Flashcards in Hormones and Receptors Deck (15):
Once again, somatostatin is released by ____________.
the delta cells of the pancreas
What paracrine function does somatostatin have?
It inhibits the release of insulin from pancreatic beta cells.
Hormones can be autocrine, paracrine, and/or endocrine. This does not depend on ____________.
There are four chemical backbones for hormones: __________________.
- Tyrosine: epinephrine, norepinephrine, dopamine, thyroxine
- Peptides: hypothalamic (oxytocin, vasopressin, GnRH, TRH)
- Proteins: insulin, growth hormone, glucagon
- Steroids: corticosteroids, testosterone, vitamin D
What four functional categories of hormones does Dr. Vijayaraghavan want us to know?
- Water/minerals: ADH, aldosterone
- Energy: insulin
Which kind of hormones are contained in and secreted by calcium-dependent exocytosis?
Water soluble hormones; this occurs because these hormones are made inside cells but need to pass through the plasma membrane.
______________ hormones are controlled only by transcription factors.
Fat soluble hormones (controlled this way because they cannot be stored in vesicles)
It's the level of the __________ hormone that is regulated.
free (i.e., not bound to protein)
Describe the process of bioassay.
Bioassays are ways of measuring the effect of the hormone. For example, if you have radiolabeled glucose in a dish of myocytes and you add insulin, then you can determine how much glucose entered cells (by washing off the excess radiolabeled solution).
Which kinds of hormones have receptors?
Those that are water-soluble: the tyrosine-derived ones, the proteins, and the peptides
Give the three types of receptors and the kinds of hormones that bind to each.
- GPCR: hypothalamic
- Cytokine: GH, PRL
- EGFR: insulin
Trace the signaling pathway that leads to the production of thyroid hormone.
Hypothalamus: secretes thyroid-releasing hormone, which acts on the pituitary gland.
Pituitary: secretes thyroid-stimulating hormone, which acts on the thyroid.
Thyroid: secretes thyroid hormone, which (among other things) acts as a negative feedback mechanism on the hypothalamus (to decrease secretion of thyroid-releasing hormone).
Describe the pattern of secretion of GHRH.
Minute by minute, GHRH is released in short, pulsatile bursts. Over the whole day, however, it goes through a long sinusoidal fluctuation, with a peak in the night and a trough around noon.
What percent of fat-soluble hormones exist in the free (unbound) state?