Hormones

Endocrine System:

• The other communication system in the body

• Ductless glands that produce and secrete hormones

  Hormones:

  • Chemical messengers secreted into the bloodstream to guide and regulate such process such as growth, reproduction, metabolism, mood and sexual development.

  In a way hormones are like neurotransmitters in the nervous system.

  • They are stored for subsequent release as chemical messengers.

  • They diffuse through the bloodstream and bind to special receptors on target cells.

  • Some chemical substances function as hormones when they're released in the endocrine system or as neurotransmitters in the nervous system.

  However there are some important differences between hormones and neurotransmitters.

  • Neural messages generally are transmitted short distances in lightning speed along specific pathways, but hormones takes longer, travel further can be measured in seconds to minutes.

  Hypothalamus and pituitary gland

  • Much of the endocrine system is controlled by the nervous system through the hypothalamus.

  • The hypothalamus releases hormones or releasing factors.

  • Which in turn causes pituitary gland to release a variety of hormones that stimulate the actions of other endocrine glands.

  Oxytocin

  • Oxytocin is a hormone that is released from the pituitary gland.

  • Oxytocin is best known for its roles in female reproduction - it is released in large amounts during labour facilitating birth and breastfeeding.

  • Skin contact causes oxytocin to be released.

  Recent studies have begun to investigate oxytocin's role in various behaviours, including bonding between mothers and babies. Studies found that:

  • Oxytocin levels spike after new mothers look at or touch their newborns and may help bonding.

  • Administration of oxytocin in virgin rats will induce maternal behaviours.

  • Oxytocin antagonist administration (that is, blocking oxytocin) inhibits onset of maternal behaviours (Insel, 1992)

  Oxytocin is called the love hormone because it seems to be such an effective mediator of human social behaviour.

  • The prairie vole is a socially monogamous rodent species that engages in social interactions similar to humans, including living in family groups and forming life-long social bods.

  • However the montane vole has no interest in partnership beyond one-night-stand sex.

  • Two species are 99% alike, besides prairie vole have oxytocin while montane vole does not.