Respiratory system.
Anatomical & Functional subdivisions.By
Dr. Suhail Ahmad.
The Respiratory System
Organization and Functions of the Respiratory System
Structural classifications:–upper respiratory tract– lower respiratory tract.
Upper Respiratory Tract
• Composed of– the nose– the nasal cavity– the paranasal sinuses– the pharynx (throat)– and associated structures.
• All part of the conducting portion of the respiratory system.
Lower Respiratory Tract
• Conducting portion– Larynx– Trachea–Bronchi–bronchioles and their associated structures
• Respiratory portion of the respiratory system– respiratory bronchioles– alveolar ducts– alveoli
Organization of the Respiratory System
• Functional classifications:–Conducting portion: transports air.• Nose• nasal cavity• Pharynx• Larynx• Trachea• progressively smaller airways, from the
primary bronchi to the bronchioles
Organization of the Respiratory System
• Functional classifications: continued– Conducting portion: transports air.
– Respiratory portion: carries out gas exchange.• respiratory bronchioles• alveolar ducts• air sacs called alveoli
• Upper respiratory tract is all conducting• Lower respiratory tract has both
conducting and respiratory portions
The Respiratory OrgansConducting zone– Respiratory
passages that carry air to the site of gas exchange
– Filters, humidifies and warms air
Respiratory zone– Site of gas exchange– Composed of
• Respiratory bronchioles
• Alveolar ducts• Alveolar sacs
Conducting zone labeled
Respiratory System Functions • Breathing (pulmonary ventilation): – consists of two cyclic phases: • inhalation, also called inspiration• exhalation, also called expiration
– Inhalation draws gases into the lungs. – Exhalation forces gases out of the lungs.
• Gas exchange: O2 and CO2
– External respiration• External environment and blood
– Internal respiration• Blood and cells
Respiratory System Functions • Gas conditioning:– Warmed– Humidified– Cleaned of particulates
• Sound production:– Movement of air over true vocal cords– Also involves nose, paranasal sinuses, teeth, lips
and tongue• Olfaction:– Olfactory epithelium over superior nasal conchae
• Defense: – Course hairs, mucus, lymphoid tissue
Nose
• Provides airway• Moistens and warms air• Filters air• Resonating chamber for
speech• Olfactory receptors
External nose
Skeletal framework
Bones that contribute to the skeletal framework of the nasal cavities include: • The unpaired – Ethmoid – Sphenoid, – Frontal bone– Vomer
• The paired – Nasal– Maxillary– Palatine – Lacrimal Bones– Inferior Conchae
Regions
• Each nasal cavity consists of three general regions. • The nasal vestibule is a small dilated space just internal
to the naris that is lined by skin and contains hair follicles;
• The respiratory region is the largest part of the nasal cavity, has a rich neurovascular supply, and is lined by respiratory epithelium composed mainly of ciliated and mucous cells;
• The olfactory region is small, is at the apex of each nasal cavity, is lined by olfactory epithelium, and contains the olfactory receptors
Lateral wall
• The lateral wall is characterized by three curved shelves of bone (conchae)– which are one above the other and – project medially and inferiorly across the nasal
cavity. • The medial, anterior and posterior margins of
the conchae are free.
The conchae divide each nasal cavity into four air channels: • an inferior nasal meatus between the inferior
concha and the nasal floor; • a middle nasal meatus between the inferior and
middle concha; • a superior nasal meatus between the middle and
superior concha; and • a spheno-ethmoidal recess between the superior
concha and the nasal roof.
• These conchae increase the surface area of the lateral wall.
• The openings of the paranasal sinuses are on the lateral wall and roof of the nasal cavities.
• The lateral wall also contains the opening of the nasolacrimal duct, which drains tears from the eye into the nasal cavity.
Medial wall
• The medial wall of each nasal cavity is the mucosa-covered surface of the thin nasal septum
• Oriented vertically in the median sagittal plane • Separates the right and left nasal cavities from
each other.
Medial wall
• The nasal septum consists of: – the septal nasal cartilage anteriorly – posteriorly, mainly the vomer and the
perpendicular plate of the ethmoid bone
Nasal septum(medial wall).
Blood supplyThe nasal cavities have a rich vascular supply for altering the humidity and temperature of respired air.• vessels that originate from branches of the external
carotid artery include: – sphenopalatine– greater palatine– superior labial– lateral nasal arteries
• vessels that originate from branches of the internal carotid artery are: – anterior ethmoidal – posterior ethmoidal
Blood supply
Innervation
• Innervation of the nasal cavities is by three cranial nerves. olfaction is carried by the olfactory nerve [I];
• General sensation is carried by the trigeminal nerve [V], the anterior region by the ophthalmic nerve [V1], and the posterior region by the maxillary nerve [V2];
• All glands are innervated by parasympathetic fibers in the facial nerve [VII] (greater petrosal nerve), which joins branches of the maxillary nerve [V2] in the pterygopalatine ganglion.
Innervation
Lymphatic drainage.
Paranasal Sinuses • Paranasal sinuses:– In four skull bones– paired air spaces– decrease skull bone weight
• Named for the bones in which they are housed.– frontal – ethmoidal – sphenoidal– maxillary
• Communicate with the nasal cavity by ducts. • Covered with the same pseudostratified ciliated
columnar epithelium as the nasal cavity.
Paranasal Sinuses
Paranasal sinuses– Can get infected: sinusitis
Paranasal Sinuses
PHARYNX
• The pharynx is a musculo-fascial tube behind the nasal and oral cavities.
• Funnel-shaped– slightly wider superiorly and narrower inferiorly.
• Its anterior wall is largely deficient and through this defect it communicates with the:– Nasal cavities– Oral cavity– Larynx
• The pharyngeal cavity is a common pathway for air and 'food'.
PHARYNX
• The pharynx is attached above to the base of the skull.
• It is continuous below with esophagus in the neck.
PHARYNX• Based on the anterior relationships the pharynx is
subdivided into three regions: – nasopharynx– oropharynx – laryngopharynx
• The posterior apertures (choanae) of the nasal cavities open into the nasopharynx;
• The posterior opening of the oral cavity (oropharyngeal isthmus) opens into the oropharynx;
• The superior aperture of the larynx (laryngeal inlet) opens into the laryngopharynx.
Pharynx
• Walls:– lined by a mucosa– contain skeletal muscles primarily used for
swallowing.• Flexible lateral walls– distensible– to force swallowed food into the esophagus.
Larynx
• Short, somewhat cylindrical airway• Location:– bounded posteriorly by the laryngopharynx,– inferiorly by the trachea.
• Prevents swallowed materials from entering the lower respiratory tract.
• Conducts air into the lower respiratory tract. • Produces sounds.
Larynx
• Nine pieces of cartilage– three individual pieces• Thyroid cartilage• Cricoid cartilage• Epiglottis
– three cartilage pairs• Arytenoids: on cricoid• Corniculates: attach to arytenoids• Cuniforms:in aryepiglottic fold
Nine pieces of cartilage
–held in place by ligaments and muscles. • Intrinsic muscles: regulate tension on
true vocal cords• Extrinsic muscles: stabilize the larynx
• Framework of the larynx– 9 cartilages connected by membranes and ligaments– Thyroid cartilage with laryngeal prominence (Adam’s
apple) anteriorly– Cricoid cartilage inferior to thyroid cartilage: the only
complete ring of cartilage: signet shaped and wide posteriorly
– Behind thyroid cartilage and above cricoid: 3 pairs of small cartilages
1. Arytenoid: anchor the vocal cords2. Corniculate3. Cuneiform
– 9th cartilage: epiglottis
Trachea
• A flexible, slightly rigid tubular organ– often referred to as the “windpipe.”
• Extends through the mediastinum– immediately anterior to the esophagus– inferior to the larynx– superior to the primary bronchi of the
lungs.
Trachea
• Anterior and lateral walls of the trachea are supported by 15 to 20 C-shaped tracheal cartilages.– cartilage rings reinforce and provide some
rigidity to the tracheal wall to ensure that the trachea remains open (patent) at all times – cartilage rings are connected by elastic
sheets called anular ligaments
Trachea
• At the level of the sternal angle(T-4), the trachea bifurcates into two smaller tubes, called the right and left primary bronchi.
• Each primary bronchus projects laterally toward each lung.
• The most inferior tracheal cartilage separates the primary bronchi at their origin and forms an internal ridge called the carina.
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Carina*• Ridge on
internal aspect of last tracheal cartilage
• Point where trachea branches (when alive and standing is at T7)
• Mucosa highly sensitive to irritants: cough reflex
*
Bronchial Tree
• A highly branched system– air-conducting passages–originate from the left and right primary
bronchi. • Progressively branch into narrower tubes
as they diverge throughout the lungs before terminating in terminal bronchioles.
• Primary bronchi–Incomplete rings of hyaline cartilage
ensure that they remain open. –Right primary bronchus• shorter, wider, and more vertically
oriented than the left primary bronchus. –Foreign particles are more likely to
lodge in the right primary bronchus.
Bronchial Tree
• Primary bronchi–enter the hilum of each lung
• Secondary bronchi (or lobar bronchi)–Branch of primary bronchus– left lung:• two lobes• two secondary bronchi
– right lung• three lobes• three secondary bronchi.
• Tertiary bronchi (or segmental bronchi)–Branch of secondary bronchi – left lung is supplied by 8 to 10 tertiary
bronchi. – right lung is supplied by 10 tertiary bronchi– supply a part of the lung called a
bronchopulmonary segment.
Respiratory Bronchioles, Alveolar Ducts, and Alveoli
• Contain small saccular outpocketings called alveoli.
• An alveolus is about 0.25 to 0.5 millimeter in diameter.
• Its thin wall is specialized to promote diffusion of gases between the alveolus and the blood in the pulmonary capillaries.
• The spongy nature of the lung is due to the packing of millions of alveoli together.
Respiratory Bronchioles, Alveolar Ducts, and Alveoli
• Gas exchange can take place in the respiratory bronchioles and alveolar ducts as well as in the lungs, which contain approximately 300–400 million alveoli.
Pleura and Pleural Cavities
• The outer surface of each lung is tightly covered by the visceral pleura
• Internal thoracic walls, the lateral surfaces of the mediastinum, and the superior surface of the diaphragm are lined by the parietal pleura.
• The parietal and visceral pleural layers are continuous at the hilum of each lung.
Pleura and Pleural Cavities
• The potential space between these serous membrane layers is a pleural cavity.
• The pleural membranes produce a thin, serous fluid that circulates in the pleural cavity and acts as a lubricant, ensuring minimal friction during breathing.
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CXR(chest x-ray)
Chest x rays
Normal female Lateral (male)
Pneumothorax
• There are many diseases of the respiratory system, including asthma, cystic fibrosis, COPD (chronic obstructive pulmonary disease – with chronic bronchitis and/or emphysema) and epiglottitis
example:
normal emphysema
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you might want to think twice about smoking….
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