Why does menstrual flow occur?

Menstrual flow occurs due to lack of

Fill in the blanks : The first menstrual flow begins at puberty and it is termed as .............. .

How does strobilation occur?

Sanjay is sitting in the exam hall. Before the start of the exam, he sweats a lot, with increased rate of heart beat. Why does this condition occur?

Sanjay is sitting in the exam hall. Before the start of the exam, he sweats a lot, with increased rate of heart beat. Why does this condition occur?

Why menstrual cycle does not take place before puberty and during pregnancy ?

Why does heat flow from a hot object to a cold object?