week 2 (nervous) Flashcards
(22 cards)
question: what makes up the CNS vs PNS?
CENTRAL NS
- brain and spinal cord
PERIPHERAL NS
- nerves extending to periphery of body
explain: organization of vertebrate NS
CNS -> (PNS) afferent and efferent branches
afferent branch -> sensory branch bringing info back in towards brain
efferent branch -> somatic and autonomic
⤷ somatic = skeletal musc.
⤷ autonomic = SNS, PNS, ENS
name + define: two major cell types in NS
-
glial
- not excitable
- dev, and support cells
- help with electrical isolation
- more abundant than neurons (90%) -
neurons
- electrically excitable
- carry out electrical and chemical communication
name + define: main types of glial cells (CNS)(4)
-
ependymal
⤷ circulate CSF -
astrocytes
⤷ transport nutrients
⤷ remove debris
⤷ CNS equivalent of satellite cells -
microglia
⤷ remove debris and dead cells -
oligodendrocytes
⤷ myelin formation
⤷ CNS equivalent of schwann
name + define: PNS equivalents of oligodendrocytes and astrocytes
- oligo = schwann
- astro = satellite
**CNS = PNS
name + explain: functional zones of a vertebrate neuron (4) + which are electrical vs chemical
-
signal reception - chem
- in dendrites and cell body -
signal integration - elec
- in hillock -
signal conduction - elec
- in axon -
signal transmission - chem
- in axon terminals
define: membrane potential
- voltage difference across cell mem.
- can change
⤷ changes used in signaling
question: how do excitable cells change to allow membrane potentials?
- alter cell permeability
- allows changes in electrical activity -> signal propagations
question: at each functional zone of a neuron, is it following a chemical or electrical gradient?
- signal reception = chemical
- signal integration = electrical
- signal conduction = electrical
- signal transmission = chemical
question: is the inside or outside of a cell more electronegative?
- inside
question: how is equilibrium potential maintained?
- ions will always try to make the membrane potential an equilibrium
- ex. permeability changes and K+ channels open
⤷ K+ from inside the cell will move out bc following conc./chem. gradient
⤷ but K+ always wants to be inside the cell bc of it’s electrical gradient
⤷ outward gradient eventually equals inward gradient
name: the chemical, electrical, and electrochemical gradient directions of K+ and Na+ ions at rest (-70mV)
K+
chem = out
elec = in
electrochem (net) = out
Na+
chem = in
elec = in
electrochem = in
question: what helps maintain resting mem. potential?
- passive forces
⤷ leak channels for Na+ and K+
⤷ K leak moves K in
⤷ Na leak moves Na out - active process
⤷ NaK pump
question: diff. between depol. and hyperpol.?
- depol = making it more +ive inside
⤷ membrane potential becomes more +ive - hyperpol = making it more -ive inside
⤷ membrane potential becomes more -ive
define: graded potentials
- short distance signals
- decays with distance
- summation of graded potentials determines if action potential will occur
question: how do graded potentials result in an action potential?
- sum of graded potentials reached threshold potential -> action potential
define: spatial summation vs temporal
- for graded potentials
- spatial = graded potentials from diff. sites happen at the same time
- temporal = graded potentials at same site happens repeatedly
compare: graded potentials and action potentials
GRADED
- dendrites
- depol. or hyperpol.
- short distances
- can initiate AP
- decay with time
ACTION
- axon hillock
- depol.
⤷ need to reach threshold
- all or nothing
- long distances (alon axons)
- caused by open/close ion channels
- no decay over time
name + explain: what is happening at each phase of the AP graph (3)
- phase 1 = (rapid) depolarization
- Na+ opens
⤷ when graded potentials depolarize enough to reach threshold
- Na+ coming in exceeds K+ leaving - phase 2 = rapid repolarization
- K+ opens around same time Na+ closes
- K+ exit exceeds Na+ coming in - phase 3 = hyperpolarization
- K+ channels slow to close
- hyperpolarization happens
- K+ eventually close and restores mem. potential resting value
question: which channels have a double lock (inactivation gate)? and why?
- Na+ channels
- helped refractory period
- prevents AP from going backwards
- K+ don’t have
question: how is an AP propagated along an axon?
- +ive charges at depol. area are attracted to nearby -ive areas
- spreads current to depol. adjacent regions
question: how does myelination impact conduction velocity?
- increases velocity
- allows saltatory conduction
⤷ jumps from nodes of ranvier to other nodes - less current leaks out through channels
