RESPIRATORY SYSTEM

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Respiratory SystemConsists of the respiratory and conducting zones (part)• Conducting zone (part) • Is the part of the respiratory system that just conduct or

transport air (e.g., nose, nasal cavity, pharynx, trachea)• Respiratory zone(part)• Site of gas exchange • Consists of bronchioles, alveolar ducts, and alveoliRespiratory muscles – diaphragm and other muscles that produce

ventilation.

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Respiratory System

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Major Functions of the Respiratory System

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Structure of the Nose The nose is divided into two parts right

and left divided (separated) by nasal septum

there is three bony projection from the lateral wall called conchae (superior, middle and inferior)

Nose open anteriorly at nostril and posteriorly to the pharynx

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Nasal cavityLies in and posterior to the external nose.

Is divided by a midline nasal septum.

Opens posteriorly into the nasopharynx.

The roof is formed by the ethimoid and sphenoid bones.

The floor is formed by the hard and soft palates.

Hair in the nose filter inspired air.

Olfactory mucosa lines the superior nasal cavity contains

smell receptors.

Respiratory mucosa lines the rest of the nasal cavity .

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Conchae

Superior, medial, and inferior conchae:• Protrude medially from the lateral walls• Increase mucosal area• Assist in air evaporation and moistening

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Pharynx

Funnel-shaped tube of skeletal muscle divided into three regions:• Nasopharynx Lies posterior to the nasal cavity. • Oropharynx lies posterior to the oral cavity• Laryngopharynx Lies posterior to the larynx

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Larynx (Voice Box)Attaches to the hyoid bone and opens into the laryngopharynx

superiorlyContinuous with the trachea posteriorlyThe functions of the larynx are:• Provide a patent airway• Voice production

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Framework of the Larynx• Cartilages (hyaline) of the larynx• thyroid cartilage with a midline laryngeal prominence (Adam’s

apple)• cricoid cartilage• Three pairs of small cartilages

• Epiglottis – elastic cartilage that covers the laryngeal inlet during swallowing

• Act as a switching mechanism to direct air and food into the proper channels

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Trachea• Flexible and mobile tube extending from the larynx into the

mediastinum• Composed of three layers• Mucosa – made up of goblet cells and ciliated epithelium • Submucosa – connective tissue deep to the mucosa• Adventitia – outermost layer made of C-shaped rings of hyaline

cartilage

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trachea hito

Conducting Zone(part): BronchiThe carina the site of the bifurcation of trachea and the

beginning of the right and left bronchi.

• Bronchi subdivide into secondary bronchi, each supplying a

lobe of the lungs

• Air passages undergo 23 subdivision of branching in the

lungs

Bronchioles

• Consist of cuboidal epithelium

• Have a complete layer of circular smooth muscle

• No cartilage support

• Internal mucus cells.

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Respiratory Zone(part)• begins as terminal bronchioles and divide into

respiratory bronchioles.

• Respiratory bronchioles lead to alveolar ducts, then to

terminal clusters of alveolar sacs composed of alveoli

• Approximately 300 million alveoli:

• Account for most of the lungs’ volume

• Provide surface area for gas exchange

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Lungs• Root – site of vascular and bronchial attachments

• Costal surface – anterior, lateral, and posterior surfaces in contact with

the ribs

• Apex – narrow superior tip

• Base – inferior surface that rests on the diaphragm

• Hilum –site of entrance of pulmonary and systemic blood vessels.

• Cardiac notch – cavity that accommodates the heart

• Left lung – separated into upper and lower lobes by the oblique fissure

• Right lung – separated into three lobes by the oblique and horizontal

fissures

• There are 10 segments in each lung 19

segments of the lungs

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Blood Supply to Lungs

• Bronchial arteries – provide systemic blood to the lung tissue• Bronchial veins carry out venous blood of the

lung• Pulmonary arteries provide blood(deoxygenated)

for gas exchange.• Pulmonary veins carry most venous(oxygenated)

blood back to the heart.

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Pleurae

• Thin, double-layered serous membrane

Parietal pleura covers the thoracic wall and superior

surface of the diaphragm.

Continues with the visceral plura.

Visceral pleura covers the external lung surface

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Review of Respiratory Musclesdiaphragm (70% of respiration-mainly inspiration) external intercostal (inspiration) internal intercostal (expiration)inner most , transversus thoracic and sucostalis(expiration)

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