1. Respiratory System Chapter 24

2. The main function of the respiratory system is to supply oxygen to, & eliminate carbon dioxide from the body
In order to accomplish this task, the respiratory system must work in conjunction with the cardiovascular system

3. “Respiration” refers to the overall exchange of gases between the atmosphere, blood & cells
Respiration involves 3 processes
Pulmonary ventilation
External respiration
Internal respiration

4. Anatomy Overview The respiratory tract includes:
Nose (nasal cavity) Pharynx (nasopharynx, oropharynx, laryngopharynx) Larynx Trachea Bronchi (primary, secondary (lobar), tertiary (segmental) Bronchioles
Terminal bronchioles Respiratory bronchioles Alveolar ducts
Alveoli
Nasal cavity
Pharynx
Larynx
Trachea
Bronchi
Bronchioles
Respiratory bronchioles
Right
Lung
Left Lung
Alveolar duct
Alveoli

5. Histology
Respiratory Epithelium = Pseudostratified Ciliated Columnar (PSCC)

6. Nose (nasal cavity)
Air normally enters through external nares through nasal vestibule into nasal cavity.
Nasal cavity divided by nasal septum and has a respiratory area with 3 nasal conchae (superior, middle & inferior) projecting into the midline from each lateral wall creating nasal meatuses between; and an olfactory area
Nasal cavity communicates with the paranasal sinuses in frontal, maxillary, ethmoid & sphenoid bones
Functions of nasal cavity include: warming, moistening & filtering air; olfaction

7. Pharynx
Air passes from nasal cavity, across internal nares into nasopharynx, past oropharynx & through laryngopharynx to larynx
Nasopharynx lined with PSCC epithelium, but oro & laryngopharynx lined with stratified squamous epithelium because they are also part of digestive system

8. Eustachian (auditory) tube – connects nasopharynx & middle ear cavity
Pharyngeal tonsil – lymphatic tissue embedded in wall of nasopharynx
Palatine tonsils - lymphatic tissue embedded in wall of oropharynx
Uvula – posterior tissue from soft palate; protects nasopharynx when swallowing

9. Larynx
Air passageway made of 9 pieces of cartilage – (1) Thyroid cartilage, (1) Epiglottis, (1) Cricoid cartilage, (2) Arytenoid, (2) Corniculate, (2) Cuneiform
A.K.A your “voicebox” because it contains the vocal cords

10. Larynx Thyroid cartilage – protects anterior & lateral walls of airway
Epiglottis – leaf-shaped cartilage that protects opening (“glottis”) of airway when swallowing
Cricoid cartilage – complete ring of cartilage; protects posterior wall of airway; attaches to trachea

11. Larynx
Arytenoid, corniculate & cuneiform cartilages – attach to upper (vestibular) vocal folds & lower (true) vocal cords

12. Trachea
Tough but flexible “windpipe”, anterior to esophagus
attached to cricoid cartilage (at about C6 vertebral level) & ends within mediastinum by branching into left & right primary bronchi (at T5 vertebral level)
End of trachea known as Carina
Carina

13. Trachea
Lined with respiratory epithelium
“C”-shaped pieces of hyaline cartilage protecting airway while allowing for swallowing
Trachealis muscle (smooth muscle) runs across posterior wall of trachea connecting ends of tracheal cartilage

14. Trachea
Low power
High power
Medium power

15. Bronchi
Trachea splits into a left & right primary bronchus which enters into the hilus of each lung
Within the lung, the primary bronchi branch into secondary (lobar) bronchi (3 in right lung/2 in left lung)
Secondary bronchi then branch into 10 tertiary (segmental) bronchi
Tertiary bronchi then continue to branch into smaller & smaller bronchi & then into very narrow bronchioles
Carina
This branching patterns creates the “bronchial tree”

16. Changes In Airway
As you go further down into the bronchial tree of each lung, changes in the airway occur:
increased number of airways (1 primary; 2 or 3 secondary; 10 tertiary bronchi; 6000 terminal bronchioles; millions of alveolar ducts)
decreased diameter of each airway
decreased amount of cartilage in the airways (no cartilage at all by terminal bronchioles)
increased amount of smooth muscle (relative to diameter)
lining epithelium changes from PSCC  simple squamous epithelium (in alveoli)

17. Lungs
Located within the thoracic cavity, surrounded by the double-layered pleural membrane –
parietal pleura – lines cavity wall
visceral pleura – covers the lungs

18. Lungs- Anatomical Features
Apex – extends 1” above clavicle
Base – rests on diaphragm
Hilum – at medial surface; where primary bronchus, pulmonary artery & veins enter/exit lung
Superior lobe
Inferior lobe
Oblique fissure
Superior lobe
Middle lobe
Inferior lobe
Right lung
Horizontal fissure
Oblique fissure
Left lung
Cardiac notch

19. Lung – medial surface
Groove for aorta
Hilum
Cardiac notch of Lt. lung

20. Airways within Lungs
Each lung has a primary bronchus entering at the hilus
Each lobe of a lung has a secondary (a.k.a. lobar) bronchus
Lobes are functionally divided into bronchopulmonary segments & each segment has a tertiary (segmental) bronchus
Segments are functionally divided into many lobules & each lobule receives a terminal bronchiole

21. Relationship of Airways & Pulmonary Vessels
As airways branch within lungs, they are accompanied by branches of the pulmonary artery (carrying de-oxygenated blood into the lungs), & branches of the pulmonary veins (carrying oxygenated blood out of the lungs)
As the alveolar ducts expand to form alveoli, pulmonary arterioles will branch to form a network of pulmonary capillaries, surrounding the alveoli

22. Alveoli There are about 150 million alveoli in each lung
Alveoli are expanded chambers of epithelial tissue that are the exchange surfaces of the lungs
There are about 150 million alveoli in each lung
Multiple alveoli usually share a common alveolar duct, creating “alveolar sacs”

23. Alveoli There are three types of cells found within alveoli:
Alveolar Squamous epithelial (aka “type I”) cells – primary cells making up the wall of the alveoli
Septal (aka “type II”) cells – sectrete “surfactant” to reduce surface tension which prevents alveoli from sticking together & allows for easier gas exchange
Alveolar macrophages (aka “dust cells”) – phagocytic cells that remove dust, debris & pathogens

24. Gas “exchange” occurs across the Respiratory membrane – the fused membranes of the alveolar epithelium & the pulmonary capillary endothelium