JOEL SORIA, MD

bc

I. Functions of the Respiratory System

A. Gas exchange

B. Regulation of blood pH

C. Voice production

D. Olfaction

E. Innate immunity

Content Outline

A. Nose and nasal cavity

1. External and internal nares

2. Hard palate

3. Conchae

4. Paranasal sinuses

5. Nasolacrimal ducts

bcNose and Nasal Cavity

bcNose and Nasal Cavity• Nasal Cavity extends from the nares to the choana• Nares/Nostrils – External opening of the nose• Nasal septum – Divides the nose to left and right• Hard palate – Floor of the nasal cavity• Concha – a.k.a Turbinates• Paranasal sinuses• Nasolacrimal ducts

bcPharynx

Common passageway of both food and air.

Nasopharynx – Extends up to the level of uvula.

Laryngopharynx – From the tip of epiglotis to esophagus

bcLarynx

bcTrachea

Function of the cough reflex is to dislodge foreign substances from the trachea.

Lungs

bc

A. Changing thoracic volume1. Muscles of inspiration2. Muscles of expiration

B. Pressure changes and air flow1. Changes in volume lead to changes in pressure2. Air flows form high pressure to low pressure3. Events of one respiratory cycle

C. Lung recoil – elastic forces and surface tension1. Surfactant2. Pleural pressure

D. Changing alveolar volume

Ventilation and Lung Volumes

bc

1. Tidal volume 2. Inspiratory reserve volume 3. Expiratory reserve volume 4. Residual volume 5. Functional residual capacity 6. Inspiratory capacity 7. Vital capacity 8. Total lung capacity 9. Forces expiratory vital capacity

Pulmonary Volume & Capacity

Tidal volume – air inspired or expired with each breath. 500 mL

Inspiratory Reserve Volume (IRV) – Amount of air that can be inspired forcefully after inspiration of resting volume. 3000 mL

Expiratory Reserve Volume (ERV) – Amount of air that can be expired forcefully after expiration of resting volume. 1,100 mL

Residual Volume (RV) – Volume of air still remaining in the respiratory passages after forcefull expiration. 1,200 ml

• Functional residual capacity (FRC) – ERV + RV

• Inspiratory Capacity (IC) – TV + IRV

• Vital Capacity (VC) – IRV + TV + ERV

• Total Lung Capacity (TLC) – VC + RV