neurology Flashcards
neurons
excitable cells
generate APs
carry electrical potentials
many type (classified based on structure and function)
glial cells
non-excitable cells
physical and biochemical support for neurons
many types classified based on location and function
main types of glial cells in CNS
ependymal cells
astrocytes
microglia
oligodendrocytes
ependymal cels
important for formation of the blood brain barrier
creates barriers between compartments
source of neural stem cells
astrocytes
good sweepers
source of neural stem cells
take up water, potassium, neurotransmitters
secrete neurotrophic factors( help things grow in the right directions)
help form blood brain barrier
provide substrates for ATP production
microglia
modified immune cells
scavengers ( take up things that shouldn’t be there)
oligodendrocytes
form myelin sheath
glial cells of the PNS
schwann cells
satellite cells
schwann cells
form myelin sheaths just for one single axon
secrete neurotrophic factors
satellite cells
support cell bodies
node of ranvier
where APs are regenerated
section of unmyelinated axon membrane between two Schwann cells
multiple scherosis
autoimmune degeneration of CNS myelin; progressive
body’s immune system attacks myelin
guillain barre syndrome
autoimmune degeneration of PNS myelin; sudden onset and usually temporary
graded potentials
depolarization or hyperpolarizations
excitatory or inhibatory
amplitude depends of strength of stimulus and density of receptor channels
signal loses strength with distance travelled
increase stimulus; increase activation of channels
increase channel density; increase sensitivity to stimuli
action potentials
only depolarization
all or none response depends on membrane reaching threshold potential
sources of resistance to current flow in cells
membrane resistance: varies with channel gating
membrane good insulator increase Rm
open channels allow ion flow; decrease Rm
internal resistance of cytoplasm
dpeneds of cytoplasm composition
inversely related to cell diameter
larger diameter lower Ri
suprathreshold
trigger action pottential
subthreshold
do not trigger an action potential
what are the two types of signal integration
spatial summation and temporal summation
spatial summation
