The endocrine system consists of ___.
Do endocrine glands have ducts?
No - release hormones into bloodstream
Parietal cells and G cells in the stomach have ___ so they are examples of exocrine cells.
How do hormones have specific actions i.e why don't they react with all receptors on all cells?
Hormones have distinct structures
Receptors are specific to each hormone
Receptors are found in different distributions on different cells
The tissues or cells on which a hormone acts are called ___ tissues / cells.
target tissues / cells
What are the three categories of hormone?
Modified amino acids (hormones derived from tyrosine and tyramine)
Steroid hormones (derived from cholesterol)
Peptide hormones (from proteins)
What are some examples of modified amino acid hormones?
What are some examples of steroid hormones?
What are some examples of peptide hormones?
What types of hormone are derived from:
a) tyrosine and tyramine
a) Modified amino acid hormones
b) Steroid hormones
c) Peptide hormones
What type of hormones are:
b) thyroid hormones
b) Modified amino acid
What is autocrine signalling?
Hormone causes response in the same cell
What is paracrine signalling?
Hormone exits cell and causes response in adjacent cells
What is endocrine signalling?
Hormone exits cell, enters bloodstream and causes response in distant cells
In what types of signalling do hormones:
a) enter the bloodstream and cause a response in distant cells
b) cause a response in the same cell it was made in
c) cause a response in adjacent cells?
Hormones act in (very low / very high) concentrations to cause a response in target cells.
very low concentrations
measured in mmol/L
Specific hormones affect (one / more than one) target cell.
Target cells are regulated by (only one / more than one) hormone.
Specific hormones affect several different cell types
Target cells are regulated by loads of different hormones
Binding of a ligand to a receptor to cause a cellular response (i.e carrying a signal through the cell membrane) is called ___ ___.
Seeing as hormones are present in tiny concentrations, what process often occurs when hormones bind to receptors?
to increase the number of responses to a single hormone molecule
Where are hormones deactivated?
Where they bound to the receptor
Several different hormones can work together to regulate a physiological factor like blood glucose concentration.
What is this process called?
Complementary / cooperative action
What are two processes regulated by complementary action of hormones?
Increase in blood glucose conc. during exercise - adrenaline, cortisol and glucagon working together
Normal growth - growth hormone, insulin, IGF-1 and sex steroids working together
What is antagonistic action of hormones?
Hormones have the opposite effect and work against each other
e.g insulin and glucagon - insulin decreases blood glucose conc., glucagon increases it
Amino acid based proteins like adrenaline are more commonly known as ___ hormones.
Amine hormones are synthesised (within / outwith) cells, stored in ___ and then released in response to activation of a receptor by ligand.
synthesised within cells
stored in vesicles
By what process are vesicles containing amines released from a cell?
What ion is required for exocytosis of vesicles from cells?
Amines are (hydrophilic / hydrophobic), which means they can flow freely in the blood.
(remember that thyroid hormones are hydrophobic and therefore lumped in with steroids)
Why are amine hormones always ready to be secreted from cells?
Cells have big reserves of them
Peptide hormones are cleaved off longer ___ proteins before they are stored in vesicles and released by exocytosis.