscle and ligaments
- Functions: Passageway for air
- Prevents ingested materials from entering the respiratory tract
- Epiglottis closes over the laryngeal inlet (opening) and glottis closes during
swallowing
- Produces sound for speech via the glottis
- Vibration of the vocal folds as air passes between them through the rima glottidis
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