Question

Hormone with no effect on heart beat is
A. Oxytocin
B. Adrenaline
C. Noradrenaline
D. Thyroxine

Answer 1

It is a hormone which is secreted from posterior pituitary gland and is responsible for labour pain at the time of parturition. It is the peptide hormone. It is having a significant role only in females.

Complete answer:
Oxytocin is neuropeptide with nine amino acids. It is produced in hypothalamus but released from the posterior lobe of the pituitary gland. It is the hormone which is responsible for various functions like milk ejection reflex/ letdown reflex, uterine contractions at the time of parturition. It acts synergistically with the vasopressin. This hormone is also known as love hormone or cuddle hormone because it is released when the people snuggle up.

Additional information:
Adrenaline and noradrenaline work antagonistically with each other. The adrenaline is responsible for increasing the heart beat while noradrenaline is responsible for decreasing the heart beat. Both these hormones are secreted from the adrenal medulla of the adrenal gland and both these are collectively known as catecholamines.
Thyroxine is released from the thyroid gland. Its major function is to regulate the iodine concentration in the body. Instead of it, thyroxine is also responsible for regulating the basal metabolic rate (BMR) and increases the heart rate too.

Hence the correct answer is option A i.e. Oxytocin.

Note: Oxytocin is generally released in females but it is found that it is released in male rats too and is responsible for erection. Pitocin is the synthetic Oxytocin which is given to the pregnant females at the time of parturition for the uterine contractions. Oxytocin was the first polypeptide hormone to be sequenced or synthesized. Du Vigneaud was awarded by the Nobel prize in 1955.