Question

1/ Which of the following characteristics is shared between smooth muscle and skeletal muscle?

Select one: _

a. Striated arrangement of the actin and myosin filaments _

b. Presence of T tubule network

c. Ability to contract in the absence of an action potential

d. Dependence of contraction on Ca+2 ions

2/ Which of the following conditions causes bleeding tendency after prolonged exposure to hazardous irradiation?

Select one: _

a. Vitamin K deficiency _

b. Hemophilia L

c. Chronic liver disease

_ d. Thrombocytopenia

3/ Which of the following enables smooth muscle to contract rhythmically in the absence of external stimuli?

Select one: _

a. Hyperpolarized membrane potential _

b. Ability to pump calcium to the extracellular space

c. Intrinsic pacemaker wave activity

d. Higher resting cytosolic Ca2+ concentration

4/ Which one of the following cells is an antigen presenting cell (APC)?

Select one: _

a. B cell _

b. T cell

C. Basophil

d. Mast cell - e Eosinophil

Answer 1

Option D-Dependence of contraction on Ca+2 ions

Both Skeletal muscles and Smooth muscles requires ca2+ for their contraction

Option A-False-Striated arrangement of the actin and myosin filaments are seen in Skeletal muscle but not in Smooth muscles.

Option B-False-Presence of T tubule network is feature of skeletal muscle it is not essential in smooth muscle

Option C-Ability to contract in the absence of an action potential from an External stimuli is a feature of involuntary Smooth muscle.

Q2.Option D-Thrombocytopenia.

Thrombocytopenia:It refers to Decrease in platelet count.

Platelet are essential for proper clotting of Blood---So platelet deficiency can cause Bleeding tendency.

Thrombocytopenia is a common complication seen in patients who recieves Radiational therapy.

Hemophilia,Vitamin K deficiency & Chronic liver disease can also cause Bleeding tendency but are not associated with Irradiation.

Q3.Option c. Intrinsic pacemaker wave activity

Smooth muscles like Intestinal smooth muscles have intrinsic pacemaker Activity which helps them to Contract without any External Stimulus.So these muscles are involuntary-Not under our control.

4.Option a-B Cell

Antigen-presenting cells are group of immune cells which helps to mediate cellular immune response by processing & presenting antigens to lymphocytes like T cells for recognition by certain.

Classical Examples of APCs are

1.Dendritic cells

2.Macrophages

3.Langerhans cells

4.B cells.