what is the endocrine system used for?
its used for communication around the body
How does the endocrine system work?
uses the blood circulatory system to transport its signals
What are the signals released by the endocrine system?
What are the two types of hormones which are released by the endocrine system?
protein and peptide hormones and derivatives of amino acids as well as steroid hormones
give examples of protein and peptide hormones
adrenaline, insulin and glucagon
How can protein hormones enter the cell
Proteins are not soluble in the phospholipid membrane and do not enter the cell. Instead they bind to the cell surface membrane and release a second messenger into the cell
How can steroid hormones enter the cell?
they can pass through the membrane and enter the cell and the nucleus and have a direct effect on the DNA in the nucleus.
What are endocrine glands
They are ductless glands. They release hormones directly into the blood.
What are first messengers?
non steroid hormones such as adrenaline, insulin and glucagon
What is the purpose of first messengers?
They are signalling molecules outside the cell that bind to the cell surface membrane and initiate a second messenger which stimulates a change inside the cell.
what is a G protein
G protein is activated when the hormone binds to the receptor, G protein activates adenyl cyclase which converts ATP into cAMP which initiates a cascade of enzyme controlled reactions
Give an example of an endocine gland
Adrenal gland which is located just above the kidneys
What are the adrenal glands divided into?
Outer adrenal cortex and inner adrenal medulla
What is the role of the adrenal medulla?
secretes adrenaline and noradrenaline
Describe the action of steroid hormones
The steroid hormone passes through the cell membrane of a target cell, the steroid hormone binds with a specific receptor in the cytoplasm, the receptor steroid hormone complex enters the nucleus of the target cell and binds on the to another receptor on the chromosomal material, binding stimulates the production of MRNA which code for the production of proteins
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