INTERNAL AND EXTERNAL
CELLULAR METABOLISM
ANAEROBIC GLYCOLYSIS
AEROBIC OXIDATIVE METABOLISM IN THE MITOCHONDRIA
Ventilation or breathing: air moved in and out of lungs
Oxygen and Carbon Dioxide exchange in the lungs
Oxygen and Carbon Dioxide transported by blood to and from tissues
Exchange of Oxygen and Carbon Dioxide between tissue and blood
HEART
TISSUECELL
O2 + FOOD
CO2 + H2O+ ATP
LUNGS
ATMOSPHERE
PULMONARYCIRULATION
SYSTEMICCIRCULATION
Nasal PassagesMouthPharynxLarynxTracheaBronchiAlveoliLung
Small, thin walled, inflatable sacs at end of bronchioles
Surrounded by jacket of pulmonary capillaries
Provide thin barrier and enormous surface area for gas exchange by diffusion
Type II secrete surfactant
The Mechanics of Breathing
Atmospheric pressure: 760 mm Hg
Intra-alveolar pressure: 760 mm Hg
Intrapleural pressure: 756 mm Hg
Mercury Hg
VACUUM
WEIGHT OF COLUMNOF AIR = FORCE
FORCE/AREA = PRESSURESea Level
760 mm
760 MM Hg
756 mmHg
Lungs
Intrapleural pressure
Airways
Atmosphere
Pleural Sac
ThoracicWall
Thoracic cavity larger than lungsTransmural (Across Lung Wall) pressure
gradient holds thoracic wall and lungs in close apposition
This pressure gradient is balanced by the elastic forces in the alveoli producing equilibrium
760 MM Hg
756 mmHg
Lungs
Intrapleural pressure
Airways
Atmosphere
Pleural Sac
ThoracicWall
P1V1 = P2V2
If Volume increases, Pressure must decrease
As lungs expand, pressure inside falls
Elevation of ribs expands lungsLowering of diaphragm by contraction also
expands lungsExpansion of lungs causes pressure inside to
drop below atmospheric pressureAir rushes in to fill the expanded lungs
760 mm Hg
754 mmHg
Lungs
Intrapleural pressure
Airways
Atmosphere
Pleural Sac
ThoracicWall
759mm Hg
Return of ribs to rest position causes diminishing of lung volume
Return of diaphragm to rest position also causes diminishing of lung volume
Diminishing of lung volume causes pressure in lung to raise to a higher value than atmospheric pressure
Air flows out of the lungs
760 mm Hg
756 mmHg
Lungs
Intrapleural pressure
Airways
Atmosphere
Pleural Sac
ThoracicWall
761 mm Hg
SternocleidomastoidScalenusExternal IntercostalsDiaphragm
Internal intercostalsAbdominals
Flow of air depends on the pressure gradient (atmospheric, Pa, and intra-alveolar, Pi) and the airway resistance, R
F = (Pa - Pi)/RResistance depends primarily on the radius of
the conducting airwaysParasympathetic stimulation constricts, while
sympathetic dilates
ColdsAsthma: Constriction of small airways, excess
mucus, and histamine-induced edemaBronchitis:Long term inflamitory response
causing thickened walls and overproduction of mucous
Emphysema: Collapse of smaller airways and breakdown of alveolar walls
Alveolar surface tension
Tidal Volume (TV): 500 mlInspiratory reserve volume (IRV): 3 litersInspiratory capacity (IC): 3.5 litersExpiratory reserve volume (ERV): 1 literResidual volume (RV): 1.2 litersFunctional Residual Capacity (FRC): 2.2 lVital Capacity (VC): 4.5 litersTotal Lung Capacity (TLC): 5.7 liters
IC = IRV + TV
FRC = ERV + RV
VC = IRV + TV + ERV
TLC = VC + RV
