Download RESPIRATORY SYSTEM

RESPIRATORY
SYSTEM
BREATHING MECHANISM
AND
LUNG VOLUMES &
CAPACITIES
LUNG VOLUMES AND
CAPACITIES
 Tidal volume (TV) –
normal inhale/exhale
 Inspiratory Reserve
Volume (IRV) – max inhale
after normal
 Expiratory Reserve
Volume (ERV) – max
exhale after normal exhale
 Residual Volume (RV) –
amount left in lungs after
max. exhale
GRAPH
 Vital Capacity – total
volume of max inhale to
max exhale
– IRV + TV + ERV
 Inspiratory Capacity –
Max. inhale
– IRV + TV
 Functional Residual
Capacity – amount left in
lungs after normal exhale
– ERV + RV
 Total Lung Capacity – max
amount of gas in lungs
– IRV + TV + ERV + RV
INSPIRATION
 Passive  atmospheric pressure
compared to intraalveolar pressure
– Diaphragm contracts – moves downward
 Increase volume: decrease pressure
– Added Muscles: external intercostal,
sternocleidomastoid, pectoralis minor
– surface tension of parietal and visceral
pleural membranes
– Compliance
PRESSURES
OF INSPIRATION
EXPIRATION
 Elastic Recoil –
passive process
 Decrease volume:
increase pressure
– Air moves out
 Added force: internal
intercostal +
abdominal muscles
 Non Respiratory Air
Movements
– Cough, sneeze, laugh,
cry, hiccup, yawn,
speech
CONTROL OF BREATHING
 Rhythmic, involuntary
 Respiratory center – medulla oblongata + pons
– Medullary rhythmicity center
 Dorsal: rhythm
 Ventral: forceful breaths
– Pneumotaxic area
 Rate of breathing
 Factors affecting breathing
–
–
–
–
–
CO2 and H+ ions
Low O2
Hering-Bruer Reflex
Emotional upset
Hyperventilation and Holding Breath
FACTORS
Gas Exchange & Transport
 Gas Exchange
– Partial Pressure of Gases + Diffusion
 Oxygen Transport
– 98% Hemoglobin (Oxyhemoglobin)
 Carbon Dioxide Transport
– 7% Dissolved
– 15 – 25% Hemoglobin (Carbaminohemoglobin)
– 70% Bicarbonate Ion
 Carbonic Anhydrase
 Chloride Shift
PRESSURES OF INSPIRATION
FACTORS AFFECTING
BREATHRATE
Lung Volumes and Capacities