Download Respiratory System

Respiratory System
Two Zones of the Respiratory
System

Conductive Zone – All structures that
convey air from the outside of the body
to the lungs. Includes: mouth and nose,
pharynx, Larynx, Trachea, Primary and
Secondary Bronchioles, Tertiary and
Terminal bronchioles
Two Zones Cont…

Role of the Conductive Zone:



Transport Air to the lungs
Warm and Humidify air before it reaches
Respiratory Zone (37 degrees)
Filter air taken in with each breath (dust
dirt) this is done by mucous lining.
Two Zones Cont…

Respiratory Zone – area where gas
exchange occurs. (diffusion). Includes
the respiratory bronchioles, alveolar
ducts, alveolar sacs.
Two zones cont…


The average person has about 300
million alveolar sacs. (this is
significantly reduced by conditions like
Emphysema)
Walls of alveoli contain numerous
capillaries that absorb oxygen from
alveoli and release Carbon dioxide into
alveoli through diffusion.
Respiration Terms



External Respiration – Process that occurs
within the lungs and involve the exchange of
CO2 and O2
Internal Respiration – Process that occurs at
the tissue level where O2 and Co2 are
exchanged
Cellular Respiration – Process where cells use
O2 to generate energy through different
metabolic pathways found in the
mitochondria
Mechanism of Breathing



Movement of air is dependent on pressure
differences (Air moves from high pressure to
low pressure)
Breathing is controlled by the brain stem
(specifically medulla oblongata and Pons)
When Diaphragm contracts it moves down
and creates a greater space in the chest
cavity (lower pressure when compared to the
atmosphere) thus air rushes in.
Mechanism of breathing
Cont…

Inspiration is an active process while
expiration is a passive process ( when
breathing quietly but may also be active
when forced breathing like vigorous
exercise or blowing up a balloon)
Ventilatory volumes



VE - Volume of air moved by the lungs in 1
minute (Ventilation). Influence by volume of
air in each breath and number of breaths per
minute
VT – Volume of air in each breath (Tidal
Volume, at rest 0.5L/breath, exercise 34L/breath)
F – Number of breaths taken per minute (rest
12breaths/minute)
Cont…

VE (L/min) = VT(L/breath) x f (breaths/min)

With Exercise VE could be 100-200L/min
More Respiratory Terms




Total Lung Capacity (TLC) = max volume of
air lungs can hold
Vital Capacity (VC) – Max volume of air that
can be exhaled after maximal inhalation
Residual Volume (RV) – Air the remains in the
lungs following a maximal exhalation
TLC = VC + RV
Oxygen Carrying Capacity of
the Blood



Small amounts of oxygen disolve in
plasma
Most of oxygen binds with hemoglobin
(special protein in RBC’s)
In general 21.4 ml of oxygen can be
carried per 100ml of blood
Carbon dioxide carrying
capacity of blood




5-10% of CO2 dissolves in plasma
20% binds with hemoglobin
70-75% diffuses into RBC’s to form
carbonic acid
***Regulation of blood pH (SEE
OVERHEAD)
Bicarbonate System



As exercise intensity increases the brain stem
recognizes the increase in [H+] (created from
increased anaerobic metabolism) and
stimulates an increase in VE
As VE increases CO2 gets blown off, thus reducing
the amount of CO2 in the blood.
In order to create equilibrium again in the system,
H+ binds to HCO3 9 in blood or released from
Kidneys) to form Carbonic Acid [H2CO3]. This then
further dissociates and forms more H2O and CO2.