1. Respiratory physiology:

2. Respiration Ventilation: Movement of air into and out of lungs
External respiration: Gas exchange between air in lungs and blood
Transport of oxygen and carbon dioxide in the blood
Internal respiration: Gas exchange between the blood and tissues

3. Respiratory System Functions
Gas exchange: Oxygen enters blood and carbon dioxide leaves
Regulation of blood pH: Altered by changing blood carbon dioxide levels
Voice production: Movement of air past vocal folds makes sound and speech
Olfaction: Smell occurs when airborne molecules drawn into nasal cavity
Protection: Against microorganisms by preventing entry and removing them

4. Respiratory System Divisions
Upper tract
Nose, pharynx and associated structures
Lower tract
Larynx, trachea, bronchi, lungs

5. Nasal Cavity and Pharynx

6. Nose and Pharynx Pharynx Nose
Common opening for digestive and respiratory systems
Three regions
Nasopharynx
Oropharynx
Laryngopharynx
Nose
External nose
Nasal cavity
Functions
Passageway for air
Cleans the air
Humidifies, warms air
Smell
Along with paranasal sinuses are resonating chambers for speech

7. Larynx Functions Maintain an open passageway for air movement
Epiglottis and vestibular folds prevent swallowed material from moving into larynx
Vocal folds are primary source of sound production

8. Vocal Folds

9. Trachea
Windpipe
Divides to form
Primary bronchi
Carina: Cough reflex

10. Tracheobronchial Tree
Conducting zone
Trachea to terminal bronchioles which is ciliated for removal of debris
Passageway for air movement
Cartilage holds tube system open and smooth muscle controls tube diameter
Respiratory zone
Respiratory bronchioles to alveoli
Site for gas exchange

11. Tracheobronchial Tree

12. Bronchioles and Alveoli

13. Alveolus and Respiratory Membrane

14. Lungs Two lungs: Principal organs of respiration Divisions
Right lung: Three lobes
Left lung: Two lobes
Divisions
Lobes, bronchopulmonary segments, lobules

15. Thoracic Walls Muscles of Respiration

16. Thoracic Volume

17. Pleura Pleural fluid produced by pleural membranes Acts as lubricant
Helps hold parietal and visceral pleural membranes together

18. Ventilation Movement of air into and out of lungs
Air moves from area of higher pressure to area of lower pressure
Pressure is inversely related to volume

19. Alveolar Pressure Changes

20. Changing Alveolar Volume
Lung recoil
Causes alveoli to collapse resulting from
Elastic recoil and surface tension
Surfactant: Reduces tendency of lungs to collapse
Pleural pressure
Negative pressure can cause alveoli to expand
Pneumothorax is an opening between pleural cavity and air that causes a loss of pleural pressure

21. Normal Breathing Cycle

22. Compliance Measure of the ease with which lungs and thorax expand
The greater the compliance, the easier it is for a change in pressure to cause expansion
A lower-than-normal compliance means the lungs and thorax are harder to expand
Conditions that decrease compliance
Pulmonary fibrosis
Pulmonary edema
Respiratory distress syndrome

23. Pulmonary Volumes Tidal volume Inspiratory reserve volume
Volume of air inspired or expired during a normal inspiration or expiration
Inspiratory reserve volume
Amount of air inspired forcefully after inspiration of normal tidal volume
Expiratory reserve volume
Amount of air forcefully expired after expiration of normal tidal volume
Residual volume
Volume of air remaining in respiratory passages and lungs after the most forceful expiration

24. Pulmonary Capacities Inspiratory capacity Functional residual capacity
Tidal volume plus inspiratory reserve volume
Functional residual capacity
Expiratory reserve volume plus the residual volume
Vital capacity
Sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume
Total lung capacity
Sum of inspiratory and expiratory reserve volumes plus the tidal volume and residual volume

25. Spirometer and Lung Volumes/Capacities

26. Minute and Alveolar Ventilation
Minute ventilation: Total amount of air moved into and out of respiratory system per minute
Respiratory rate or frequency: Number of breaths taken per minute
Anatomic dead space: Part of respiratory system where gas exchange does not take place
Alveolar ventilation: How much air per minute enters the parts of the respiratory system in which gas exchange takes place

27. Physical Principles of Gas Exchange
Partial pressure
The pressure exerted by each type of gas in a mixture
Dalton’s law
Water vapor pressure
Diffusion of gases through liquids
Concentration of a gas in a liquid is determined by its partial pressure and its solubility coefficient
Henry’s law

28. Physical Principles of Gas Exchange
Diffusion of gases through the respiratory membrane
Depends on membrane’s thickness, the diffusion coefficient of gas, surface areas of membrane, partial pressure of gases in alveoli and blood
Relationship between ventilation and pulmonary capillary flow
Increased ventilation or increased pulmonary capillary blood flow increases gas exchange
Physiologic shunt is deoxygenated blood returning from lungs

29. Oxygen and Carbon Dioxide Diffusion Gradients
Moves from alveoli into blood. Blood is almost completely saturated with oxygen when it leaves the capillary
P02 in blood decreases because of mixing with deoxygenated blood
Oxygen moves from tissue capillaries into the tissues
Carbon dioxide
Moves from tissues into tissue capillaries
Moves from pulmonary capillaries into the alveoli

30. Changes in Partial Pressures

31. Hemoglobin and Oxygen Transport
Oxygen is transported by hemoglobin (98.5%) and is dissolved in plasma (1.5%)
Oxygen-hemoglobin dissociation curve shows that hemoglobin is almost completely saturated when P02 is 80 mm Hg or above. At lower partial pressures, the hemoglobin releases oxygen.
A shift of the curve to the left because of an increase in pH, a decrease in carbon dioxide, or a decrease in temperature results in an increase in the ability of hemoglobin to hold oxygen

32. Hemoglobin and Oxygen Transport
A shift of the curve to the right because of a decrease in pH, an increase in carbon dioxide, or an increase in temperature results in a decrease in the ability of hemoglobin to hold oxygen
The substance 2.3-bisphosphoglycerate increases the ability of hemoglobin to release oxygen
Fetal hemoglobin has a higher affinity for oxygen than does maternal

33. Oxygen-Hemoglobin Dissociation Curve at Rest

34. Bohr effect:

35. Temperature effects:

37. Shifting the Curve

38. Transport of Carbon Dioxide
Carbon dioxide is transported as bicarbonate ions (70%) in combination with blood proteins (23%) and in solution with plasma (7%)
Hemoglobin that has released oxygen binds more readily to carbon dioxide than hemoglobin that has oxygen bound to it (Haldane effect)
In tissue capillaries, carbon dioxide combines with water inside RBCs to form carbonic acid which dissociates to form bicarbonate ions and hydrogen ions

39. Transport of Carbon Dioxide
In lung capillaries, bicarbonate ions and hydrogen ions move into RBCs and chloride ions move out. Bicarbonate ions combine with hydrogen ions to form carbonic acid. The carbonic acid is converted to carbon dioxide and water. The carbon dioxide diffuses out of the RBCs.
Increased plasma carbon dioxide lowers blood pH. The respiratory system regulates blood pH by regulating plasma carbon dioxide levels

40. CO2 Transport and Cl- Movement

42. Respiratory Areas in Brainstem
Medullary respiratory center
Dorsal groups stimulate the diaphragm
Ventral groups stimulate the intercostal and abdominal muscles
Pontine (pneumotaxic) respiratory group
Involved with switching between inspiration and expiration

43. Respiratory Structures in Brainstem

44. Rhythmic Ventilation Starting inspiration Increasing inspiration
Medullary respiratory center neurons are continuously active
Center receives stimulation from receptors and simulation from parts of brain concerned with voluntary respiratory movements and emotion
Combined input from all sources causes action potentials to stimulate respiratory muscles
Increasing inspiration
More and more neurons are activated
Stopping inspiration
Neurons stimulating also responsible for stopping inspiration and receive input from pontine group and stretch receptors in lungs. Inhibitory neurons activated and relaxation of respiratory muscles results in expiration.

45. Modification of Ventilation
Chemical control
Carbon dioxide is major regulator
Increase or decrease in pH can stimulate chemo- sensitive area, causing a greater rate and depth of respiration
Oxygen levels in blood affect respiration when a 50% or greater decrease from normal levels exists
Cerebral and limbic system
Respiration can be voluntarily controlled and modified by emotions

46. Modifying Respiration

47. Regulation of Blood pH and Gases

48. Herring-Breuer Reflex
Limits the degree of inspiration and prevents overinflation of the lungs
Infants
Reflex plays a role in regulating basic rhythm of breathing and preventing overinflation of lungs
Adults
Reflex important only when tidal volume large as in exercise

49. Ventilation in Exercise
Ventilation increases abruptly
At onset of exercise
Movement of limbs has strong influence
Learned component
Ventilation increases gradually
After immediate increase, gradual increase occurs (4-6 minutes)
Anaerobic threshold is highest level of exercise without causing significant change in blood pH
If exceeded, lactic acid produced by skeletal muscles

50. Effects of Aging
Vital capacity and maximum minute ventilation decrease
Residual volume and dead space increase
Ability to remove mucus from respiratory passageways decreases
Gas exchange across respiratory membrane is reduced