Ion-channel Coupled Receptors Flashcards
Which types of cells are ICCR’s found?
Excitable cells ⚡️
ICCR’s convert what type of signals?
Chemical and mechanical to electrical
Upon ligand binding…
- Conformational changes occur, leading to formation of channel/pore
- Molecules such as Ions (like K and Na) pass through membrane in or out to propagate travelling signal
What determines which ions pass the membrane?
The specific dimensions of the ion channel, the amino acids that line said channel, the associated receptor and the binding ligand
What are ion-channel coupled receptors also known as?
Ligand-gated ion channels
What usually binds to the receptors of these ICCR’s? Give examples of each
Neurotransmitters (acetylCholine) or peptide hormones (Growth hormone)
Oxytocin is both a neurotransmitter & peptide hormone that acts on ICCR’s
What affect does the passage of ions have on the cell in question?
As ions carry charge, the electronic membrane potential can be altered through unequal distributions across the extracellular and Intracellular environments
What is the usual ionic composition of the Intracellular and extracellular environments? And what do their differences create?
Na concentration greater outside than inside
K concentration greater inside than outside
This creates an electrochemical gradient, which upon channel opening, ions flow down to restore electrochemical equilibrium.
What happens when the bound ligand detaches?
The ion pore closes and the refractory period begins, after which ion channel formation can occur once again
Where are ICCR’s often found?
Mostly on synaptic structures of neurones and other excitable cells.
Briefly detail the sequences of synaptic transmission
- Presynaptic neuron is excited
- Vesicles containing neurotransmitter are released into synaptic cleft
- These bind ion-channel coupled receptors on surface of post-synaptic neuron causing ion channel opening
- Ions flow in or out of post-synaptic neuron
What occurs if the signal is excitatory or inhibitory?
Excitable : ion movement elevates potential of post-synaptic neuron
Inhibitory ✋: ion movement decreases potential of post-synaptic neuron
What threshold must be achieved for the post-synaptic to relay signal the incoming signal?
The motherfucking ACTION POTENTIAL!!
To where are ion-channel coupled receptors bound?
The membrane (insane in)
What type of ICCR’s are found in high abundance on the plasma membrane (sarcolemma) of muscle fibres/cells, why so and what is the primary source of the binding ligand?
The receptors are called muscle-type nicotinic AcetylCholine receptors (AChRs). They bind AcetylCholine and cause muscle contraction. Found in high abundance at neuromuscular junctions between motor neurones (primary source of AcetylCholine) and muscle cells.