Self-test questions: Chapter 25

. The plasma of a normal adult:

is about 60% water.

accounts for 10% of body weight

contains about 8 mmoles l^-1 of potassium (k⁺)

contains about 140 mmoles l^-1 of sodium (na⁺)

. For a healthy adult of 65-70 kg body weight:

The blood pH is 7.0

There are about 4.5 x 10¹² red cells per litre.

The blood volume would be about 5 litres.

There are about 1 x 10⁹ leukocytes per litre.

. Which of the following statements concerning normal human red cells is correct?

Are released into the circulation as immature cells called reticulocytes.

Live in the blood for about 120 days.

Rely on glycolysis for their ATP production.

Are formed by budding off from large precursor cells called megakaryocytes.

. The following statements refer to gas carriage by the blood which are correct?

After leaving the lungs, each litre of blood contains about 20 ml of oxygen.

Haemoglobin is half saturated with oxygen when the PO2 is about 3.3 kPa (25 mm Hg) and PCO2 is 5.3 kPa (40 mm Hg),

As the PCO2 rises, the affinity of haemoglobin for oxygen is decreased

Each litre of arterial blood contains about 500 ml of carbon dioxide

. Which of the following statements regarding the platelets is correct?

Are present in greater number than red cells.

Secrete the main clotting factors.

Will adhere to the walls of damaged blood vessels.

Aggregate in the presence of prostacyclin.

. Neutrophils are agranulocytes

True

False

. Haemophilia B is caused by a deficiency of factor IX

True

False

. People with blood group AB have antibodies to both A and B red cell antigens

True

False

. The following statements refer to the mechanisms of haemostasis which are correct?

Both extrinsic and intrinsic pathways lead to the activation of Factor X

All the clotting factors are produced by the liver

Coagulation can be prevented by adding EDTA or citrate to a sample of blood

Haemostasis is significantly impaired when the platelet count falls below 25 �10⁹ l^-1 (i.e. 25,000 per microlitre).

Failure of haemostasis is always caused by a deficiency of Factor VIII

Haemostasis is initiated when tissue factor comes into contact with blood

. A sample of blood from young man is found to contain 4.8x10¹² red cells l^-1, 14.8 g dl^-1 haemoglobin and has a haematocrit of 0.45. These values all fall within the normal range.

True

False

. From the values given for the previous question, which of the following statements about the blood sample are correct? For parts (c) and (d) refer to Figure 25.6 for the change in Hb saturation with PO2. Assume that PCO2 is 5.3 kPa (40 mm Hg); 1 g Hb binds 1.34 ml O2 when fully saturated and O2 solubility is 0.225 ml l^-1. kPa (0.03 ml l^-1 mm Hg^-1). You may find it helpful to use a calculator.

The average volume of the red cells is 94x10^-15l (94 fl).

The total amount of haemoglobin in each red cell is 50x10^-12g.

The amount of oxygen carried by 1 dl blood (100 ml) when the PO2 is 13.3 kPa (100 mm Hg) is 19.5 ml O2

The amount of oxygen carried by 1 dl (100 ml) blood when the PO2 is 5.3 kPa (40 mm Hg) 10ml.

. Mrs S is 35 years old and has been chronically tired and experiences palpitations on exercise. She looks pale and is experiencing heavy periods. A blood test shows that she has a haemoglobin of 8 g dl^-1 with a MCV of 70 fl. Which of the listed conditions is the likely cause of her malaise?

Sickle cell disease

Thalassaemia

Macrocytic anaemia

Microcytic anaemia

. Mr O who is of African origin, complains of being tired and lethargic. He becomes breathless on exertion but is otherwise well. A blood test reveals his haemoglobin to be 7 g dl^-1 and his haematocrit is 38.5% with a red cell count of 3.5x10¹² per litre. What is the likely cause of his symptoms? (Hint: first calculate mean red cell volume and corpuscular haemoglobin)

Macrocytic anaemia

Microcytic anaemia

Sickle cell disease

Thalassaemia

. Mr T has had a motorcycle accident which has ruptured an artery in his leg. On arrival in hospital he is found to have a blood haemoglobin of 5 g dl^-1 and it is decided to give him a blood transfusion to restore his blood volume. A short while after commencing the transfusion, he complains of feeling hot and is found to have a temperature of 40�C with a low blood pressure. What would be the most likely cause of this development?

He has acquired an infection from his wounds

He has been given a transfusion of incompatible blood

He is suffering from hypotension caused by blood loss

Self-test questions: Chapter 25

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