Exam IV

• According to Henry's law, the amount of oxygen dissolved in blood is directly proportional to the PO2 of the blood
• O2 bound to hemoglobin is 98.5% while O2 dissolved in plasma is 1.5%
• Hemoglobin is a protein that consists of 4 copies of the globin protein all bound together in a quaternary structure with heme groups in each protein; iron is in each of these groups. Can be oxygenated or deoxygenated
• Hemoglobin saturation = O2 bound to Hb/Max capacity of Hb to bind O2 * 100
• Factors that determine Hb saturation include:

  • Blood PO2
  • Amount of hemoglobin in blood
• Anemia is diagnosed when a blood test shows a hemoglobin value of <13.5 g/dL in males and <12.0 g/dL in females
• As PO2 increases, hemoglobin saturation increases until it reaches 60 mmHg

  A) Unloaded O2

  B) systemic venous

  C) systemic arterial

  
• The more oxygen binds to hemoglobin, the higher oxygen affinity becomes
• During the slope of the PO2 vs saturation graph, blood passes through the pulmonary arteries to get oxygenated and then passes through the systemic arteries where oxygen then goes to the tissue
• ideal unloading of oxygen to tissue is between 20-60 mmHg
• O2 bound to Hb doesn't contribute to the partial pressure of O2 in the blood. It is the plasma that contributes
• Pulse oximeter measures oxygen saturation
• O2 binds to globin in hemoglobin
• Most oxygen from alveoli is moved into the hemoglobin so PO2 remains lower in the blood (<2% dissolved) to facilitate simple diffusion
• AS you move into the tissue, plasma PO2 is lower than RBC PO2 and at its lowest in mitochondria PO2 so, with the help of the diffusion gradient, oxygen moves from the RBC, to the plasma, and finally into the mitochondria
• In most tissue, hemoglobin is still 75% oxygenated when the oxygen leaves to the mitochondria
• Active hyperemia is when there is less oxygen in the blood leading to vasodilation to occur to get more oxygen in the blood
• O2 is lowest in the mitochondria because it is needed for aerobic respiration
• If the saturation curve shifts to the right, then it has a less affinity for oxygen making Hb saturated slower
• If the saturation curve shifts to the right, then there is a greater affinity for oxygen making Hb getting saturated faster
• If a higher temperature is present, this allows for more metabolization to take place, so we would need more O2 causing the saturation curve to shift to the right. Vice versa for cold
• 2,3 - DPG is made from glycolysis and allows for allosteric binding of hemoglobin causing a decreased affinity for oxygen. This causes the curve to shift to the right allowing for more O2 release
• At a higher altitude, less O2 is present so DPG increases so that the hemoglobin affinity for O2 lowers allowing for more O2 release
• When acidosis occurs, blood pH is lower allowing for more H+ ions to bind to hemoglobin causing a lower O2 affinity
• Carbon monoxie distorts Hb so less O2 binds to it' it has a higher affinity for hemoglobin and can look saturated
• Fetal hemogobin has a higher affinity for O2 than adult hemoglobin; prenatal steals O2 from mom
• CO2 production is toxic because it generates H+. If rising H+ is not buffered, then changes in pH will take place making it more acidic
• At rest, the body makes about 200 mL CO2/min diffusing into the blood. CO2 is more soluble in water than O2
• Carbonic anydrase breaks down CO2 and water to form carbonic acid which can also turn into bicarbonate and H+
• CO2 comes from cellular expiration, tissues, and breaking down sugar
• CO2 moves using a high to low diffusion gradient from the cells to the capillaries where Hb is to the alveoli where it is expired
• 10% of CO2 goes into the plasma where it will allow HCO3- to buffer by binding to H+ and prevent blood from becoming acidic
• Chloride shift prevents charge change from happening in the RBCs by moving Cl- ions in while HCO3- moves out
• The venous side of the capillaries has the highest H+ concentration because CO2 is released in this area
• H+ binds to deoxygenated Hb
• Only a small amoutn of H+ generated in blood remains free. When released, H+ becomes a part of the buffer system
• Total-blood carbon dioxide level = dissolved Co2 + HCO3- + CO2 in carbaminohemoglobin
• dorsal respiratory group is controlled by inspiratory motor neurons and activate external intercostal muscles as well as the diaphragm
• the ventral respiratory group is controlled by expiratory motor neurons and activate internal intercostal muscles
• action potential signaling causes skeletal muscles, like the diaphragm, to contract