lecture 18 Flashcards
Describe oxygen and carbon dioxide concentration gradients and net gas movements between the alveoli and the pulmonary capillaries.
- Oxygen and carbon dioxide exchange: Oxygen (O₂) moves from areas of higher concentration in the alveoli (lungs) to lower concentration in the pulmonary capillaries (blood), while carbon dioxide (CO₂) moves from the blood, where its concentration is higher, to the alveoli, where the concentration is lower.
- Driving force: This movement occurs due to differences in partial pressures (concentration gradients). The partial pressure of O₂ is higher in the alveoli than in the blood, so O₂ moves into the blood. Conversely, the partial pressure of CO₂ is higher in the blood than in the alveoli, so CO₂ diffuses into the alveoli.
pulmonary - OB COT
Analyze how oxygen and carbon dioxide movements are affected by changes in partial pressure gradients (e.g., at high altitude).
High altitude: At higher altitudes, the atmospheric pressure and partial pressure of oxygen (PO₂) decrease, which leads to a reduced gradient between the alveoli and the blood. This results in less efficient oxygen diffusion into the blood. The body compensates by increasing ventilation, increasing red blood cell production, and altering hemoglobin affinity for oxygen.
Describe oxygen and carbon dioxide concentration gradients and net gas movements between systemic capillaries and the body tissues.
o Oxygen movement: In the systemic capillaries, the partial pressure of oxygen is higher in the blood than in the tissues, so oxygen diffuses from the blood to the tissues.
o Carbon dioxide movement: The partial pressure of carbon dioxide is higher in the tissues than in the blood, so CO₂ diffuses from the tissues into the blood.
COB BOT
Explain the influence of cellular respiration on oxygen and carbon dioxide gradients that govern gas exchange between blood and body tissues.
o Cellular respiration: As tissues metabolize glucose, they produce CO₂, which increases the CO₂ concentration in the tissues. This creates a gradient that facilitates CO₂ diffusion into the blood. Simultaneously, oxygen is consumed in cellular respiration, lowering the oxygen concentration in the tissues, which facilitates the diffusion of oxygen from the blood into the tissues.
Describe the ways in which oxygen is transported in blood, and explain the relative importance of each to total oxygen transport.
o Hemoglobin (Hb): The majority of oxygen is transported bound to hemoglobin in red blood cells. Hemoglobin binds oxygen in the lungs and releases it in the tissues.
o Dissolved oxygen: A small portion of oxygen is transported dissolved directly in the plasma, but this is minimal compared to hemoglobin-bound oxygen.
Interpret the oxygen-hemoglobin saturation curve at low and high partial pressures of oxygen.
o Low PO₂: At low partial pressures of oxygen (e.g., in the tissues), hemoglobin releases oxygen more readily.
o High PO₂: At high partial pressures of oxygen (e.g., in the lungs), hemoglobin binds oxygen more readily, reaching full saturation.
Explain the changes in hemoglobin affinity for oxygen when the curve shifts to the right or the left.
o Shift to the right: When the oxygen-hemoglobin curve shifts to the right (due to factors like increased CO₂, lower pH, increased temperature, or increased 2,3-DPG), hemoglobin has a lower affinity for oxygen, which facilitates oxygen release in tissues.
o Shift to the left: When the curve shifts to the left (due to factors like decreased CO₂, higher pH, lower temperature, or decreased 2,3-DPG), hemoglobin has a higher affinity for oxygen, facilitating oxygen binding in the lungs.
List factors that shift the oxygen-hemoglobin saturation curve to the right, and explain how this results in increased oxygen release at the tissues.
o Increased CO₂: Higher CO₂ levels reduce hemoglobin’s affinity for oxygen, promoting oxygen release.
o Lower pH: Acidosis (low pH) enhances oxygen release from hemoglobin. (Bohr effect)
o Increased temperature: Heat decreases oxygen affinity, aiding oxygen release.
o Increased 2,3-DPG: This byproduct of glycolysis reduces hemoglobin’s oxygen affinity, facilitating oxygen delivery.
List factors that shift the oxygen-hemoglobin saturation curve to the left, and explain how this facilitates oxygen binding to hemoglobin in the lungs.
o Decreased CO₂: Lower CO₂ levels increase hemoglobin’s affinity for oxygen.
o Higher pH: Alkalosis (high pH) increases the oxygen affinity of hemoglobin.
o Decreased temperature: Lower temperatures increase oxygen affinity.
o Decreased 2,3-DPG: This enhances oxygen binding to hemoglobin.
Indicates that hemoglobin has a higher affinity for oxygen and is more reluctant to release it to the tissues
Describe the oxygen-fetal hemoglobin saturation curve and its impact on oxygen delivery to fetal tissues.
o Fetal hemoglobin (HbF): The oxygen dissociation curve for fetal hemoglobin shifts left compared to adult hemoglobin, which allows the fetus to extract oxygen from maternal blood more efficiently in the placenta.
Describe the ways in which carbon dioxide is transported in blood and explain the relative importance of each to total carbon dioxide transport.
o Bicarbonate ion (HCO₃⁻): The majority of CO₂ is transported in the blood as bicarbonate ions, formed when CO₂ reacts with water in red blood cells to form carbonic acid.
o Carbamino compounds: Some CO₂ binds to proteins (mainly hemoglobin) forming carbamino compounds.
o Dissolved CO₂: A smaller amount of CO₂ is dissolved directly in plasma.
State the reversible chemical equation for the reaction of carbon dioxide and water to carbonic acid and then to hydrogen ion and bicarbonate ion.
o CO₂+H₂O↔H₂CO₃↔H⁺+HCO₃⁻
Explain the relationship between pH and hydrogen ion concentration.
o pH and H⁺ concentration: pH is inversely related to the concentration of hydrogen ions (H⁺) in solution. A lower pH corresponds to a higher H⁺ concentration, and a higher pH corresponds to a lower H⁺ concentration.
Predict how changing the partial pressure of carbon dioxide will affect the pH in the plasma, and how changing the pH will affect the partial pressure of carbon dioxide in the plasma.
o Increase in CO₂: An increase in CO₂ lowers blood pH (acidosis) due to the formation of carbonic acid, which dissociates into H⁺ and bicarbonate ions.
o Decrease in CO₂: A decrease in CO₂ raises blood pH (alkalosis) by reducing H⁺ concentration.
.Describe the locations and functions of the brainstem respiratory centers.
o Medulla oblongata: Contains the ventral respiratory group (VRG), which controls the rhythm of breathing, and the dorsal respiratory group (DRG), which integrates sensory input and modifies the rhythm.
o Pons: Contains the pontine respiratory group (PRG), which helps smooth the transition between inhalation and exhalation.
List and describe the major chemical and neural stimuli to the respiratory centers.
o Chemical stimuli: The primary stimuli are increased CO₂ levels (via blood pH changes) and decreased O₂ levels. Chemoreceptors in the carotid and aortic bodies sense changes in blood chemistry.
o Neural stimuli: Stretch receptors in the lungs (Hering-Breuer reflex) prevent over-inflation, and voluntary control from the cerebral cortex can modulate breathing.
Explain how the respiratory system relates to other body systems to maintain homeostasis.
o Oxygen supply: The respiratory system ensures adequate oxygenation of blood to meet metabolic demands of the body.
o Acid-base balance: Through the regulation of CO₂ levels, the respiratory system helps maintain pH homeostasis in the blood.
o Collaboration with other systems: The respiratory system works with the circulatory system to transport gases and with the renal system to regulate blood pH.
the types of oxygen transport
dissolved in blood plasma (1.5%)
dissolved in bound to hemoglobin (98.5%)
oxygen binds to the iron atoms in heme pigment, each molecule of hemoglobin has 4 heme pigments
how is carbon dioxide transported
- 7-10% is dissolved in plasma
- 20% is bound to hemoglobin
- 70% is converted to bicarbonate ions
