Respiratory System Overview

Respiratory System Overview

• The main function of the respiratory system is gas exchange, specifically the supply of oxygen and disposal of carbon dioxide.
• Other functions include warming air, phonation (voice production), immunological function, and endocrine functions.
• The conducting zone is made up of rigid conduits that carry air to the sites of gas exchange (nose, nasal cavity, pharynx, trachea, bronchi).
• The respiratory zone is where gas exchange occurs (bronchioles, alveolar ducts, alveoli).
• Respiratory muscles, including the diaphragm, are crucial for breathing.
• The upper respiratory tract includes nasal cavity, pharynx, and larynx; the lower respiratory tract includes trachea, bronchi, and lungs.

Nose

• The nose has a pyramid shape with a lateral wall, floor, base, and nasal septum.
• The internal nose has superior, middle, and inferior nasal concha.
• Bones forming the roof include the ethmoid bone and frontal bone.
• The ethmoid bone, nasal bones, and inferior nasal conchae form the lateral wall.
• The floor is composed of the maxillary and palatine bones.
• The nasal septum is a medial wall formed by nasal bones, vomer, and septal cartilage.
• Contains air-filled chambers (paranasal sinuses) that lighten the skull and are connected to nasal cavities to warm and humidify inhaled air.

Paranasal Sinuses

• Paranasal sinuses are air-filled chambers located in the skull bones.
• Connected to nasal cavities.
• Lighten the skull.
• Contribute to phonation.
• Involved in air warming.

Nasal Cavity

• The nasal cavity is a part of the upper respiratory tract.
• It includes the vestibule, hard palate, and oral cavity.
• Has superior, middle and inferior nasal conchae, responsible for warming, conditioning, and filtering air.
• Contains olfactory bulb and olfactory region.
• Houses sphenoid and frontal sinuses

Pharynx

• The pharynx is a fibromuscular tube acting as a conduit for digestive and respiratory systems.
• It has three parts: nasopharynx, oropharynx, and laryngopharynx.
• Divided into sections based on their location and function during swallowing and breathing.
• The soft palate and epiglottis are crucial for blocking the nasal cavity and larynx during swallowing.

Pharynx: Bony Substrate & Ligaments

• The parts involved include the medial plate of the pterygoid process of the sphenoid, scaphoid fossa on sphenoid bone, petrous part of the temporal bone.
• Ligaments and muscular attachments are important for movement and support.

Pharynx Muscles

• Muscles like the superior, middle, and inferior constrictors are important for constriction of the pharynx.
• Longitudinal muscles (stylopharyngeus, salpingopharyngeus, palatopharyngeus) elevate the pharynx.
• Vagus nerve (X) is the primary nerve for both the pharyngeal constrictors and longitudinal muscles.

Pharynx Vascularization

• Ascending pharyngeal artery, facial artery, maxillary and lingual arteries supply blood vessels to the pharynx.
• Veins parallel arteries in general.

Pharynx Innervation

• Vagus nerve (X) largely responsible for motor innervation.
• Sensory innervation is from various branches of specific cranial nerves (V2, IX).

Gag Reflex

• A reflex action involving the glossopharyngeal (IX) and vagus (X) nerves.
• A stimulated posterior pharynx elicits the gag reflex from the nerves.

Tonsils

• Lymph tissue collections in the mucous membrane, part of the body's defense mechanism.
• Pharyngeal tonsils (adenoids), located in nasopharynx.
• Palatine tonsils, located on the lateral oropharynx walls.
• Lingual tonsils, located on the base of the tongue.

Nasopharynx

• The first part of the pharynx, located behind the nasal cavity.
• It includes the Eustachian tube and pharyngeal tonsils.
• Crucial for respiration and the auditory tube opening.

Eustachian Tube

• A tube connecting the middle ear to the nasopharynx.
• Function is equalization of air pressure between the middle ear and the atmosphere.
• More horizontal route for infections in kids.

Oropharynx

• Region of the pharynx situated inferior to the soft palate and superior to the epiglottis.
• Includes the lingual tonsils and palatine tonsils.
• Plays a role in both the digestive and respiratory systems.

Laryngopharynx

• Located immediately superior to the esophagus and inferior to the oropharynx.
• A transition zone from the respiratory to digestive tracts.

Clinical Applications

• Includes endoscopic procedures, nosebleeds, and tonsillitis&tonsillectomy.
• Infection of pharyngeal tonsils can obliterate nasopharynx.

Surface Anatomy

• Visual representation of the structures of the pharynx, nose, and other components.