exam review - quiz 6 Flashcards
name: types of propagation (2)
- unmyelinated axon
- continuous conduction
- AP at one spot + propagate by stim. adjacent regions
- AP in 1 direction only - myelinated axons
- saltatory conduction
- voltage gated Na+ channels at nodes
- faster AP flow
explain: continuous conduction
- unmyelinated axon
- mvt. of ions = local current
- only one direction because absolute refractory period desensitizes region
explain: saltatory conduction
- myelinated axon
- depol. at small regions at nodes of ranvier
- less ATP needed bc don’t need to reestablishb resting potential as much
- only one direction
name: factors affecting propagation speed (3)
- axon diameter
- more SA = more voltage gated Na+ channels = faster local current = faster propagation - amount of myelination
- heavy > lighter - temperature
- cool - slower
⤷ bc channels = prot. and prot. affected by temp.
name + describe: nerve fiber types (3)
Type A
- large diameter (fast)
- myelinated (fast)
- conduct at 15 - 20m/s
- motor neurons supplying skeletal and most sensory neurons
Type B
- medium diameter
- lightly myelinated
- conduct at 3 - 15m/s
- part of ANS
Type C
- small diameter (slower)
- unmyelinated (slower)
- conduct at 2m/s or less
- part of ANS
define: synapse
- junction between cells that allow comm.
- 2 types = elec. and chem.
explain: electrical synapse
- junction between 2 cells
- important for coordinated conditions
⤷ ex. cardiac musc., smooth musc.
-
explain: chemical synapse
- AP arrives at presyn. term. causing voltage gated Ca2+ channels to open 2. Ca2+ diffuses into cell stimulating exocytosis of synaptic vesicles
⤷ releases neurotransmitter - neurotransmitter diffuses from presynaptic term across synaptic cleft
- neurotransmitters combine w/ receptor sites causing ligand gated Na+ channels to open
- Na+ diffuses into cell and depol.
- no direct transfer of ATP
⤷ relies on neurotransmitters
explain: methods of removal of neurotransmitters (3)
- diffusion
- down conc. gradient - enz. degradation
- acetylcholine
- acetylcholinesterase = receptor
⤷ breaks down acetylcholine into acetic A and choline - uptake by neurons or glial cells
- neurotransmitter transporters
- prozac = serotonin reuptake inhibitor
⤷ lets serotonin stay in syn. cleft for longer (used as depression treatment)
- neurotransmitter transported takes norepinephrine back to presynaptic term. to reuse or degrade
explain: types of postsynaptic potentials (2)
- excitatory postsynaptic potential (EPSP)
- depol.
- may reach threshold to prod. AP - inhibitory postsynaptic potential (IPSP)
- hyperpol.
- inhibits resp.
- decreases AP (moves away from threshold)
**summation = adding signals
⤷ spatial = several axons releasing neurotrans. to same cell body
⤷ temporal = same area releasing many times
define: vertebral column, vertebral foramen, vertebral canal, intervertebral foramina
- vert. column = stack bone
- vert. foramen = openings in vertebrae
⤷ creates vertebral canal - vertebral canal = canal housing spinal cord
- intervertebral foramina
⤷ spaces between vertebrae
explain: shape of spinal cord
- not uniform, 2 enlargements
1. cervical (upper)
2. lumbosacral (lower) - conus medullaris = inferior end (tapered)
- filum terminale = anchors spinal cord to vertebral cord
explain: inside of spinal cord
- white matter = 2 halves (inside), 2 columns in half
⤷ each column subdivided into nerve tracts (fasciculi) - up and down
- myelinated
- gray matter = 4 categories
1. post horns = sensory nerves
2. anterior horns = motor neurons to skeletal musc.
3. lat. horns = ANS
**commisure = axons cross
name: regions of spinal cord (nerve numbers not plexuses)
- cervical = C1 - C8
- thorasic = T1 - T12
- lumbar = L1 - L5
- sacral = S1 - S5
- coccygeal = Co
question: how many pairs exit through each region in/around vertebral column?
- 1st pair exits between skull and first cervical vertebrae
- 4th pair exits via sacral foramina