Human Respiratory System

 

I.  Upper respiratory tract

 

A.     Nose and nasal cavity

1.      External nares – nostrils

 

2.  Nasal conchae – (singular: concha); bony projections of the lateral walls of the nasal cavity

                                    a.  superior nasal conchae

                                    b.  middle nasal conchae

                                    c.  inferior nasal conchae

                       

                        3.  Nasal meatuses - groove-like passageways between the conchae

                                    a.  superior nasal meatus

                                    b.  middle nasal meatus

            c.  inferior nasal meatus

                       

4.  Nasal septum

                                    a.  perpendicular plate of ethmoid

                                    b.  vomer

                                    c.  septal cartilage

                       

5.  The nasal cavity is separated from the oral cavity by the bony hard palate and the posterior muscular soft palate.  The uvula is the cone shaped posterior tip of the soft palate.

 

6.  Internal nares (posterior nasal apertures) – openings connecting the nasal cavity to the nasopharynx

 

            B.  Paranasal sinuses – spaces within certain bones of the skull; lined with mucous membrane; drain mucous into the nasal cavity.

                        1.  Ethmoid sinuses (ethmoid air cells)

                        2.  Maxillary sinuses

                        3.  Frontal sinuses

                        4.  Sphenoid sinuses

 

C.  Pharynx

1.  Nasopharynx – superior portion of the pharynx

a.  auditory (Eustachian) tube opening

                                    b.  pharyngeal tonsil (adenoid) – single tonsil in the posterior wall of the nasopharynx

           

2.  Oropharynx – intermediate portion of the pharynx

                                    a.  palatine tonsils – paired tonsils found in the lateral walls of the oropharynx

                                    b.  lingual tonsils – paired tonsils at the base of the tongue

 

3.  Laryngopharynx – inferior portion of the pharynx

 

 

II.  Lower respiratory tract

           

            A.  Larynx – “voice box”; connects the laryngopharynx to the trachea

1.  thyroid cartilage – “Adam’s apple”; reinforces the larynx anteriorly and laterally

2.  hyoid bone – superior to the thyroid cartilage

3.  cricoid cartilage – complete ring of cartilage forming the inferior portion of the larynx

                        4.   epiglottis – closes the opening of the larynx (glottis) during swallowing

5.  arytenoid cartilages – paired cartilages found at the posterior and superior border of the cricoid cartilage; involved in changing the tension of the vocal folds (true vocal cords)

                        6.  vocal folds (true vocal cords) – lower pair; produce sound

7.  vestibular folds (false vocal cords) – upper pair; assist in closing glottis

8.  glottis – the opening between the true vocal cords

 

B.  Trachea

 

                        1.  tracheal cartilages – incomplete C-shaped rings

 

C.  Bronchi – branches of the trachea (singular: bronchus)

                        1.  primary bronchi

2.  secondary (lobar) bronchi – deliver air to each lung lobe

                        3.  tertiary bronchi

 

            D.  Bronchioles – lack cartilage rings

 

            E.  Alveoli – (singular: alveolus); small, grape-like clusters of air sacs deep within the lungs; this is where gas exchange occurs

 

F.     Microscope slides of lung tissue:  Be able to identify –

1.  bronchus – note the presence of cartilage plates and respiratory epithelium (pseudostratified ciliated columnar epithelium lining)

2.  bronchiole – no cartilage plates present and mostly lined with simple cuboidal epithelium

3.      respiratory airways: this is where gas exchange occurs

a.      alveolar ducts

b.      alveolar sacs

c.      alveoli – note the simple squamous epithelium

 

III.  Lungs

 

            A.  Parietal pleura – “sac-like” covering of the lungs; lines the wall of the thoracic cavity

            B.  Visceral pleura – tightly covers the lungs

            C.  Pleural cavity – potential space between the parietal and visceral pleura

            D.  Lobes of the lung:

                        1.  right lung – superior lobe; middle lobe; inferior lobe

                        2.  left lung – superior lobe; inferior lobe

 

IV.  Respiratory physiology

 

A.  Muscles of pulmonary ventilation (breathing):

1.      Muscles involved in normal (quiet) breathing:

a.  diaphragm

b.  external intercostals

 

2.      Muscles involved in forced (labored) inspiration:

a.  external intercostals

b.      serratus anterior

c.      sternocleidomastoid

d.      pectoralis minor

 

3.  Muscles involved in forced (labored) expiration:

a.  internal intercostals

b.      rectus abdominis

c.      external oblique

d.      internal oblique

e.  transverse abdominis

 

B.  Spirometer – instrument used to measure volumes of air exchanged in breathing.

 

Note:  For the following volumes and capacities, know the average values for men and women given in Figure 25.4 on page 444 of your lab manual.

 

C.  Tidal volume (TV) – air moved in (or out) of the lungs during quiet breathing

 

D.  Inspiratory reserve volume (IRV) – air that can be inhaled during forced breathing beyond the tidal volume

 

E.  Expiratory reserve volume (ERV) – air that can be exhaled during forced breathing after the tidal volume is exhaled

 

F.  Vital capacity (VC) – during forced breathing, the maximum volume of air that can be exhaled (or inhaled); VC=TV+IRV+ERV

 

G.  Residual volume (RV) – air that remains in the lungs after a maximum forced expiration

 

 

Note: Be able to calculate TV, IRV, ERV and VC:

 

            Example:        If given -          ERV = 1000 ml

                                                            TV = 500 ml

                                                            VC = 4600 ml

 

                                    Question: What is the IRV?

 

                                    Solution:         VC = TV+IRV+ERV

                                                                     IRV = VC – (TV+ERV)

                                                                     IRV = 4600 – (500+1000)

                                                                     IRV = 4600 – 1500

                                                                     IRV = 3100 ml

 

 

 

 

Last Updated:  12/31/2006