5.1 HY Mechanisms of Hormone Action Flashcards
What are hormones?
They are secreted by glands and are signaling molecules that are secreted directly into the blood stream to distant target tissues, causing the cell to change in gene expression or cellular functioning.
In what ways can hormones be classified by their chemical identities? (x3)
Peptides
Amino Acid Derivatives.
Steroids
What are peptide Hormones? And an example?
ADH, insulin.
Made up of amino acids that are derived from larger precursor polypeptides that have been cleaved during posttranslational modification. They are sent to the Golgi Apparatus for further modification.
They are large, and cannot pass through the cell membrane.
What is the difference between first messenger and second messenger?
What is this known as?
The first messenger would bind the the extracellular receptor, triggering a second signal, or the second messenger.
This is known as a signaling cascade.
How long do peptide hormone effects last?
Not long, but they are rapid to work.
This is because the second messenger casacades are transient, and it’s easy to turn them on and off.
How do peptide hormones travel around?
They travel around in the blood stream.
They are water soluble, so they don’t require a binding agent.
How do steroid hormones work?
They are generally derived from cholesterol.
Because they are non-polar, they can generally cross the cell membrane pretty easily.
Their receptors are generally intracellular.
Once they bind to the receptor, they can bind directly to DNA, causing increased or decrease transcription of a hormone.
How long do steroid hormones last?
They are slower to work, but longer lasting, because they cause alterations in the amount of mRNA and protein present in a cell by direct action on DNA.
What is dimerization?
What type of hormone is it associated with?
This is the pairing of two receptor-hormone complexes.
This is associated with steroid hormones.
How are steroid hormones carried around?
What may happen if there’s a lot of the carrieres?
Must be carried by proteins in the blood stream, such as albumin or sex-binding globulin.
Therefore, if attached, they are inactive.
If there’s a lot of the protein, it may cause reduced active hormone in circulation.
What’s the difference between direct hormones and Tropic Hormones?
Direct= secreted and act directly on target tissue
Tropic= require an intermediary, such as GNRH, LH, or those that are released by the pituitary. These are usually released by the hypothalamus.
Trop=Greek, to turn
What are amino acid-derivative hormones?
They are derived from one or two amino acids, with some modifications.
For example thyroid hormones are made from tyrosine modified by the addition of several iodine atoms.
How do amino acid derivative hormones work?
Ugh, no great answer. It’s variable.
Some work intracellularly, others in cascades.
Catecholamines= g protein coupled receptors
Thyroid hormone= bind intracellularly.
How can you differentiate peptide/Amino-derivative hormones and steroid hormones by names?
Peptide/Amino Derivative- ends in -in or -ine (insulin, vasopressin, thyroxine, triiodothyronine)
Steroid: ends in -one, -ol, or -oid (glucocorticoids, mineralocorticoids, aldosterone)
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