RESPIRATORY TREE 

I   Respiratory System

            A.  Functional divisions 

                        1.  Conducting structures - carry air to and from the lungs

                        2.  Respiratory units - exchange gases between air and blood

            B.  Anatomy of Conducting Structures

                        1.  pharynx

                                    a.  openings

                                    b.  swallowing

                        2.  larynx                                                  

                                    a.  cartilages

                                    b.  vocal folds

                        3.  trachea

                                    a.  �C� - shaped cartilages

                        4.  primary bronchi

                                    a.  carina

                                    b.  right bronchus vs. left bronchus

                        5.  secondary (lobar) bronchi

                        6.  tertiary (segmental) bronchi

                        7.  terminal bronchioles

                                    a.  structural transitions from bronchi to bronchioles

            C.  Anatomy of  Respiratory Units

                        1.  gross anatomy: lungs

                                    a.  surface anatomy

                                    b.  pleura and pleural cavity

                                                1.  pneumothorax

                                    c.  lobes -> segments --> lobules --> respiratory units --> alveolus

                        2.  microscopic anatomy:  alveolus

                                    a.  wall thinness

                                    b.  Type II cells: surfactant

                                                1.  infant respiratory distress syndrome

                                    c.  �dust�  cells

            D.  Surface area to volume ratio

                        1.  5 lobes vs. 500 million alveoli

                        2.  structural principle

            E.  Disorders

                        1.  asthma

                        2.  COPD

II   Pulmonary ventilation

            A.  inspiration (inhalation) - need to increase volume

                        1.  resting:  contract diaphragm to lengthen thoracic cavity and contract external intercostals to widen the thoracic cavity

                        2.  active:  contract diaphragm, external intercostals, scalenes, and sternocleidomastoid to increase lung volume even more

            B.  expiration (exhalation) - need to decrease volume

                        1.  resting:  relax diaphragm and external intercostals

                        2.  active:  relax diaphragm and external intercostals and also contract internal intercostals and abdominal muscles to decrease volume more

At the end of this unit, you should be able to:

     - distinguish between conducting and respiratory portions of the respiratory system

     - describe the pharynx, its openings and the process of swallowing

     -  describe the structures of the larynx:  the cartilages, vocal folds, glottis

     -  explain the effect of tightening and of loosening the vocal ligaments (cords)

     - locate the trachea in the body and discuss how its structure fits its function

     -  distinguish between the primary, secondary, and tertiary, bronchi and the regions of the lungs they supply

     -  describe the structural changes between primary bronchi and terminal bronchioles

     - identify and describe the gross anatomy of the lungs (lobes, hilus)

     -  identify and describe the pleural membranes and cavity

     -  draw and label an alveolus of the lung

     -  explain how the structure of an alveolus fits the role of gas exchange

     -  explain how surface area is increased in the lung and why this is important

     -  state the general principle which explains why air flows in and out of the lungs (pressure - volume relationships)

     -  explain how the volume of the thoracic cavity is increased and decreased during rest

     -  explain how the volume of the thoracic cavity is increased and decreased during activity

     -  describe the conditions of pneumothorax, hypoxia, asthma, COPD

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