1. Respiratory Physiology

2. Mechanics of Breathing

3. 4 distinct events
Pulmonary ventilation: air is moved in and out of the lungs
External respiration: gas exchange between blood and alveoli
Respiratory gas transport: CV system transports oxygen and carbon dioxide between lungs & tissues
Internal respiration: gas exchange between blood & tissue cells

4. Cellular respiration: actual use of oxygen & production of carbon dioxide in the cells to make energy: C6H12O6 + 9O2  6CO2 + 6H2O

5. Pulmonary ventilation: Depends on pressure changes
Breathing
Inspiration = moving air into the lungs
Expiration = moving air out of lungs
Breathing Mechanism Animation

6. Pressure Relationships
Intrapulmonary pressure
Pressure within the alveoli (lungs)
Changes with phases of breathing
Always equalizes itself with atmospheric pressure
Intrapleural pressure
Pressure within intrapleural space
Always 4 mmHg less than intrapulmonary pressure

7. Lung Pressure Atelectasis – term for lung collapse
pneumothorax – air in the intrapleural space due to trauma causing lung collapse
Pneumothorax

8. Atelectasis

9. Inspiration Main inspiratory muscles
Diaphragm & external intercostals
Thoracic dimensions change to increase volume of thoracic cavity by 0.5 liters
Intrapulmonary pressure drops 1-3 mmHg and air rushes in for normal quiet inspiration
A deep forced inspiration requires activation of accessory muscles

10. Expiration A passive process dependent on natural lung elasticity
The lungs recoil, alveoli compress, volume decreases,, intrapulmonary pressure rises, gas outflows to equalize the pressure with atmospheric pressure
Forced expiration requires contraction of abdominal muscles

12. Respiratory Sounds
Bronchial sounds: produced by air rushing through trachea & bronchi
Vesicular sounds: produced by air filling lungs
Bronchial vs. Vesicular

13. Respiratory Sounds Wheezing: whistling sound Rales: rasping sound
Wheezing vs rales

14. Physical factors influencing
Pulmonary ventilation can be influenced by 4 physical factors
Respiratory passage resistance
Lung compliance
Lung elasticity
Alveolar surface tension forces

15. Respiratory passage resistance
Friction as air moves through passages
Smooth muscle bronchoconstriction Disorders such as asthma
Local accumulations of mucus, infectious material, and tumors will also cause the air flow to be reduced

16. Asthma

17. Lung compliance The ease with which lungs can readily expand
Affected by the elasticity of the lungs and the thoracic cage
Diminished by 2 main factors:
Fibrosis of the lung tissue
Ossification and/or muscle paralysis impairs flexibility of the thoracic cage

18. Lung fibrosis

19. Lung Elasticity Essential for normal expiration
Emphysema: tissue becomes less elastic and more fibrous (alveolar walls break down and surface area is lost)

21. Alveolar Surface Tension Forces
Surface tension – molecules of liquid hold together with hydrogen bonds
Surfactant – substance which interferes with cohesion of water molecules so less energy is needed to expand the lungs
IRDS – Infant Respiratory Distress Syndrome

22. Gas Exchanges in the Body

23. Gas exchanges occur: Between the blood and the alveoli AND
Between the blood and the tissue cells
Takes place by simple diffusion
Depends on pressures of oxygen & carbon dioxide that exist on opposite sides of the exchange membrane
Always move from high to low pressures

24. Factors influencing internal & external respiration

25. Factors that Influence: Ratio Relationships
Partial pressure gradients and gas solubilities Oxygen = has low solubility but steep partial pressure gradient Carbon dioxide = has solubility ~20x greater than oxygen but very low partial pressure gradient

26. Factors influencing internal & external respiration
Thickness of respiratory membranes
0.5 to 1.0 micrometers
edematous (swollen) tissue can be caused by congestion and pneumonia - hinders diffusion
Hypoxia = oxygen deprivation

27. Edematous lung tissue

28. Factors influencing internal & external respiration
Surface Area
50-70 square meters for gas exchange

29. Factors influencing internal & external respiration
Surface Area
Emphysema
Walls of alveoli break down
Less surface area to volume ratio

30. Control of Respiration

31. Nerves
The two nerves that transmit to the respiratory muscles are the phrenic and intercostal nerves
The neural centers that control respiration rate & depth are located in the medulla & pons
Irritation to phrenic nerve is responsible for hiccups (spasm of diaphragm muscle)

32. Breathing Terms Eupnea = normal respiration rate
Approx breaths per min
Hyperpnea = higher than normal rate
Apnea = No rate
Dyspnea = general term for abnormal rate
Physical factors, conscious control, emotional factors, and chemical factors all influence rate & depth

33. Hyperventilation Respiratory alkalosis results
Deep & rapid respiration
Too much CO2 is vented out of the body
Respiratory alkalosis results

34. Hyperventilation treatment
Trap CO2 and rebreathe it – building back up the levels of CO2 until they are normal again.

35. Hypoventilation
Slow & shallow respiration (usually caused by a disease process)
Not adequate expiration so CO2 is not vented out of the body

36. Disorders of Respiratory System

37. COPD
Chronic Obstructive Pulmonary Disorder A group of disorders that block airflow & make breathing difficult

38. Chronic Bronchitis chronic mucus production
Impairs ventilation and gas exchange
Reduction of airway diameter
Causative factors: cigarette smoking

39. Emphysema
Alveolar walls collapse = loss of surface area so less gas diffusion
Causative factor: cigarette smoking

40. 4 features in common Both emphysema and chronic bronchitis have:
Smoking history
Dyspnea
Coughing & pulmonary infections
Will develop respiratory failure, hypoxia, acidosis

42. Lung Cancer
Basic Info
1/3 of all cancer deaths are due to lung cancers
90% have a smoking history
Metastasizes very rapidly due to vascularity of lungs

43. Metastasis

44. 3 types of lung cancer Squamous cell carcinoma Adenocarcinoma
Small cell carcinoma

45. Squamous cell carcinoma
Begins in larger bronchi & bronchioles
Forms masses that have bleeding cavities within them

46. Adenocarcinoma Nodules that develop in peripheral areas of lung
Develop from alveolar cells & bronchial glands

47. Small cell carcinoma Originate in primary bronchi
Grow into small grape like clusters in mediastinum
Very aggressive cancer

48. Treatments Resection of diseased portion of lung (thoracotomy)
Radiation therapy
Chemotherapy

49. Lung Resection

50. Cystic Fibrosis Genetic disorder – recessive
Causes oversecretion of thick mucus that clogs respiratory passages & other organs
Impairs food digestion by clogging ducts that secrete enzymes

51. Cystic Fibrosis

52. SIDS - Sudden Infant Death Syndrome
Sudden, unexplained death of an infant less than 1 year old
Possibly caused by brain abnormalities that control respiration, heart rate, or consciousness
Environmental factors to reduce risks – sleep on back not on stomach, firm crib with no blankets or stuffed animals or pillows
Sudden infant death syndrome (SIDS): Risk factors - MayoClinic.com

54. Asthma
Bronchoconstriction of passageways in response to allergen, temperature changes, & exercise
Can be managed with medication