Decreased level of oestrogen in the human body leads to:

In old age, people often suffer from stiff and inflamed joints. What is this condition called? What are the possible reasons for these symptoms?

Which of the following is an incorrect statement about myasthenia gravis?
$(I)$ It is not an autoimmune disorder.
$(II)$ It affects the neuromuscular junction.
$(III)$ It occurs due to low $Ca^{++}$ in body fluid.
$(IV)$ Paralysis of skeletal muscle is a symptom of myasthenia gravis.

Osteoporosis,an age-related disorder of the skeletal system,is characterized by:

Which of the following is an autoimmune disorder affecting the joints?

At times,the ligaments are overstretched or torn. This condition is called: