Cell Communication

Question 1

1st messengers

Answer 1

Ligands that bind to receptors on or within responding cells

Released by signalling cells

Question 2

2nd messengers

Answer 2

Initiate changes in structure and function in responding cells
Receptors transduce signals into second messengers within the responding cells

Question 3

Water soluble ligands include (2)

And where do they bind

Answer 3

Proteins and peptides
Amines
They bind to cell surface receptors
Cannot move through cell membranes but can travel through blood and tissues unassisted

Question 4

Lipid soluble membranes bind to

Answer 4

Intracellular receptors
Require binding proteins for blood/tissue transport
Can move through cell membranes

Question 5

Agonists vs antagonists

Answer 5

Agonists mimic ligand activity and activate receptors to initiate signal transduction
Antagonists prevent receptor activation/signal transduction

Question 6

What two classes of hormones are lipid soluble?

Answer 6

Steroids

Thyroid hormones

Question 7

Endocrine

Answer 7

Travel in blood to distant organs

Many ligands known as hormones

Question 8

Paracrine

Answer 8

Travel within the same tissues/organs
In immune system ligands often known as cytokines
In nervous system organized as synapses

Question 9

Autocrine

Answer 9

Act on same cell that produces them
Important during development
Ligands often released and then sequestered in extracellular matrix until release by proteolysis to initiate receptor binding