Gas Exchange Flashcards
Explain how the structure of the ventilation system is adapted to its function
-air is carried to the lungs in the trachea and bronchi, and then to the alveoli in the bronchioles
- Trachea:
Tube that allows air to travel into and out of the lungs to and from the atmosphere
- Lungs:
Take in fresh air (oxygen) from atmosphere and get rid of carbon dioxide from blood
- Bronchi:
Tubes (right and left) that carry air into lungs (from trachea) and out of lungs
-Bronchioles:
Smaller tubes that carry air to and from the alveoli (from the bronchi) - ↑SA
- Alveoli:
Clusters of air sacs (↑SA) at ends of bronchioles - Gas exchange with the blood (O2 and CO2), thin walls, rich capillary network, increased surface area, moist
-type 1 pneumocytes:
flattened and thin to minimize diffusion distance
-type 2 pneumocytes
stores components to make surfactant
explain the antagonistic roles of the internal and external intercostal muscles, as well as the diaphragm and abdominal muscles in the processes of inspiration and expiration
-different muscles are required for inspiration and expiration because muscles only do work when they contract.
-Inspiration (breathing in)
Diaphragm muscles contract (flatten downwards) and external (on outside)
intercostal muscles contract (pull ribs up
and out)
b. Thoracic cavity volume and lung volume increase (pressure of air in lungs drops below atmospheric pressure – air rushes in through mouth or nasal passage to equalize)
-Expiration (breathing out)
a.) Diaphragm muscles relax (curves upward), abdominal wall muscles contract (pushing diaphragm up), external intercostal muscles relax (ribs fall), and internal (on inside) intercostal muscles contract (pulling ribs back down)
b.) Thoracic cavity volume and lung volume decrease (pressure of air in lungs rises above atmospheric pressure – air rushes out to equalize)
Be able to explain the process of gas exchange in the alveoli of the lungs and the role of the ventilation system in maintaining concentration gradients of CO2 and O2 between the alveoli and the capillaries surrounding them.
-gas exchange is a passive process (diffusion), the lungs function to continually cycle fresh air into the alveoli
-high O2 in alveoli allows diffusion of O2 into the blood and low CO2 in alveoli
allows diffusion of CO2 out of blood and into alveoli
- O2 diffuses from the lungs through the alveoli walls INTO the blood (capillaries) and CO2 diffuses OUT of the blood (capillaries) through the alveoli walls and into the lungs
Explain how to use a spirometer to measure ventilation rate
Spirometer (measures volume of gas inhaled/ expelled per breath) - Note: changes in volume are shown as increasing (breathing in) or decreasing (breathing out) over time on a graph and each breath is one “wave” (shows tidal volume - amount of O2 in or out in in one breath)
Describe how the structure of hemoglobin and myoglobin are related to their functions and their oxygen dissociation curves.
-An oxygen dissociation curve shows the relationship between oxygen levels (as partial pressure) and the % saturation of oxygen-carrying molecules
Hemoglobin:
-Shows a sigmoidal (S-shaped) curve
-High saturation at high pressures
Myoglobin:
-Higher affinity for oxygen than hemoglobin
-Releases oxygen to muscle
cells when levels of O2 in
blood are extremely low
explain WHY and how the body adapts to gas exchange at high altitudes
- RBC production increases (more RBC’s = more hemoglobin = more O2 transport) - this causes kidneys to excrete excess fluid though = more urination = dehydration (so need more H2O)
- RBCs are produced with more hemoglobin molecules in them (these also have a slightly different structure which gives them a higher affinity for oxygen - shifts oxygen dissociation curve to the left - ↑ % saturation of Hb at lower pO2)
- Vital capacity increases (more air in/out per breath = increased rate of gas exchange)
- Muscles produce more myoglobin (capillaries become more dense too – more O2 diffusion into cells and binding by myoglobin)
- Kidneys secrete alkaline urine (remove excess HCO3- to improve buffering of blood pH)
- Greater lung surface area/ larger chest size – if living permanently at high altitude
Be able to describe the different ways that carbon dioxide is carried in the blood.
Carbon dioxide is carried in the blood (from the tissues to the lungs) in one of three ways:
1. Bound to hemoglobin (HbCO2 - binds to globin, not heme, so does not compete with oxygen)
2. Dissolved in the blood plasma (in water portion - forms carbonic acid/ bicarbonate ions)
3. In erythrocytes (RBC’s) as carbonic acid (~75% of CO2 carried this way!):
Describe how blood pH is maintained (and know the range of “normal” pH in the body).
-chemoreceptors are sensitive to changes in blood pH, and pH of blood is regulated to stay within the (VERY) narrow range of 7.35 to 7.45 (to avoid the onset of disease)
-Plasma proteins act as pH buffers by removing excess H+ ions (that would ↑ acidity) or by removing excess OH- ions (that would ↑ alkalinity)
Be able to diagram and explain the Bohr shift
-Respiring tissues release MORE CO2 into the blood, which LOWERS the pH of the blood
-↓in pH shifts the oxygen dissociation
curve to the RIGHT causing ↓affinity of hemoglobin for oxygen = MORE O2 is released to respiring cells
