What are the four hormone classes? 17.2
● Hormones can be divided into two major groups on the basis of the chemical structure- derived from amino acids or lipids
1. Amine Hormone- Amino acids with modified groups (norepinephrines carboxyl group is replaced with a benzene ring)
2. Peptide Ho...
● Hormones can be divided into two major groups on the basis of the
chemical structure- derived from amino acids or lipids
1. Amine Hormone- Amino acids with modified groups
(norepinephrines carboxyl group is replaced with a benzene
ring)
2. Peptide Hormone- Short chains of linked amino acids
3. Protein Hormone- Long chains of linked amino acids
4. Steroid Hormones- Derived from the lipid cholesterol
Which are lipid soluble vs. water soluble? Why and how does this affect
how they act on the cell membrane? 17.2
● A steroid hormone directly initiates the production of proteins
within a target cell. Steroid hormones easily diffuse for the
cell membrane. The hormone binds to its receptor in the
cytosol, forming a receptor hormone complex. The receptor
hormone complex then enters the nucleus and binds to the
target gene on the dna. Transcription of the gene creates a
messenger rna that is translated into the desired protein
within the cyto plasma.
, ● Water soluble hormones cannot diffuse through the cell
membrane. These hormones must bind to a surface cell
membrane receptor. The receptor then initiates a cell-
signaling pathway within the cell involving G proteins,
adenylyl cyclase, the secondary messenger cyclic AMP
(cAMP) and protein kinases. In the final step, these protein
kinases phosphorylate proteins in the cytoplasm. This
activates proteins in the cell that carry out the changes
specified by the hormone.
What are examples of synergistic, permissive and antagonistic ways
hormones interact with their target organs?
● Synergistic- When two or more hormones work together to produce a particular result. May be
complimentary or additive. ex. additive: epinephrine and norepinephrine seperately produces an
increase in heart rate, when acting together in same concentrations stimulates an even greater
cardiac rate. ex. complimentary: estrogen, cortisol, prolactin and oxytocin work together to enable
the mammary gland to secrete milk.
● Permissive: When the action of a second hormone enhances the responsiveness of a target organ
to the second hormone, or when it increases the activity of the second hormone. ex. prior
exposure of the uterus to estrogen induces the receptor hormones for progesterone, which
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