Intro To Endocrinology Flashcards
Hormones secreted from the hypothalamus (5)
Thyrotropin releasing hormone (TRH)
Corticotropin releasing hormone (CRH)
Gonadotropin releasing hormone (GnRH)
Somatostatin
Dopamine
Hormones secreted from the anterior pituitary gland (7)
Thyroid stimulating hormone (TSH)
Follicle stimulating hormone (FSH)
Luteinizing hormone (LH)
Adrenocorticotropic hormone (ACTH)
Melanocytes stimulating hormone (MSH)
Growth hormone (GH)/growth hormone releasing hormone (GHRH)
Prolactin
Hormones secreted from the posterior pituitary gland (2)
Antidiuretic hormone (ADH)
Oxytocin
Hormones secreted from the thyroid gland (3)
Triiodothyronine (T3)
Tyroxine (T4)
Calcitonin
Hormones secreted from the parathyroid gland (1)
Parathyroid hormone (PTH)
Hormones secreted from the pancreas (2)
Insulin
Glucagon
Hormones secreted from the adrenal medulla (2)
Norepinephrine
Epinephrine
Hormones secreted from the kidney (2)
Renin
1,25-dihydroxycholecalciferol
Hormones secreted from the adrenal cortex (3)
Cortisol
Aldosterone
Adrenal androgens
Hormones secreted from the testes (1)
Testosterone
Hormones secreted from the ovaries and corpus luteum (2)
Estradiol
Progesterone
Hormones secreted from the placenta (4)
Human chorionic gonadotropin (hCG)
Estriol
Progesterone
Human placental lactogen (hPL)
Three classes of hormones
Protein and peptides
Amines
Steroids
Protein and peptide hormones are synthesized as _____ or a _____(not active).
____ is removed in the ER to produce a prohormone.
They are packed into ____ and cleaved by ______ generating the active form.
Larger polypeptides
Preprohormone
Signal peptide
Vesicles
Proteolytic enzymes
Protein and peptide hormones are stored in secretory vesicles until _____.
Stimulus for exocytosis?
Endocrine cell is stimulated
Increase of intracellular Ca caused by membrane depolarization
OR
Activation of G-protein-coupled receptor followed by increase in CAMP and activation of PKA
Steroid hormones are synthesized and secreted by ____.
Examples?
Modifications of cholesterol?
Adrenal cortex, gonads, corpus luteum
Cortisol, aldosterone, estradiol, estriol, progesterone, testosterone, 1,25-dihydroxycholecalciferol
Remove/add side chains, hydroxylation of steroid nucleus, aromatization of the steroid nucleus
Steroid hormones are synthesized from ____ which comes from what two sources?
Cholesterol
80% taken up as LDL particles through receptor mediated endocytosis
De novo synthesis from acetyl coenzyme A
Action of a steroid hormone that allows it to modulate gene transcription by interaction with intracellular nuclear receptors
Genomic action
Action of a steroid hormone that allows it to have rapid steroid action through receptor mediated or direct steroid membrane interactions
Nongenomic action
Amine hormones are derived from ____.
What are their two groups?
Tyrosine
Catecholamines and thyroid hormones
These amine hormones are synthesized in the cytosol and secretory granules
They act though cell-membrane associated receptors
Catecholamines
These amine hormones are synthesized by the thyroid gland and stored as _____ in follicles within the gland.
They cross the cell membrane and act through nuclear receptors
Thyroid hormones
Thyroglobulin in follicles
Thyroid (amine) hormones have the ___ half life and ___ clearance.
Steroid hormones?
Protein hormones?
Longest; smallest
Middle; biggest
Shortest; middle
Secretion of hormones is regulated by two mechanisms?
____ to an endocrine cell increases or decreases hormonal secretion
____ some element of the physiological response feeds back, directly or indirectly, on the endocrine gland and changes secretion rate
Neuronal input
Feedback mechanism (positive and negative)
Describe negative feedback:
Long-loop feedback?
Short-loop feedback?
Ultra short-loop feedback?
Hormone released from the 3rd tier (peripheral endocrine gland) feeds all the way back to the 1st tier (hypothalamus) and 2nd tier (pituitary gland)
Hormone secreted from 2nd tier feeds back to 1st tier
Gland inhibits its own secretion
Major endocrine axis
Hypothalamus-pituitary-adrenal gland axis (HPA)
Hypothalamus-pituitary-thyroid gland axis (HPT)
Hypothalamus-pituitary-gonads axis (HPG)
Negative feedback in which the secretion of a hormone is stimulated or inhibited by a a change in the level of a specific extracellular signal
Example?
Response-driven negative feedback
Insulin regulates blood glucose levels; blood glucose concentration turns on or off insulin secretion
How are the secretions from the first tier of the endocrine axes regulated (hypothalamus)?
What are its two major inputs and what do they do?
Descending and ascending neuronal inputs
Suprachiasmatic nucleaus (SCN): impose a circadian rhythm on the secretion of hypothalamic releasing hormones and endocrine axes
Pineal gland: releases melatonin which feedbacks info about day/night to the SCN
Physiological stress influences hormone release from the hypothalamus
Receptors have a ____ to the hormone actions through a _____ complex.
The responsiveness of a target tissue to a hormone is expressed in the ____ relationship.
Sensitivity occurs when a hormone concentration produces ___ of the maximal response.
Specificity
Hormone-receptor complex
Dose-response relationship
50%
How do you up-regulate a hormone?
Increase the number of receptors, increase the sensitivity of the target tissue when hormone levels are low, decrease the degradation of existing receptors, activate receptors
How do you down-regulate a hormone?
Reduce the number of receptors, decrease the sensitivity of the target tissue when hormone levels are high, increase the degradation of existing receptors, inactivate/desensitize receptors
What are the five major mechanisms of hormone action of target cells?
Adenylyl cyclase
Phospholipase C
Steroid hormone
Guanylyl cyclase
Tyrosine kinases
Adenylyl cyclase mechanism of hormone action:
1st messenger?
Primary effector?
2nd messenger?
Secondary effector?
Hormones (ACTH, LH, FSH, TSH, glucagon)
Adenylyl cyclase
cAMP
PKA
Phospholipase C mechanism of hormone action:
1st messenger?
Primary effector?
2nd messenger?
Secondary effector?
Hormones (GnRH, TRH, GHRH, oxytocin)
Phospholipase C
IP3/DAG/Ca
PKC or calmodulin
Steroid hormone mechanism of hormone action:
1st messenger?
Primary effector?
2nd messenger?
Secondary effector?
Hormones (thyroid hormones, glucocorticoids, aldosterone, estrogen, testosterone)
No second messenger
Act through cytosolic/nuclear receptors (hormone binding end and a DNA binding end)
Hormone-receptor complex acts as transcription factor that regulates the rate of transcription of a gene
Guanylyl cyclase mechanism of hormone action:
1st messenger?
Primary effector?
2nd messenger?
Secondary effector?
Hormones (atrial natriuretic peptide/ANP, NO)
Guanylate cyclase
cGMP
PKG
Tyrosine kinase mechanism of hormone action has two major categories
How do they work?
What are examples of each?
Receptor tyrosine kinases (have intrinsic tyrosine kinase activity within the receptor; when activated, the intrinsic tyrosine kinase phosphorylation itself and other proteins; examples are nerve growth factor, epidermal growth factor receptors, insulin, and insulin-like growth receptors)
Tyrosine kinase-associated receptors (associate non-covalently to proteins that have tyrosine kinase activity; example is JAK)
