Quiz 2 Flashcards
steroid hormones are synthesized from
cholesterol
Steroid hormones act through — and — mechanisms
genomic (classical) and nongenomic
The classical mechanism is through interactions of the
steriod hormones with cytoplasmic or nuclear receptors
Hormone-recptor complexes bind to
specific seuences in the DNA (hormone response elements, HRE)
Hormone-recptor complexes interact with
interact with co-activators/corepressors to effect gene expression.
Membrane HRs (hormone receptors) also exert modulatory effects on nuclear HR through signaling pathways targeting
nuclear HR and co-activators (e.g., phosphorylation changes)
Membrane receptor binding of steroid hormones initiates various signaling pathways and activates other transcription factors that can lead to transcription of some genes without
HREs
Sex hormones or their analogs are used in the treatment of a variety of
diseases
Analogs of sex hormones also have a number of ”—” uses that can have serious side effects
recreational
Vitamin D2 (ergocalciferol) and Vitamin D3 (cholecalciferol) are prohormones that require
metabolic activation to generate the most active chemical form
Vitamin D3 is required for
proper calcium and phosphorus absorption needed to build strong bones and teeth
what is the best source of vitamin D3?
the sun
The sun is the best source of Vitamin D because it converts
7-dehydrocholesterol to Vitamin D3
many — are also high in vitamin D3
foods
Diary products in the U.S. are supplemented with Vitamin D3 to help avoid
deficiency state
The activation pathway involves a UV-activated step which means that Vitamin D3 must either
be obtained via the diet or by produced via a sunlight activated step and then transported to the liver for conversion to 25-(OH)D3
25-(OH)D3 is measured to assess
adequate intake of Vitamin D
It is converted in the kidney (and a few other tissues such as skin and immune system cells) to the active form of
1,25-(OH)2D3
Vitamin D metabolites are transported in the blood bound to
Vitamin D binding protein
1,25-(OH)2D3 functions to regulate
Ca2+ and phosphate homeostasis
It binds to the Vitamin D Receptor, which is a transcription factor that forms a heterodimer with the RXR to
regulate transcription. It can also act via membrane receptors
1,25(OH)2D3 is synthesized in the kidney in response to
PTH
PTH is secreted when
serum Ca2+levels are low
Rickets and osteomalacia are diseases caused by
Vitamin D deficiency
Vitamin D insufficiency is now appreciated to be associated with increased risk of several other diseases, including
the structures of the oral cavity
Growth factors play critical roles in (2)
embryonic development and repair processes of human tissues and organs
Growth factors can be synthesized in a number of tissues and can act
locally or on other target tissues
Growth factor production generally involves
post-translational proteolytic processing of a larger precursor molecule to produce the active form
They bind to specific receptors (homo- or hetero- dimers or tetramers) and activate
specific intracellular signaling pathways
Some growth factors are selective in terms of their
range of responsive tissues, while other growth factors have a broad range among many tissues
They are often — and — restricted with regard to their pattern of expression
temporally and spatially
Myostatin is
an inhibitory factor which regulates muscle mass
TGF-β plays a prominent role in all four phases of wound healing:
hemostasis, inflammation, proliferation, and remodeling
TGF-β and BMPs also play critical roles in the embryonic development of the (2)
craniofacial region and teeth
Abnormal expression of various growth factors are associated with
disease
Growth factors are being used to treat human disease and development of new therapies is expect to
increase with time
Efforts are underway to target expression of growth factors and/or their receptors as targets for
disease treatment
