fundamental principles of cellular signalling Flashcards
describe the two types of connections (synpases) between cells.
Electrical where the cells are physically connected and there is a pathway through one cell to the next for example endothelial cells ( line our blood vessels) cardiac myocytes and epithelia
These are known as low resistance pathways - they are formed from proteins called connections
Chemical synapse - where what is happening in one cell causes the release of a transmitter a chemical which diffuses a short distance and interacts with a receptor molecule causing chain of events in other cell
what is paracrine signalling
a chemical being released from a cell diffuses to neighboring cells and interacts with a receptor
describe endocrine signalling
Endocrine another type of chemical signalling - example hypothalamic pituitary access where chemical is released from one cell and passes through the bloodstream the interacts with receptors on another cell
give 2 examples of synaptic signalling
Synaptic - neuronal conduction or neuromuscular junction
what are the 4 receptor families
Ligand gated
G protein coupled
Tyrosine kinase linked
Nuclear
what are the 2 ion channels
Voltage gated
Ligand gated
what are the 4 main areas that can be targeted for therapeutic effect ( drug action)
Receptors: 4 receptor families
Ion channels
Transporters
Enzymes
what are nuclear receptors
nuclear receptor found mainly on the cytosol upon binding of the agony this receptor agonist complex moves to the nucleus and alters gene transcription
describe ion channels and their key features.
Proteinaceous pores meaning they are holes going through the membrane made from one or more protein
Their key features: a gating mechanism - opens the pores ( dictates when it wool opens or close ) selective permeability - preference of one type of ion over another. High transfer rate - movement of many ions leads to recordable current. An aqueous pore - connecting internal and external media
how can channels be classified
Permanent ion - classified by the nature of ion that passes through the channel - can be highly selective or nonselective
Gating mechanism -classified by the mechanism by which they open what is the impetus that causes the molecular change and the pathway , the nature of the molecular mechanism that opens the ion pathway - can be the membrane potential changing (voltage) , binding of a ligand - this can be external chemical binding or internal molecule usually the ion calcium or mechanical stretch
describe voltage gated channels
Na+ channel - more sodium externally than internally so flow is internal to external - local anaesthetics target this channel and blocks it . Examples include lignocaine or procainamide
Ca2+ channel- the same as sodium - dihydropyridines target this channel as well as anti hypertensives
K+ channel - more potassium internal than externally so flow is internal to external. Antiarrhythmic agents such as vernakalant
Cl- channel
briefly describe ligand gated channels
Channels that are not open by a change in voltage but by binding of a ligand
Neurotransmitter receptor - binding of a molecule such as Glu causes an ion channel to open. Barbiturates stabilise Glycine activated ion channel
Ca 2+ activated K + channel
Cyclic nucleotide gated channel -
what is an exchanger and give an example
Exchanger- swapping of an ion for another example sodium / potassium ATPase - drugs used for heart failure block this transporter example being ouabain and digoxin pr cl/hco3 exchanger
what are antiporters
where an ion is replaced by another one. A Lot of these are in the kidney and they get targeted by drugs that help us pass more urine example Na /Cl
describe the mechanism of maintaining calcium levels in the cytoplasm
exchanger that pumps out calcium in return for sodium ion coming in
Proteins that pump out calcium while consuming ATP calcium atpase pumps
Similar pumps located in endoplasmic reticulum
Pumping mechanism in mitochondria
Number of molecules that will bind to calcium and this calcified molecule goes off
