RESPIRATORY SYSTEM

Chapter 13

Bio 221

RESPIRATORY SYSTEM FUNCTIONS

Gas Exchange (pick-up O2, eliminate CO2)

Filter, Warm & Humidify AirProtectionSpeechRegulate pH

RESPIRATORY SYTEM ORGANIZATION

Upper Respiratory Tract (Outside Thorax)- Nose Pharynx

Lower Respiratory Tract (Inside Thorax)- Larynx Lungs

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Upper Respiratory Tract

Composed of:- the nose- the nasal cavity- the paranasal sinuses- the pharynx (throat)

Conducts, conditions & filters air

UPPER RESPIRATORY TRACT

Nose

- External Nares/Anterior Nasal Aperture (nostril)

- Nasal Cavity

* Hairs & Mucus (Trap debris)

* Ciliated mucosa (conditions air); cilia move mucus down to pharynx

* Divided by nasal septum

* Nasal Conchae Bones (turbulence)

* Olfactory epithelium with receptors (smell)

* Receives tear drainage25-6

Tear Drainage

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UPPER RESPIRATORY TRACT continued

- Paranasal Sinuses (4)* Bone cavities* Reduce weight; sound resonance* Lined with Mucous Membrane; conditions

air* Empty into Nasal Cavity

- Internal Nares/Posterior Nasal Aperture (Opening between Nasal Cavity & Nasopharynx)

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Pharynx (Throat)- Between Nasal Cavity, Oral Cavity & Larynx- Passageway for Air & Food- Protected by tonsils, mucosa- 3 Divisions

* Nasopharynx* Oropharynx* Laryngopharynx

UPPER RESPIRATORY TRACT continued

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Pharynx

Nasopharynx- Anterior nasal aperture Soft palate (uvula)- Posterior to nasal cavity - Includes Pharyngeal tonsil & Tubal tonsils

(around openings to Auditory tubes)- Air passageway- Soft palate prevents food/water from entering

nasopharynx during swallowing

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Pharynx

Oropharynx- Soft Palate Base of tongue/hyoid bone- Posterior to oral cavity- Includes palatine & lingual tonsils- Shared passageway (air, food, water)

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Pharynx

Laryngopharynx- Base of tongue/hyoid bone Opening to

Esophagus- Continuous with larynx & esophagus- Shared passageway (air, food, water)

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Lower Respiratory Tract

Composed of- the larynx

- the trachea

- the bronchial tree

- the lungs

Conducts air, conditions air, gas exchange

Lower Respiratory Tract - Larynx

Hyoid bone through cricoid cartilageAir PassagewayPrevents food/water from entering lower

respiratory tractSound production (speech)Supported by cartilage

Glottis is a Slit-like Opening into Larynx;Produces Speech with Vocal Cords

Larynx - Cartilages

• Epiglottis• Covers Glottis (opening of larynx)

• Prevents food from Entering Trachea

• Thyroid Cartilage• “Adam’s Apple”

• Cricoid Cartilage• Inferior, Encircles Vocal Cords

Lower Respiratory Tract - Trachea

Conducts airReinforced with “C”-shaped tracheal

cartilagesNo cartilage posteriorly; allows swallowingExtends from larynx to primary bronchiRuns through MediastinumAnterior to esophagus

Trachea

Lower Respiratory Tract- Bronchial Tree

Branching passageways; Conduct airSupported by cartilagePrimary Secondary TertiaryRight primary bronchus

- more vertical, shorter & wider than left

- aspirated objects enter & lodge

Different branches of bronchial tree serve different lung regions.

Primary bronchi lungs

Secondary bronchi lobes

Tertiary bronchi lung segments

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Bronchial Tree – Terminal bronchiolesStructural Modifications

Ciliated epithelium non-ciliated (macrophages remove particles)

Incomplete cartilaginous rings plates scattered pieces no cartilage

As cartilage , smooth muscle

Respiratory Zone – sites of gas exchange in lungs

Air conduction & gas exchangeThinner epithelium for gas exchangeIncludes:

- Respiratory bronchioles- Alveolar ducts- Alveoli & Alveolar sacs

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Alveoli

Site of most gas exchange (diffusion)Microscopic out-pouchingSimple squamous E.T., supported by thin

elastic basement membraneSource of spongy texture

Alveolar Cells

Type I alveolar cells (squamous epithelial)

- Main site of gas exchange

Type II alveolar cells- Secrete alveolar fluid & surfactant, surface

tension, prevents collapse- Secrete anti-bacterial proteins

Alveolar macrophages (Dust cells)

Fibroblasts (produce reticular & elastic fibers)

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Lungs - Location

Paired (“spongy”) OrgansContain bronchial tree & respiratory zoneWithin pleural cavities; separated by

mediastinumEnclosed & protected by pleura (serous)

- Visceral – surface of lungs- Parietal – attached to thoracic cavity wall

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Lungs – Regions & Surfaces

• Apex (Superior Extension, Above Clavicle)

• Base (Inferior, Rests on Diaphragm)

• Hilum (Vertical slit on Mediastinal Surface)

• Cardiac Notch (Recess on Left Lung)

Lungs – Gross Anatomy

Lobes- Right: superior, middle, inferior- Left: superior, inferior

Fissures- Right: Horizontal, right oblique- Left: left oblique

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Different branches of bronchial tree serve different lung regions.

Primary bronchi lungs

Secondary bronchi lobes

Tertiary bronchi bronchopulmonary segments

Lung LobulesSmallest visible

division of lungsWrapped in elastic

C.T.Contain:

bronchiole & its branches, arteriole, venule, lymphatic vessel

Ventilation (Breathing)Mechanics of moving air in & outDepends on gas moving from high to low pressure

(Boyle’s Law)

Quiet Inspiration- Diaphragm & external intercostals contract- Size of thoracic cavity - Pressure - Air flows in

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Ventilation continued

Quiet Expiration- Nerve impulses cease, diaphragm & ext.

intercostals relax- Size of thoracic cavity - Pressure - Gases flow out

Spirometry

Respiratory Volumes- Tidal Volume (Amount in Single, Relaxed

Breath or Breathing Cycle, 500 ml)- Inspiratory Reserve Volume (Amount

Forcibly Taken in Above TV, 3,000 ml) - Expiratory Reserve Volume (Amount

Forcibly Exhaled after TV, 1,000 ml) - Residual Volume (Always Remains in

Lungs) - Vital Capacity (Max. Amount Exhaled, TV

+ IRV + ERV, 4,500 ml)

RESPIRATION (Gas Exchange)

Occurs in two locations:- External Respiration

* Between Alveoli & Pulmonary Capillaries

* O2 diffuses into blood & CO2 diffuses out

- Internal Respiration* Between Systemic Capillaries & Interstitial

Spaces

* O2 diffuses out of blood & CO2 diffuses in

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RESPIRATORY SYSTEM PHYSIOLOGY continued

- CO2 Transport:

* Bicarbonate Ion (HCO3-) in RBCs

* Attached to Hemoglobin* Plasma

Control of Breathing

Respiratory Regulatory Center- Medulla – sets the basic rate & rhythm

* CO2 changes (pH) act as primary stimulus

- Pons – smooths respiratory pattern

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Control of Breathing

Chemoreceptors - Medulla oblongata monitors CO2 & pH of

CSF- Aorta & Carotid Artery detect changes in

oxygen concentration

Peripheral Chemoreceptors