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Lecture 1 endo. Schreier

Terms in this set (34)

Stimulation of prolactin and oxytocin secreation by breast feed are examples of
Positive feedback
chemical messenger acts back on the same cell or same cell type
that released it, localized effect.
Autocrine signalling
Examples of autocrine signalling....

— Adrenergic neuron → _____ → presynaptic alpha 2 -adrenergic receptors inhibiting NE release
— T-lymphocyte → _____ → T-lymphocyte
— Platelet → _____ → Platelet
— NE
— IL-2
— thromboxane A2
chemical messenger acts on a different cell type in the same tissue
or organ, localized effect
Paracrine
hormone (chemical messenger) secreted by cells of a specific
gland into the extracellular fluid, circulates in the bloodstream and acts at a
distant site (target cell).
Endocrine
neuron directly releases hormone into the bloodstream.
Neurocrine
Order of endocrine signalling
1. Extracellular stimulus
2. Regulated secretion of a hormone into circulation
3. Hormone binds to specific receptor in cells or one or more target organs
4. Triggers a change in cell activity that usually maintains homeostasis
How does the hormone limit the time available to act on tissues
By metabolizing
______ regulation of hormone secretion is rare and usually involves regulating a reproductive function to its completion
Positive feedback regulation***
Examples of positive feedback...
— Oxytocin and uterine contractions (childbirth)
— estrogen and LH surge (ovulation)
— stimulation of prolactin and oxytocin by breast feeding***
_____ regulation of hormone secretion is most common and usually involves regulating physical parameters within a narrow physiological range
Negative feedback regulation
Increased thyroid hormone decreases _____
TRH and TSH
When is growth hormone secretion greatest?
During sleep (and varies with age)
Stimuli that increase GH secretion...
Hypoglycemia, exercise, stress, sleep, puberty
Catecholamines, peptide, and protein hormones are ______
Water soluble
Water soluble hormones are stored in secretory vesicles, released by secretory vesicle exocytosis that is controlled via _____
Cytoplasmic concentration of Ca2+ and/or cAMP
How does somatostatin decrease release of other hormones?
Inhibits adenylate cycloserine and decreases cAMP
peptide hormone synthesis
*1. Hormone gene (DNA)
2. Regulated transcription
3. hnRNA processing and exon splicing
*4. mRNA
5. Ribosome
6. Dock to RER
*7. PREPROHORMONE synthesis and processing at RER
*8. Transport of PROHORMONE to golgi
*9. Pack HORMONE into vesicles by golgi
10. Vesicles transported along microtubules (kinesins and dyneins)
11. Regulated exocytosis
Peptide/protein hormones are stored as _____ and released via _____
— as membrane-bound secretory vesicles

— via exocytosis
What do steroid hormone producing cells typically have?
Extensive mitochondria, SER, and lipid droplets containing cholesterol esters

[steroidogenic enzymes reside within inner mit. membrane or membrane of SER]
How are steroid hormones regulated?
At the level of the uptake, storage, and mobilization of cholesterol and steroidogenic enzyme activity and gene expression (enzyme protein synthesis)
Order of hormones by plasma half life from shortest to longest.

- proteins, steroids, thyroid, catecholamines
Catecholamines, proteins, steroids, thyroid
Steroid hormone-receptor complex usually acts by _____
Binding to specific sequences on DNA (hormone regulatory elements) to alter the expression of specific genes
What do steroid hormone-receptor complex form? And acts as a?
— forms a dimer
— as a transcription factor regulating gene transcription
Example: Aldosterone binds to _____ receptors (transcription factors) and forms _____ that bind to specific ______ on DNA to regulate expression of specific genes
- mineralocorticoid; dimers; hormone regulatory elements
Vasopressin (ADH) acts on which receptors in the kidney epithelial cells?
G-protein (Gas) associated V2 receptors alpha
Vasopressin (ADH) acts at V2 receptors to increase _____ gene transcription and synthesis of _____
AQP2
What does CREBP do?
Increases AQP2 transcription (delayed physiological response; synthesis of AQP2)
Vasopressin (ADH) acts on which receptors in the plasma membrane of vascular smooth muscle cells to increase DAG, IP3, and Ca++ levels?
G-protein (Gaq) coupled V1 receptors
linked enzyme to Gas (ASH, E) and Gai (E, somatostatin)
Adenylyl cyclase (AC)
Linked enzyme to Gaq (ADH, E)
Phospholipase C (PLC)
ANP receptor type?
Guanylyl cyclase
Insulin receptor type?
Tyrosine kinase
Growth hormone receptor type? Linked enzyme?
tyrosine kinase; JAK/STAT family of tyrosine kinases
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