441. Which of the followings statement is TRUE?
A. At least 100ml air need to enter the circulation before clinically significant problems of air embolism is encountered.
B. Acute decompression sickness manifests as acute obstruction of blood vessels around the joints, skeletal muscle, lungs & cerebral circulation.
C. Chronic decompression sickness is associated with aseptic necrosis of femoral, tibial & humoral heads.
D. 99% cases of fat embolism is clinically silent.
E. All of the above.

442. Symptoms of fat embolism from fractured shaft of femur include the following EXCEPT:
A. Anaemia
B. Leukopaenia
C. Thrombocytopaenia
D. Pulmonary insufficiency
E. Impaired conscious state

443. The most common cause of infarction of an organ or tissue is:
A. Venous occlusion due to twisting of the organ
B. Trapped viscus under peritoneal adhesions
C. Thromboembolism
D. Compression of organ in the hernial sac.
E. Ballooning of atheroma secondary to haemorrhage into the plaque.

444.In non-progressive phase of shock, the following mechanism or reflexes are activated:
A. Baroreceptor reflex
B. Renin-angiotensin-aldosterone system
C. Antidiuretic hormone
D. Sympathetic-catecholamine release
E. All of the above

445. Which of the following are NOT reversible changes of shock?
A. Acute tubular necrosis
B. Subendocardial necrosis
C. Adult Respiratory Distress Syndrome (ARDS)
D. Haemorrhagic enteropathy
E. Central lobular haemorrhagic necrosis in the liver.

446. How many % of peripheral lymphocytes are T cells?
A. 30-40%
B. 40-50%
C. 50-60%
D. 60-70%
E. 70-S0%

447. What is the normal ratio of CD4: CDS T cells in adults?
A. 1:1
B. 2:1
C. 3:1
D. 1:2
E. 1:3

448. Which of the following statement is TRUE?
A. CD4+ T cells only recognize antigen presented with MHCn molecule by antigen presenting cell.
B. CDS+ T cells only recognize antigen presented with MHCj molecule by antigen presenting cell.
C. T HI cells secretes 1L2 & IFNy to facilitate macrophage dependent immune response.
D. T H2 cells secretes 1L4 & IL5 to aid antibody synthesis
E. All of the above

449. How many % of peripheral lymphocytes are B cells?
A. 10-20%
B. 20-30%
C. 30-40%
D. 40-50%
E. 50-60%

450. Which of the following statement is FALSE?
A. B cells transform to plasma cells after antigen stimulation.
B. All B cells have IgM on their cell surface.
C. IgM on B cell surface is important for signal transduction
D. B cell antigen specificity is conferred by somatic rearrangement of Ig genes
E. Non-polymorphic molecules such as complement receptors & FcyR are found on B cell surface.