The endocrine system Flashcards
The endocrine system
A network of glands in the body which secrete chemical messengers called hormones
This system works with the nervous system to regulate the physiological processes of the human body
But, the nervous system sends information via nerves whereas the endocrine system utilises blood vessels to move hormones around the body
Endocrine glands
These produce and secrete hormones
Major glands: pituitary gland, adrenal glands, testes and ovaries
Each gland is regulated by feedback
Example:
The hypothalamus will send a signal to the pituitary gland (releasing hormone 1), causing the pituitary gland to reduce a stimulating hormone into the blood stream to affect a target gland. Once this gland releases its hormone, the rising levels of this hormone will work to shut down the secretion of the stimulating hormone, which results in stable concentrations of hormones in the blood stream
The pituitary gland
This is controlled by the hypothalamus
It releases hormones which control other glands
For example, ACTH is released by the anterior (front of the) pituitary gland when responding to long term stress. In turn, ACTH stimulates the adrenal cortex to produce cortisol
The adrenal gland
Two adrenal glands, located just above the kidneys
Each gland has two parts: an outer part known as the adrenal cortex, and the inner part known as the adrenal medulla
The adrenal medulla will release adrenaline and noradrenaline, which will help to prepare the body for fight or flight
The adrenal cortex releases cortisol in response to long term stress, which weakens the immune system
Hormones
Chemical messengers found in the bloodstream
Each hormone will only affect a certain number of cells, known as target cells
Each target cell will have receptors which can only bind to a certain hormone
Once enough hormones are bound to the receptors, there is a physiological reaction in the target cell
