ch 13 Flashcards
cell signaling
cell signaling
cells communicate with environment and each other
main stages of cell signaling (4)
stimulus/signal
receptor
signal transduction pathway
response/effector
what stimuli prompts cell signaling
deviation from homeostasis
types of signals
electrical
mechanical
light
temperature
chemical
electrical signals
sent in the form of ions
examples of electrical signals
voltage-gated channels
neurons firing
mechanical signals
stretching/pulling/pushing forces can also be signals
examples of mechanical signals
mechanically gated channels
baroreceptors
baroreceptors
protein receptors in vessels that sense and correct blood pressure
light signals
light conveys information
examples of light signals
photoreceptors in the eye
photoreceptors
cells that convert light into electrical information
temperature signals
temperature conveys information
temperature examples
thermoreceptors in the skin
thermoreceptor
parts of sensory neurons that help sense changes in temp
chemical signals
nutrients
hormones
proteins
neurotransmitters
more
ligand
chemical signal that binds to a particular receptor
different types of cell-cell communication
endocrine s.
paracrine s.
autocrine s.
direct s.
endocrine signaling
signaling molecules secreted by specialized cells
molecule travels through bloodstream
molecule binds and alters distant target cell
paracrine signaling
signaling molecules are secreted
molecule binds to NEARBY cell
autocrine signaling
signaling molecules are secreted
molecule binds to the cell that secreted it
direct signaling
signal molecule extends from one cell
molecule binds to adjacent cell
the two cells are in physical content
types of receptors (2)
intracellular receptors
membrane-bound receptors
intracellular receptors
receptor inside the target cell
ex. estrogen receptor
membrane-bound receptors
transmembrane proteins
dimerize
receptors are brought together by ligand
autophosphorylation
phosphorylation of self
G-coupled protein receptors (GPCRs)
spans cell membrane
major drug target
associated with G proteins
G-coupled protein receptors (GPCRs) mechanism
1) off- no ligand bound, GDP bound to alpha subunit
2) activation- ligand binds, GDP exchanged for GTP, alpha dissociates from gamma/beta
3) signal propagation- alpha and gamma/beta subunits interact with other proteins, those proteins propagate signal
signal transduction pathways
cascade of events between signal and response
involves proteins activating other proteins
response
occurs to address the initial stimulus and return to homeostasis
glucocorticoids
stress hormones
cause cells to increase metabolism and more
brain tells kidney to release them
glucocorticoids signaling pathway
1) glucocorticoids travel through the membrane
2) bind to intracellular glucocorticoid receptor
3) releases receptor from its repressor protein
4) receptors dimerize and go to nucleus
5) they act as transcription factor to activate genes involved in stress hormones
JAK/STAT signaling
activates immune cells
JAK/STAT signaling pathway
1) cytokine binds outside of cell
2) causes receptors to dimerize
3) receptors activate JAK proteins
4) JAK proteins phosphorylate STAT proteins
5) STAT proteins dimerize and go to nucleus
6) acts as transcription factor to activate immune cells
TNF-(alpha) signaling
helps the body respond to pathogens and inflammation
TNF-(alpha) signaling pathway
1) TNF-(alpha) protein binds TNF receptor
2) activates cytosolic proteins, which phosphorylate lKB
3) lKB gets degraded
4) this releases NF-KB, which goes to the nucleus
5) acts as transcription factor
6) activates genes involved in inflammation and immunity
feedback loops
they produce something that inhibits themselves
