Ch 49: Gas Exchange (Respiratory System) Flashcards
How do organisms exchange O2 and CO2?
By diffusing along their concentration gradients
Factors that determine diffusion rates
Medium
Surface area
Concentration gradient
Diffusion path length
Ventilation
Breathing
By maximizing ability to bring fresh air to the surface, we increase the concentration gradient
Actively moving high O2 and low CO2 to the surface
Perfusion
Actively moving blood containing low O2 and high CO2 to the surface
Nasal passage and oral cavity
Bring air in and join together at the pharynx
Larynx
Voice box
Trachea
Gas pipe
Diaphragm
Seals cavity at the bottom of the lungs
Site of gas exchange
The alveoli
What facilitates gas exchange?
Thin walled alveoli and capillaries
Emphysema
Most lethal lung disease
Inflammation damages and destroys walls of alveoli
Functional areas of the lungs are reduced
Causes - smoking and genetics
Mucus escalator disorder
When the cilia in the mouth do not bring up the dust and particles
Main cause - smoking
Surfactant
Detergent like substances that reduce lung surface tension and facilitate inflation
Respiratory distress syndrome
When premature babies’ lungs don’t function properly
Surfactant isn’t present
Must use respirator until it develops
Inhalation
Bringing in air
Diaphragm contracts and pulls down
Lungs and the thoracic cavity expand
Exhalation
Releasing air
Diaphragm relaxes and moves up
Lungs and thoracic cavity contract
Hemoglobin
Carries O2 in the blood
Has 4 polypeptide subunits that can each reversibly bind to oxygen
Myoglobin
Single polypeptide molecule
Has a high affinity for O2
Transfers O2 from blood to muscles
Provides a reserve for high metabolic demand for O2
Carbonic anhydrase
Mediates reversible conversion between CO2 and HCO3
Dorsal medulla
Innervates the diaphragm
Initiates inhalation
Controls the respiratory system
Ventral medulla
Regulates muscles that expand or contract the rub cage
Control both inhalation and exhalation
