External&Internal Respiration

RESPIRATION

INTERNAL AND EXTERNAL

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INTERNAL RESPIRATION

CELLULAR METABOLISM

ANAEROBIC GLYCOLYSIS

AEROBIC OXIDATIVE METABOLISM IN THE MITOCHONDRIA


EXTERNAL RESPIRATION

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


EXTERNAL AND INTERNAL RESPIRATION

HEART

TISSUECELL

O2 + FOOD

CO2 + H2O+ ATP

LUNGS

ATMOSPHERE

PULMONARYCIRULATION

SYSTEMICCIRCULATION


THE RESPIRATORY SYSTEM

Nasal PassagesMouthPharynxLarynxTracheaBronchiAlveoliLung


Alveoli

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 surfactantwww.freelivedoctor.com

Alveoli and Pulmonary Capillaries


RESPIRATION

The Mechanics of Breathing


PRESSURES AT REST

Atmospheric pressure: 760 mm Hg

Intra-alveolar pressure: 760 mm Hg

Intrapleural pressure: 756 mm Hg


BAROMETRIC PRESSURE

Mercury Hg

VACUUM

WEIGHT OF COLUMNOF AIR = FORCE

FORCE/AREA = PRESSURESea Level

760 mm


REST PRESSURES

760 MM Hg

756 mmHg

Lungs

Intrapleural pressure

Airways

Atmosphere

Pleural Sac

ThoracicWall


THE TRANSMURAL PRESSURE GRADIENT INFLATES THE LUNGS

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


REST PRESSURES

760 MM Hg

756 mmHg

Lungs


Airways

Atmosphere

Pleural Sac

ThoracicWall


AIR IS A COMPRESSABLE GAS WHICH OBEYS BOYLE’S LAW

P1V1 = P2V2

If Volume increases, Pressure must decrease

As lungs expand, pressure inside falls


INSPIRATION

Elevation of ribs expands lungsLowering of diaphragm by

contraction also expands lungsExpansion of lungs causes pressure

inside to drop below atmospheric pressure

Air rushes in to fill the expanded lungs


INSPIRATION

760 mm Hg

754 mmHg

Lungs


Airways

Atmosphere

Pleural Sac

ThoracicWall

759mm Hg


EXPIRATION

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


EXPIRATION

760 mm Hg

756 mmHg

Lungs


Airways

Atmosphere

Pleural Sac

ThoracicWall

761 mm Hg


MUSCLES OF INSPIRATION

SternocleidomastoidScalenusExternal IntercostalsDiaphragm


MUSCLES OF EXPIRATION

Internal intercostalsAbdominals


AIRWAY RESISTANCE

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


Resistance and Disease

Colds Asthma: Constriction of small airways, excess

mucus, and histamine-induced edema Bronchitis:Long term inflamitory response

causing thickened walls and overproduction of mucous

Emphysema: Collapse of smaller airways and breakdown of alveolar walls

Alveolar surface tension


LUNG VOLUMES

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


LUNG VOLUMES


LUNG VOLUMES: RELATIONSHIPS

IC = IRV + TV

FRC = ERV + RV

VC = IRV + TV + ERV

TLC = VC + RV


External&Internal Respiration

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