“the precious envelope” what is the evolutionary trend? amphibian reptile mammal

“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?