Neurons & Neural Communication Flashcards
1
Q
2 types of cells in nervous system
A
- neurons
- glia
2
Q
3 types of glial cells
A
- oligodendrocytes
- astroglia
- microglia
3
Q
function of oligodendrocytes
A
- myelinate/insulate MANY neurons in CNS -> create myelin sheath
- similar function to Schwann cells (mylinate ONE neuron each in PNS)
4
Q
function of astroglia
A
- aka: astrocytes
- ensheath tripartite synapse and ensure ionic balance within synapse
- play a role in neuronal communication
5
Q
function of microglia
A
act as immune cells in CNS
6
Q
tripartite synapse
A
the proximity of presynaptic membrane, postsynaptic membrane, and surrounding glia and the way these 3 synaptic components produce activity at the synapse
7
Q
major parts and functions of neurons
A
- nucleus: contains genetic material
- cell body: surrounds nucleus and other organelles inside neuron
- dendrites: receive signals and carry them to cell body
- axon: carries signals away from cell body (has synaptic bouton/pre-synaptic membrane at end of branch)
8
Q
types of synapses
A
- axosecretory: axon terminal secretes directly into bloodstream
- axioaxonic: axon terminal secretes into another axon
- axiodendritic: axon terminal ends on dendrite spine
- axoextracellular: axon with no connection secretes into extracellular fluid
- axosomatic: axon terminal ends on soma
- axosynaptic: axon terminal ends on another axon terminal
9
Q
resting membrane potential
A
- To measure: put intracellular electrode in neuron and extracellular electrode into extracellular fluid, measure difference
- Healthy neuron has RMP (or membrane voltage) of between –60 and –80 mV (~70 mV)
- at rest, more sodium ions outside neuron and more potassium ions inside neuron
10
Q
generation and conduction of post-synaptic potentials (PSPs)
A
- occur when a neutrotransmitter molecule binds to a post-synaptic receptor, creating one of two localized effects (EPSP or IPSP)
- transmission of PSPs graded (varies in size, NOT all-or-none), rapid, and decremental (decreases over time) -> travels like an electrical signal along an uninsulated wire
11
Q
Excitatory post-synaptic potential (EPSP)
A
- 1 effect of an NT binding to post-synaptic receptor
- Depolarizes the membrane (ie. Decrease membrane potential from -70 to -67 -> gets closer to 0)
- Increases likelihood that postsynaptic neuron will fire an action potential (AP)
12
Q
Inhibitory post-synaptic potential (IPSP)
A
- 1 effect of an NT binding to post-synaptic receptor
- Hyperpolarizes the membrane (ie. Increase the membrane from -70 to -72 -> gets further from 0)
- Decreases likelihood that postsynaptic neuron will fire an action potential (AP)
13
Q
summation of PSPs
A
- both EPSPs and IPSPs sum spatially and temporally
- spatial summation: when PSPs are released from multiple synapses, combining to produce a greater effect (either greater EPSP or IPSP, or cancel out 1 EPSP and 1 IPSP)
- temporal summation: when multiple PSPs are released from one synapse in rapid succession, combining to produce a greater effect (either greater EPSP or IPSP)
14
Q
What is an Action Potential (AP), and how is it generated?
A
- massive momentary reversal of the membrane potential (e.g., from -70 to +55 mV)
- not graded (“all or none”: either happens or doesn’t), not decremental, less rapid than PSPs
- occurs if the sum of the EPSPs and IPSPs is enough to depolarize membrane at axon initial segment above its threshold of excitation (ex. -65mV)
15
Q
Ionic basis of Action Potentials
A
- AP generation and conduction are both the result of voltage-activated ion channels
- when membrane is depolarized (due to PSPs), sodium channels open, driving excitation (lots of sodium outside cell; wants to move in)
