Homeostasis/Signalling Molecules Flashcards
What single does of paracetamol can kill someone? Chronic dosing can affect the function of which organ?
10g
Liver function
What are endogenous signalling molecules?
Signalling molecules within the body
What are the two classes of exogenous signalling molecules?
Exogenous I = natural (e.g. Plant based)
Exogenous II = synthetic
Give two examples of endogenous I drugs
Morphine
Aspirin
What is the normal core body temperature?
37 degrees Celsius
What acts as the ‘controller’ in body temperature regulation?
Hypothalamus
Which responses would be seen after an increase in core body temperature? (2)
Sweat glands activated
Peripheral vessels dilate (vasodilation)
Which responses would be seen after a decrease in core body temperature?
Skeletal muscle contraction (shivering)
Peripheral vessels constrict (vasoconstriction)
Below which temperature is considered hypothermia?
35 degrees Celsius
Above which temperature is considered hyperthermia?
38 degrees Celsius
Endocrine signalling molecules (hormones) can be categorised into which 3 categories?
Hydrophilic 1 - CATECHOLAMINES
Hydrophilic 2 - PEPTIDES & PROTEINS
Lipophilic - STEROIDS
Give an example of a catecholamine signalling molecule
Noradrenaline
Give an example of a peptide and a protein signalling molecule
Oxytocin
Insulin
Give an example of a steroid signalling molecule
Testosterone
Where are the receptors for catecholamines?
In the plasma membrane
Where are the receptors for peptide/protein signalling molecules?
In the plasma membrane
Where are the receptors for steroid hormones?
Intracellular (cytosolic or nuclear)
What is the plasma half-life of catecholamines, peptides/proteins and steroids respectively?
Catecholamines = seconds Peptides/proteins = minutes Steroids = hours
What response do catecholamines result in after binding to its receptor?
Causes a change in membrane potential
Triggers synthesis of cytosolic second messengers
What response do peptide/protein hormones cause after binding to its receptor?
Triggers synthesis of cytosolic second messengers
Triggers protein kinase activity
What is autocrine signalling?
Signalling molecules released, act on receptors on the same cell causing Intracellular changes
What is paracrine signalling?
Signalling molecules released into nearby extracellular environment and bind to receptors on nearby cells, causing their effects
What is an example of a paracrine signalling molecule?
A neurotransmitter
What distance and timeframe do neurotransmitters typically work over?
~20nm
Milliseconds
What does an excitatory neurotransmitter do?
Increases firing rate post synaptically
What does an inhibitory neurotransmitter do?
Decreases firing rate post synaptically
Neurotransmitters can be grouped into which 3 categories with which exception?
Amino acids
Monoamines
Peptides
Exception = ACh
Is acetylcholine excitatory or inhibitory?
Excitatory
Name 4 monoamine neurotransmitters.
State whether they are excitatory, inhibitory or both.
Adrenaline (excitatory)
Noradrenaline (excitatory)
Dopamine (both)
Serotonin (excitatory)
Name 3 amino acid neurotransmitters.
State whether they are excitatory, inhibitory or both.
Glutamate (excitatory)
Glycine (largely inhibitory)
GABA (inhibitory)
Apart from neurotransmitters, which are the other local chemical mediators used in paracrine signalling?
Cytokines - e.g. Interleukins, histamine
Nitric Oxide
Eicosanoids - e.g. Prostaglandins
Which signalling molecules does autocrine signalling use?
Shares many paracrine signalling molecules - e.g. Cytokines and growth factors
What distance do autocrine signalling molecules typically work over once released from the cell?
Microns
What is RITE a mnemonic for? What does each letter stand for? What is an exception to this mnemonic?
Describing DRUG TARGETS
Receptors
Ion channels
Transporters
Enzymes
Chemotherapy drugs are an exception - work on structural proteins/dna
What is KING a mnemonic for? What does each letter stand for?
Describing different drug target RECEPTORS
Kinase-linked receptors
Ion channels (ligand-gated)
Nuclear/intracellular receptors
G protein coupled receptors
What is an example of a kinase linked receptor? How do they cause an effect?
Cytokine receptor
Binding results in phosphorylation of proteins —> signalling cascade —> gene transcription
What is an example of a nuclear receptor? How does it cause an effect?
Oestrogen receptor (lipid soluble molecule e.g. Steroids)
Binds to gene transcription factors —> activates/inactivates a gene
What sorts of molecules bind to ligand gated ion channels?
‘Fast’ neurotransmitters e.g. ACh, GABA, NMDA
What sorts of molecules bind to GPCRs?
Hormones
Opiates
Slow neurotransmitters e.g. Muscarinic ach, serotonin, dopamine, adrenaline, noradrenaline
What are the three types of GPCR? What is the difference between them?
Gs, Gi and Gq
They activate different intracellular signalling pathways
What are the 4 major ion currents in cells?
Na+
K+
Cl-
Ca2+
How can phosphorylation help to facilitate/inhibit the activity of ion channels?
Phosphorylation of intracellular sites on the channels by PKA/PKC
PKA/PKC can be activated by GPCR pathways
Transporters are important in the re-uptake of neurotransmitters such as…
How is this done?
Noradrenaline
Serotonin
Glutamate
Co-transported with Na+ (symported)
