hormones Flashcards
What are hormones
Signalling molecules that are released into the blood
Why can hormones contact almost all cells in the body
They are released into the blood
Which cells are affected by hormones
Only cells with receptors for the specific hormone are affected
What are cells with the correct receptors for the specific hormone called
Target cells
Define target cells
For any given hormone, target cells are cells in the body that have a specific receptor for that hormone
Describe endocrine glands
Glands in the endocrine system that release hormones straight into the blood
What is the endocrine system
Communication system that uses hormones as signalling molecules
What are exocrine glands
Glands that secrete molecules into a tube called duct, which takes molecules to where they are used
What do exocrine glands in the pancreas do
Secrete digestive enzymes into the small intestine
What do endocrine glands in the pancreas do
Secrete insulin into the blood
How many types of hormone are their
2
What are the 2 types of hormone
peptide hormone and steroid hormones
Describe peptide hormones
They are made out of amino acids joined to form a protein
Describe steroid hormones
Formed from lipids
Describe the solubility of peptide hormones in cell surface membrane and how it effects them
They are insoluble in the cell surface membrane so cannot enter cells
What is the only way peptide hormones can influence target cells
By binding to receptors on target cell surface
What does the binding of the peptide hormone to the receptor on target cell cause
Causes the release of molecules inside the cell which carry out an effect
Describe the solubility of steroid hormones in cell surface membrane and how it effects them
Steroid hormones are soluble in the cell-surface membrane so can enter cells as it is hydrophobic like the phospholipid tails
What do steroid hormones do when they get in the cell
They bind to proteins and enter the nucleus, where they have an effect on DNA
What do we call the first messenger
The peptide hormone that binds to the receptors on the target cell
What does binding of the peptide hormone with the receptor cause
Causes the release of a chemical inside the cell (second messenger)
Define the second messenger
A signalling molecule inside a cell that stimulates a change in the activity of the cell
What does the second messenger do
Carries about changes inside the cell by changing enzymes and protein channels
