Hormones - special chemical messengers in the body that are created in the endocrine glands. These messengers control most major bodily functions, from simple basic needs like hunger to complex systems like reproduction, and even the emotions and mood.
Estrogen - the main sex hormone. It causes puberty, prepares the body and uterus for pregnancy, and regulates the menstrual cycle. During menopause, estrogen level changes cause many of the uncomfortable symptoms women experience.
Progesterone - similar to estrogen but not considered the main sex hormone. Like estrogen, it assists with the menstrual cycle and plays a role in pregnancy.
Cortisol - has been called the ‘stress hormone’ because of the way it assists the body in responding to stress. It does not cause stress, it releases it as a consequence of stress.
Melatonin - levels changes cause throughout the day, increasing after dark to trigger the responses that cause sleep.
Testosterone - the main sex hormone in men. It causes puberty, increases bone density, triggers facial hair growth, and causes muscle mass growth and strength.
Testosterone
Testes inside testicles
Released in higher quantities during puberty. Main sex hormone.
Higher rates of testosterone have been linked to aggressive behaviour.
The effect of testosterone is aggression.
Cortisol
Adrenal gland
Stress hormone
Released to support the body during high levels of stress to aid the functioning of immune system- reducing inflammation in the body.
A balance is key.
Too much can weaken the immune system causing inflammation. This destroys the number of white blood cells in the immune system and vulnerable to illness. Reduce function of memory.
High cortisol = high in glucocorticoid = destroys neurons in hippocampus = decrease in memory.
The effect of too much cortisol is poor health/death.
Berthold (1849)
The 3 Rs do not exist yet (not until 1980s)
DO NOT USE IN 9 MARKER
ANIMAL STUDY
Aim: Testosterone and its role in Aggression in Castrated Roosters
Role of testosterone on Male Behaviour
IV: Testosterone Production
DV: Impact on Aggressive Behaviour
Research Method: Observation, Field
Ethics
✓ Reduction - Couldn't use smaller number or it could affect validity
Method
6 Healthy Roosters were Castrated
Split into 3 groups
Group 1 (Control) - Stayed Castrated
Group 2 - Translated Testicles of another rooster
Group 3 (Control) - Reimplanted with own testicles
Results
Castrated Roosters - ↓ Aggressive, ↓ Masculine, Lost Interest to hens
↓ Crow, Fight, Mate
Group 2 and 3 - Behaved normally
Autopsies of Group 2 and 3
Reimplanted Testicles had continuous blood-flow
Didn't establish nerve connections
Application | DIVER |
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Brady (1958)
The 3 Rs do not exist yet (not until 1980s)
DO NOT USE IN 9 MARKER
ANIMAL STUDY
Aim: Investigate whether stress of receiving shocks could cause stress-related illness - and whether this changes with the degree of control over the shock
Ulcers - Stress Related Disease
IV: Choice of Avoidance / Ability to make a choice
DV: Gastric Ulcers / Health
Research Method: Lab, Observation
Ethics
X Reduction - Could've used 4
✓ Reduction
They have emotions and personalities like humans - Need more of them to apply it outward to humans
X Refinement
They're killed - Could've just stopped once you can see signs of gastric Ulceration
✓ Replacement - Can't Replace with Humans
Method
8 Monkeys (4 Groups of 2)
Pairs of Monkey
Executive Animal - Can pull a lever to stop the shock
Has the ability to make a choice to stop the shock
Yoked Animal - Can do nothing to stop the shock
Monkeys received electric foot shocks
Shocked from Feet - Electricity travels upwards from the bottom - Loses current as it goes up - Less Impactful on Internal Organs - Want to make sure it's the stress, not the shock, that causes Ulcer
Signalled by preceding tone - Gives executive animal chance to avoid
Results
After 23 days
Executive Monkey - Died of Gastric Ulceration (Stomach Ulcer)
Yoked Monkey - Remained Healthy
Conclusion
The shocks themselves were not severely stressful
Avoiding the shock was more stressful
Avoid the Shock -> Causes Stress -> ↑ Cortisol -> Negative Impact on Health
Application | DIVER |
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Bremner (2003)
Aim: Investigate role of PTSD on Hippocampus Volume and Matter
IV - PTSD
DV - Hippocampus Volume
Research Method - Quasi
Method
33 Women Participants
3 Groups
10 women - early childhood sexual abuse + PTSD
12 women - early childhood sexual abuse, No PTSD (Control Group)
11 women - no abuse, no PTSD (Control Group)
MRI to measure Volume of hippocampus
PET to measure activity of hippocampus during verbal declarative memory test
Results
Group 1 (SA + PTSD)
16% ↓ volume than Group 2 (SA + NO PTSD)
19% ↓ volume than Group 3 (NO SA + NO PTSD)
Group 1 - Lack of activity in hippocampus - smaller volume = less activity
PTSD impacts size of hippocampus -> Smaller hippocampus causes them to perform worse
Why It Shrinked
PTSD -> Ongoing Stress -> Body releases cortisol to counter it
Stress is ongoing -> Cortisol keeps being released -> Large Chemical Imbalance
Glucocorticoid released to counter imbalance -> More Cortisol = More steroid released -> Neural Death
Neural Death -> Hippocampus shrinks
Application | DIVER |
This leads to an increase in glucocorticoid (which is a steroid), causing the destabilisation of neurons in the hippocampus, impacting memory negatively | D - Quantitative
- 1 Control Variable - 2 Control Groups - Especially Group 2
R - Testable
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