(IEMR2)Hormones, Hormone Receptors and Mechanisms of Hormone Action Flashcards
Chemical transport take place through what general operations?(3-6 points)
Diffusion, Osmosis, faciliate transport, active transport, exocytosis, endocytosis and hormone transport in circulation
Most hormones are what type of macromolecule?
peptides or proteins
What are the three general type of hormone structures?(3 points)
protein and peptide hormones, steroid hormones, and tyrosine derivatives
What are examples of group of hormones in the group of tyrosine derivatives?(2 points)
**thyroid hormones **and catecholamines
What are examples or hormones that are synthesized form modified tryptophan?(1-2 points)
Serotonin and melatonin
Peptide hormones are synthesized in what general location?
they’re synthesized in the cell
How are peptide hormones synthesized and released generally speaking?(7 points)
Peptides hormones are transcribed from mRNA, **translated **into a polypeptide. This process creates a preprohormone. The preprohormone is modified to turn into a prohormone. the prohormone is modified and turned into a hormone. The hormone is stored in granules for release later due to the fact that synthesis takes a long time. The exocytosis of the hormone is calcium depedent.
What is longer, the synthesis of a peptide hormone or hte synthesis of a steroid hormone?
the synthesis of a peptide hormone
What tends to be generally larger, peptide hormones or steroid hormones?
steroid hormones tend to be bigger than peptide hormones
What has a longer half-life, peptide hormones or steroid hormones?
peptide hormones have a relatively shorter half-life than steroid hormones
What group of hormones in the body have the longest half-life?
thyroid hormones
What are examples of hormones that are produced by one gene, i.e., one gene producing one hormone?(1-2 points)
insulin and growth hormone
insulin is produced by one gene, two genes are multiple genes?
one gene
What gene is known to produce many hormones?
POMC
What are examples of hormones produced by the POMC gene?(2-3 points)
MSH, ACTH and α-endorphin
What are examples of hormones that are produced by two genes?(2-3 points)
FSH, LH and TSH
LH is produced by one gene, two genes are multiple genes?
two genes
TSH is produced by one gene, two genes are multiple genes?
two genes
How do peptide hormones exit the cell after processing is complete?
Peptide hormones exit the cell via calcium dependent exocytosis
What are the two general sources of cholesterol?(2 points)
Circulating LDL or synthesized from acetate
What basic intracellular step is necessary for the synthesis of steroids from cholesterol?
mobilzation of cholesterol into the mitochondria
How is cholesterol mobilized into the mitochondria for steroid hormone synthesis?
The StAR enzyme completes this step when it combines with cholesterol
Where is the location of StAR?
inner-mitochondrial membrane
What is the action of the enzyme StAR?(2 points)
Side chain cleavage to form pregnenolone
What exits the mitochondria after the action of StAR takes place?
pregnolone
What enzymes assist with the movement of pregnolone outside of the mitochondria?
SER(enzymes associated with smooth membranes in the cytoplasm)
What is SER?
enzymes associated with smooth membranes in the cytoplasm
Does pregnenolone re-enter the mitochondria or is it used immediately for the synthesis of steroid hormones?
It may require re-entry into the mitochondria
Why does stroage of steroid hormones take place?
they don’t
Is modification always necessary after secretion of steroid hormones?
yes, modification may be required
What are the three main classes of steroid hormones?(3 points)
mineralcorticoids, glucocorticoids and androgenstendione
What is the precursor and end substarte for the three main classes of steroids?(3-6 points)
**pregnenolone **goes through a series of steps to become aldosterone. 17-OH pregnenolone goes through a series of reactions to become cortisol. DHEA goes through a series of reactions to become androgenstendione.
What are two grouops of hormones that are modified tyrosine molecules?(2 points)
catecholamines and thyroid hormones
Where are catecholamines stored?
secretory vesicles
Where are thyroid hormones stored?
colloid
What special about the storage of thyroid hormones?
they stored in colloids and they’re formed as part of the thyroglobulin molecule
What specific group of hormones are water soluble?(2 points)
most peptides and amines
What large category of hormones are associated with proteins in plasma?
lipid soluble or hydrophobic hormones
Why do diabetics take insulin orally?
insulin doesn’t work orally because they’re going to be deactivated through the digestive process
What specific group of hormones have the longest half-life?
thyroid hormones
What is the relative half-life of peptides?
short
What is the relative half-life of catecholamines?
very short
What is the relatively half-life of steroids?
long
What is the initial event in hormone action?
binding of hormone to the receptor
The binding of the hormone to the receptor involves what properties of the interactions between the receptor and the hormone?(2 points)
The receptor affinity for the hormone it’s binding and the receptor specificity for the hormone it is binding
What general type of molecules are the hormone receptors?
proteins
The binding site for the hormone on the reeptor is referred to as what?
the effector site or the hormone binding site(s)
Stress induces the release of what specific hormone?
cortisol
What provides specificity for hormone-cell interaction?
receptors
Where is the general location of hormone receptors?(3 points)
cell wall, cytoplasm or nucleus
Do cells possess receptors for all hormones?
no
Is it possible for a single hormone to have multiple receptors?
yes, i.e., CCK has a receptor on the pancreas an a receptor in the brain
The distribution of the hormone or the hormone receptor determines which cells respond?
distribution of the hormone receptor
Are hormone receptors limited to one cell type or are they distributed on most cells?
It can be one or the other depending on the hormone receptor
Binds and exerts biological effect similar ot hormone
agonist
binds and exhibits a supraphysiological response
superagonist
binds and produces a subphysiological response
partial agonist
Binds to receptor but does not activate it(no physiological response)
antagonist
Most cells in the body have receptors for what specfic hormone?
insulin
High specificity between hormone receptor and ligand is characterized by what?
homologous binding but not perfect
High affinity for hormone receptor and ligand is characterized by what?(2 points)
adequate binding at low hormone concentrations
Affinity for a partcicular hormone compared to affinity for another hormone determines what hormone receptor-ligand property?
specificity
Under normal circumstances, it is possbiel to gain a response from a hormone without the presence of a hormone receptor?
no