Biopsychology

• Define 'endocrine system'

  One of the body's major information systems that instructs glands to release hormones directly into the bloodstream. These hormones are carried towards target organs in the body. Communicates via chemicals.
• Define 'gland'

  An organ that synthesises substances such as hormones (chemical messengers)
• Define 'hormone'

  A biochemical substance that circulates in the blood but only affects target organs. They are produced in large quantities and have powerful effects but disappear quickly.
• Define 'fight or flight response'

  The way an animal responds when stressed. The body becomes physiologically aroused in readiness to fight an aggressor or, in some cases, flee.
• Define 'adrenaline'

  A hormone produced by the adrenal glands which is part of the human body's immediate stress response system. Adrenaline has a strong effect on the cells of the cardiovascular system - stimulating heart rate, contracting blood vessels and dilating air passages.
• Glands and hormones

  - The endocrine system works alongside the nervous system to control vital functions in the body.

  - The endocrine system acts slower than the nervous system but has widespread and powerful effects.

  - Various glands in the body produce hormones. These are secreted into the bloodstream and affect any cell that has a receptor for that particular hormone.
• The endocrine system and ANS working together: Fight or flight response

  - When a stressor is perceived, the hypothalamus activates the pituitary gland and this triggers activity in the sympathetic nervous system (a part of the ANS). The ANS changes from its normal resting state (parasympathetic state) to the physiologically aroused sympathetic state.
• Adrenaline

  - Adrenaline is a hormone released from the adrenal medulla (a part of the adrenal glands) into the bloodstream.

  - Adrenaline triggers physiological changes, such as increased heart rate, which creates the physiological arousal necessary for the fight or flight response.
• Immediate and automatic

  - All of this happens in an instant as soon as the threat is detected.

  - This is an acute response and an automatic reaction in the body. The physiological changes associated with this sympathetic response include increase HR, increated breathing rate, dilated pupils, and inhibition of digestion and saliva production.

  - These changes explain why stress and panic can induce a 'sick' feeling.
• Parasympathetic action

  - Once the threat has passed, the parasympathetic nervous system returns the body to its resting state.

  - The parasympathetic nervous system works in opposition to the sympathetic nervous system, i.e. its actions are antagonistic.

  - The parasympathetic nervous system acts as a brake and reduces the activities of the body that were increased in the actions of the sympathetic nervous system.

  - This is referred to as a 'rest and digest' response.
• Stress-related illness

  - Constant triggering of the fight or flight response in chronic stress has long-term effects on physical and mental health.

  - The fight or flight response shuts down the immune and digestive systems, causes high blood pressure and results in anxiety.

  - There is also an increased risk of heart disease, obesity and IBS. There is a general lowering of resistance to diseases and can result in depression.