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Ch 37 Gas Exchange & Transport - Coggle Diagram
Ch 37 Gas Exchange & Transport
Gas Laws
Pressure
: force exerted by gasses on the surfaces that they contact. Gases are normally present as a mixture of different types of molecules,
Partial pressure
is the pressure of a single type of gas in a mixture of gases.
Total pressure
is the sum of all the partial pressures of a gaseous mixture.
Partial Pressure of Gases
-
Dalton’s law
: Law of partial pressures. States that a specific gas type in a mixture exerts its own pressure; thus, the total pressure exerted by a mixture of gases is the sum of the partial pressures of the gases in the mixture.
Dalton’s Law in Respiration
- Gas flows High to Low Pressure.
Atmospheric Pressure
: Higher Partial Pressure of O2. Higher Partial Pressure of O2.
Differences
= passive diffusion (molecules diffuse from a region of higher concentration to a region of lower concentration)
Henry’s Law
- Henry’s law describes the behavior of gases when they come into contact with a liquid, such as blood. Greater number of gas molecules = the greater number of gas molecules that will dissolve in the liquid.
Composition of Air
- Relative concentration of gases is nitrogen > oxygen > water vapor > carbon dioxide. The amount of water vapor present in alveolar air is greater than that in atmospheric air. Gas exchange removes oxygen from and adds carbon dioxide to alveolar air. Partial pressures of oxygen and carbon dioxide change, affecting the diffusion process that moves these materials across the membrane.Causes oxygen to enter and carbon dioxide to leave the blood more quickly
VENTILATION AND PERFUSION
Ventilation
=movement of air into and out of lungs.
Perfusion
=the flow of blood in pulmonary capillaries. For gas exchange to be efficient: volumes should be compatible. Factors that cause ventilation & perfusion imbalance: Regional gravity effects on blood, Blocked alveolar ducts, Disease.
Mm Hg means millimeters of mercury (Hg = mercury). Partial pressure of oxygen in alveolar air is about 104 mm Hg. Partial pressure of the oxygenated pulmonary venous blood is about 100 mm Hg. Sufficient ventilation-oxygen enters the alveoli at a high rate and the partial pressure of oxygen remains high. Insufficient ventilation-partial pressure of oxygen in the alveoli drops.
Counteracting body mechanisms
Alveolus insufficient ventilation. Redirection to other alveoli. constricting the pulmonary arterioles that serves the dysfunctional alveolus results in redirection of blood. Simultaneous vasodilation to pulmonary arterioles that blood is redirected to allowing greater blood flow. Stimuli for adjusting blood flow: CO2, O2 and PH levels.
Regulation
-
Ventilation
: regulated by the diameter of the airways.
Perfusion
: regulated by the diameter of the blood vessels. Diameter of bronchioles is sensitive to the partial pressure of carbon dioxide in alveoli. Greater partial pressure of carbon dioxide in alveoli=bronchioles increase diameter. Decreased level of oxygen in blood supply=bronchioles increase diameter.
Gas Exchange
Occurs at two sites in the body: Lungs - oxygen is picked up and carbon dioxide is released. Tissues - oxygen is released and carbon dioxide is picked up. External respiration: exchange of gases with the external environment. occurs in the alveoli of the lungs. Internal respiration: exchange of gases with the internal environment. occurs in the tissues.
Actual gas exchange occurs due to diffusion. Energy not required to move O2 or CO2 across membranes. Gasses follow pressure gradients that allow them to diffuse. Respiratory membrane is highly permeable to gases. Respiratory and blood capillary membranes are very thin. Large surface area throughout lungs.
RESPIRATION
External Respiration
External respiration refers to gas exchange that occurs in the alveoli. Carbon dioxide is released in the opposite direction of oxygen, from the blood to the alveoli. Occurs as a function of partial pressure differences.
Internal Respiration
Internal respiration occurs at tissue level. Partial pressure gradients opposite of those at respiratory membrane.
TRANSPORT OF GASES
Exchange of oxygen and carbon dioxide requires both gases must be transported between the external and internal respiration sites. Both gases require a specialized transport system for gas molecules to be moved between the lungs and other tissues.
OXYGEN TRANSPORT IN THE BLOOD: Oxygen is transported via the blood. Transport from lungs to tissues relies on erythrocyte. Hemoglobin binds O2 molecules to erythrocyte. Each hemoglobin molecule can carry up to four molecules of oxygen. Oxygen diffuses across the respiratory membrane also diffuses into the red blood cell and is bound by hemoglobin.
CARBON DIOXIDE TRANSPORT IN THE BLOOD: CO2 from tissues dissolves in plasma. Travels through bloodstream to pulmonary capillaries. Diffuses across respiratory membrane into alveoli. Exhaled during pulmonary ventilation.