I would think it would depend on the situation. Basic first aid may be all that is required for certain wounds or accidents. In other circumstances it should be administered until a trained professional can take over.
The answer is the endometrium. The functional layer of the endometrium thickens in preparation for inception and implantation of the fertilized egg. When the released ova fail to be fertilized, the corpus luteum in the ovary disintegrates, and the subsequent drop in estrogen and progesterone levels results in menstruation as the endometrium also disintegrates.
Spinal cells signal the pitutary gland to release thyroid stimulating hormones (TSH)
Keratin is a <span>water-insoluble fibrous protein that is responsible for strong hair and nails. Hope this helped =)</span>