Biopsychology - The Endocrine System and the Fight or Flight Response Flashcards
What are the key features of the endocrine system?
The endocrine system works alongside the nervous system to control vital functions in the body through the action of hormones.
It works much more slowly than the nervous system but has widespread and powerful effects.
What are glands?
Glands are organs in the body that produce hormones.
The major endocrine gland is the pituitary gland, located in the brain. It is called the ‘master gland’ because it controls the release of hormones from all the other endocrine glands in the body.
What are hormones?
Hormones are secreted in the bloodstream and affect any cell in the body that has a receptor for that particular hormone.
For example, thyroxine produced by the thyroid gland affects cells in the heart and also cells throughout the body which increase metabolic rates. This in turn affects growth rates.
Give an example of when the endocrine system and the autonomic system work in parallel.
The fight or flight response.
- When a stressor is perceived, the hypothalamus triggers activity in the sympathetic branch of the ANS. The ANS changes from its normal resting state (the parasympathetic state) to the physiological aroused sympathetic state.
- The stress hormone adrenaline is released from the adrenal medulla into the bloodstream.
- Adrenaline triggers physiological changes in target organs in the body and causes, e.g. increased heart rate, dilation of the pupils, decreased production of saliva. This is called the fight or flight response.
- Once the threat has passed, the parasympathetic nervous system returns the body to its resting state. This acts as a ‘brake’ and reduces the activities of the body that were increased by the actions of the sympathetic branch (sometimes referred to as the ‘rest and digest’ response).
What is the difference between the sympathetic state and the parasympathetic state?
Sympathetic State:
- increases heart rate
- increases breathing rate
- dilates pupils
- inhibits digestion
- inhibits saliva production
- contracts rectum
Parasympathetic State:
- decreases heart rate
- decreases breathing rate
- constricts pupils
- stimulates digestion
- stimulates saliva production
- relaxes rectum
What hormone does the pineal gland release?
Melatonin: Affects reproductive development and daily physiological cycles.
What hormones does the pituitary gland release?
Growth hormone: Controls growth of bones and muscles.
Anti-diuretic hormone: Increases reabsorption of water in kidneys.
Gonadotrophins: Controls development of ovaries and testes.
What hormone does the thyroid gland release?
Thyroxine: Controls rate of metabolism and rate that glucose is used up in respiration, and promote growth.
What hormone does the adrenal gland release?
Adrenaline: Prepares the body for emergencies, increases heart rate and rate and depth of breathing, raises blood sugar level so more glucose is available for respiration, diverts blood from gut to limbs.
What hormones does the pancreas release?
Insulin: Converts excess glucose into glycogen in liver.
Glucagon: Converts glycogen back to glucose in liver.
What hormones do the ovaries release?
Oestrogen: Controls ovulation and secondary sexual characteristics.
Progesterone: Prepares the uterus lining for receiving an embryo.
What hormone do the testes release?
Testosterone: Controls sperm production and secondary sexual characteristics.
What hormone does the thymus release?
Thymosin: Promotes production and maturation of white blood cells.
