THE HUMAN BODY

RESPIRATORY SYSTEM

TYPES OF RESPIRATION

• DIRECT:

– Gas exchange through membranes

• INDIRECT:

– Specialized cells used for respiration

• 2 stages:

– external: environment to blood

– internal: blood to cells

Purpose for respiration

• To provide gas exchange

– oxygen in

– carbon dioxide out

External Respiration

• Environment to blood

• nostrils-nasal passage-pharynx-larynx-trachae-bronchi-bronchial tubes-lungs-bronchioles-alveolus

• air-lungs-body-lungs-air

• inspiration-expiration cycle

• organs involved: ribs, muscles, diaphragm, abdomen

External Respiration Cont.

• Process involves air pressure

– air moves from high pressure to low pressure

– 760 mm Hg = atmospheric pressure

– 756 mm Hg = interthorasic pressure

– 760 mm Hg = lung pressure

Inspiration

• muscles contract - rib cage elevates - chest size increases - pressure in thorasic cavity decreases to 753 mm; therefore lung pressure decreases to 758 mm and air goes into lungs

• Lungs do not breath; muscles do the breathing

Expiration

• Muscles relax - rib cage depresses - increases pressure in lungs to 762 mm - therefore air moves out

Internal Respiration

Internal Respiration Cont.

• Exchange from alveoli to capillaries:

– oxygen pressure in alveoli higher; oxygen pressure in capillaries is lower; therefore oxygen diffuses into capillaries

– carbon dioxide pressure in alveoli lower; carbon dioxide pressure in capillaries higher; therefore carbon dioxide diffuses into alveoli

• Once gas is exchanged, oxygen is carried by hemoglobin

– Hb-Fe + O₂ <=====> Hb-FeO₂

Factors that effect respiration

• Exercise: increases demand for oxygen

• Elevation: both increase and decrease

• Air pressure: both increase and decrease

• Temperature: both increase and decrease

• Oxygen levels: both increase and decrease

• Pollution: smoke, carbon monoxide

• Humidity

Carbon Dioxide Transport

• Moves through membranes much easier than oxygen

• about 10% of carbon dioxide is dissolved in the plasma

• about 20% attaches to hemoglobin

• the remaining 70% passes into RBC’s and forms carbonic acid

Metabolism

• Total of all processes

• types:

– anabolism: CHO, Proteins, fat building

– catabolism: breakdown of food

• rates:

– depend on activities

– basal metabolic rate: energy required to maintain life

Lung Capacities

• Total air capacity of lungs = ~6 liters

• normal air exchange (tital air) = .5 liters

• total air exhaled and inhaled (vital capacity) = 4.5 liters

• frequency of breathing = average 12/min

• supplemental air = air exhaled by forcing it all out

• residual air = air left in lungs after you force all you can out