Endocrinology Basics I and II Flashcards
What are classes of the amine hormones?
Catecholamines
Indoleamines
Thyroid Hormones
What are the monoamines?
Catecholamines
Indoleamines
What is the half life of monoamines like?
VERY short (2-3 minutes)
What is the half life of peptide hormones like?
Medium length (4-170 minutes)
What is the half life of steroid like?
Long (minutes to hours)
What are examples of catecholamines?
Dopamine
Norepinephrine
Epinephrine
What is the precursor for catecholamines?
Tyrosine
What is the enzyme for the rate limiting step for the formation of catecholamines?
Tyrosine Hydroxylase
What is Tyrosine Hydroxylase activated by?
Sympathetic Activity
What is Tyrosine Hydroxylase activated by?
Sympathetic Activity
What are the main 2 organs that dopamine is made in?
Brain and Adrenal Gland
What is the NT function of dopamine?
Activates reward pathways and is involved in attention and mood
What is the hormone function of dopamine?
Inhibits prolactin release from the anterior pituitary
What is the hormone function of dopamine?
Inhibits prolactin release from the anterior pituitary
Where do dopaminergic neurons arise from?
Arcuate nucleus
What converts dopamine into norepinephrine?
Dopamine Beta-hydroxylase
Where is norepinephrine converted into epinephrine?
Adrenal Glands
What is the enzyme for the rate limiting step for the formation of catecholamines?
Tyrosine Hydroxylase
Where is norepinephrine converted into epinephrine?
Adrenal Glands
What is the precursor for indoleamines?
Tryptophan
What is the enzyme for the rate limiting step for the formation of indoleamines?
Tryptophan Hydroxylase
What are examples of indoleamines?
Serotonin
Melatonin
What is the function of serotonin in the brain?
It is the “happiness” hormone
What is the function of serotonin in the body?
Serves as a vasoconstrictor and stimulates smooth muscle contraction
What produces most of the serotonin in the body?
Enterochromaffin cells in the gut
What is the function of drugs that act as selective serotonin reuptake inhibitors?
SSRIs work to increase the concentration of serotonin at the synaptic cleft and is used to treat depression.
Causes negative feedback on serotonin synthesis.
What is the main enzyme in monoamine metabolism?
Monoamine Oxidase
What is measured in urine to determine the catecholamine levels?
VMA
Where is melatonin made?
Pineal Gland
How is melatonin made?
It is converted from tryptophan into serotonin into melatonin
What is rate limiting step of melatonin synthesis?
N-acetyltransferase and it is the most active at night.
What is melatonin and inhibitor of?
Potent inhibitor of reproduction
What circadian rhythm is melatonin tied with?
Melatonin begins secretion during the dark. Duration of the dark period is important to
get the full physiological effects of melatonin
How are peptide hormones processed?
Peptide hormone is made as preprohormone and then the signal is cleaved which will form the prohormone. The pro hormone is the combination of the hormone and the copeptide.
What is related with the half life of the hormone?
Size of the hormone is directly related to half life
What are steroids derived from?
All derived from cholesterol precursor
What is negative feedback?
A stimulates B which inhibits A
What is positive feedback?
A stimulates B stimulates A
What are the features of classical endocrine glands?
Ductless and secrete hormone directly into blood or extracellular space.
What is the etiology and effect of cretinism?
It is a congenital deficiency caused by iodine deficiency during development that causes short stature/impaired bone formation, mental retardation and delayed motor development.
What is the etiology and effect of multiple endocrine neoplasia?
It is a genetic disease caused by characterized by 2-3 tumors in multiple endocrine glands
What is the most common endocrine disorder?
Diabetes Mellitus Type II
What is endocrine signaling?
Hormones secreted into the blood acting on downstream target tissues.
What is paracrine signaling?
Hormones secreted into the interstitial space acting at nearby cells.
What is autocrine signaling?
Hormones secreted into the interstitial space acting back on same cell.
What is the non-specific binding protein of hormones?
Albumin
What are the 2 methods bound hormones are delivered to targets?
- Steroid hormone is released at membrane and it freely diffuses across the lipid bilayer.
- Hormone bound complex binds to megalin and and endocytic vesicle forms.
What is the specificity of hormone:receptor binding?
It is the ability to distinguish between similar substances
What is the affinity of hormone:receptor binding?
It is measured as Kd which is defined as the ligand concentration that occupies 50% of binding sites
