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Anatomy and Physiology
Terms in this set (28)
Decrease in receptor number in response to high concentration of hormone
complementary process that involves increases of a cellular component, such as RNA or protein
release of a hormone in response to another hormone
endocrine glands that are controlled by and interact with the nervous system
Amino acid or protein based hormones are
o water soluble and therefore must bind to a cell membrane receptor to have a biological effect. Once bound, these types of hormones trigger a secondary messenger system causing a cascading of events within the cell thus inducing a biological outcome.
Steroid hormones are
o lipid based (synthesized from cholesterol) and are therefore lipid soluble. Thus, they must be transported in the blood stream bound to a protein carrier. They enter the target cell membrane without and bind to a receptor in the cytoplasm or nucleus. Once bound to a receptor, that attach to DNA and induce transcription and translation.
Hormone must bind to
target cells, in turn, altering cellular activity.
This could be an increase of a decrease in normal cell processes.
Cells contain receptors on
for a hormone to have a biological effect, they have to
bind to a receptor that "fits" that hormone.
o Change in membrane permeability or change in membrane potential via opening or closing ion channels.
o Stimulate enzyme or other protein synthesis or degradation within the cells.
o Activate or deactivate enzymes
o Stimulate mitosis
Polypeptide hormones (water soluble) make use of
secondary messenger system.
3 types of secondary messenger systems
cAMP, PIP2, Throsine Kinase
- Factors that influence how great a biological effect a hormone has:
o Concentration of the hormone
o Number of receptors on cell membrane for the hormone
o Affinity between the hormone and receptor
o Blood volume
- Hormone release is triggered by:
o Endocrine gland stimuli
o Nervous system modulation - nervous system can override/reset the endocrine system i.e. glucose during exercise Hypothalamus and SNS depress insulin secretion to allow greater glucose in the blood stream.
- Three types of endocrine stimuli for hormonal release:
up regulation and down regulation
Hypothalamus - Cortisol Releasing Hormone (CRH) >> Anterior Pituitary gland -
Adrenocorticotropic Hormone (ACTH) >> Adrenal Cortex - Cortisol
Hypothalamus - Growth Hormone Releasing Hormone (GHRH) >> Anterior Pituitary gland -
Growth Hormone (GH) >> Liver -Insulin-Like Growth Factors
Hypothalamus - Growth Hormone Inhibiting Hormone (GHIH) >> Anterior Pituitary gland
Inhibits Growth Hormone (GH)
Hypothalamus - Thyroid Releasing Hormone (TRS) >> Anterior Pituitary gland - Thyroid stimulating Hormone (TSH) >>
Thyroid - Thyroxine and Triiodothyronine (T4 & T3 respectively)
Hypothalamus - Gonadotropic Releasing Hormone (GnRH) >> Anterior Pituitary gland -
Luteinizing Hormone (LH) >> Males - Testes release Testosterone; Females Ovaries release Estrogen
· Hormone binds to receptor >> activates G protein >>
Activates Adenylate Cyclase >> catalyzes the formation of cAMP >> activates cascade of protein kinases
PIP2 (Phosphatidyl inositol bisphosphate) flow
Hormone binds to receptor >> activates G protein >> Activates Phospholipase C >>
splits PIP2 into DAG and IP3 >> DAG activates cascade of protein kinases >>IP3 Releases intracellular calcium >> Combines with calmodulin >> activates protein kinases cascade
Tyrosine Kinase (receptor/enzyme)
Hormone binds with tyrosine receptor (monomer) >> hormone tyrosine complex binds with a second tyrosine >> complex forming dimer >> Tyrosine kinase dimer has multiple phosphorylated sites that can trigger several different cascade of events. Gone wrong, has been linked to cancer.
Endocrine system works via long distance therefore, releases hormones into
- the blood stream and the effects on target tissue/cells are not usually in close proximity to the gland. Endocrine glands are ductless.
"to excite" and influences metabolic activity
The hormone is a chemical messenger sent via
blood stream to the target cell's extracellular fluid.
Exocrine, autocrine, and paracrine
not considered part of the endocrine system because they work in close distances to the glands secreting the hormones, and they have ducts.
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