Introduction Endocrine Systems & Receptors 2016 2 Flashcards
What are the 3 main ways in which hormone levels are influenced ?
- Negative feedback
- Neuroendocrine secretion
- Diurnal rhythm
Describe the idea of negative feedback in terms of hormone secretion
Hormone secreted inhibits further secretion of itself
Describe the idea of neuroendocrine secretion of hormones
There is a sudden burst of hormone secreted following a specific stimulus e.g. stress
Describe the idea of diurnal rhythm in relation to hormone secretion
Secretion rates fluctuate depending on what time of the day it is
What are the 3 main types of hormone receptors ?
- G-protein coupled receptors (GPCR)
- Receptor kinases
- Nuclear receptors - Class I, Class II, Hybrid class
GPCR and receptor kinases are cell surface receptors, Nuclear receptors are intracellular receptors
Match the hormone to the receptor which they mainly act on:
- Mainly amines
- Mainly proteins/peptides
- Mainly steroids
- Mainly lipids
- T3 and other substances
GPCR, receptor kinases, Nuclear receptors (class I, class II, hybrid class)
- Mainly amines - GPCR
- Mainly proteins/peptides - receptor kinases
- Mainly steroids - class I
- Mainly lipids - class II
- T3 and other substances - hybrid class
Look over the GPCR cAMP pathway
Look over the GPCR (IP3, PKC pathway)
Describe signaling via receptor kinases (insulin used as the example)
- Unbound
- Binding of insulin causes autophosphorylation of intrcellular tyrosine residues
- Recruitment of multiple adapter proteins, notably IRS1 that are also tyrosine phosphorylated
- Insulin receptor substrates produced
- Cellular effects
Describe signaling via nuclear receptors
- Steroids are lipophilic, so enter cells by diffusion
- COmbine with intraceullar receptor
- Receptor steroid complex movies to the nucleus
- Forms dimer and binds to hormone response elements in DNA
- Transcription of specific genes either switched ‘on’ or ‘off’
- This alters mRNA
- Translation
- Proteins formed
