Respiratory System Anatomy

• The presentation covers the anatomy of the respiratory system, focusing on how oxygen is obtained and carbon dioxide is removed.
• Discusses the anatomy of the nasal cavity, pharynx, larynx, trachea, tracheal tree, lungs and pleura.

Organs of the Respiratory System

• The main components include: the nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, alveoli (air sacs), lungs, and pleura.

Functional Divisions

• Conductive portion acts as ducts: Includes the nasal cavity, pharynx, larynx, trachea, bronchi, and bronchioles.
• Respiratory portion is where gas exchange (CO2 and O2) occurs: Consists of respiratory bronchioles and alveoli.

The Nose

• Only externally visible part of the respiratory system.
• Consists of two parts: the external nose and the nasal cavity.
• Air enters through the external nares (nostrils).
• The interior contains a nasal cavity divided by a nasal septum.

Functions of the Nose

• Respiration
• Olfaction via olfactory receptors
• Protection of the lower respiratory passage
• Air conditioning of inspired air
• Voice resonance
• Resonating chamber for speech
• Nasal reflex function, such as sneezing

External Nose

• Pyramidal projection of the face.
• Its parts include the tip, root, dorsum, ala, and nostrils.

The Nasal Cavity

• Large, irregular cavity divided by a nasal septum.
• Opens anteriorly through external nares (nostrils) and posteriorly into the nasopharynx via internal nares (choana).
• Dorsal part forms the base of the cranium, and the floor is the roof of the mouth.
• Superior portions form the olfactory region for the sense of smell.

Nasal Cavity Regions

• Regions consist of the vestibule, respiratory region and olfactory region.

Lateral Wall of Nasal Cavity

• Has three bony projections: superior, middle, and inferior conchae (turbinates).
• Each concha has a corresponding meatus (superior, middle, and inferior).

Paranasal Air Sinuses

• Four bilateral, air-filled spaces within skull bones surrounding the nasal cavity.
• Located in the maxilla, frontal, sphenoid, and ethmoid bones.
• Functions include lightening the skull, acting as resonance chambers for speech, and producing mucus that drains into the nasal cavity.
• Infection of these sinuses is called sinusitis.

Pharynx (Throat)

• Muscular passage connecting the nasal cavity to the larynx.
• Fibromuscular tube, 12-14 cm long, extending from the skull base to the sixth cervical vertebra (C6).
• Located behind the nasal cavity, mouth, and larynx, and is wider superiorly.
• Three regions: nasopharynx, oropharynx, and laryngopharynx.
• The oropharynx and laryngopharynx serve as common passageways for air and food.

Parts of Pharynx

• Consists of the nasopharynx, oropharynx and laryngopharynx.

The Nasopharynx

• Superior region behind the nasal cavity, located above the soft palate.
• Closed off during swallowing and serves only as an air passageway.
• Contains the pharyngeal tonsil, auditory tube, and pharyngeal recess.

The Oropharynx

• Middle region behind the mouth, arch-like.
• Extends from the soft palate's lower surface to the epiglottis' upper border.
• Contains palatine tonsils, located in the lateral walls of the fauces, and lingual tonsils, covering the tongue's posterior surface.

The Laryngopharynx

• Inferior region attached to the larynx, serving as a passage for both food and air.
• Communicates with the laryngeal cavity and esophagus.

Larynx

• Voice box/organ of phonation connecting the pharynx and trachea.
• Extends from the tongue's root and hyoid bone to the trachea.
• Located in front of the laryngopharynx, from the 3rd to 6th cervical vertebrae.
• Until puberty, the size of the larynx is similar in both sexes but enlarges in males, forming the Adam's apple and a deeper voice.
• Made of cartilage and contains vocal cords.
• Functions include phonation, respiration, protection, and deglutition (closed during swallowing, open during breathing).

Larynx Cartilages

• 3 large, single cartilages: thyroid, cricoid, and epiglottis.
• 3 pairs of small cartilages: arytenoid, corniculate, and cuneiform.

Vocal Cords

• Vocal folds located within the larynx at the top of the trachea.
• Open during inhalation and close during swallowing and phonation.
• Vestibular folds (false vocal cords) have no role in sound production.

Trachea (Windpipe)

• Extends from the cricoid cartilage to the sternal angle (T4), where it divides into the right and left main bronchi at the carina.
• Consists of cervical and thoracic parts.
• Made of 15-20 C-shaped cartilages.
• Closed posteriorly by the trachealis muscle.

Tracheal Tree

• Main bronchus (primary bronchi)
• Lobar or secondary bronchi
• Segmental or tertiary bronchi
• Bronchiole
• Terminal bronchiole
• Respiratory bronchiole
• Alveolar duct and alveoli

Bronchial Tree (Conducting Zone)

• Extensively branching respiratory passageways.
• Primary bronchi (main bronchi) are the largest, and the right main bronchus is wider and shorter than the left.
• Secondary (lobar) bronchi: Three on the right, and two on the left.
• Tertiary (segmental) bronchi branch into each lung segment.
• Bronchioles are small and less than 1 mm in diameter, lacking cartilage in their walls.
• Terminal bronchioles are less than 0.5 mm in diameter.

Respiratory Structures and Organs-Alveolus

• Functional unit of the respiratory system with an extensive network of capillaries.
• Cup-shaped and located at the end of the bronchioles.
• Covered with surfactant to prevent collapsing.
• Human lungs contain approximately 700 million alveoli.

Lungs

• Conical-shaped organs enveloped by a serous membrane (pleura).
• Has an apex base, costal surface, and medial surface.
• Apex is in the root of the neck above the clavicle.
• Base rests on the diaphragm.

Lobes of the Lungs

• Lungs have lobes separated by deep fissures.
• The right lung has three lobes (superior, middle, and inferior) separated by horizontal and oblique fissures.
• The left lung has two lobes (superior and inferior) separated by an oblique fissure.

Lung Differences

• Right Lung: three lobes and two fissures
• Left Lung: two lobes and one fissure
• Right Lung: short and wide as opposed to long and thin on the left
• Left Lung: has the cardiac notch, the right does not.

Hilum of the Lung

• Wedge-shaped area on the central portion of each lung's medial side.
• Structures found include the principal bronchus, pulmonary artery, two pulmonary veins, bronchial vessels, pulmonary autonomic plexus, lymph nodes, and connective tissue.

Pleura

• Serous membrane surrounding the lungs.
• Has two layers: the visceral pleura, which invests the lungs (adherent to the organ), and the parietal pleura, which covers the thoracic wall's internal surface.

Important Notes on Blood Vessels

• All arteries typically carry oxygenated blood except for the pulmonary artery, which carries deoxygenated blood.
• All veins carry deoxygenated blood except for the pulmonary vein, which carries oxygenated blood.

Breathing

• Pulmonary ventilation, consists of two phases: inspiration and expiration.
• Inspiration means air flows into the lungs.
• Expiration means gases exit the lungs.

Inspiration (Inhalation)

• The diaphragm and intercostal muscles contract, increasing the size of the thoracic cavity.
• External air is then pulled into the lungs due to an increase in intrapulmonary volume.
• Accessory muscles of inspiration include the sternocleidomastoid, scalene, serratus anterior, pectoralis minor, latissimus dorsi, and subclavius.

Expiration (Exhalation)

• Generally a passive process relying on the lungs' natural elasticity.
• Muscles relax, pushing air out.
• Forced expiration involves contracting internal intercostal muscles to depress the rib cage.
• Accessory muscles of exhalation include internal intercostal muscles, abdominal muscles, and quadratus lumborum.

Anatomy of the respiratory system, detailing the nasal cavity, pharynx, and larynx. Gas exchange happens in the respiratory portion, which includes respiratory bronchioles and alveoli. The nose, the only externally visible part, has external nares and a nasal cavity.