Receptors/Signaling

• alpha 1
• alpha 2
• beta 1
• beta 2

vasoconstriction

increase of heart rate

bronchodilation

• phospholipids
• cholesterol
• proteins

• passive - facilitated diffusion, simple diffusion, etc.
• active - primary, secondary

• intercellular signaling
• intracellular signaling

• cell-to-cell/direct
• autocrine
• paracrine
• nervouse/synaptic
• endocrine

• the fastest type of intercellular signaling
• gap junctions- channels connect 2 cells together & ions go through
• ex: heart gap junctions- heart can contract all at same time

• signaling to yourself
• occurs in conjunction with paracrin
• --> localized effect

• signals with neighboring cells
• occurs almost everywhere

ex. capillary beds

• neural signaling
• in neuron, in a gland...occurs very quickly

neuroendocrine

• signaling mol are hormones
• (secreted directly to bldstrm to find target cell. travels as far as bldstrm takes it)

ex. hypothalamus & pituitary- neurons secrete ADH into bld in pituitary- goes into bldstrm

ligand

• aka chemical messenger or 1st messenger
• extracellular mol that binds receptor
• --> can activate or inhibit intracell. signaling

• endogenous- produced by body
• (ex. hormones, paracrine factors, etc.)

• exogenous- administered to body
• (ex. drugs, toxins)

ability of ligand to initiate a cellular effect

most are agonists!

• ligand that has both receptor affinity & efficacy
• (binds to receptor and initiates cell effect)

endo/exogenous

ligand has receptor affinity but no efficacy

(blocks access of agonist- competitive antagonist)

endo/exogenous

if antagonist binding to receptor, agonist can't bind- so competing for that spot!

• located on CM or intracell. mol
• binds ligand
• modifies signal transduction pathway (turns on/off)

• activates cascade of intracell. signaling
• molecular chain of events- mods cell activity

kinases- phosphorylates

phosphotases- dephosphorylates

• opening ion channels
• initiating gene transcription
• translation
• protein synthesis
• secretion of proteins

altered metabolism

altered gene expression

altered cell shape or movement

• altering enzyme activity
• regulation of genes, transcription
• protein production
• altering something inside cytosk. protein
• change shape or ability or mvmt of cell

due to continuous or repeated exposure of ligand (or drug) to receptor

• receptor sequestration
• receptor down-regulation
• receptor inactivation
• inactivation of signaling protein
• production of inhibitory protein

if not as many receptors on cell surface then not much activity

• decrease gene transcription of receptor, so cells make less of that receptor
• due to prolonged increased levels of ligand signaling

• turns off!
• receptors get phosphorylated

• turns off!
• something binds to receptor but signal is turned off

• signaling causes synthesis of some kind of protein that inhibits signal
• similar to neg. fdbck

• increased gene transcription of receptor
• due to prolonged decreased levels of ligand

no.

• OVERactivation does (or underactivation)
• form of negative feedbk

• cell membrane receptors
• intracellular receptors