Flashcards in Ch.11 The Nervous System Deck (60):
receive sensory input, interpret it,
and send out appropriate commands
3 interconnected functions:
sensory input, integration, motor output
conduct signals from sensory receptors
interpret sensory signals and formulation of response.
conduction of signals to effector cells
CNS consists of:
brain, spinal cord
PNS consists of:
cranial nerves, ganglia, spinal nerves
relay messages. afferent (sensory info in) and efferent (motor commands out).
Efferent leads to:
somatic (voluntary movement) EAT A BANANA and autonomic (unconscious responses) DIGEST BANANA
autonomic leads to :
parasympathetic (rest and digest) and sympathetic (fight or flight/ getting excited)
two main cell types:
glial cells and neurons
glial cells (neuroglia)
supporting cells that wrap around neurons
transmit electrical signals
CNS neuroglial cells (4 types):
Astrocytes, Microglial, Ependymal, Oligodendroctyes
support, transport glucose, metabolize neurotransmitters
branched (processes). Immunity, macrophages (digest/ engulf/ breakdown)
cilia, circulates cerebrospinal fluid (CSF). Cuboidal columnar. (cushoning) inbetween skull and brain
generates myelin sheath.
PNS Neuroglial cells (2 types):
Shwann Cells, Satellite Cells
Shwann cells: (no arms)
flattened cells, wrap around axons that form myelin sheath in PNS
Satellite cells: (flat, no arms)
flattened cells surround cell bodies to provide support framework.
structural unit of nervous system
Neurons consist of :
dendrites, axon, myelin sheath, cell body (nucleus/ nucleolus), axon terminals
Cell body (soma/ perikaryon):
Amitotic nature (repair not divide), Axon hillock (axon originates), Neurofibrils (intermediate filaments maintain shape)
short, branching, pass electrical impulse on to cell body. electrical signals passed along GRADED POTENTIAL.
slender long processes, conduct electrical impulses. (collaterals= side branches)
Axons 2 movements:
anterograde (towards axon terminus), retrograde (towards cell body).
gap between dendrites of one neuron and axon terminals of another neuron
myelin sheath (insulates to protect elecritcal impulse from shorting out). White matter.
Two cells giving rise to myelin sheath:
shwann cells in PNS and Oligodendrocytes in CNS
Nodes of Ranvier:
myelin sheath gaps
structural classification (3):
Multipolar, Bipolar, Unipolar.
many dendrties, one axon (Most in CNS). purkinje fibres (heart), pyrimidal cells, granule.
one fused dendrite and axon.
one process emerging from cell body
CNS cluster of cell bodies on the neurons
PNS cluster of cell bodies on the neurons
membrane ion channels:
leakage (always open), Gated Channels (chemically, voltage, mechanically)
chemically gated channels:
open with the binding of specific neurotransmitters (sodium/ potassium)
voltage gated channels:
open and close in response to membrane potential
mechanically gated channels:
open and close to physically deformation of receptors
resting membrane potential
K+ greater intracellular and membrane more permeable to K+ so "leaks" or diffuse out of cell. SODIUM POTASSIUM PUMP (moves K+ back into cell) And sodium moves in (pump moves it out) . -70mv
unequal sharing of electrons. (opp charges at both ends)
-70mv (depolarization) -80mv (hyperpolarization) -60 (repolarization)
2 types of electrical signals :
graded potential, action potentials
decreases with distance travelled.
occurs in muscle cells. always the same "wave" regardless of stimilus. (DOES NOT DECREASE OVER TIME) de-polarizing, hyperpolarizing, polarizaing.
4 stages of action potential:
resting state, depolarization, repolarization, hyperpolarization
Na and K channels closed. activation gates closed / inactivation gates open.
moving up. Na+permeability increases; membrane potential reverses. Na+ gates open; K+ gates remain closed.
dropping back down to close. Na+ gates close, K+ gates open.
"undershoot" takes a little while to close. K+ gates close.
propagation of action potential:
constantly being attracted to the negatives. impulses will only travel in one direction away from the trigger zone.
speed up impulse:
temperature (warmer), myelin sheath (insulation/ prevent leakage), larger diameter