1

Respiratory System

2

I. Functions and Development

  A. The term respiration includes three separate but related functions. 1- ventilation (breathing) 2- gas exchange 3- oxygen utilization.

 1. The exchange of gases (oxygen and carbon dioxide) between the air and blood is called external respiration.

3

4

2. Gas exchange between the blood and tissues is known as internal respiration.

 3. It is estimated that an adult breathes about 9-20 times per minute, ventilating about 5-6 liters of air during this period.

5

4. If a person stops breathing, - lose consciousness after 4-5 min.- May suffer brain damage after 7-8 min.- Will die after 10 min.

6

B. Physical Requirements of the Respiratory System

 1. The structures through which gas is exchanged must be thin-walled and selectively permeable so that diffusion can occur easily.

 2. The membrane must be kept moist so that oxygen and carbon dioxide can be dissolved in water to help in diffusion.

7

3. A rich supply of blood must be present.

 4. The surface for gas exchange must be located deep in the body so that the incoming air can be sufficiently warmed, moistened, and cleansed of airborne particles.

8

5. There must be effective ventilation mechanism to constantly replenish the air.

9

C. Functions of the Respiratory system. 

1. Providing oxygen to the bloodstream and removing carbon dioxide.

 a. Gas exchange; the earth is made up of 78% nitrogen and 21% oxygen.

10

Gases Inhaled Exhaled

N2 78.62% 74.9%O2 20.84% 15.3%CO2 .04% 3.6%H2O 1.25% 5.9%

11

2. Sound production or vocalization as expired air passes over the vocal cords.

 3. Assisting in abdominal compression during urination, defecation, and childbirth. The abdominal muscles become more effective during a deep breath when the air is held in the lungs by closing the glottis and fixing the diaphragm.

12

13

Vocal cords

14

15

4. Providing protection and reflexive non-breathing.

16

D. Basic Structure of the Respiratory System

1. The major passages and structures of the respiratory system are the nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles and alveoli within the lungs.

17

18

Alveoli

19

20

2. The respiratory system is frequently divided into the conducing divisions and respiratory divisions.

3. Conducting includes all the cavities and structures that transport gases to and from alveoli.

21

4. The alveoli, the funcitonal units of the system, constitute the respiratory portion.

22

E. Embryological development of the respiratory system.

1. Cephalization-forming the head of the baby is apparent early in development.

23

2. The formation of the nasal cavity occurs at three and half-four weeks of embryonic life.

3. The mouht, or oral cavity, develops at the same time as the nasal cavity.

24

4. Alveoli form about 8 weeks of development and the supporting lung tissue begins to form.

5. The complete structure of the lungs is not fully developed until about 26 weeks. (about 7 months.

25

II. Conducting passages

A. Nose

1. The nose includes an external portion that juts out from the face an internal nasal cavity for the passage of the air.

26

NOSE

27

2. The nasal septum divides the nasal cavity into: two lateral halves each are referred to as nasal fossa.

3. Each nasal fossa opens to the nostrils or anterior nares.

28

29

4. Three functions that are associated with the nasal cavity are:

a. Warming the air.b. Smellc. Voice

30

B. Paranasal Sinuses

1. Paired air spaces in certain bones of the skull are called paranasal sinuses. These sinuses are named acording to the bones in which they are formed.

31

2. Maxillary, frotnal spehenoidal and ethmoidal sinuses.

3. Each sinus has drainage ducts within the nasal cavity on its own side.

4. Sinuses may help to warm and moisten the air.

32

33

5. The sinuses are also responsible for some sound.

6. Most importantly sinuses function to decrease the weight of the skull while giving structural strength.

34

C. Pharynx

1. The pharynx connects the nasal and oral cavities to the larynx at the base of the skull.

35

36

2. The supporting walls of the pharynx are composed of skeletal muscle, and the lumen is lined with a mucous membrane.

3. There are sevreal paired lymphoid organs called tonsils.

37

38

JOKE TIME

39

4. The pharynx has both respiratory and digestive functions and speech sound.

5. The pahrynx is divided into three regions, nasal, oral and laryngeal.

6. The nasopharynx has only respiratory functions.

40

7. It is the upper most portion of the pharynx.

8. A penddulous uvula hangs from the middle, lower border of the soft palate.

41

42

9. The paired auditory, or Eustachian tube connect the nasopharynx with the middle ear davities.

10. Pharyngeal tonsils or adenoids are inovled during the act of swallowing. The soft palate and uvula are elevated to block the nsasal cavity cavity and prevent frood from entering.

43

44

11. Sometimes a person may breath while they are drinking, if this occurs before the uvula blocks the nasopharynx, fluid will come out the nose.

45

46

12. The oropharynx is the middle portion of the pharynx between the palate and the level of the hyoid bone.

13. The base of the tongue forms the anterior wall fo the oropharynx.

47

48

14. The laryngopharynx is the lower most portion of the pharynx.

15. The laryngopharyns is invovled in respiratoy and digestive systems.

49

50

D. Larynx

1. The larynx- or voice box forms the entrance into the lower respiratory system as it connects the laryngopharynx with the trachea.

51

2. The larynx has two main functionsa. Prevent food or fluid from entering the trachea and lungs during swallowing.b. Produce sound

3. It is composed of nine cartilages, three and large single structures, and six ar paired smaller structures

52

53

4. The laryngeal muscles are extremely important in closing the glottis during swallowing and in speech.

5. There are two groups of laryngeal muscles-extrinsic and intrinsic.

54

6. Extrinsic muslces are responsible for elevating the larynx during swallowing and intrinsic muscle, when contracted change the length, position and tension of vocal cords.

55

7. Mature males generally have thicker and longer vocal cords than females; therefore the vocal cords of males vibrate more slowly and produce lower pitches.

8. The trachea, commonly called the windpipe, is a rigid tube. It connects the larynx to the primary bronchi.

56

9. The mucosa (surface lining of the lumen) containing many mucus-secreting goblet cells.

10. Inhaled dust particles stick to the mucus, and the cilia sweep it out into a cough reflex.

57

11. In some people the goblet cells over produce mucoous and this is one reason people might have asthma.

12. The bronchial tree is named because it is composed of a series of respiratory tubes as they extend into the lung.

58

13. The trachea leads to a right and left primary bronchus.

14. The borchus divides deeper in the lungs to form secondary bronchi and segmental bronchi.

59

15. The bronchial tree continues to branch into yet smaller tubules called bronchioles.

16. There is little cartilage in the bronchioles, which contain thick smooth muscles that can constrict or dialate these areas.

60

61

18. Asthma is an infectious or allergenic condition that invovles the bronchi. During an asthmatic attack, there is a spasm of the smooth muscles in the lower bronchioles.

62