1. Chapter 13
Respiratory System

2. Introduction:
Our cells require an abundant supply of oxygen to carry out vital functions.
We cannot do without oxygen for even a little while, as we can without food or water.

3. Functions of the Respiratory System:
Oversees gas exchanges between the blood and external environment
Passageways to the lungs purify, warm, and humidify the incoming air

4. Organs of the Respiratory System:
Trachea
Bronchi
Lungs – which contain alveoli (terminal air sacs)
Nose
Pharynx
Larynx

5. Organs

6. Upper Respiratory Tract

7. The Nose (“pug” or “ski-jump” in shape)
The only externally visible part of the respiratory system
Air enters the nose through the external nares (NOSTRILS)
The inferior of the nose consists of a nasal cavity divided by a NASAL SEPTUM

8. Anatomy of the Nasal Cavity
Olfactory receptors are located in the mucosa on the superior surface
The rest of the cavity is lined with respiratory mucosa
Moistens air
Traps incoming foreign particles
Lateral walls have projections called CONCHAE
Increases the surface area exposed to the air
Increases air turbulence within the nasal cavity

9. Anatomy of the Nasal Cavity
The nasal cavity is separated from the oral cavity by the palate
Anterior hard palate (bone)
Posterior soft palate (muscle)
DISORDER: Cleft Palate – A genetic defect due to the failure of the bones forming the palate to fuse. It results in breathing difficulty as well as chewing and speaking.

10. Paranasal Sinuses Cavities within bones surrounding the nasal cavity:
Frontal Bone
Sphenoid Bone
Ethmoid Bone
Maxillary Bone

11. Paranasal Sinuses Functions of the sinuses: Lighten the skull
Act as resonance chambers for speech
Produce mucus that drains into the nasal cavity

12. Pharynx (THROAT) Muscular passage from nasal cavity to larynx
Three regions of the pharynx:
Nasopharynx = superior region behind nasal cavity
Oropharynx = middle region behind mouth
Laryngopharynx = inferior region attached to larynx

13. Pharynx (THROAT) The nasopharynx is where air enters.
The oropharynx and laryngopharynx are common passageways for air and food (food empties into the esophagus).

14. Pharynx (THROAT) Structures of the Pharynx:
Auditory tubes enter the nasopharynx
Tonsils of the pharynx
Pharyngeal tonsil (adenoids) = in the nasopharynx
Palatine tonsils = in the oropharynx
Lingual tonsil = at the base of the tongue

15. Larynx (VOICE BOX) Routes air and food into the proper channels
Plays a role in speech
Made of 8 rigid hyaline cartilages and a spoon-shaped flap of elastic cartilage (EPIGLOTTIS)

16. Larynx (VOICE BOX) Structures of the Larynx: Thyroid Cartilage
Largest hyaline cartilage
Protrudes anteriorly (ADAM’S APPLE)
Epiglottis
Superior opening of the larynx
Routes food to the esophagus and air toward the trachea
Vocal Cords – vibrate with expelled air to create sound (speech)
Glottis – opening between vocal cords

17. Larynx (VOICE BOX)
Place your hand midway on the anterior surface of the neck. Swallow. Can you feel the larynx rising as you swallow?

18. Trachea (WINDPIPE) Connects larynx with bronchi
Lined with ciliated mucosa
Beat continuously in the opposite direction of incoming air
Expel mucus loaded with dust and other debris away from the lungs
Walls are reinforced with C-shaped hyaline cartilage - the open parts of the rings allow our esophagus to expand when we swallow a large piece of food.

19. Trachea (WINDPIPE)
Smoking destroys the cilia within the trachea. Without these cilia, coughing is the only means of preventing mucus from accumulating in the lungs.
Because the trachea is the only way air can enter the lungs, tracheal obstruction is life threatening. Many people have suffocated after choking on a piece of food that suddenly closed off the trachea. The Heimlich Maneuver, a procedure in which the air in a person’s own lungs is used to “pop out,” or expel an obstructing piece of food, has saved the lives of many people.

20. Primary Bronchi
Right and Left primary bronchi are formed by division of the trachea
Right bronchus is wider, shorter, and straighter than the left and more common for an inhaled foreign object to become lodged.
Bronchi subdivide into smaller and smaller branches

21. Lungs Occupy most of the thoracic cavity
Apex – superior portion of each lung – near the clavicle
Base – inferior portion – rests on the diaphragm
Each lung is divided into lobes by fissures:
Left lung = 2 lobes
Right lung = 3 lobes

22. Lungs Coverings of the Lungs:
Pulmonary (Visceral) Pleura = covers the lung surface
Parietal Pleura = lines the walls of the thoracic cavity
Pleural Fluid = fills the area between layers of pleura to allow gliding

23. Lungs
DISORDER: Pleurisy – Inflammation of the pleura and can be caused by decreased secretion of pleural fluid. The pleural surfaces become dry and rough, which results in friction and stabbing pain with each breath.

24. After the primary bronchi enter the lungs, they subdivide into smaller branches which forms the Respiratory Tree Divisions:
Primary Bronchi
Secondary Bronchi
Tertiary Bronchi
Bronchioles
Terminal Bronchioles

25. Bronchioles Smallest branches of the bronchi
Terminal bronchioles end in alveoli

26. Alveoli
Gas exchange takes place within the alveoli in the respiratory membrane

28. Gas Exchange Gas crosses the respiratory membrane by diffusion
Oxygen enters the blood
Carbon dioxide enters the alveoli
Macrophages add protection

29. Respiratory Physiology:
The major function of the respiratory system is to supply the body with oxygen and to dispose of carbon dioxide.
To do this, at least four events, collectively called RESPIRATION, must occur.

30. Events of Respiration:
Pulmonary ventilation - moving air in and out of the lungs (BREATHING)
External respiration - gas exchange between pulmonary blood and alveoli
Respiratory gas transport - transport of oxygen and carbon dioxide via the bloodstream
Internal respiration - gas exchange between blood and tissue cells in the systemic capillaries

31. Mechanics of Breathing PULMONARY VENTILATION
Completely a mechanical process
2 phases
Inspiration = flow of air into lungs
Expiration = air leaving lungs

32. Inspiration: Diaphragm and the muscles in between the ribs contract
The size of the thoracic cavity increases
External air is pulled into the lungs

33. Expiration or Exhalation:
As muscles relax, air is pushed out of the lungs
Forced expiration can occur mostly by contracting the internal rib muscles to depress the rib cage

34. Nonrespiratory Air Movements
Can be caused by reflexes or voluntary actions
Examples
Cough and Sneeze - clears lungs of debris
Laughing - emotionally induced response
Crying - emotionally induced mechanism
Yawn - triggered by need to increase the amount of oxygen in the blood
Hiccup - spasms of the diaphragm; sounds come from the air hitting the vocal folds of the glottis

35. Respiratory Volumes and Capacities
Normal breathing moves about 500 mL of air with each breath (TIDAL VOLUME)
Many factors affect respiratory capacity:
A person’s size
Sex
Age
Physical condition

36. Respiratory Sounds Sounds are monitored with a stethoscope
Bronchial Sounds - produced by air rushing through the trachea and bronchi
Vesicular breathing sounds - soft sounds of air filling alveoli
Diseased respiratory tissue, mucus, or pus can produce abnormal sounds such as RALES (a rasping sound) and WHEEZING (a whistling sound).

37. External Respiration Oxygen movement INTO the blood
Carbon dioxide movement OUT of the blood
Blood leaving the lungs is OXYGEN RICH and CARBON DIOXIDE POOR

38. Internal Respiration Exchange of gases between blood and body cells
An opposite reaction to what occurs in the lungs
Carbon dioxide diffuses OUT of tissue TO blood
Oxygen diffuses FROM blood INTO tissue

39. Neural Regulation of Respiration
Activity of the respiratory muscles is transmitted to the brain by nerves
Neural centers that control rate and depth are located in the medulla
The pons appears to smooth out respiratory rate
Normal respiratory rate is respirations per minute

41. Factors Influencing Respiratory Rate and Depth
Physical Factors
Increased Body Temperature
Exercise
Talking
Coughing
Volition - conscious control
Holding the breath when swimming
Breathing while singing
Emotional Factors

42. Factors Influencing Respiratory Rate and Depth
Chemical Factors
Carbon dioxide levels
Level of carbon dioxide in the blood is the main regulatory chemical for respiration
Increased carbon dioxide increases respiration
Oxygen levels
Changes in oxygen concentration in the blood are detected by chemoreceptors in the aorta and carotid artery

43. Respiratory Disorders

44. Chronic Obstructive Pulmonary Disease (COPD)
Exemplified by chronic bronchitis and emphysema
Major causes of death and disability in the United States
Features of these diseases
Patients almost always have a history of smoking
Labored breathing becomes progressively more severe
Coughing and frequent pulmonary infections are common
Most victims retain carbon dioxide
Those infected will ultimately develop respiratory failure

45. Emphysema Alveoli enlarge Chronic inflammation promotes lung fibrosis
Airways collapse during expiration
Patients use a large amount of energy to exhale
Overinflation of the lungs leads to a permanently expanded barrel chest

46. Chronic Bronchitis
Mucosa of the lower respiratory passages becomes severely inflamed
Mucus production increases
Pooled mucus impairs ventilation and gas exchange
Risk of lung infection increases
Pneumonia is common

47. Lung Cancer Accounts for 1/3 of all cancer deaths in the United States
Increased incidence associated with smoking

48. Sudden Infant Death Syndrome (SIDS)
Apparently healthy infant stops breathing and dies during sleep
Some cases are thought to be a problem of the neural respiratory control center
1/3 of cases appear to be due to heart rhythm abnormalities

49. Asthma Chronic inflamed hypersensitive bronchiole passages
Response to irritants with coughing and wheezing

50. Developmental Aspects of the Respiratory System
Lungs are filled with fluid in the fetus
Lungs are not fully inflated with air until two weeks after birth
Important birth defects:
Cystic fibrosis – over-secretion of thick mucus clogs the respiratory system
Cleft palate

51. Aging Effects: Elasticity of lungs decreases Vital capacity decreases
Blood oxygen levels decrease
Stimulating effects of carbon dioxide decreases
More risks of respiratory tract infection

52. Respiratory Rate Changes Throughout Life:
Newborns - 40 to 80 respirations per minute
Infants - 30 respirations per minute
Age respirations per minute
Adults - 12 to 18 respirations per minute
Rate often increases somewhat with old age