Graded Potentials Flashcards
How are graded potentials graded?
Stimulus intensity is signalled in their amplitude.
How are graded potentials decremental?
The potential becomes smaller as they travel along a membrane. Acts locally.
How are graded potentials summated?
A single neurone has many synapses.
If two postsynaptic potentials occur at the same time, they can add together.
Describe temporal and spatial summation.
Temporal - same synapse in a short time.
Spatial - many synapses at once.
Describe how summated synapses are inhibited.
Inhibitory synapses hyperpolarise the membrane.
Can inhibit the synapse itself.
How are graded membranes excitatory or inhibitory?
Opening ion channels generates ion gradients.
Describe the normal concentrations of ions inside the cell, relative to outside the cell.
High K+.
Low Na+, Cl-, and Ca2+.
How are cells depolarised?
Na+ in, K+ out - fast EPSP (ionotropic).
K+ in - slow EPSP (metabotropic).
How are cells hyperpolarised?
Cl- in - fast IPSP (ionotropic).
K+ out - slow IPSP (metabotropic).
What are some examples of graded potentials?
Sensory; postsynaptic; NMJs; pacemakers.
