Biology Chapter 9: cell communication

for exam 3 (LAW)

Ligand

a signaling molecule released by a cell

Receptor

a protein which specific ligands bind to

Signal transduction

chain reaction once receptor binds a ligand

Interstitial fluid

ECF within tissues and organs

negative feedback

response that counteracts a stimulus

positive feedback

response that intensifies a stimulus

synaptic signaling

nerve cells release a signal:

Neurotransmitter

• diffuses across a synapse

• binds to receptors on targeted cells

paracrine signaling

important in early development

signal diffuses locally in ECF

• affects neighboring cells

• binds to receptors

• coordinates clusters of cells

endocrine signaling

signal released into circulatory system

• travels throughout the body

• only cells with specific receptor respond

• animals and plants use this mechanism extensively

Intracellular receptor

located within the cell

Membrane receptor

located in cell membrane

Signal transduction advantages

1) Amplification of signal

2) Diversity of response

3) Multiple points of control