Respiratory system 1- Ventilation 2- Gas Exchange 3- Oxygen utilization

1. Respiratory System

2. Respiratory System
1- Ventilation
2- Gas Exchange
3- Oxygen
utilization

4. Structure of the respiratory system
Trachea »»»»» Alveoli
Conducting zone (nose to terminal
bronchioles)
Respiratory zone (respiratory bronchioles to
alveoli)

6. Conducting
zone
Mouth
Nose
Pharynx
Larynx
Trachea
Bronchioles (Primary to Terminal)
Anatomical dead space

8. What is the physiological dead
space???

9. Conducting
zone
Function:
Warming
Humidification
Filtration
Cleaning

10. Respiratory
zone
Respiratory
Bronchioles to Alveoli
Where gas exchange
take place

11. Thoracic cavity
• Diaphragm
• Pleural membranes
– Parietal Pleura
– Visceral Pleura
– Intrapleural space

13. Mechanics of ventilation
Movement of air from higher to lower pressure
between the conducting zone and terminal
bronchioles

15. Mechanics of
ventilation
Factors :
Physical properties of the lungs
Compliance
Elasticity
Surface tension
Intraplural pressure
Intrapulmonary (Intra-alveolar)
pressure

16. Intraplural
pressure
Pressure inside
the plural space
Sub atmospheric
- 2 to - 6 mmHg

18. Intrapulmonary
(Intra-alveolar)
pressure • Pressure inside the alveoli
• During Insp. (- 1 and up to
-70 mmHg)
• During Expi. (1 up to 100
mmHg)

19. Transpulmonary pressure
Difference between the intraplural and intr-alveolar

20. Physical
properties of
the Lungs
Compliance
Elasticity
Surface Tension

21. Compliance
The stretch ability of the
lungs
The ease with which the lungs
can expand under pressure
The changes in lungs volume
per change in
transpulmanary pressure
(ΔV/ΔP)

22. Factors affecting Compliance
The streachability of
the lung tissues
Pulmonary fibrosis

23. Elasticity
Tendency to returnee to original size after
distension
Factors affecting elasticity:
- Elastic resistance
- Surface tension

24. Surface TensionDue to fluids filling
the alveoli

26. Surfactant
It is phospholipids to lower
surface tension of the alveoli
Preventing the alveoli from
collapse
Produced by type II alveolar
cells
Respiratory distress syndrome
(RDS, in premature babies)
Acute respiratory distress
syndrome (adults)

27. Respiratory
distress
syndrome
(RDS)
In premature
babies
Due to less
surfactant
secreted

29. Acute respiratory distress syndrome
Adults
In septic shock (fall in blood pressure
due to wide spread vasodilatation)
Inflammation »»»» cause increase
capillary and alveolar permeability

30. Acute
respiratory
distress
syndrome
»»»»
Accumulation of
protein rich fluid in
the lungs
»»»» Reduction
surfactant & lower
compliance

31. Mechanics of
breathing
Breathing (inspiration &
expiration)

32. Inspiration :
Quiet:
- Diaphragm
- External intercostal
Deep:
- Scalene
- Pectorals minor
-Strenocleidomstoid

34. Expiration
Quiet Exp.:
01
Is a passive
process
02
Relaxation of
diaphragm &
external
intercostal
03
Forced Exp. :
• Internal intercostal
muscles
• Abdominal muscles
04

35. Pulmonary function test
Spirometry
To measure
lung volumes
& capacities

37. lung volumes
• Tidal volume
• Inspiratory reserve volume
• Expiratory reserve volume
• Residual volume

38. 1- Tidal volume :
• Volume of gas inspired or expired in quiet respiratory cycle
• 0.5 Litters

40. 2- Inspiratory reserve volume
• The maximum volume of gas that can be inspired during
forced breathing above the tidal V.
• 2 - 3.3 L

42. 2- Expiratory reserve volume
The maximum volume of gas that can be expired during
forced breathing above the tidal V.
0.7 - 1 L

44. 4- Residual volume
• The volume of gas remaining in the lung after a maximum
expiration
• 1 - 1.2 L

46. Lung capacities
• Total lung capacity
• Vital capacity
• Inspiratory capacity
• Functional residual capacity

47. Total lung capacity
• The total amount of air in the lungs after maximal
inspiration
• 4 - 6 L

49. Vital capacity
• The maximum amount of air that can be expired after
maximal inspiration
• 3 - 4.8 L

51. Inspiratory capacity
• The maximum amount of air that can be inspired after a
normal tidal expiration
• 2.5 - 3.5 L

53. Functional residual capacity
• The amount of air remaining in the lungs after normal tidal
expiration
• 1.8 - 2.2 L

55. Gas exchange
• Mainly exchange of O2 and Co2

56. Factors effecting Gas exchange
• Alveolar capillary membrane
• Partial pressure of gases across the alv. Cap. M.
• Mol. wt. Of the gas
• Surface area
• Temp.
• Diffusion capacity

57. Transport of oxygen
• 98 % combined with Hb as oxyhaemoglobin
• 2 % dissolved

58. The oxygen-haemoglobin
dissociation curve

59. The oxygen-haemoglobin dissociation curve
• S shaped

60. Factors affecting the O-Hb curve
1- Temperature
2- Partial pressure of Co2
3- 2,3-diphosphoglycerate (2,3-DPG)
4- pH

61. • Shift to the right
• Shift to the left

62. All cause shift to the right
• High Po2
• High temp.
• Low pH (high H ions)
• 2,3-GPD

63. Transport of Co2
1- Most Co2 in plasma inter RBC, dissolved form
2- Some react with H2O to form carbonic acid
3- Small portion of the dissolved react with amino group
carbamino haemoglobin

64. Control of Ventilation
• Nervous control of Ventilation
• Chemical control of Ventilation

67. Nervous control of Ventilation
• Medullary Respiratory centers (provide out put for
respiratory muscles)
1- Dorsal Resp. group (control Insp.)
2- Ventral Resp. group (control Insp.& Expr.)

69. Nervous control of Ventilation
• Pons Respiratory group
• Influence the output from MRC
• 1- Apneustic center
• 2- Pneumotaxic center

71. Chemical control of respiration
Factor Peripheral
chemo. Recp.
Central chem.
Recp.
↓ PO2
Only if very
very low
↑ventilation
↑ PCO2
Weak effect ↑ ↑ ↑ ↑
ventilation,
the main
factor
affecting
ventilation

72. Chemical control of respiration
Factor Peripheral
chemo.
Recp.
Central
chemo.
Recp.
↑H Stimulate
ventilation,
important
for acid
base
Can not
penetrate
CSF