Endocrine system

Introduction

• The endocrine system has a series of glands that release hormones throughtout the body
• The endocrine system works alongside the nervous system but at a much slower pace
• The fight or flight response - response to threat - is one reaction in the endocrine system

The function of the endocrine system

• Glands in the endocrine system produce chemicals (hormones) that are released into the blood
• They travel around the body, stimulating organs and other body tissues into action
• Hormones can influence many human behaviours
• The nervous system and endocrine system are linked by the hypothalamus - a small structure in the brain that regulates a lot of body drives, such as hunger, thirst and sex
• The hypothalamus controls the pituitary gland by communicating to it what hormones need to be released from which glands, and when
• The pituitary gland is often referred to as the 'master gland' due to its role in stimulating other glands such as the adrenal glands and gonads (testes/ovaries) to produce their own hormones

Fight or flight response

• When faced with a potential threat in the environment, the nervous system will pass a message to the brain and then on to the rest of the body to alert it into action
• This is believed to be a survival instinct as it happens without conscious awareness
• The fight or flight response helps us to react quickly and prepares our body to stand and fight or to run away from the threat
• Step 1: The amygdala (area of the brain for emotional behaviour and motivation) identifies a threat. The hypothalamus communicates th threat to the sympathetic nervous system to trigger a fast response
• Step 2: The message travels down the SNS to the adrenal medulla. The adrenal medulla releases the hormone adrenaline into the bloodstream
• Step 3: Adrenaline in the bloodstream will trigger the fight or flight response, preparing the body to stand and fight or to run away from the threat. The fight or flight response involves various physical changes such as increased heart rate, increased blood pressure, pupil dilation and increased muscle tension
• Step 4: Once the adrenaline has started to wear off, the parasympathetic nervous system acts to bring the body back to its normal state