Alveoli = hollow sacks interconnected with passageways
Around outside of alveoli extensive capillary network
Elastin fibres of alveoli make it elastic
When you breathe in it expands from energy stored in elastin fibres
Lungs
-Two lungs: Principal organs of respiration
--Right lung: Three lobes
--Left lung: Two lobes
=Divisions
-Lobes, bronchopulmonary segments, lobules
Pleura
Pleural fluid produced by pleural membranes
Acts as lubricant
Helps hold parietal and visceral pleural membranes together
--Pleural fluid –transmits force from rib cage to lungs...very slippery
Reduces irritation of pleural membrane
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
Alveolar Pressure Changes I
1.Barometric P. = Alevolar P.=no air movement
Alveolar Pressure Changes II + III
2.increase thoracic vol = inc alv. vol, dec P.
Barometric Presure greater > alv. P. air moves into lungs.
3. end of inspiration
Alveolar Pressure changes IV
Decreased thoracic volume results in decreased alveolar volume and increased alveolar pressure. Alveolar pressure is greater than barometric air pressure and air moves out of the lungs.
Changing Alveolar Volume
Lung recoil
Causes alveoli to collapse resulting from
>>Elastic recoil and surface tension
>>>Surfactant: Reduces tendency of lungs to collapse
Changing Alveolar Volume II
--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
Compliance I
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
Compliance II
--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
