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Bronchioles and Alveoli

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