3: MRI 2 Flashcards
What forces control ion movement in neuron cells
electrical & concentrational:
- positive charge is attracted to negative environment (Na+ flows into the negative cell)
- Potassium diffuses across the membrane (Then more Na+ is moved outside and less K+ inside)
)
What is Na+
Sodium
What is K+
Potassium
What is the resting potential of a neuron? (neuron at rest)
~ -70/65mV (concentration of ions is kept constant through Na+/K+ pumps)
What is the action potential threshold of a neuron?
~ -55mV (Once threshold is reached, the Na+ voltage gated channels are opened, the potassium channel is slower)
What are the ‘nodes of ranvier’?
periodic gap in the insulating sheath (myelin) on the axon of certain neurons that serves to facilitate the rapid conduction of nerve impulses
How are neurotransmitters removed from synapses?
- Reuptake
- Enzymes break them down and recycle
What are IPSP and EPSP
IPSP - inhibitory postsynaptic potential
EPSP - excitatory postsynaptic potential
What % of neuronal energy do POSTSYNAPTIC POTENTIALS consume?
37.5%
What % of neuronal energy do ACTION POTENTIALS consume?
15.8%
What % of neuronal energy do RESTING POTENTIALS consume?
15%
What % of neuronal energy does PRESYNAPTIC TRANSMITTER RELEASE consume?
3.8%
What % of neuronal energy does TRANSMITTER RECYCLING consume?
3%
What % of neuronal energy does HOUSEKEEPING consume?
25%
How do PET scans work?
- Create radioactive glucose and inject it
- increased bloodflow results in increased concentration of the radioactive substance in a brain region
- A positron is shot at and clashes with an electron and releases gamma rays in two directions (each time a random direction - sum of them allows to zero in on where the rays come from)
