Question

What secretes a hormone that increases the body's metabolic rate, promotes alertness, quicken reflexes and stimulates the fetal nervous system?

Answer 1

The adrenal glands.

Explanation:

The steroid hormone cortisol from the cortex of the adrenal glands . This steroid hormone is more important in altering the body’s metabolism (i.e. raising plasma glucose) under conditions of longer-term, ongoing (chronic), rather than acute, stress.
http://www.yourhormones.info/Hormones/Adrenaline.aspx

These effects include controlling the body’s blood sugar levels and thus regulating metabolism, acting as an anti-inflammatory, influencing memory formation, controlling salt and water balance, influencing blood pressure and helping development of the foetus. In many species cortisol is also responsible for triggering the processes involved in giving birth.
More details about cortisol and specific physical actions are here:
http://www.yourhormones.info/hormones/cortisol/