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Pathophysiology > Chapter 13 - Alterations In Oxygen Transport > Flashcards

Chapter 13 - Alterations In Oxygen Transport Flashcards

1
Q

What is the percentage of blood cells in the blood volume?

What is the percentage of blood plasma in the blood volume?

A

Blood cells make up 45% of blood volume.

Blood plasma makes up 55% of the blood volume.

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2
Q

What makes up the composition of blood plasma?

A

Blood plasma is made of 92% water and 7% plasma proteins.

Substances include:
Nutrients, ions, plasma proteins, metabolic wastes, hormones, and enzymes

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3
Q

What is the pH of normal blood?

A

7.35 to 7.45

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4
Q

What are the three plasma proteins? What do they do?

A

Plasma proteins contribute to colloid osmotic pressure; important for maintaining blood pressure.

  1. Albumin - essential for maintaining blood volume and pressure.
  2. Globulin - consists of alpha (transports bilirubin, lipids, & steroids), beta (transports iron and copper in plasma), Gamma (contains antibody molecules)
  3. Fibrinogen - inactive precursor of fibrin (makes blood clot framework)
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5
Q

List three characteristics of RBCs (or erythrocytes):

A

Most numerous component (4.2 - 6.2 million cells/mm3)
Transports O2
Removes CO2 (buffers pH)s
Lives for 80 to 120 days

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6
Q

What is reversible deformability?

A

When RBC assume a torpedo-like shape to circulate through capillaries (2 um) and return to biconcave disk shape (7.2 um in diameter)

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7
Q

List at least three characteristics of platelets:

A

150K to 400K circulate
The Spleen acts as a reserve pool for an additional 1/3 of the body’s platelets.
Average Life span is peripheral blood is 4 to 5 days

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8
Q

What is hematopoiesis?

A

Process from pluripotent ill stem cells to mature differentiated red cells, neutrophils, eosinophils, basophils, monocytes, and platelets.

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9
Q

What is the total blood volume?

A

5 to 6 Liters or 7% to 8% of body weight.

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10
Q

What is the lifespan of RBCs?

A

80 to 120 days

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11
Q

What is the concentration of RBCs

A

4.2 - 6.2 million cells/mm3

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12
Q

What is the concentration of leukocytes, or WBCs?

A

5,000-10,000/mm3

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13
Q

What are platelets and what is the concentration of platelets?

A

Platelets are not cells but they are small fragments of megakaryocytes.

Concentration is 150,000 to 400,000 cells/mm3

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14
Q

What do RBCs develop from?

A

RBCs develop from pluripotential stem cells in the bone marrow

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15
Q

What growth hormone stimulates pluripotential stem cells in the bone marrow to make RBCs?

A

Erythropoietin is the hormone that stimulates pluripotential stem cells to produce RBCs.

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16
Q

What organ secretes erythropoietin and when does this occur?

A

Erythropoietin is secreted from the kidneys when the kidneys detect low oxygen tension in the blood.

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17
Q

What happens to RBC during development?

A

During development of the RBC, the RBCs lose their nuclei and other cytoplasmic organelles.

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18
Q

What is a reticulocyte and what does an increased blood reticulocyte count indicate?

A

Reticulocytes are immature RBCs that still retain some cellular organelles. An elevated blood reticulocyte count indicates increased RBC production.

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19
Q

What is the major component of the RBC?

A

Hemoglobin

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20
Q

What makes up hemoglobin?

A

Hemoglobin is composed of two pairs of polypeptide chains, each which has a heme molecule attached. Oxygen can bind reversible to an iron molecule at the center of each heme.

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21
Q

How many molecules of oxygen can a fully saturated hemoglobin molecule carry?

A

4

22
Q

What is oxyhemoglobin?

A

A fully oxygen saturated hemoglobin molecule.

23
Q

Which 3 nutrients are crucial for the development of RBCs?

A

Iron
Vitamin B12
Folate

24
Q

How does a lack of intrinsic factor effect RBC production?

A

Lack of intrinsic factor inhibits the absorption of B12 from the small intestine and is a risk factor for anemia.

25
Q

What do RBCs rely on for energy production and why?

A

RBCs rely on glycolysis for energy production because they lack mitochondria.

26
Q

Why does RBC energy production decline and what happens to the RBC that loses energy production?

A

RBC energy production declines because of RBC aging and loss of essential glycolytic enzymes. SO, the cell swells, is trapped in the spleen, and is removed from circulation.

27
Q

What is the byproduct of RBC degradation and where are the byproducts excreted?

A

Bilirubin - a toxic substances that is conjugated in the liver and excreted in the urine and bile.

28
Q

What percentage of oxygen being transported in the blood is bound to hemoglobin?

A

97%

29
Q

What percentage of oxygen transported in the blood is dissolved in plasma and what is this number measured as?

A

3% of oxygen is dissolved in the plasma. It is this 3% which is measured as PaO2.

30
Q

What percent of hemoglobin is saturated with oxygen at a normal PaO2?

A

95-100%

31
Q

What is the venous hemoglobin saturation percentage and why?

A

Venous hemoglobin saturation is about 75% because 25% of the bound oxygen is unloaded to the tissues.

32
Q

What does the oxyhemoglobin dissociation curve describe?

A

The oxyhemoglobin dissociation curve describes the relationship between the partial pressure of oxygen and hemoglobin saturation.

33
Q

What is the partial pressure of oxygen in the lung compared to the tissue?

A

In the lung, where PO2 is high (100 mm Hg), oxygen is loaded onto hemoglobin.
In the tissue, where PO2 is low (40 mm Hg), oxygen is unloaded from hemoglobin to tissue.

34
Q

What affects the affinity of hemoglobin for oxygen?

A

Temperature, acid-base status, 2,3-DPG levels, and carbon dioxide concentration.

35
Q

What is the affinity of hemoglobin for oxygen at the tissue levels and why?

A

Affinity of hemoglobin for oxygen is decreased at the tissue level due to increased levels of acid, 2,3-DPG, and carbon dioxide. This is known as a shift to the right of the oxyhemoglobin dissociation curve.

36
Q

Where does a shift to the right of the oxyhemoglobin dissociation curve occur and what does it cause to happen?

What about a shift to the left?

A

A shift to the right of the oxyhemoglobin dissociation curve occurs at the tissue level due to increased levels of acid, 2,3-DPG, and carbon dioxide, which enhances the unloading of oxygen to the tissue.

A shift to the left occurs in the lungs, where blood is more alkalotic and carbon dioxide levels are lower. This increased affinity of hemoglobin for oxygen at the lung facilitates oxygen binding.

37
Q

How is the oxygen content of arterial blood calculated?

A

Add the amount bound to hemoglobin (Hb) plus the amount dissolved in plasma:
CaO2 = (Hb 1.34 SaO2) + (PaO2 0.003).

38
Q

How is oxygen delivery to the body tissues calculated?

A

Multiply CaO2 by cardiac output (CO): O2 =CaO2 * CO 10.

39
Q

What is the Fick equation?

A

The Fick equation is used to estimate the consumption of oxygen by tissues:

O2 = CO(CaO2 - CO2) 10.

40
Q

What happens to oxygen consumption as a result of increased tissue metabolism?

A

Increased tissue metabolism causes an increase in oxygen consumption.

41
Q

What is carbaminohemoglobin?

A

Carbaminohemoglobin is formed when hemoglobin binds with carbon dioxide at the tissue level and is transported to the lungs where the CO2 is eliminated.

42
Q

What is carbon anhydride?

A

RBCs contain the enzyme carbon anhydride, which greatly increase the conversion of carbon dioxide and water into HCO3- and H+ at the tissue level. In the lungs, this reaction reverses to produce CO2, which is then eliminated by the lungs.

43
Q

What are the general effects of anemia due to?

A

The general effects of anemia are due to tissue hypoxia and efforts to compensate for low oxygen-carrying capacity.

44
Q

What are some signs and symptoms of anemia?

A 
Vasoconstriction, 
Pallor
Tachypnea 
Dyspnea 
Tachycardia 
Ischemic pain
Lethargy 
Lightheadedness 
- In addition, signs & symptoms relating to the specific cause of the anemia may be present, which are helpful in determining the cause of anemia.
45
Q

What may cause some of the different types of anemia?

A

Anemia may be due to abnormally low production of red cells and/or excessive loss or destruction.

Aplastic Anemia = decreased production of RBCs that may be due to stem cell failure.

Renal disease = lack of erythropoietin

Nutritional deficiencies of iron, vitamin B12, or folate.

Excessive RBC loss may be due to hemolysis (e.g., ABo and Rh incompatibility, drugs) or bleeding (e.g. Surgery, trauma)

Inherited disorders of RBCs often impair production and increase destruction of RBCs.

46
Q

What factors determine the cause of anemia?

A

Determination of the cause of anemia is based on the:

History, differential signs and symptoms, and results of laboratory studies

47
Q

What are the 6 major types of anemia and their important differentiating features?

A

Aplastic Anemia: History of toxic or radiation injury to bone marrow. Accompanying leukopenia and thrombocytopenia. RBCs are normocytic (RBCs are normal in size but small in numbers) and normochromic (normal concentration of hemoglobin but insufficient number of RBCs).

Chronic Renal Failure: History of renal disease. Decreased erythropoietin level and erythropoietin responsiveness. RBC are normocytic and normochromic

Vitamin B12 and Folate deficiency: History of poor nutrient intake or gastrointestinal disease. Accompanying neurologic dysfunction. RBC are magaloblastic [many large immature and dysfunctional RBCs] (macrocytic) (Macrocytic means “a large cell” with low hemoglobin concentration).

Iron deficiency: History of poor nutrient intake or chronic blood loss. Decreased serum ferritin and iron levels. RBCs are macrocytic and hypochromic

Hemolytic: History of ABO or Rh incompatibility or drug exposure. Increased bilirubin level, jaundice, positive direct anti globulin test. RBCs are normocytic and normochromic

Acute blood loss: History of trauma, surgery, or known bleeding. Accompanying manifestations of volume depletion. RBCs are normal. Anemia may not be apparent until fluid loss is replaced.

48
Q

What are some inherited disorders of the RBC and why are these RBCs predisposed to early destruction?

What is often seen as a sign with inherited disorders of RBCs?

A

Inherited disorders include: Thalassemia, sickle cell anemia, spherocytosis, G6PD deficiency.

Here the RBCs are predisposed to early destruction due to abnormalities in hemoglobin structure, cell shape, membrane structure, or energy production.

Manifestations of hemolysis (e.g. Bilirubin, jaundice) are often present.

49
Q

What is the general management of anemia?

A

The general management of anemia is aimed at removing the cause, if possible; restoring oxygen carrying capacity with blood transfusion when necessary; and preventing the complications of ischemia (e.g. With rest, oxygen therapy) and hemolysis (e.g. Increased fluid intake, management of high bilirubin levels).

50
Q

What are the three types of polycythemia and how is polycythemia typed?

A

Polycythemia is typed by cause.

Polycethemia vera = associated with neoplastic transformation of bone marrow stem cells. Findings include an absence of hypoxemia and dehydration, accompanied by leukocytes is and thrombocytosis.

Secondary polycythemia = is due to chronic hypoxemia, with a resultant increase in erythropoietin production. Here there is a history of lung disease or living at high altitudes. Hypoxemia evident on blood gas evaluation. Erythropoietin level is elevated.

Relative polycythemia = due to dehydration, which causes a spurious increase in RBC count. History of fluid loss or poor intake. Accompanying manifestations of dehydration.

51
Q

What is the treatment for polycythemia?

What treatment may be used of polycythemia vera?

A

Treatment is aimed at removing the cause, if possible.

Treatment for polycythemia Vera may employ the use of phlebotomy and bone marrow-suppressing agents.

52
Q

What are two major complications of polycythemia?

A

Increased blood viscosity and the risk of thrombi.

Pathophysiology (9 decks)

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