The Endocrine System Chapter 2.1 Biological level of analysis

The endocrine system Another way of transmitting information in the body is via the endocrine system. The vehicle used to transmit information through the endocrine system is provided by hormones. Hormones are chemicals that are carried by the blood from one location to another, more distant location. These chemical messengers take longer to transmit their information than the nervous system, but their effects are usually longer lasting.

What is the endocrine system?

Learning outcome: explain, using examples, functions of two hormones on human behaviour The glands produce the hormones Two Examples of hormones and their functions: Melatonin (pineal gland) regulation of sleep Oxytocin (“the love hormone”) and its effect on trust in economic behaviour Cortisol (stress hormone) and its effect on memory Adrenaline (adrenals gland) flight or fight response, arousal

Functions of the human endocrine system

Melatonin Melatonin is a hormone secreted by the pineal gland in the brain. It helps regulate other hormones and maintains the body's circadian rhythm. The circadian rhythm is an internal 24-hour “clock” that plays a critical role in when we fall asleep and when we wake up.

Melatonin When it is dark, your body produces more melatonin; when it is light, the production of melatonin drops. Being exposed to bright lights in the evening or too little light during the day can disrupt the body’s normal melatonin cycles. For example, jet lag, shift work, and poor vision can disrupt melatonin cycles.

Melatonin By taking melatonin in the early evening may improve one’s ability to fall asleep. However, higher levels of melatonin has been shown in research to contribute to SAD (seasonal affective disorder) – a subcategory of depression that is characterized by sleepiness and tiredness and cravings for carbohydrates. Higher rates of SAD in Scandinavia Study: Avery et al. 2001

Adrenaline also called Epinephrine Adrenaline is produced in the adrenals gland flight or fight response, arousal

Adrenaline KE0 KE0 When it is produced in the body it stimulates the heart-rate, dilates blood vessels and air passages, and has a number of more minor effects. Adrenaline is naturally produced in high-stress (psychological stress) or physically exhilarating situations (hard labor)

“Fight or flight” The term "fight or flight" is often used to characterize the circumstances under which adrenaline is released into the body. It is an early evolutionary adaptation to allow better coping with dangerous and unexpected situations. With dilated blood vessels and air passages, the body is able to pass more blood to the muscles and get more oxygen into the lungs in a timely manner, increasing physical performance for short bursts of time.

1.Within seconds of any situation which causes you to become upset, which is fight-or-flight, the primitive amygdala (trauma center in your mid-brain) automatically sounds a general alarm. 2.The adrenal system promptly floods the body with adrenaline and stress hormone (cortisol). 3.Non-essential physiological (body) processes switch off. Digestion stops, skin cools, and blood is diverted from viscera and small muscles into the outer, large muscles in preparation for a burst of emergency action (fight/flee/freeze). 4.Breathing quickens and becomes shallow, the heart races, and blood pressure skyrockets, infusing the body with oxygen while the liver releases glucose for quick fuel. 5.The entire body is suddenly in a state of high alert, ready for fight-or-flight.

Adrenaline One example is ; When there is fire, a person can suddenly carry heavy stuff that he/she cannot usually carry in normal condition. It is the adrenalin hormone that is responsible in that sudden strength.

Fight-or-flight is designed only for emergencies: not for everyday living! Our culture today places so many demands on us, that we live in this state too often for good health and well-being. We experience this response on a regular basis through pressure at work, traffic jams, anticipating the future or stewing about a past event, family and relationship challenges, the intensity of school, and many more situations that are not life-threatening. But some seek it too: adrenaline junkies!

Used in the treatment of: Severe allergic reactions To restore the heartbeat of patients suffering cardiac arrest To treat severe asthma, adrenaline relaxes the muscles in the bronchi (the large air passages into the lungs). Study: Adrenaline and emotion (Schachter and Singer 1962)

Oxytocin and trust Is secreted by the hypothalamus after being stimulated by the pituiary gland and released into the blood stream – released in men and women during touching and sex Also during childbirth – could explain the “strong” bond between mother and child, or at least secure it – experiments done on rats which confirmed these findings (see p. 274) Study: The role of oxytocin in trust in economic behaviour (2008) by Baumgartner et al. Or Morhenn et al. 2008

Cortisol and memory Produced by the adrenal gland in response to stress Chronic stress may result in prolonged cortisol secretion which can lead to physiological changes such as damaged immune system, impairment of learning and memory Study: Experiment on cortisol and memory by Newcomer et al. 1999

task Remember the learning outcome: you only have to know how two hormones work and back it up with research Pick two hormones and read their studies and write a summary about each study (include aim, procedure and findings)