1.The partial pressure of arterial oxygen approximates that of pulmonary air (10

Question

1.The partial pressure of arterial oxygen approximates that of pulmonary air (100 mm Hg). This enables 99% of arterial oxygen to be transported as:

oxyhemoglobin

a dissolved gas

oxymyoglobin

2. Where is the partial pressure of arterial oxygen detected?

carotid bodies

chemosensitive region of the brainstem

lungs

all of the above

3. Animals have an autonomic reflex that becomes active whenever the partial pressure of arterial oxygen falls below 80 mm Hg. Is this reflex present in anemic subjects at low elevation?

yes

no

4. An animal’s erythrocytes:

provide a distributed surface from which oxygen diffuses from capillaries into peripheral tissue

help prevent oxygen toxicity

contain an enzyme that converts carbon dioxide and water into carbonic acid

all of the above

5. Approximately 1% of circulating erythrocytes are lost per day. Senescent erythrocytes are removed from the bloodstream as it passes through the liver and spleen. The hemoglobin from these cells is destroyed. Protein subunits are degraded into amino acids. The porphyrin portion of the heme prosthetic group is degraded into bilirubin, a pigment secreted into bile at a rate of approximately 4 mg per kg body weight per day. What happens to the iron atoms released by hemoglobin degradation?

excreted

recycled

degraded

6. Jaundice (or icterus) is caused by hyperbilirubinemia. This condition is diagnosed by a yellowish tinge to skin or the white of the eyes. Jaundice can be hepatocellular, hemolytic, or obstructive. Obstructive jaundice is caused by:

damaged hepatocytes

damaged erythrocytes

the inability of bile to flow from the liver

7. If circulating erythrocytes are destroyed at a rate of 1% per day, then an equivalent number must be added to the bloodstream if erythrocyte density is to remain stable. Erythrocytes are generated by a process known as erythropoiesis. This process is stimulated by erythropoietin, a glycoprotein hormone from the kidneys. Where does erythropoiesis occur?

liver

spleen

bone marrow

8. Approximately 2% of an animal’s hemoglobin is lost daily within circulating erythrocytes when oxygen dissociates from oxyhemoglobin as the superoxide anion. Such dissociation forms methemoglobin rather than deoxyhemoglobin. This reaction is doubly bad because methemoglobin cannot bind oxygen, and the superoxide anion is a highly reactive, free radical gas. These problems are counteracted by

removal of affected erythrocytes from the bloodstream

enzymes within erythrocytes

hemoglobin synthesis

all of the above

Explanation / Answer

Question No 1.

Answer: 99% of arterial oxygen is transported as oxyhemoglobin. Haemoglobin is a conjugated protein found in red blood cells and consists of four haem groups, containing iron and four polypeptide chains. Each of these haem groups can combine with one molecule of oxygen to form oxyhaemoglobin, which is bright red and gives arterial blood its distinctive colour. This process is known as oxygenation. Every molecule of haemoglobin can thus carry four molecules of oxygen.

Question No 2.

Answer: The partial pressure of arterial oxygen is detected by carotid bodies. The carotid body (carotid glomus or glomus caroticum) is a small cluster of chemoreceptors and supporting cells located near the fork (bifurcation) of the carotid artery (which runs along both sides of the throat).

Question No 3.

Answer: Yes. Anemia with a decrease in the hemoglobin content lowers oxygen content (cO2, mL/dL) only, while Oxygen partial pressure (pO2, mmHg) and oxygen saturation (sO2, %) remain normal (anemic hypoxemia).

Question No 4.

Answer: All of the above.

Question No 5.

Answer: The iron atoms get recycled. Iron is removed from heme molecules in the phagocytes. The macrophages can store iron or release it to the blood. In the plasma, it binds to the protein transferrin and is carried to the bone marrow where the iron can be used to synthesize new hemoglobin. Excess iron can be stored in the bone marrow and liver. Some iron is lost in the bile.

Question No 6.

Answer: Obstructive jaundice is caused by the inability of bile to flow from the liver.This might be due to blocked bile ducts caused by gallstones, or tumours of the bile duct which can block the area where the bile duct meets the duodenum.

Question No 7.

Answer: Erythropoiesis occurs in the bone marrow.In the early fetus, erythropoiesis takes place in the mesodermal cells of the yolk sac. By the third or fourth month, erythropoiesis moves to the liver. After seven months, erythropoiesis occurs in the bone marrow.

Question No 8.

Answer: All of the above

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.