Which of the following substances, if introduce in the blood stream, would cause coagulation, at the site of its introduction?
Fibrinogen
Prothrombin
Heparin
Thromboplastin
D.
Thromboplastin
Lipoproteinaceous, thromboplastin is released by the injured tissue. It reacts with Ca2+ ions present in blood and forms prothrombinase enzyme. Later, in the presence of Ca2+ ions, it inactivates heparin (anticoagulant) and catalyses prothrombin (inactive plasma protein) into an active thrombin protein.
Thrombin acts as an enzyme and catalyses fibrinogen (soluble plasma protein) into an insoluble fibre like polymer, fibrin. These form a dense network upon the wound and trap blood corpuscles and thus form a clot. This further seals the wound and stops bleeding
In blood vessels, thromboplastin does not release due to which blood does not clot. However, external thromboplastin causes blood clotting at the site of its introduction due to formation of prothrombinase enzyme.
CO is harmful to human being because
it decreases CO2 concentration
it competes O2 to combine with haemoglobin
it is carcinogenic
it depletes O2 layer
Haemophilia is more commonly seen in human males than in human females because
this disease is due to an X- linked dominant mutation
a greater proportion of girls die in infancy
this disease is due to an X- linked recessive mutation
this disease is due to a Y- linked recessive mutation
The epithelial lining in the alveoli of the frogs facing lung cavity is
squamous ciliated
columnar ciliated
columnar nonciliated
squamous nonciliated
The first heart sound is produced when
diastole begins
semilunar valve close quickly
interventricular pressure decrease
bicuspid and tricuspid valve close quickly
G-6-P dehydrogenase deficiency is associated with haemolysis of
lymphocytes
RBCs
platelets
leucocytes
