“The Precious Envelope”
What Is The Evolutionary Trend?
AMPHIBIAN
REPTILE
MAMMAL
WHY?
Nasopharyngeal Passages
Pharynx
Larynx & Vocal Cords
SWALLOWING & EPIGLOTTIS
BRONCHI = “branch”
ALVEOLI
• Highest Surface Area To Volume Ratio
• Ultimate destination of deoxygenated blood from pulmonary artery
• Covered with capillaries to facilitates diffusion of O2 and CO2
GasAir entering lungs -
Inhaled airAir leaving lungs -
Exhaled air
Oxygen 21% 16%
carbon dioxide
0.03% 3%
Nitrogen 78% 78%
water vapor
small amount significantly moist
Inhaled v. Exhaled Air
James Eads’ Caissons
Nitrogen Narcosis
Why Does Tissue Suffocation Occur When Trapped In A Fire?
How Is This Similar To Drowning?
High Altitude Cerebral Edema
How Did He Do It?
How To Prevent Altitude Sickness
• Oxygen• Acclimation To
Elevation– Ascend 300m day– 2days rest/1000m
Diamox– Acidifies blood at night
to increase breathing rate
Control of Breathing
pH and Breathing
• pH of blood measured in carotid arteries (neck)
• Info relayed to pons & medulla of the hindbrain
• If pH is too acidic, rate of breathing must increase
• If pH too basic, rate of breathing must slow down
• Messages sent to diaphragm via Vagus nerve
NEGATIVE PRESSURE BREATHING
RESPIRATION & BOYLE’S LAW
• P1V1 = P2V2
• Ambient Air Pressure = appx. 14.7 lb/in2
• As size of thoracic cavity increases, pressure in chest drops below ambient pressure
• As size of thoracic cavity decreases, pressure increases above ambient pressure
How Does The Heimlich Maneuver Work In Terms Of Boyle’s Law?
How Does Boyle’s Law Explain A Collapsed Lung?