Question

Lack of relaxation between successive stimuli in sustained muscle contraction is known as
1) Spasm.
2) Fatigue.
3) Tetanus.
4) Tonus

Answer 1

Hint: This is a neuro-muscular disease caused by bacteria Clostridium tetani. This affects the junction between a motor neuron and sarcolemma of muscle fibre. This junction is also known as neuromuscular junction.

Complete answer:
Tetanus- This is a disease caused by bacteria affecting the neuromuscular junction and can lead to death. It is also known as lock-jaw disease. The bacteria produce neurotoxin which affects the neuromuscular junction. These neurotoxins amplify the chemical signal reaching the sarcolemma causing continuous muscle contraction which leads to tightening of the muscles of that area.
Spasm- Spasm is a sudden involuntary muscle contraction and twitches which leads to muscular cramp.
Fatigue- Muscle fatigue is a disease in which muscle ability to generate force decreases. It makes it hard for people to work normally suffering from this. Muscle fatigue occurs due to doing excessive exercise.
Tonus- Muscle tonus is a state in which muscle is in a partially or slightly contracted state due to successive flow of nerve impulses to the sarcolemma.

So, the correct answer is “Option 3”.

Note:
Tetanus is acquired when a cut or wound gets infected by the bacteria Clostridium tetani. It can occur in anyone at any age but it is more likely to occur in new born babies if proper hygiene conditions and care are not provided to them. They are more likely to get the infection through the umbilical cord. It can be prevented by taking vaccines and getting immunized.