Review Sheet: Ventilatory System
Inhalation: Active process.
Conducting Airway- Nasal cavity (Nasal conchae, hairs, mucus, blood vessels).
Pharynx (throat), larynx (voice box), epiglottis, trachea (windpipe), bronchi (bronchus), bronchioles, alveoli (gas exchange).
Exhalation: Passive process.
(gases flow from high to low pressure)
Normal exhale: diaphragm relaxes (goes up), air forced out.
Forced exhalation: accessory muscles (intercostal, pec minor, pec major, traps, rhomboids) assist to further make the chest
cavity smaller.
Respiratory Terms
Mechanics of Breathing:
What is the purpose of the pleural membranes and fluid?
What is their function in breathing?
Changes in PCO2, PO2 & pH are
monitored by chemoreceptors in blood
How is ventilation controlled?
Bohr Effect
Acid build up in blood- cause pH to be
lower (become more acidic) pH lower 7.4,
then hemoglobin binding to oxygen
decreases. Medulla signals lungs to
breathe.
Chemoreceptors send input to brain
respiratory centers in medulla
Nerve impulses sent to effector
(respiratory muscles) to control force
& frequency of breathing
This changes the ventilation rate and
depth of breathing
Ventilation changes restore the arterial
blood gas & pH to their normal ranges
Oxygen transport
98% of oxygen in the blood is transported by hemoglobin as oxyhemoglobin within the RBC.
Remaining oxygen is dissolved in blood plasma. Binding occurs in lungs.
Carbon dioxide transport
70% bicarbonate ions, 23% bond to hemoglobin (carboyhemoglobin), 7% dissolved in plasma.
Lung hyperinflation
Stretch receptors in the pleura and large airways send inhibitory signals to the inspiratory center
during very deep inspirations, protecting against excessive stretching of the lungs.
Hyperventilation
Rapid, deep breathing. Removal of large quantities of CO2with little change in O2. Blood becomes
less acidic (increase pH). Result is decreased desire to breathe because blood is not acidic enough to
signal the release of O2. Feeling of dizziness.
Brought on by: stressful situation, COPD.
Solution: Breathe in & out of paper bag to increase Co2 levels.
Hypoventilation
Slow shallow breathing. Build-up of CO2 in lungs. (more acidic). Leads to respiratory acidosis (can’t
remove CO2 from lungs, too acidic.)
Brought on by: being extremely over weight, fatigue, medical conditions and drug overdose.
Solution: medication to stimulate breathing.