L23 Extracellular Signalling Flashcards
why do cells communicate with one another?
regulate their development and organisation into tissues
control their growth and division
co-ordinate their functions
how might cell communication break down?
signal may be lost or no longer sent ie in type 1 diabetes (lost as beta cells in pancreas no longer able to synthesise insulin)
target may ignore the signal ie in type 2 diabetes (insulin is ignored by defective target receptor)
signal doesn’t reach its target eg multiple sclerosis (nerve impulse doesn’t reach its target due to breakdown of myelin sheath surrounding neurone)
too much signal eg brain damage (excitotoxicity) - signal (glutamate neurotransmitter contributes to neuronal degeneration and death)
multiple breakdowns ie cancer
how do cells communicate with one another?
Remote signalling by secreted molecules
Contact signalling by plasma membrane-bound molecules (‘Juxtacrine’ signalling)
Contact signalling via gap junctions - directly join the cytoplasms of interacting cells, thereby allowing the passage of chemical and electrical signals from one interacting cell to its partner.