Nervous system (4) Flashcards
Oligodendrocytes
Myelin cells in CNS
Schwann cells
Myelin cells in PNS
Astrocytes
nourish neurons and form the blood-brain barrier
Ependymal cells
line the ventricles of the brain and produce cerebrospinal fluid, supports the brain, and serves shock absorber.
Microglia
phagocytic cells that ingest and break down waste products and pathogens in the CNS.
Resting membrane potential
-70mV , maintained by Na+/K+ ATPase
Temporal summation
multiple signals are integrated during a relatively short period of time
Spatial summation
integration of multiple signals close to each other in space.
Three main methods by which NT’s action can be stopped
Enzymatic degradation (ACh breaks down by AChE)
Reuptake (serotonin 5-HT) (Dopamine) (Norepinephrine)
Diffusion (Nitric oxide NO)
Brain:
White matter
Grey matter
White matter - consists of axon encased in myelin sheaths. (Inside part of brain)
Grey matter- consists of unmyelinated cell bodies and dendrites. (Outside part of brain)
Spinal cord:
White matter
Gray matter
White matter- outside of the cord
Grey matter- inside part of the cord
Monosynaptic reflex arc
single synapse between the sensory neuron that recieves the stimulus and the motor neuron that responds to it. (knee-jerk reflexs)
Polysynaptic reflex arc
at least one interneuron between the sensory and motor neurons. (stepping on the nail involves withdrawal reflex. reflex will include hip muscles and hamstring muscles pulling the foot away from the nail).
Absolute Refractory period
No amount of stimulation can cause another action potential to occur.
Relative refractory period
There must be greater than normal stimulation to cause an action potential because the membrane is starting from a potential that is more negative than its resting state.
