Endocrine Part 3 Receptors Miliotic Flashcards
How do hormones signal?
Hormones bind to receptors causing receptors to change conformation and activity, which triggers intracellular signalling pathways and affects protein synthesis or modification.
What are the two types of hormone signaling based on hormone properties and what kinds of receptors do they bind to?
Hydrophobic hormones bind to intracellular receptors, while hydrophilic hormones bind to receptors on the plasma membrane
What are common characteristics of hormone receptors? (5)
Receptors are large proteins, saturable, specific, reversible, and can be found in the cell membrane, cytoplasm, or nucleus.
What is the idea behind a receptor being saturable?
Receptors have a limited number of binding sites, so increasing the hormone concentration beyond a certain point will not increase the response
What are the four types of plasma membrane receptors?
G protein-coupled receptors (GPCR), receptor-enzyme receptors, receptor channels, and integrin receptors.
What type of hormone do intracellular receptors bind to and what is the result of this?
Intracellular receptors bind lipid-soluble hormones and directly alter gene transcription, leading to genomic effects.
How do G protein-coupled receptors (GPCRs) work?
GPCRs activate G proteins, which can open ion channels or alter enzyme activity through the adenylyl cyclase-cAMP system.
What are the three types of G proteins?
Gs, Gi, Gq
what is the job of Gs?
Activates adenylyl cyclase, increasing cAMP.
what is the job of Gi?
Inhibits adenylyl cyclase, decreasing cAMP.
what is the job of Gq?
Activates phospholipase C, leading to the production of DAG and IP3, which activate protein kinase C and increase calcium levels.
What happens during fight or flight responses mediated by GPCRs?
Epinephrine and norepinephrine bind to adrenergic receptors, causing physiological effects like glucose release, muscle contraction, and vasoconstriction in different tissues.
What type of gene do intracellular receptors affect?
genes with specific hormone response elements.
How is hormone signalling modulated? (5)
Through hormone degradation
receptor up-regulation or down-regulation
receptor desensitization
breakdown of second messengers
feedback mechanisms that reduce hormone secretion.
What is the difference between how peptide and steroid hormones act on cells?
Peptide hormones bind to surface receptors and trigger intracellular signalling cascades.
Steroid hormones penetrate the membrane, bind to intracellular receptors, and influence gene transcription.
