Functions of hormones in human behaviour

The IB Syllabus Says…. Using one or more examples, explain the functions of two hormones in human behavior

What are hormones? Hormones are chemicals that affect behavior. They are produced by the glands that make up the endocrine system

The Endocrine System & Hormones Endocrine glands secrete chemicals called hormones directly into the bloodstream where they are carried to all parts of the body Like neurotransmitters, hormones have receptor cites – so some hormones only effect certain parts of the body The effects of hormones is slower than neural transmission – it may be minutes or hours before the response occurs and the effects are longer lasting Hormones enter directly into the bloodstream, so they take longer to produce changes in behaviour than neurotransmitters. Some chemicals serve as both hormones and neurotransmitters. Note: Neural and hormonal processes are complementary

Hormones and their functions….

Some important glands…. Hypothalamus – secretes hormones which then influence the pituitary gland to secrete corresponding hormones (see stress response) The pituitary gland ‘ the pea sized governor’ or ‘master gland’ secretes hormones into the body maintaining homeostasis – this steady state relies on a feedback loop – when enough of a hormone has been secreted – the gland then stops producing that hormone The adrenal glands are located above the kidneys is play an important role in the stress response, it regulated by ACTH from the pituitary gland. The adrenal glands secrete corticosteroids – which increase resistance to stress promote muscle development and cause the liver to release stored sugar – making energy available in emergencies Adrenal medulla – produces epinephine (adrenaline) and norepineprine (nor-adrenaline) – which heightens emotional responsiveness – but the specific emotion may depend on the persons situation. The sympathetic branch of the nervous system causes the adrenal medulla to release a mixture of adrenaline and noradrenaline in times of stress

The effect of the hormone Oxytocin on behavior…. Oxytocin is a hormone that is produced by the hypothalamus after being stimulated by the pituitary gland. As a hormone, it plays a role in inducing labour contractions and lactation. Oxytocin is released with touches and hugs. It is associated with bonding between a mother and her child as well as between lovers. Oxytocin appears to change the brain signals related to social recognition via facial expression, perhaps by changing the firing of the neurons of the amygdala.

The effect of the hormone Oxytocin on behavior…. The amygdala plays an important role in processing emotional stimuli. Oxytocin has been called “the love hormone” because it seems to be such an effective mediator of human social behaviour. If oxytocin is given to healthy individuals it seems that brain circuits involved in fear regulation are affected, and there is an increase in trust and generosity. Kosfiled et al (2005) carried out a clinical trial with 194 male participants and found that those who received a intranasal dose of Oxytocin were more likely to be more trusting in a role play situation, than participants who received a placebo. Research is being carried out to see whether people suffering from social anxiety may benefit from doses of oxytocin.

The effect of the hormone Melatonin on behavior…. Through the study of the hormone melatonin, researchers hope to find a solution for those who suffer from insomnia (the inability to fall asleep) and jet lag. The production of melatonin by the pineal gland is stimulated by darkness and inhibited by light. Melatonin levels in the bloodstream peak in the middle of the night, and gradually decrease towards morning. As the days get shorter and winter approaches, the earlier onset of darkness means that we can become tired earlier. Until recent history, humans in temperate climates had up to 18 hours of darkness in the winter months. The use of artificial lighting has increased the “awake time” dramatically. Melatonin release correlates with the circadian rhythm—the biological clock that is based on a 24-hour day/night cycle. It is suggested that taking melatonin in the early evening may improve one’s ability to fall asleep.

The effect of the hormone Melatonin on behavior…. However, there is some evidence (Rosenthal 1987) that higher levels of melatonin contribute to seasonal affective disorder (SAD)—a subcategory of depression that is characterized by sleepiness and lethargy—as well as cravings for carbohydrates. Reduced levels of sunlight in autumn and winter are believed to disrupt the circadian rhythm in certain people, leading to this form of depression. This is perhaps why we see higher levels of SAD in Scandinavia. As increased sunlight improves the symptoms, phototherapy is often the main treatment for people with SAD. In phototherapy, people are exposed to bright light for several hours each day. Despite claims of some success with this treatment, there is a lack of definitive evidence of its effectiveness. Whether it is light therapy to combat depression or melatonin pills to aid sleep, one has to be careful about seeking quick solutions to complex questions.

Mini presentations…. Prepare to give a mini presentation, also prepare 5 questions to ask the audience Group 1: What hormones are/ what the endocrine system is/ Some hormones and their functions Group 2: The effect of the hormone Oxytocin on behavior Group 3: The effect of the hormone Melatonin on behavior.

Quick quiz on hormones & behavior What are hormones? What is the name of the bodies hormonal system? Do hormones travel faster or slower than neurotransmission? What are the names of three glands and three hormones associated with these glands? What is another name for the pituitary gland? What hormones do the adrenal glands release? What behaviors is Oxytocin associated with in pregnant women? What can trigger the release of Oxytocin? What has Oxytocin been called? What are the aims, procedures, findings and conclusions of Kosfield et al. (1995) study? (include the IV & DV) What mental disorder might Oxytocin help treat? For what reasons have people studied the effects of the hormone Melatonin? What glands are associated with the production of Melatonin? When are levels of Melatonin at their peak in the endocrine system? What medications contain Melatonin? What mental disorder did Rosenthal et al. (1987) connect high levels of melatonin to? What are the symptoms of the above mental disorder? Why does the said mental disorder occur? And in what countries is it a major problem? What treatment is recommended for this mental disorder? If we give simple biological explanations for complex behaviors, this can be called …………………….

Quick quiz on hormones & behavior What are hormones? What is the name of the bodies hormonal system? Do hormones travel faster or slower than neurotransmission? What are the names of three glands and three hormones associated with these glands? What is another name for the pituitary gland? What hormones do the adrenal glands release? What behaviors is Oxytocin associated with in pregnant women? What can trigger the release of Oxytocin? What has Oxytocin been called? What are the aims, procedures, findings and conclusions of Kosfield et al. (1995) study? (include the IV & DV) What mental disorder might Oxytocin help treat? For what reasons have people studied the effects of the hormone Melatonin? What glands are associated with the production of Melatonin? When are levels of Melatonin at their peak in the endocrine system? What medications contain Melatonin? What mental disorder did Rosenthal et al. (1987) connect high levels of melatonin to? What are the symptoms of the above mental disorder? Why does the said mental disorder occur? And in what countries is it a major problem? What treatment is recommended for this mental disorder? If we give simple biological explanations for complex behaviors, this can be called …………………….

SAQ… Using one or more examples, explain the functions of two hormones in human behavior

SAQ writing workshop 1st paragraph: Outline how you will answer the question, identifying the two hormones you will write about, and briefly mention the endocrine system 2nd paragraph: Explain the effect of Oxytocin on behavior, be sure to integrate Kosfield et al (1995), and at the end of the paragraph clearly connect back to the which is asking about its effect on behavior 3rd paragraph: Explain the effect of Melatonin on behavior, be sure to integrate Rosenthal et al. (1987), and SAD and at the end of the paragraph clearly connect back to the which is asking about its effect on behavior 4th paragraph: Conclusion – although hormones are influential, other factors also play an important role in behavior – its important not to be reductionist.

HW Complete SAQ on the effects of hormones on behavior and submit by email to marshalldy@ismanila.org before Mondays lesson.