Chapter 9 Flashcards
Cell Communication
A molecule that binds another specific molecule, delivering a signal in the process
Ligand
Cells that are affected by chemical signals
target cell
Ligand that is used during the transfer of signal between cells of the nervous system
neurotransmitter
Signals mainly move through the bloodstream as ligands
hormone
Small watery channels that exist between cells
gap junction
Channels that exist between plant cells
plasmodesmata
Small molecules that move between cells
intracellular mediator
Conversion of an extracellular signal into an intracellular one
signal transduction
After the ligand binds to a cell-surface receptor, the intracellular signal sets this off to result in some change
signaling cascade.
Why do cells need communication?
Respond to external stimuli and to each other
What are the four categories of chemical signaling in multicellular organisms?
Autocrine, direct, paracrine, endocrine
What is the main difference between the four categories?
Distance that the signal has to travel to reach the target cell
Be able to describe each of the four categories in terms of the distance the signal travels, how quickly it elicits a response, and how long the effect lasts.
Autocrine-neighboring cells or the same cells
Direct-group of neighboring cells
Paracrine-close proximity-quick response; short-lived effect
Endocrine-bloodstream; slow response long-lasting effect
Give examples of each of the four categories of chemical signaling in the human body.
Autocrine-embryo development or viral infection
Direct-contraction of the heart
Paracrine-nervous system; neurotransmitters
Endocrine-hormones
What is the benefit of using intracellular mediators in gap junctions and plasmodesmata in tissues of animals and plants?
It allows for some small molecules to move between cells
