Endocrine System Flashcards
Affinity
Strength of binding between receptors and hormones
Genomic response - signal molecule type
Hydrophobic/ lipophilic
Non-Genomic Response - Signal Molecule type
Hydrophilic/ lipophobic
Genomic response - location of receptor
In cytosol, in nucleus, or on cell surface
Non-Genomic response- location of receptor
Only cell surface
Signal transduction pathways form a _______. What is the final step of it?
Cascade
Conversion of substrate to product is the final step of the cascade
______ _____________ allows a small amount os signal to have a large effect
Signal amplification
“One ligand is amplified into many intracellular molecules”
GPCR: cAMP signaling mechanism
- Signal molecule binds to G protein-coupled receptor (GPCR), which activates the G protein
- G protein turns on ADENYLYL CYCLASE, an amplifier enzyme
- Adenylyl cyclase converts ATP to cyclic AMP (cAMP)
- cAMP activates protein kinase A
- Protein kinase A phosphorylates other proteins, leading ultimately to a cellular response
GPCR: PIP2 - CA 2+ signaling mechanism
- Signal molecule activates receptor and associated G protein
- G protein activates PHOSPHOLIPASE C (PLC), and amplifier enzyme
- PLC converts membrane phospholipids into diaclyglycerol (DAG), remains in the membrane, and IP3, diffuses into the cytoplasm
- DAG activates PROTEIN KINASE C, phosphorylates proteins
- IP3 binds to ligand gated channel on the SER and releases Ca 2+ into cytosol, creating a Ca 2+ signal
Isoforms
Up-regulation
Target cells form more receptors in response to low hormone levels
Down-regulation
Target cells lose receptors in response to high hormone levels
Desensitizes the target cells to prevent them from overreacting to persistently high levels of hormones
Half-life
Time required for level of hormone in blood level to decrease by half
