Upload
ahsphysio
View
453
Download
3
Embed Size (px)
DESCRIPTION
Respiratory physiology awh 01[1]
Citation preview
3/12/2013
1
Respiratory Physiology
Lecture 1
Andreas W. Henkel, Ph.D.
Prehistory of breathing
Early animals (580 million years ago)
didn’t need lungs !
3/12/2013
2
Evolution of breathing
Evolution of breathing
Fish swim
bladder turns
into lungs
3/12/2013
3
Human breathing
What is respiration?
� Movement of gases
� Gas exchange
� Transport of gas (oxygen and carbon
dioxide) in blood
3/12/2013
4
The airways
Conducting zone:
nose, mouth
air pipe (trachea)
bronchial tree
terminal bronchioles
The airways
Conducting zone:
- Warming and humidifying of air
- Mucus expulsion (300 cilia per cell)
- Small particle removal by ciliated cells
Common diseases:
Asthma, bronchitis
3/12/2013
5
Respiratory zone
Alveoli
Numbers : 300.000.000
Size : 0.25 – 0.5 mm
Surface : 60 – 80 m3
Garbage disposal: Macrophages clean alveoli
Respiratory zone
3/12/2013
6
Mechanics of breathingTwo pleural membranes
Parietal membrane attached to rib case and visceral membrane attached to lung
Pneumothorax
3/12/2013
7
Mechanics of breathingPressures
� Atmospheric pressure = 760 mm Hg
� Intrapleural pressure = 754 mm Hg –
pressure between pleural layers
� Intrapulmonary pressure = 757 mm Hg–
varies, pressure inside lungs
Mechanics of breathing
� Quiet breathing
– Diaphragm and external and
internal intercostals muscles
� Forced breathing
- Accessory muscles
(Scalene, pectoralis minor and
sternocleidomastoid)
3/12/2013
8
Mechanics of breathing
Normal outside
air pressure:
760 mm Hg
Inhale:
Alveolar press.
-3 mm Hg
Exhale:
Alveolar press.
+ 3 mm Hg
-3
-6
Alveoli are 250 times softer and elastic than a rubber balloon
Mechanics of breathing
3/12/2013
9
Mechanics of breathing
Inspiration/Inhalation
� Diaphragm & External intercostal muscles
� Increases volume in thoracic cavity as
muscles contract
� Volume of lungs increases
� Intrapulmonary pressure decreases
(757 mm Hg)
3/12/2013
10
in rest during inhalation
Expiration/Exhalation
� Inhalation muscles relax
� Thoracic-, internal intercostal and
abdominal muscles contract
� Volume of thoracic cavity decreases
� Volume of lungs decreases
� Intrapulmonary pressure increases
(763 mm Hg)
� Forced expiration is active
3/12/2013
11
Pulmonary ventilation
Factors that influence pulmonary air flow
Diameter of airways, esp. bronchioles
controlled by
Sympathetic & Parasympathetic NS
3/12/2013
12
Pulmonary ventilation
Air pressure in alveoli is inversely
proportional to the alveolar volume
Enlarging volume
= lower pressure
Pulmonary ventilationBoyle’s law
3/12/2013
13
Pulmonary ventilationBoyle’s law
Boyle’s law: p = k / V
Example: inflating a rubber balloon
- difficult (blow hard) at the beginning
- easy after initial inflation
Pulmonary ventilationSurface Tension
� Lung collapse
� Surface tension tends to oppose alveoli
expansion
� Pulmonary surfactant reduces surface tension
� Surfactant = surface active agent
3/12/2013
14
Pulmonary ventilationLaplace’s law
tension * thicknessPressure = -----------------------
radius
tension = elastic resistance
(e.g. soft rubber – hard rubber)
Reduced by surfactants
Pulmonary ventilation
� Surfactants lower tension !
� Surfactants cover the inner side of alveoli
� Surfactant of the alveoli:
Dipalmitoyl-lecithin (10) – protein (1)
When the alveoli volume gets smaller :
� surfactant concentration gets higher
� tension gets lower
� inhalation becomes easier
3/12/2013
15
Spirometry
� Analyze and measure many lung parameters
� Useful for diagnostics of lung diseases
� Useful for sport medicine
Spirometry
3/12/2013
16
Lung Volumes & Capacitiesquiet breathing
� Tidal Volume (500 mls)
� Respiratory Rate (12 breaths/minute)
� Minute Respiratory Volume (6000 mls/min)
3/12/2013
17
Lung Volumes & Capacitiesforced inhalation
� Inspiratory Reserve Volume
(♂ 3000, ♀ 2100 ml)
� Inspiratory Capacity (TV + IRV)
3/12/2013
18
Lung Volumes & Capacitiesforced exhalation
� Expiratory Reserve Volume
(♂ 1200, ♀ 800 ml)
� Residual Volume (1200 ml)
� Functional Residual Capacity (ERV + RV)
– Air left in lungs after exhaling the tidal volume
quietly
3/12/2013
19
Lung Volumes & Capacities
� Vital Capacity
� IRV + TV + ERV = ♂ 4700, ♀ 3400ml
� Maximum amount of air that can be moved
in and out of lungs
Inspiratory Tidal Expiratory
3/12/2013
20
Lung Volumes & CapacitiesTraining effect
Lung Volumes & Capacities
� Total Lung Capacity (♂ 5900, ♀ 4400)
� Dead air volume (150 ml) –
air not in the alveoli
3/12/2013
21
Lung diseases
Dyspnea : subjective shortness of breath
Asthma: bronchiolar constriction, inflammation,
mucous secretion
Constriction: leucotriens + histamine
from mastcells (allergy)
Bronchiodilation : beta 2 receptors agonist:
terbutalin
beta 1+ 2 receptors agonist:
epinephrine (β1 in heart !)
3/12/2013
22
Lung diseases
Emphysema: destruction of alveolar tissue
Smoke stimulates macrophages to secrete
proteolytic enzymes
Genetic disease:
no anti α-trypsin inhibitor is produced
Lung diseasesChronic obstructive pulmonary disease (COPD)
Causes: bronchitis and/or emphysema,
inflammation other cause
Pulmonary fibrosis
To much fibrous connective tissue disrupts the
structure of the lung.
Causes: small particle inhalation, black lung coal
dust