Lecture 12 Flashcards
Hemoglobin is composed of how many subunits?
4
Which term is used to describe hemoglobin with only one molecule of oxygen bound to it?
Oxyhemoglobin
Carbon dioxide is transported in different forms in the blood. What is the most common form?
Bicarbonate ion
what are the forms CO2 is transported?
(1) carbonic acid
(2) carbamino compounds –> bound to hemoglobin as carbaminohemoglobin
(3) dissolved gas
How is most carbon dioxide transported in the blood?
As bicarbonate
What does oxygen bind to in the hemoglobin molecule?
heme group
True or false: The majority of dissolved carbon dioxide in the blood is transported as carbaminohemoglobin.
false
majority is transported as carbonic acid
Hemoglobin that is not bound to oxygen is called ______.
deoxyhemoglobin
Which term refers to the exchange of gases (O2 and CO2) that occurs in the capillary networks between the blood and the body’s cells?
Systemic gas exchange
According to this oxyhemoglobin dissociation curve, how much of the oxygen bound to hemoglobin is released into the tissues as the blood flows through the systemic capillaries?
22%
Which is true about carbon dioxide loading?
Carbonic anhydrase catalyzes the conversion of CO2 and H20 into bicarbonate and hydrogen ions.
Choose all the forms in which carbon dioxide is transported in the blood.
Dissolved gas
Bicarbonate ion
Carbaminohemoglobin
The enzyme found in erythrocytes that catalyzes the formation of carbonic acid, which then dissociates into bicarbonate and hydrogen ions, is ___ anhydrase.
carbonic
Most carbon dioxide in the blood is transported in the form of ______ dissolved in the plasma.
bicarbonate
Choose all that occur during the “chloride shift” in red blood cells.
Chloride ions are transported into the RBC.
Bicarbonate ions are transported out of the RBC.
True or false: All of the oxygen transported in the blood is usually unloaded at a systemic capillary.
false
Where does systemic gas exchange occur?
At the capillary networks of the tissues
Where is most carbon dioxide loaded into the blood?
Systemic capillary beds
Oxygen loading in the lungs decreases hemoglobin’s affinity for H+. How does this promote alveolar gas exchange?
The released H+ combines with HCO3- to form free CO2, which can diffuse out of the blood.
Which best describes the action of carbonic anhydrase?
It converts carbon dioxide and water to carbonic acid which dissociates into bicarbonate and hydrogen ions.
what are the 4 factors that stimulate oxygen unloading in response to metabolic rates of different tissues?
(1) lowered P O2 –> lower P O2 == releases more oxygen
(2) higher temp temp –> higher temp == more oxygen unloading
(3) lower pH –> (Bohr effect) lower pH == more oxygen unloading
(4) increased BPG –> increased BPG == more oxygen unloading
True or false: The chloride shift allows RBCs to continue to produce carbonic acid.
True
chloride shift allows HCO3- to be pumped out of RBC in exchange for Cl- to come in from blood plasma
Higher temperatures ___ the unloading of oxygen from hemoglobin.
promote
RBCs usually leave the systemic capillaries at about 75% oxygen saturation. Which term refers specifically to the oxygen remaining in the blood after it passes through a capillary bed?
Venous reserve
Which term refers to the exchange of gases (O2 and CO2) that occurs in the capillary networks between the blood and the body’s cells?
Systemic gas exchange
The Bohr effect occurs because CO2 lowers the pH of the blood, which (as this graph illustrates) facilitates the unloading of oxygen from hemoglobin. Given this, what is the physiological significance of the Bohr effect?
More oxygen is released to tissues that have higher metabolic rates.
more CO2 –> more H+ –> H+ binds to hemoglobin –> causes unloading of oxygen
According to this figure, most of the carbon dioxide you exhale comes from which of the following?
Bicarbonate ions transported into the RBCs and used to generate free CO2.
Bisphosphoglycerate (BPG) promotes which of the following?
Oxygen unloading
Oxygen is unloaded in the body tissues because the affinity of hemoglobin for oxygen is lower in the systemic capillaries (compared to its affinity in the alveolar capillaries). Which factor contributes to this?
CO2 produced in the peripheral tissues leads to increased H+ concentration.
Is P O2 higher in tissue fluid or in alveoli of lungs?
higher in alveoli of lungs. Tissue uses oxygen very rapidly –> leads to low P O2 in tissue
Deoxygenated blood can carry more carbon dioxide, whereas oxygenated blood has a lower carbon dioxide carrying capacity. This phenomenon is known as the ___ effect.
Haldane
Active tissues are warmer than less active ones. Based on that information and the graph shown here, which of the following statements is true?
More oxygen will be delivered to more active tissues.
What is the normal systemic arterial blood gas value for PO2?
95 mm Hg
True or false: All of the oxygen transported in the blood is usually unloaded at a systemic capillary.
False
some oxygen remains in blood, providing a venous reserve of oxygen
For a given PO2, hemoglobin unloads ___ oxygen at lower pH.
more
A general term for a drop in the pH of blood below 7.35 is ___
acidosis
Choose all the hormones that promote oxygen delivery to tissues by stimulating bisphosphoglycerate (BPG) synthesis.
epinephrine
testosterone
growth hormone
thyroxine
A blood pH of 7.55 is called ______.
alkalosis
Which best summarizes the Haldane effect?
The rate of CO2 loading into the blood is increased in metabolically active tissues.
What is the normal systemic arterial blood value for PCO2?
40 mm Hg
Which term refers to an excess of carbon dioxide in the blood?
Hypercapnia
RBCs usually leave the systemic capillaries at about 75% oxygen saturation. Which term refers specifically to the oxygen remaining in the blood after it passes through a capillary bed?
Venous reserve
True or false: Evidence suggests that ventilation increases more quickly in response to high levels of CO2 than it does to low levels of O2 in the blood.
True
A blood pH of 7.1 would be called ______.
acidosis
Hypoxic drive refers to a condition where the respiratory centers of the brainstem respond to which of the following?
PO2 of arterial blood
Which term refers to an acid-base imbalance in which the blood pH is higher than 7.45?
Alkalosis
Deoxygenated blood can carry more carbon dioxide, whereas oxygenated blood has a lower carbon dioxide carrying capacity. This phenomenon is known as the ___ effect.
Haldane
The term ___ describes a condition where there is an excess of CO2 in arterial blood (PCO2 greater than 43 mm Hg).
hypercapnia
Peripheral chemoreceptors trigger an increase in ventilation in response to which of the following?
High levels of blood CO2
Which factor is typically responsible for setting the respiratory rate in healthy individuals?
Cerebrospinal fluid pH
what are the 3 chemical stimuli ranked in order of breathing effect?
(1) CSF pH
(2) P CO2 of arterial blood
(3) P O2 of arterial blood
Which best summarizes the Haldane effect?
The rate of CO2 loading into the blood is increased in metabolically active tissues
Hypoxic drive refers to a condition where the respiratory centers of the brainstem respond to which of the following?
PO2 of arterial blood
