1. Lecture 23: The Respiratory System
Lecturer: Dr. Barjis
Room: P307
Phone: (718)

2. Learning Objectives
Describe the primary functions of the respiratory system
Identify the organs of the respiratory system and describe their functions
Define and compare the processes of external and internal respiration

3. Learning Objectives
Summarize the physical principles governing the movement of air into the lungs and the diffusion of gases into the blood
Explain the important structural features of the respiratory membrane
Describe how oxygen and carbon dioxide are picked up, transported and released in the blood

4. Functions of the respiratory system
Gas exchange between air and circulating blood
Moving air from the exchange surface of the lungs
Protection of respiratory surfaces
Production of sound
Provision for olfactory sensations

5. Organization of the respiratory system
Respiratory system is divided into upper and lower respiratory systems.
Upper respiratory system
Nose, nasal cavity, paranasal sinuses, pharynx
Lower respiratory system
Larynx, trachea, bronchi, bronchioles, alveoli

6. The Components of the Respiratory System
The hard palate separates the nasal cavity from the oral cavity

7. The Respiratory tract
Conducting passageways carrying air to and from the alveoli
Upper respiratory passages filter, warm and humidify incoming air
Lower passageways include delicate conduction passages and alveolar exchange surfaces

8. The Nose, Nasal Cavity, and Pharynx
Nasal conchae creates turbulence as air passes through the nasal cavity.
Turbulence makes the air bounce, thus small microorganisms will be trapped in the mucus

9. The pharynx Shared by the digestive and respiratory systems
Divided into three sections:
Nasopharynx – superior portion
Oropharynx – continuous with the oral cavity
The portion of pharynx that receives oth air and food
Laryngopharynx

10. The larynx Receives inhaled air from pharynx through glottis
Larynx protects the glottis
Food/drink that touch the vestibular or vocal folds trigger coughing reflex
Larynx consist of 3 large cartilages
Thyroid – is largest laryngeal cartilage
Cricoid – ring shaped cartilage
Epiglottis – is an elastic cartilage that prevents food and water from entering the larynx

11. The Larynx

12. The Larynx Sound production
Air passing through the glottis vibrates the vocal folds producing sound waves
Pitch depends on conditions of vocal folds
Diameter
Length
Tension

13. The Glottis

14. The laryngeal musculature
The Larynx
The laryngeal musculature
Muscles of the neck and pharynx position and stabilize the larynx
When swallowing these muscles
Elevate the larynx
Bend the epiglottis over the glottis
Intrinsic muscles control tension on the vocal folds and open the glottis

15. The trachea
A tough, flexible tube running from the larynx to the bronchi
Held open by C-shaped tracheal cartilages

16. The Anatomy of the Trachea

17. The bronchi
Trachea branches in the mediastinum into right and left bronchi
Bronchi enter the lungs at the hilus
The two primary bronchi branches further to secondary bronchi as they enter the lungs
Secondary bronchi branches into tertiary bronchi and tertiary bronchi branches into brancheoles within the lung
As they branch, amount of cartilage in their wall reduces and amount of smooth muscle increases

18. Lobes and surfaces of the lungs
Lobes of the lung are separated by fissures
Right lung has three lobes
Left lung has two lobes

19. The Gross Anatomy of the Lungs

20. The bronchial tree
System of tubes formed from the primary bronchi and their branches
Primary bronchi branch into secondary bronchi
Secondary bronchus goes to each lobe of the lungs
Secondary bronchi branch into tertiary bronchi
Tertiary bronchi supply air to a single bronchopulmonary segment

21. The Bronchi and Lobules of the Lung

22. The Bronchi and Lobules of the Lung

23. The bronchioles
Each tertiary bronchus branches several times and give rise to bronchioles
Bronchioles branches into terminal bronchioles where each terminal brancheole:
Delivers air to a single pulmonary lobule
Terminal bronchiole becomes respiratory bronchioles

24. Summary of air flow Broncheoles
Nasal cavity
Pharynx
Nasopharynx
Oropharynx
Laryngopharynx
Larynx
Trachea
Bronchi
Primary Bronchi
Secondary Bronchi
Tertiary Bronchi
Broncheoles
Terminal Broncheoles
Respiratory Broncheoles
Alveoli –is the only site of gas exchange

25. Cells of the respiratory membrane include
Septal cells
Scattered in respiratory membrane
Septal cells produce surfactant
Surfacant prevents the alveoli from colapsing
Alveolar Macrophage
Macrophages patrol epithelium and engulf foreign particles
Animation: Respiratory Structures (see tutorial)

26. Alveolar Organization

27. The pleural cavities and pleural membranes
Each lung is covered by one pleura
Pleura is a serous membrane lining the pleural cavity
Parietal pleura - covers the inner surface of thoracic wall
Visceral Pleura - covers the surface of the lungs
Pleural fluid – fills and lubricates the space between the pleura

28. Respiratory physiology is a series of integrated processes
Internal respiration
Exchange of gases between interstitial fluid and cells or between the blood and interstitial fluid or capillaries and interstitial fluid.
Oxygen diffuses from the capillaries to the interstitial fluid and from the interstitial fluid to the cell
Carbon dioxide diffuses from the cell to the interstitial fluid and from the interstitial fluid to the capillaries.
External respiration
Exchange of gases between interstitial fluid and the external environment i.e. gas exchange between circulating blood and alveoli.
Oxygen diffuses from the alveoli to the capillaries
Carbon dioxide diffuses from the capillaries to the alveoli.

29. Respiratory physiology is a series of integrated processes
The steps of external respiration include:
Pulmonary ventilation
Gas diffusion
Transport of oxygen and carbon dioxide
Oxygen bounds to hemoglobin and is transported from the lungs to the cells.
Carbon dioxide is transported in the form of bicarbonate ions from the cell to the lungs
Reactions are completely reversible

30. An Overview of Respiratory Processes and Partial Pressures in Respiration
Animation: Respiratory Processes and Partial Pressures in Respiration (see tutorial)

31. An Overview of Key Steps in Respiration

32. Pulmonary Ventilation
The physical movement of air into and out of the lungs
Movement of air
Relationship between intrapulmonary pressure and atmospheric pressure determines direction of air flow
Boyle’s Law
Boyle’s law state that pressure and volume has inverse relationship i.e. the higher the volume the lower the pressure, and the lesser the volume the higher the pressure
Volume depends on movement of diaphragm and ribs

33. Mechanisms of Pulmonary Ventilation

34. Respiratory cycle
Respiratory cycle is single cycle of inhalation and exhalation
Amount of air moved in one cycle is called tidal volume
Animation: Pulmonary Ventilation (see tutorial)

35. Mechanisms of breathing
Quiet breathing (eupnea)
In quite breathing diaphragm and external and internal intercostals muscles are required (work)
Forced breathing (hyperpnea)
In forced breathing in addition to the diaphragm and intercostals muscles accessory muscles are needed

36. Respiratory volumes Tidal Volume (VT)
Amount of air inhaled or exhaled with each breath
Vital capacity
Tidal volume plus expiratory and inspiratory reserve volumes
Residual volume
Air left in lungs after maximum exhalation

37. Respiratory Volumes and Capacities

38. Gas Exchange The gas laws Daltons Law and partial pressure
Individual gases in a mixture exert pressure proportional to their abundance
In a mixture of gases like air the total pressure is the sum of pressure by the individual gas
Diffusion between liquid and gases (Henry’s law)
The amount of gas in solution is directly proportional to their partial pressure

39. Henry’s Law and the Relationship between Solubility and Pressure

40. Henry’s Law and the Relationship between Solubility and Pressure

41. Diffusion and respiratory function
Gas exchange across respiratory membrane is efficient due to:
Differences in partial pressure
Small diffusion distance
Lipid-soluble gases
Large surface area of all alveoli
Coordination of blood flow and airflow

42. Oxygen transport Carried mainly by RBCs, bound to hemoglobin
The amount of oxygen carried by hemoglobin depends upon:
PO2 pH
temperature
BPG
Fetal hemoglobin has a higher O2 affinity than adult hemoglobin

43. The Oxygen-Hemoglobin Saturation Curve

44. The Effect of pH and Temperature on Hemoglobin Saturation

45. A Functional Comparison of Fetal and Adult Hemoglobin

46. Carbon dioxide transport
7% dissolved in plasma
70% carried as carbonic acid
23% bound to hemoglobin
carbaminohemoglobin

47. Carbon Dioxide Transport in Blood

48. A Summary of the Primary Gas Transport Mechanisms

49. Respiratory reflexes
Respiratory centers are modified by sensory information including
Chemoreceptor reflexes
Level of carbon dioxide
Baroreceptors reflexes
Hering-Breuer reflexes
Prevents overinflation
Protective reflexes

50. You should now be familiar with:
The primary functions of the respiratory system
The organs of the respiratory system and their functions
The processes of external and internal respiration
The physical principles governing the movement of air into the lungs and the diffusion of gases into the blood
The important structural features of the respiratory membrane
How oxygen and carbon dioxide are picked up, transported and released in the blood