1. The Respiratory System

2. Respiration – four distinct processes must happen
Pulmonary ventilation – moving air into and out of the lungs
External respiration – gas exchange between the lungs and the blood
Transport – transport of oxygen and carbon dioxide between the lungs and tissues
Internal respiration – gas exchange between systemic blood vessels and tissues

3. Major Functions of the Respiratory System
Moving air to and from lungs
Provide extensive area for gas exchange
Protecting respiratory surfaces
Produces sound
Provide olfactory sensations

4. The Components of the Respiratory System

5. The nose and nasal cavity consists of:
External nares
Nasal cavity
Vestibule
Superior, middle
and inferior meatuses
Hard and soft palates
Internal nares
Nasal mucosa

6. Function of the Nose
The only externally visible part of the respiratory system that functions by:
Providing an airway for respiration
Moistening and warming the entering air
Filtering inspired air and cleaning it of foreign matter
Serving as a resonating chamber for speech
Housing the olfactory receptors
Sinuses in bones that surround the nasal cavity
Sinuses lighten the skull and help to warm and moisten the air

7. Pharynx
Funnel-shaped tube of skeletal muscle that connects to the:
Nasal cavity and mouth superiorly
Larynx and esophagus inferiorly
It is divided into three regions
Nasopharynx
Oropharynx
Laryngopharynx

8. Larynx (Voice Box)
Attaches to the hyoid bone
The three functions of the larynx are:
To provide a patent airway
To act as a switching mechanism to route air and food into the proper channels
To function in voice production
Epiglottis – elastic cartilage that covers the laryngeal inlet during swallowing

9. Movements of Vocal Cords

10. Trachea
Flexible and mobile tube extending from the larynx into the mediastinum
Composed of three layers
Mucosa – made up of goblet cells and ciliated epithelium
Submucosa – connective tissue deep to the mucosa
Adventitia – outermost layer made of C-shaped rings of hyaline cartilage

11. The primary bronchi
Trachea branches in the mediastinum into right and left bronchi
Bronchi enter the lungs at the hilus
Right bronchus is wider and steep compare to the left.
Right has three and Left has two secondary bronchi

12. The bronchial tree
System of tubes formed from the primary bronchi and their branches
Primary bronchi branch into secondary
Secondary bronchus goes to each lobe of the lungs
Secondary bronchi branch into tertiary bronchi
Tertiary bronchi

13. Lobes and surfaces of the lungs
Lobes of the lung are separated by fissures
Right lung has three lobes
Left lung has two lobes
Concavity on medial surface = cardiac notch

14. The bronchioles Ultimately branch into terminal bronchioles
Delivers air to a single pulmonary lobule
Terminal bronchiole becomes respiratory bronchioles
Respiratory bronchioles end in ducts and sacs
Respiratory exchange surfaces connected to circulatory system via pulmonary circuit

15. Gas Exchange Gas exchange occurs across
the respiratory membrane of the
alveoli. The respiratory
membrane is a composite
structure consisting of three
parts
The squamous epithelial cells lining the alveolus
The endothelial cells lining an adjacent capillary
The fused basal laminae that lie between the alveolar and endothelial cells

16. Histology of Lungs
Pneumocytes type I : squamous epithelial cells; sites for gas exchange
Pneumocytes type II: also called septal cells. Produce surfactant, an oily secretion containing phospholipids and proteins; reduces the surface tension, keeps the alveoli open.
Alveolar macrophage: also called dust cells; phagocytize any particles that have eluded other defenses.

17. Alveolar Surface Tension
Surface tension – the attraction of liquid molecules to one another at a liquid-gas interface
The liquid coating the alveolar surface is always acting to reduce the alveoli to the smallest possible size
Surfactant, a detergent-like complex, reduces surface tension and helps keep the alveoli from collapsing

18. Respiratory System
Consists of the respiratory and conducting zones
Respiratory zone
Site of gas exchange
Consists of bronchioles, alveolar ducts, and alveoli
Conducting zone
Provides rigid conduits for air to reach the sites of gas exchange
Includes all other respiratory structures (e.g., nose, nasal cavity, pharynx, trachea etc.)
Respiratory muscles – diaphragm and other muscles that promote ventilation

19. Dead Space
Anatomical dead space – volume of the conducting respiratory passages (150 ml)
Alveolar dead space – alveoli that cease to act in gas exchange due to collapse or obstruction
Total dead space – sum of alveolar and anatomical dead spaces

20. Breathing
Breathing, or pulmonary ventilation, consists of two phases
Inspiration – air flows into the lungs
Expiration – gases exit the lungs

21. Pulmonary Ventilation
Modes of Breathing
Respiratory movements are classified
By pattern of muscle activity
Into quiet breathing and forced breathing

22. Pulmonary Ventilation
Quiet Breathing (Eupnea)
Involves active inhalation and passive exhalation
Diaphragmatic breathing or deep breathing
Is dominated by diaphragm
Costal breathing or shallow breathing
Is dominated by ribcage movements

23. Pulmonary Ventilation
Forced Breathing
Also called hyperpnea
Involves active inhalation and exhalation
Assisted by accessory muscles
Maximum levels occur in exhaustion
Other variations of breathing:
Apnea—temporary cessation of breathing
Dyspnea—labored, gasping breathing; shortness of breath

24. Respiratory Volumes
Tidal volume (TV) – air that moves into or out of the lungs with each breath (approximately 500 ml)
Inspiratory reserve volume (IRV) – air that can be inspired forcibly beyond the tidal volume (3000ml)
Expiratory reserve volume (ERV) – air that can be evacuated from the lungs after a tidal expiration(1200 ml)
Residual volume (RV) – air left in the lungs after strenuous expiration ( ml)

25. Respiratory Capacities
Inspiratory capacity (IC) – total amount of air that can be inspired after a tidal expiration (IRV + TV)
Functional residual capacity (FRC) – amount of air remaining in the lungs after a tidal expiration (RV + ERV)
Vital capacity (VC) – the total amount of exchangeable air (TV + IRV + ERV)
Total lung capacity (TLC) – sum of all lung volumes (approximately 6000 ml in males)

27. Alveolar Ventilation Physiologic (total) dead space
Sum of anatomic dead space and any pathological alveolar dead space
A person inhales 500 mL of air, and 150 mL stays in anatomical dead space, then 350 mL reaches alveoli
Alveolar ventilation rate (AVR)
Air that ventilates alveoli (350 mL) X respiratory rate (12 bpm) = 4,200 mL/min.
Of all the measurements, this one is most directly relevant to the body’s ability to get oxygen to the tissues and dispose of carbon dioxide

28. Pulmonary Ventilation
Pulmonary Volumes and Capacities.

29. Gas Exchange Composition of Air Nitrogen (N2) is about 78.6%
Oxygen (O2) is about 20.9%
Water vapor (H2O) is about 0.5%
Carbon dioxide (CO2) is about 0.04%

30. Composition of Air
Dalton’s law—the total atmospheric pressure is the sum of the contributions of the individual gases
Partial pressure: the separate contribution of each gas in a mixture
At sea level 1 atm of pressure = 760 mm Hg
Nitrogen constitutes 78.6% of the atmosphere, thus
PN2 = 78.6% x 760 mm Hg = 597 mm Hg
PO2 = 20.9% x 760 mm Hg = 159 mm Hg
PH2O = 0.5% x 760 mm Hg = 3.7 mm Hg
PCO2 = 0.04% x 760 mm Hg = 0.3 mm Hg
PN2 + PO2 + PH2O + PCO2 = mmHg

31. Copyright 2009, John Wiley & Sons, Inc.

32. Gas Exchange
An Overview of Respiratory Processes and Partial Pressures in Respiration.

33. Gas Exchange
Figure 23–19b An Overview of Respiratory Processes and Partial Pressures in Respiration.
Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

34. Gas Transport
Gas transport—the process of carrying gases from the alveoli to the systemic tissues and vice versa
Oxygen transport
98.5% bound to hemoglobin
1.5% dissolved in plasma
Carbon dioxide transport
70% as bicarbonate ion
23% bound to hemoglobin
7% dissolved in plasma

35. Oxygen Hemoglobin—molecule specialized in oxygen transport
Four protein (globin) portions
Each with a heme group which binds one O2 to the ferrous ion (Fe2+)
One hemoglobin molecule can carry up to 4 O2
Oxyhemoglobin (HbO2)—O2 bound to hemoglobin
Deoxyhemoglobin (HHb)—hemoglobin with no O2
100% saturation Hb with 4 O2 molecules
50% saturation Hb with 2 O2 molecules

36. Copyright 2009, John Wiley & Sons, Inc.

37. Gas Transport Oxygen–Hemoglobin Saturation Curve
Is a graph relating the saturation of hemoglobin to partial pressure of oxygen
Higher PO2 results in greater Hb saturation
Is a curve rather than a straight line
Because Hb changes shape each time a molecule of O2 is bound
Each O2 bound makes next O2 binding easier
Allows Hb to bind O2 when O2 levels are low

38. Gas Transport The Oxygen–Hemoglobin Saturation Curve
Is standardized for normal blood (pH 7.4, 37°C)
When pH drops or temperature rises
More oxygen is released
Curve shifts to right
When pH rises or temperature drops
Less oxygen is released
Curve shifts to left

39. Gas Transport
An Oxygen—Hemoglobin Saturation Curve.

40. The Effects of pH and Temperature on Hemoglobin Saturation.
Gas Transport
The Effects of pH and Temperature on Hemoglobin Saturation.

41. 2,3-bisphosphoglycerate (BPG)
Gas Transport
2,3-bisphosphoglycerate (BPG)
RBCs generate ATP by glycolysis
Forming lactic acid and BPG
BPG directly affects O2 binding and release
More BPG, more oxygen released

42. Gas Transport
Carbon Dioxide Transport in Blood.

43. Gas Transport
A Summary of the Primary Gas Transport Mechanisms: Oxygen Transport.

44. Carbon Dioxide
Relative amounts of CO2 exchange between the blood and alveolar air differs
70% of exchanged CO2 comes from carbonic acid
23% from carbamino compounds
7% dissolved in the plasma
Blood gives up the dissolved CO2 gas and CO2 from the carbamino compounds more easily than CO2 in bicarbonate

45. Systemic Gas Exchange
Systemic gas exchange—the unloading of O2 and loading of CO2 at the systemic capillaries
CO2 loading
CO2 diffuses into the blood
Carbonic anhydrase in RBC catalyzes
CO2 + H2O  H2CO3  HCO3− + H+
Chloride shift
Keeps reaction proceeding, exchanges HCO3− for Cl−
H+ binds to hemoglobin

46. Gas Transport
A Summary of the Primary Gas Transport Mechanisms: Carbon Dioxide Transport.