MCAT Biology : Hemoglobin, Blood Cells, and Blood Proteins
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Example Question #31 : Hemoglobin, Blood Cells, And Blood Proteins
Which of the following is not a component of blood plasma?
Water
Albumin
Thrombin
Red blood cells
Red blood cells
The plasma portion of the blood is the extracellular matrix that suspends the erythrocytes and lymphocytes traveling through circulation. The plasma contains water, proteins (chiefly albumin), electrolytes, and clotting factors (such as thrombin). Whole blood contains the cells, as well as thx extracellular plasma. Blood serum refers to blood plasma that has had the clotting factors removed.
Example Question #32 : Hemoglobin, Blood Cells, And Blood Proteins
Mature erythrocytes contain which of the following organelles?
Nucleus
None of these
Golgi apparatus
Mitochondria
None of these
Mature erythrocytes (red blood cells) do not contain a nucleus and lack most organelles. While immature, the erythrocyte contains a nucleus, but this gets extruded in order to make more room for hemoglobin to transport oxygen. It is important to understand the implications of not having any additional organelles; the red blood cell cannot derive energy from the citric acid cycle and cannot produce, transport, or exocytose proteins. This may seem like a problem, but it actually prevents the red blood cell from consuming the oxygen that it is transporting. If erythrocytes contained nuclei or mitochondria, they would metabolize the oxygen attached to hemoglobin, failing to deliver it to other tissues.
Example Question #33 : Hemoglobin, Blood Cells, And Blood Proteins
A mature erythrocyte primarily derives its energy from which of the following metabolic processes?
Lactic acid fermentation
Glycolysis
Oxidative phosphorylation
Glycogenolysis
Glycolysis
The mature erythrocyte (red blood cell) contains no nucleus, mitochondria, Golgi apparatus, or endoplasmic reticulum. Consequently, the red blood cell can only derive energy from glycolysis, the anaerobic breakdown of glucose in the cytosol. Mitochondria would be required for any other metabolic process.
Example Question #34 : Hemoglobin, Blood Cells, And Blood Proteins
What enzyme is responsible for converting fibrinogen to fibrin, which helps platelets form clots in response to vessel injury?
Complement
Thrombin
Platelet monoamine oxidase
Prothrombin
Thrombin
Thrombin, created from prothrombin after activation by coagulation factors from the liver, is responsible for turning fibrinogen to fibrin. Fibrin adheres to endothelial cells and platelets to allow clots to form in response to vessel damage. Complement helps attract immune cells to the site of injury. Platelet monoamine oxidase degrades amines, such as serotonin, in neuronal synapses.
Example Question #35 : Hemoglobin, Blood Cells, And Blood Proteins
Which of the following cell types does not possess a nucleus in its mature form?
Erythrocytes
Neurons
Granulocytes
Adipocytes
Erythrocytes
Erythrocytes are chiefly responsible for delivering oxygen to cells throughout the body and do not possess nuclei in their mature form. The absence of a nucleus and mitochondria from mature erythrocytes prevents transported oxygen from being consumed by the carrier cell, instead of being delivered to the body.
Granulocytes are a division of white blood cells and frequently have lobed or multiple nuclei. Neurons contain nuclei in their somas and adipocytes contain peripheral nuclei, located close to the membrane.
Example Question #103 : Circulatory System
Carbonic anhydrase is a very important enzyme that is utilized by the body. The enzyme catalyzes the following reaction:
A class of drugs that inhibits this enzyme is carbonic anhydrase inhibitors (eg. acetazolamide, brinzolamide, dorzolamide). These drugs are commonly prescribed in patients with glaucoma, hypertension, heart failure, high altitude sickness and for the treatment of basic drugs overdose.
In patients with hypertension, carbonic anhydrase inhibitors will prevent the reabsorption of sodium chloride 
When mountain climbing, the atmospheric pressure is lowered as the altitude increases. As a result of less oxygen into the lungs, ventilation increases. From the equation above, hyperventilation will result in more 
Carbonic anhydrase inhibitors are useful in patients with a drug overdose that is acidic. The lumen of the collecting tubule is nonpolar. Due to the lumen's characteristic, molecules that are also nonpolar and uncharged are able to cross the membrane and re-enter the circulatory system. Since carbonic anhydrase inhibitors alkalize the urine, acidic molecules stay in a charged state.
How will excess intake of a carbonic anhydrase inhibitor affect the hemoglobin dissociation curve?
Shifts up
Shifts to the right
Shifts to the left
No change
Shifts down
Shifts to the right
Carbonic anhydrase inhibitors will decrease the blood's pH. Conditions that will shift the hemoglobin dissociation curve to the right are increased temperature, increased 2,3-DPG, and decreased pH.
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