Cell communication Flashcards
Define affinity
Tendency of a chemical to bind to a receptor
What actions do atropine inhibit?
Increase in heart rate and salivation
Effect of curare and nicotine
No contraction
Effect of curare and nerve stimulation
No contraction
What is the effect of nicotine and curare acting on a muscle?
Stimulates a nerve which produces a substance and mimics the action of nicotine
What protein is a receptor?
A macromolecular protein
What is a chemical mediator?
An extracellular signal molecule
What is the cascade for chemical signalling?
Extracellular signal molecule
Receptor protein
Intracellular signalling protein in cytosol
Effector proteins
What are the 3 types of effector proteins?
Metabolic enzyme
Transcription regulatory protein
Cytoskeletal proteins
What is the downstream effect of metabolic enzyme?
Altered metabolism
What is the downstream effect of transcription regulatory protein?
Altered gene expression
What is the downstream effect of a cytoskeletal protein?
Altered cell shape or movement
What cells can integrate information?
Single cells
What allows coordinated responses involving multiple organisms?
One receptor being expressed by many cell types
What allows amplification for signalling?
Different types of receptors using similar signal transduction methods
How does contact dependent communication work?
A cell surface-bound signal molecule binds to a protein receptor on an adjacent target cell.
How does paracrine communication work?
The signalling cell sends local mediators into extracellular fluid in their neighbourhood which bind to receptors on target cells
How does Neuronal communication work?
A neurotransmitter travels down a neurons axon and diffuses through a synaptic cleft and binds to the receptor on the target cell.
They travel electrically
How does endocrine communication work?
Hormones are secreted into the blood stream from the signalling cell to receptors on the target cell.
What is the shortest range of cellular communication?
Contact dependent
What are the 2 main areas contact dependent communication are used?
Development (delta-notch signalling)
Immune responses
Describe Immune responses using contact-dependent signalling
T cells interact with MHC class receptors on apc’s
Apc’s become activated so they can recognise infected/damaged cells
Where does paracrine communication act?
Locally
What can paracrine signalling turn into if effective?
Autocrine signalling
- If responds to mediators released
How are paracrine signals stored?
In vesicles
Or synthesised on demand
What are 2 types of paracrine vesicles?
Proteins (growth factors)
Amino acid derived mediators (histamine)
What are 2 paracrine signals synthesised on demand?
Gases (Nitric oxide)
Lipids (endocannabinoids)
When is paracrine signalling used?
Inflammation
Cell proliferation
Wound healing
What is the paracrine receptors mechanism in pharmacology?
Mast cells detect allergens and become activated.
Activated mast cells secrete mediators (histamine ect).
Drugs will block the mediators produced
What is the paracrine intracellular signalling induced by chemical mediators in pharmacology?
Drugs target enzymes which synthesise mediators which cause inflammation
e.g. Eicosanoids which are lipid derived paracrine mediators
What does Nitric oxide cause?
Relaxation of smooth muscle cells
Vasodilation
Activated NO synthase releases NO across membranes. The NO binds to gualynly cyclase which causes a rapid relaxation of smc. The smc lines the walls of blood vessels and causes dilation.
What is the mechanism of viagra?
Inhibits the enzyme which breaksdown cGMP, prolonging the action of nitric oxide.
This means smooth muscle will take longer to relax
What is the speed of neuronal signalling?
Very fast
How can drugs act on neuronal signalling?
At the pre or post synaptic terminals
What do drugs affecting the presynaptic terminal do ? Example?
Influence neurotransmitter synthesis, storage or release
Amphetamines (storage)
What do drugs affecting the postsynaptic terminal do ? Example?
Influence neurotransmitter receptors
Nicotine/Curare
What are 3 possibilities that horomones can be?
Amino acid derived
Proteins
Steroids
