Pharmacology Flashcards
What is a hormone?
A chemical signal, typically associated with glands, that has a slow but longer acting effect on its target organ (compared to neurotransmission)
What are the 3 types of cell signalling?
Autocrine: cell self-signals
Paracrine: Cell signals to cells beside it
Endocrine: Cells signals via the blood circulation
Why does endocrine control involve low concentrations of hormone?
Hormones are:
Potent: only need a small conc to illicit response
selective: Will bind to specific receptor (no need to keep increasing until something sticks)
Sharing: More than one type off hormone will bind to a receptor
What are ‘complementary’ hormones?
Hormones that ‘work together’ to achieve a common physiological goal (e.g. prevent hypoglycemia/hypokalaemia, encourage growth)
What are ‘antagonistic’ hormones?
Hormones that counter the action of another hormone/signal; Usually in order to return a physiological value back within its normal limits
What are the 3 main chemical classes of hormones and note their synthesis, storage and release
Amines: presynthesised -> stored in vesicles -> released via Ca2+ exocytosis
Peptides/Proteins: Presythesised -> stored in vesicles -> released via Ca2+ mediated exocytosis
Steroids: Synthesised and released on demand
How is steroid synthesis influenced
Cholesterol availability: Cholesterol is the starting product in steroid synthesis
Conversion rate to pregnenolone: Rate limiting step
What ‘state’ must steroids be in to be biologically active?
Unbound/ ‘free’ from carrier proteins
What 3 ways do carrier proteins influence steroids in the body?
Amount of steroid in blood: More carrier proteins means more steroid can enter circulation
Steroid reservoir: Inactivates steroid that is unbound so can be used later
Buffering: Carrier proteins would bind to steroid added to blood. This would inactivate it and resist any deviations that increased steroid concentration would cause
Name 3 examples of carrier proteins
Globulins
Albumin
transthyretin
What are the 3 influences on hormone control?
Negative feedback: Where the end product disrupts earlier steps in the mechanism
Neurological factors: stress and mood can stimulate release of hormones (e.g. cortisol)
External processes: Such as circadian rhythm and elimination from body.
What are the 3 receptor types associated in hormone signalling and which hormone groups use them?
G-proteins
Amines
Peptides/proteins
Receptor kinases:
Peptides/proteins
Nuclear receptors:
I: Steroids
II: lipids
III: Hybrids (thyroid)
What is the action of Gs in signal transduction?
S for stimulation
Increases conversion ATP to cAMP (via adenylyl cylcase)
Increases PKA action
Increased phosphorylation
What is the action of Gi in signal transduction
I for inhibition
Decreases ATP TO cAMP (via adnelyl cylase)
This increases PKA action
Reduced phosphorylation
Impact of Gq on signal transduction
Increased PLC: increased PIP2 to IP3 releases more calcium
Increased PKC: Increased phosphorylation of target proteins
Outline action of insulin on receptor kinases
Insulin binds to receptor Autophosphorylation of intracellular tyr residues and IRS1 Metabolic effects (via Akt/PKB)
Give a brief outline of steroid action
Cross plasma membrane (as lipophilic)
Bind to intracellular receptors and crosses nuclear membrane
Forms dimer and binds to specific parts of DNA
Upregulates and downregulates transcription of proteins for desired effect
