week 2 Flashcards
diff between CNS and PNS?
CNS: brain + spinal cord. receives/processes info from organs and returns info to organs w instructions on what to do.
PNS: all other neurons in body. provides communication between CNS and organs.
afferent vs efferent neurons?
- afferent: input– transmit info from organs to CNS, i.e., sensory info.
- efferent: output– transmit info from CNS to effector organs.
somatic vs autonomic
- somatic: skin and muscles, voluntary activities.
- autonomic: nerves connected to organs, involuntary activities.
key diff between neurons and glial cells
- neurons are excitable
- glial cells are support cells
define: a) soma, b) dendrites, c) axon, d) axon hillock, e) axon terminal
a) soma: body, contains nucleus/organelles
b) dendrites: receive info
c) axon: transmit APs
d) axon hillock: where axon originates and where APs are initiated
e) axon terminal: release neurotransmitters
anterograde vs retrograde transport
anterograde: moving products from soma to axon terminal.
retrograde: moving products from axon terminal to soma.
4 types of glial cells and their functions
- astrocytes: clean transmitter.
- microglia: protect CNS from foreign matter.
- oligodendrocytes (myelinate)
- schwann cells (myelinate)
why is myelin important?
- allows signal to be transmitted without much signal loss over distance.
- in other words, increases membrane resistance.
key diff between oligodendrocytes and schwann cells?
- one oligodendrocyte forms several myelin sheaths and myelinates sections of several axons (CNS).
- one schwann cell forms one myelin sheath and myelinates one section of an axon (PNS).
node of ranvier
- gaps between myelinated sections of axon
what happens when many myelin sheaths are damaged? symptoms? one solution?
- multiple sclerosis: the slowing down/blockage of signal between neurons
- symptoms: visual disturbances, muscle weakness, numbness/”pins and needles”, thinking/memory problems
- one solution: reduce leakiness by blocking potassium channels
define: a) leak channels
b) ligand-gated channels
c) voltage-gated channels
a) always open, throughout entire neuron, determine resting potential
b) open/close in response to ligand binding, at dendrites and soma, cause synaptic potentials
c) open/close in response to membrane potential changes, sodium and potassium channels are mainly in axon hillock, calcium channels mainly in axon terminal
T or F: all cells in the body generate a membrane potential, even non-excitable ones.
true
typical resting MP of neuron?
-70 mV
what 2 things do we need for a resting MP?
- concentration gradients (ion pumps)
- semi-permeable membrane (ion channels)
__% of the resting membrane potential is directly due to Na+/K+-ATPase.
this consumes ___ of the body’s energy
20%
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