Week 2- chemical messengers Flashcards
(17 cards)
what does direct communication consist of?
gap junctions and anchored extracellular messengers
what does indirect communication consist of?
chemical messengers and target cell receptors (ligand)
define the different classifications of chemical messengers?
paracrine: chemical that signals nearby cells (histamine)
autocrine: signals the same cell that secreted it
endocrine: released directly into the blood (thyroxine)
neurocrine: released into ECF by neurons (NT)
mechanism of action for IP3?
releases calcium from intracellular stores, calcium alters enzyme activity, exocytosis, muscle contraction
mechanism for action for DAG?
activates protein kinase C and phosphorylates proteins
mechanism of action for calcium?
binds to calmodulin and other binding proteins and alters enzyme activity, exocytosis, muscle contraction and channel opening
mechanism of action for cAMP?
activates cAMP dependant protein kinase
A G protein activates plasma membrane adenylyl cyclase which catalyzes the formation of cAMP from ATP
receptor channel?
a conformational change resulting in the opening or closing of the ion channel
eg, ACh, nicotine
receptor enzyme?
activation of tyrosine kinase activity resulting in self phosphorylation and phosphorylation of other tyrosine containing proteins
eg, insulin, IGF1
G protein coupled receptor?
activated G protein stimulates the activity of an enzyme or ion channel
eg, LH, FSH, ACTH
integrin receptor?
alters the organization of the cytoskeleton which results in cellular movement
eg, collagen, fibrinogen
name 2 inhibitory NT?
GABA, Glycine
name 3 excitatory NT?
NE/E, ACh
opens sodium channels and depolarizes the membrane
what is a neurohormone?
hormone secreted from endocrine gland, released into bloods from neurons
eg, oxytocin and ADH
hormone?
chemical secreted by a gland, sent to the blood, and target cell
what are second messengers?
a substance whose release within a cell is promoted by a hormone and which brings about a response by the cell.
what are the differences between the receptors in cell signalling and the receptors that activate a reflex arc?
cell signalling: proteins on/ inside the cell that bind to the ligand and trigger a response in cell and receive specific chemical messengers
reflex arc: not proteins but entires cells or parts of cells that cause signal to be sent to integrating centre and initiate a response involving many cells
