Lecture Quiz ( Monday) Flashcards
Paracrines
Definition: Chemical messengers that act on neighboring cells within the same tissue.
Example: Growth factors in wound healing.
Autocrines
Definition: Chemical messengers that act on the same cell that secretes them.
Example: Immune cells releasing cytokines to activate themselves.
Neurotransmitters
Definition: Chemical messengers released by neurons to transmit signals across synapses.
Example: Acetylcholine, dopamine.
Hormones
Definition: Chemical messengers secreted by endocrine glands into the bloodstream to target distant organs.
Example: Insulin, adrenaline.
Amino Acid Messengers
Definition: Chemical messengers derived from individual amino acids.
Example: Glutamate, glycine.
Amine Messengers
Definition: Chemical messengers derived from amino acids but containing an amine group.
Example: Norepinephrine, serotonin
Peptide/Protein Messengers
Definition: Chains of amino acids that function as chemical messengers.
Example: Insulin, growth hormone.
Steroid Messengers
Definition: Lipid-soluble chemical messengers derived from cholesterol.
Example: Testosterone, cortisol.
Eicosanoid Messengers
Definition: Chemical messengers derived from fatty acids, typically involved in inflammation or immunity.
Example: Prostaglandins, leukotrienes.
Specificity
Definition: The ability of a receptor to bind to a specific ligand or messenger.
Affinity
Definition: The strength with which a ligand binds to its receptor.
Saturation
Definition: The point at which all receptors are bound by their specific ligands.
Up-Regulation
Definition: An increase in the number of receptors on the surface of a cell, making it more sensitive to a messenger.
Channel-Linked Receptors
Definition: Receptors that directly open or close ion channels when bound by a ligand.
Enzyme-Linked Receptors
Definition: Receptors that activate enzymes upon ligand binding, initiating intracellular signaling.
G Protein-Linked Receptors
Definition: Receptors that activate G proteins, which then trigger various intracellular effects.
Ligand-Gated Channels
Definition: Ion channels that open or close in response to the binding of a chemical messenger (ligand).
Fast Ligand-Gated Channels
Definition: Ion channels that open or close immediately upon ligand binding
Slow Ligand-Gated Channels
Definition: Ion channels that are indirectly opened by a ligand through second messengers like G proteins.
Amplifier Enzyme
Definition: An enzyme activated by a receptor that amplifies the strength of a signal within the cell, such as adenylate cyclase.
Paracrines communicate with?
communicate
with neighboring cells
Neurotransmitters are released by?
neurons from
axon terminal
Hormones are released from?
endocrine glands
(usually), diffuse into blood
what is Lipophilic?
(aka: hydrophobic)
* Lipid soluble, readily cross
membrane, do not dissolve in
plasma
what is Lipophobic?
(aka:hydrophilic)
* Water soluble, do not cross
membrane, dissolve in plasma
Amino Acid Messengers
Lipophilic or Lipophobic?
Can it cross the plasma membrane?
Does it dissolve in plasma?
Lipophobic (Hydrophilic)
No
Yes
Amine Messengers:
Lipophilic or Lipophobic?
Can it cross the plasma membrane?
Does it dissolve in plasma?
Lipophobic (Hydrophilic)
No
Yes
Peptide/Protein Messengers:
Lipophilic or Lipophobic?
Can it cross the plasma membrane?
Does it dissolve in plasma?
Lipophobic (Hydrophilic)
No
Yes
Steroid Messengers:
Lipophilic or Lipophobic?
Can it cross the plasma membrane?
Does it dissolve in plasma?
Lipophilic (Hydrophobic)
Yes
No
Eicosanoid Messengers:
Lipophilic or Lipophobic?
Can it cross the plasma membrane?
Does it dissolve in plasma?
Lipophilic (Hydrophobic)
Yes
No
Amino Acid Messengers
Function:
Synthesis:
Solubility:
Functional Classification:
Function: Neurotransmitters in brain and spinal cord
Synthesis: Must be synthesized in the neuron that secretes them
Solubility: Lipophobic (Hydrophilic)
Functional Classification: Neurotransmitters
Amine Messengers
Function:
Synthesis:
Solubility:
Functional Classification:
Derived from: Amino acids
Synthesis: Most are synthesized in the secretory cell
Solubility: Lipophobic (Hydrophilic)
Functional Classification: Paracrines, Neurotransmitters, Hormones
Peptide/Protein Messengers
Function:
Synthesis:
Solubility:
Functional Classification:
Most chemical messengers are: Polypeptides
Size: Contain 3-100 amino acids
Solubility: Lipophobic (Hydrophilic)
Functional Classification: Paracrines, Neurotransmitters, Hormones
Steroid Messengers
Function:
Synthesis:
Solubility:
Functional Classification:
Cross plasma membrane: Yes, so cannot be stored
Synthesis: Synthesized on demand
Solubility: Lipophilic (Hydrophobic)
Functional Classification: Hormones
Eicosanoid Messengers
Function:
Synthesis:
Solubility:
Functional Classification:
Produced by: Almost all cells in the body
Synthesis: Synthesized on demand
Solubility: Lipophilic (Hydrophobic)
Functional Classification: Paracrines
Additional Info: May contribute to pain/inflammatory response
Anti-inflammatory drugs: Target enzymes involved in eicosanoid synthesis (e.g. aspirin)
Aspirin: Decreases blood clotting
