week 5 - steroid hormones Flashcards
what is signal transduction
the biochemical mechanism responsible for transmitting extracellular signals across from the plasma membrane and throughout the cell
information changes into a chemical signal
often ends with covalent or non-covalent modification of intracellular target proteins
what is signal transduction essential for
communication between cells and environment, leading to the appropriate physiological response
cholesterol function in cell signalling
metabolic precursor to steroid hormones and bile acids
excess levels contribute to cardiovascular disease
potent signalling molecules have a critical role in:
cell development
reproductive biology
organismal physiology
role of glucocorticoids
regulation of glucose metabolism
role of progesterone
menstrual cycle, development of mammary tissue
role of mineralocorticoids
salt and water balances
role od androgens
regulate the development and maintenance of male characteristics in vertebrates (testosterone)
role of estrogens
development and regulation of female reproductive system
hormones can be categorised as:
endocrine (steroids)
paracrine (growth factor)
autocrine
how do steroid hormones exit endocrine cells
by diffusing out across membranes, they bind to transport proteins that keep them soluble and contact receptor proteins in the cells of target tissues
how do steroid hormones diffuse into target cells
they bind to hormone receptors in the cytoplasm and move to the nucleus
hormone-bound receptors in the nucleus triggers changes in gene expression, by serving as transcription factors interacting with a specific DNA-binding protein or a response element in the DNA
cell-cell specific physiological responses are controlled by nuclear receptors and are governed by three parameters:
cell-specific expression of nuclear receptors
localised bio-availability of ligands
differential accessibility of target gene DNA sequences in chromatin to nuclear receptor binding
