Endocrine, Paracrine, Autocrine, Intracrine Regulatory Factors Flashcards
What do cell expressions array?
Sensing proteins or receptors to recognised specific stimuli
What are the 3 main routes for receptor based signals?
Nervous system, endocrine system and locally produced factors
What is autocrine signalling?
Cell targets itself
What is gap junction signals?
A cell targets a cell connected by gap junctions
What is paracrine signalling?
A cell targets a nearby cell
What is endocrine signalling?
A cell targets a distant cell through the bloodstream
What does the endocrine system do?
Secrete endocrine cells a long way from target cells, hormones released into bloodstream to travel to cell
What types of cells can respond to hormones?
cells with specific receptors
What types of receptors are there?
Intracellular and extracellular
what is the rate of hormones?
Slow acting
What do hormones regulate?
Homeostatis and gradual changes
What are hormones produced by?
Endocrine cells, some nerves and non-endocrine cells e.g insulin
What is an example of simple endocrine pathway?
Low blood glucose to secrete glucagon goes to liver for glycogen breakdown
What is an example of simple neurohormone pathway?
Suckling, posterior pituitary secretes oxytocin smooth muslce in breast releases milk
What is a simple neuroendocrine pathway example?
Sensory nueron signals, hypothalamus secretes prolactin hormon ant pituitary secretes prolact mammary gland then milk production
What does 1/2 main type of hormone do?
Enter cell and bind to intracellular receptors e.g steroid hormones like oestrogens
What does 2/2 main type of hormone do?
Bind to receptors on PM e.g insulin and cant enter cell, act via secondary messenger
What type of signals to cells detect?
Chemical and physical
What do physical signals do?
Converted to chemical at level of receptor
What type of signalling does physical follow?
Rhodopsin signallinh
When are secondary messengers produced?
When hormone binds a cell surface receptor
What are the 2 main types of secondary messengers?
cAMP and Ca
How is cAMP formed?
Increase activity of adenyl cyclase which converts ATP to cAMP
What does cAMP activate?
Series of enzyme reactions, through cascade effect and amplification
What bacteria is cholera caused by?
Vibrio chloerae
What clinical feature does cholera cause?
Severe diarrhoea
What is produced by the cholera toxin and where does it enter?
Cholera toxin enters gut cells, binds covalently to g protein that controls adenyl cyclase
How does increased adenyl cyclase cause death with cholera?
Increased AC activity, increase cAMP , increase active transport of ions by intestinal cells, increase sodium and water in gut
When does paracrine signalling occur?
When a cell releases signalling molecule into its immediate enviroment and molecule bound by effects
What is an e.g of paracrine signalling?
Somatostatin acts on nieghbour cells and inhibits insulin secretion
When does autocrine signalling occur?
cell releases a regulatory molecule which is bound by its own receptors
What does autocrine signalling act on?
cell which released it, positive feedback IGF
What is intracrine signalling?
Intracellular signalling - between different parts of same cell e.g nucleus and organelles
What happens in intracrine signalling?
Molecules dont leave cell
What are steroid hormones?
non-polar lipid soluble structure that can cross PM to a steroid receptor
What does steroid hormones affect?
Regulation of gene expression
What blocks the receptor from binding to dna till hormones present?
Inhibitor
What are the 3 functional domains of a steroid receptor?
Hormone binding domain, DNA binding domain, domain that interacts with coactivators to affect gene expression
What are 3 types of membrane receptors?
Channel linked, enzymatic and g protein receptors
What are channel linked receptors?
Ion channel that opens in response to ligand
What are enzymatic receptors?
Receptor is enzyme activated by ligand
What is g protein couples receptors?
G protein bound to gtp assist in transmitting signal
What are receptor tyrosine kinases?
Membrane receptors, activated by dimerization and autophosphorylation when bound by ligand, activates receptor adds a phosphate to tyrosine on response protein e.g insulin
What happens in the kinase cascade?
Series of protein kinases that phosphorylate in sucession, amplifies signal of few signal molecules illiciting large cell response
What at MAP kinases activated by?
Kinase cascades
What are Gprotein receptors?
bind to g proteins, switch on by receptor activates effector proteins enzyme
What does effector protein activate?
Second messenger which generates cellular response to original signal
What happens with the nervous system?
Stimulation at dendrites alters electrical properties in PM and releases stores neurotransmitters sucy as ACH which bind to receptor on cell surface
