L1- Basics Flashcards
Describe the morphology of classic endocrine ducts.
Classic endocrine glands are ductless (and therefore have to be highly vascularized)- main feature
They secrete hormones directly into the blood stream or extracellular space.
The entire organ is dedicated primarily to endocrine function.
What is the main non-classic endocrine organ of the brain?
The hypothalamus
What hormones are released by the kidney (a non-classical endocrine organ)?
Renin, Vitamin D (in its active form), erythropoietin (EPO)
What hormones are released from the heart (a non-classical endocrine organ)?
Atrial/Brain natriuretic peptide (ANP/BNP)
What hormones are released from the liver (a non-classical endocrine organ)?
Insulin-like growth factor (IGF-1)
What hormones are released from the GI tract (non-classical)?
serotonin and ghrelin
What hormones are released from adipose tissue (non-classical endocrine organ)?
Leptin
Differentiate a primary endocrine defect from a secondary/tertiary defect
Primary: problem with the endocrine gland
Secondary/tertiary: problem elsewhere
Endocrine pathologies are characterized by what?
Hormone imbalances
What is the timing of the onset of symptoms of most endocrine disorders?
Slow- symptoms can take a long time to develop and may seem unrelated
Describe cretinism
Congenital disorder due to iodine deficiency during development- presents as short stature, impaired bone formation, mental retardation and delayed motor development
What is the etiology of multiple endocrine neoplasia? WHat is it?
MEN: genetic
Characterized by 2-3 tumors in multiple endocrine glands (pituitary, parathyroid, entero-pancreatic
Type 1 diabetes is what type of disorder?
autoimmune
What is Sheehan’s syndrome?
Post-partum hemorrhage/shock that results in massive pituitary death
What is the most common endocrine pathology?
Diabetes mellitus Type II- everyone is fat now.
What is the purpose of hormone binding proteins?
Hormone binding proteins bind to hormones in the blood to facilitate transport. This generally increases the half-life of hormone in the blood.
Are hormone binding protein-bound hormones bioavailable?
No
What types of hormones are generally bound by hormone binding proteins?
Steroid hormones (which are lipophilic)
IGF-1, GH, T4/T3
What nonspecific binding hormones carries many different hormones through the blood?
Albumin
Discuss the relative amount of bound/unbound sex hormones in the blood
Nearly all of the sex hormones are bound by either SHBG or albumin in the blood
How are “bound” hormones delivered to the cell?
1) The hormone may be released at the membrane and freely diffuse across the membrane (steroid hormones)
2) Hormone/binding protein complex binds to megalin on the outside of the cell and enters via endocytosis
Discuss the specificity and affinity of hormone/receptor binding.
Hormones bind their receptors with high specificity and high affinity
Where do lipophobic hormones bind? How do they signal?
Lipophilic hormones bind to cell surface receptors. They signal through secondary messenger systems like IP3/DAG and cAMP
What is the lifespan of a lipophobic hormone?
They are rapidly internalized or degraded
