05. Hormones and Aggression Flashcards
What hormone is the pituitary gland associated with?
Master gland, produces many hormones, eg growth hormones and controls other glands.
What hormone is the thyroid gland associated with?
Controls the body’s metabolism.
What hormone is the adrenal gland associated with?
Produces adrenalin involved in fight or flight.
What hormone are the testes associated with?
Produces testosterone.
What hormone are the ovaries associated with?
Produces oestrogen and progesterone.
What hormone is the pineal gland associated with?
Produces melatonin linked to sleep.
What is a hormone?
-A hormone is a biochemical messenger that circulates in the bloodstream and only affects target organs and other glands. They are produced by glands that make up the endocrine system. They act more slowly than the nervous system but have widespread and powerful effects.
-The endocrine system and the nervous system often work together to control vital bodily functions (eg the fight or flight response to environmental stressors).
How do hormones work?
-Hormones are secreted directly into the bloodstream by glands. They will circulate until they reach a receptor protein in a target organ. The detection of the hormone by the receptor will cause a change in cell functioning at the target organ.
-For example, in women the pituitary gland secret the luteinising hormone (LH) into the bloodstream. LH circulates until it reaches the receptor protein in the ovaries. The detection of LH by the ovaries stimulates ovulation.
What is the role of testosterone in the body?
-Testosterone is the male sex hormone (androgen) responsible for the development of male reproductive organs, the production of sperm, and secondary sexual characteristics (eg facial hair).
-In males, testosterone is mainly produced in the tests, although a small amount is also produced in the adrenal glands. Testosterone is at high levels when males are going through puberty.
-Females also produce testosterone, in the ovaries and adrenal glands, but at a much lower level.
-Testosterone is thought to be involved in producing aggressive behaviour in males and females.
Describe the role of estradiol in aggression.
-The hormone estradiol plays a role in dominance, motivation for power and physical aggression among females.
-Estradiol is produced especially within the follicles of the ovaries, but also in other tissues including the testicles, adrenal glands, fat, liver, the breasts and the brain.
Describe the role of adrenaline (epinephrine) in aggression.
-Adrenaline is a stress hormone also known as epinephrine.
-It is released from the adrenal glands and its major action, along with noradrenaline, is to prepare the body for ‘fight or flight’. Which is an automatic response to perceived danger or threat, causing heart and breathing rates to increase in preparation to fight or flee from danger.
-While the fight/flight response doesn’t necessarily cause fighting, it is mediated by the release of adrenaline, which can make a person more aggressive.
Describe the dual hormone hypothesis.
-Although testosterone is the primary hormone associated with aggression, the endocrine system is complex and a second hormone, cortisol, is also thought to be involved.
-Cortisol is secreted by the adrenal glands to protect the body from the effects of stress and increases when a person is stressed.
-Suggests that bodily systems that regulate aggression and control stress response are interacting with each other.
-Dual hormone hypothesis states that high levels of testosterone lead to aggressive behaviour, but only when cortisol is low. When cortisol is high, testosterone’s influence on aggression is blocked. This may be because high cortisol increases anxiety, the likelihood of social withdrawal and therefore decreases aggression.
-Therefore the interaction of these two hormones determines the likelihood of aggressive behaviour.
-Combined activity of testosterone and cortisol may be a better explanation of human aggression than either hormone alone.
How can the link between hormones and aggression be applied?
-This theory has been applied to society to ensure animals, especially pets, are domesticated. Castration has been a routine method for making domestic and farm animals more manageable for decades.
-Beeman (1947) castrated male mice and found that levels of aggression were reduced. He later injected the mice with testosterone which re-established their aggressiveness.
-When castration occurred, this caused lower levels of testosterone to be produced and aggression was reduced.
-This therefore directly relates to the theory of high testosterone linking to increased aggression because when testosterone is lowered aggression also decreases.
