Chapter 5: Chemical Messengers Flashcards
(43 cards)
Type of muscles that use direct communication through gap junctions
Cardiac & Smooth
Most common type of communication between secretory and target cells
Chemical messenger
Functional class of chemical messengers that are molecules locally produced and released
Cytokines
Functional class of chemical messengers that may act as a hormone, NT, or both
Neurohormones
Component of the Cytokine functional class of chemical messengers that contain growth and clotting factors
Paracrine
specific form of cell-cell communication in which a secretory cell produces a signal to induce changes in nearby/target cells, altering the behavior or differentiation of those cells
Paracrines

type of chemical messenger that transmits signals across a chemical synapse, such as a neuromuscular junction, from one neuron (presynaptic) to another “target” neuron (postsynaptic), muscle cell, or gland cell.
Neurotransmitters (NT)

chemical messengers that are secreted directly into the blood, which carries them to organs and tissues of the body to exert their functions
Hormones
What chemical property allows Testosterone and Prostaglandins to bind to receptors inside the cell?
Lipophilic
molecule that binds to a receptor
ligand
Paracrine ligands move by?
Diffusion
Hormone ligands move by?
Blood transport
How do hydrophilic messengers work?
- Endocrine cell secretes messenger by exocytosis
- Messengers dissolve into the blood vessel quickly

How do hydrophobic messengers operate?
- Endocrine Cell secretes by diffusion
- Binds to carrier proteins in the blood

time for a chemical to decrease concentration in half
messenger half-life
type of messengers that have a relative short life & example
dissolved in plasma
Insulin <10 min
type of messengers that have a relative long half-life & example
bound to plasma protein
Cortisol 1/2 life = 90 min
Process of producing response in target cell
Signal Transduction
Signal Transduction steps? (2)
- Messenger binds to receptor
- Binding results in a response
4 Components of Signal Transduction
- Specificity
- Brief & reversible binding
- Affinity- strength of binding
- Location
- Lipophobic ligands- cell membrane
- Lipophilic ligands- within cell
Strength of a target response depends on (3)
- Concentration of messenger (ligand)
- # of receptors/target cell
- Receptor affinity for messenger
Process by which the receptor number decreases on the target
May result from?
Effect on messenger?
Down-regulation
May result from excess messenger
Sensitivity to messenger decreases & Tolerance to messenger develops
Process by which the receptor number increases on the target cell
May result from?
Effects?
Up-regulation
May result from too little messenger
Sensitivity to messenger increases
chemical which binds to the receptor and mimics the normal response
agonist





