Endocrine System (Signaling) Flashcards
Ligand
-A chemical messenger that can bind to a specific receptor
-Two types of ligand receptors: hydrophilic and hydrophobic
Hydrophilic ligand
-Transmembrane protein
-Cannot cross target cell membrane
Hydrophobic ligand
-Intracellular proteins
-Can cross target cell membrane
Receiver
Ligand binding receptor
Transducer
Conformational change of the receptor
Amplifier
Signal transduction pathway increases the number of molecules affected
Responder
Something that responds to the signal
receptor agonist
Activate receptor
receptor antagonist
Block receptors
Know how stimulatory vs. inhibitory signals work together to control cell signaling.
-Stimulatory: Activates that piece that releases the secondary messenger
-Inhibitory: Blocks the secondary releaser preventing it from being activated
Know the difference between positive and negative feedback.
-Positive: Output acts as a further stimulus
-Negative: Output reduces the stimulus
Extracellular domain of membrane-bound receptors.
-Receive chemical messenger (ligand)
-Changes in response to this binding
Transmembrane domain of membrane-bound receptors.
-Signal transfers through this section
-Anchors into transmembrane
Intracellular domain of membrane-bound receptors.
Releases secondary messengers by physical change in receptor shape
Know what a 7-transmembrane domain receptor is and one specific example of a 7-transmembrane domain receptor.
-Receptor where anchor has seven cross points
-Example: G-protein-coupled receptor (GCPRs)
Know the 4 major classes of cell surface receptors.
-G-protein-coupled receptors (GCPRs): We focus on this
-Ion-channel receptors
-Tyrosine kinase linked receptors
-Receptors with intrinsic enzymatic activity
Know what G-protein-coupled receptors are.
-Transmembrane protein that interacts with intracellular G-proteins.
-G-proteins: Named for their ability to bind guanosine nucleotides.
-Activate second messengers.
Be able to list and describe the steps in the G-protein cycle.
1.Binding of hormone induces a conformational change in receptor
2.Activated receptor binds to G alpha subunit
3.Activated receptor causes conformational change in G alpha triggering dissociation of GDP
4.Binding of GTP to G alpha triggers dissociation of G alpha both from the receptor and from G beta gamma
5.Hormones dissociates from receptor; G alpha binds to effector, activating it
6.Hydrolysis of GTP to GDP causes G alpha to dissociate from the effector and reassociate with G beta gamma.
Know how intracellular receptors affect mRNA production.
-Regulate the transcription of target genes by binding to specific DNA sequences
-Increasing or decreasing mRNA production.
Know how peptide hormones are synthesized and then made ready to exit the cell.
-Made in advance: Made in ER and stored in vesicles until needed
-Released through exocytosis.
Know how steroid hormones are synthesized and then made ready to exit the cell.
-Synthesized on demand
-Released through diffusion.
Characteristics of receptors for protein hormones.
-Utilize plasma membrane receptors
-Can not directly enter the center
-Must act through a second messenger system
Characteristics of receptors for steroid hormones.
-Fast response: Membrane receptor (myometrial contraction)
-Slow response: Nuclear receptors (secretion of cervical mucus), Diffuse into cell, Attach to specific nuclear receptors, and Do NOT require a second messenger