nervous system notes Flashcards
what is the nervous system?
master controlling and communication system
how does the nervous system communicate?
via electricity and chemicals (neurotransmitters)
sensory input
gathered by sensory receptors
integration
processing of sensory input
motor output
activation of effector organs (muscles and glands)
what two regions are in the CNS?
Central
Peripheral
where is the PNS located
outside of the CNS
spinal nerves
to and from the spinal cord (there are 31)
cranial nerves
to and from the brain (there are 12)
functions of PNS
Sensory
Motor
sensory
somatic
visceral
somatic
from skin and skeletal muscles and joints to CNS
visceral
from visceral organs
motor
somatic
autonomic
somatic nervous system
voluntary: conscious control of skeletal muscles
autonomic
regulates smooth muscle, cardiac muscle and glands
sympathetic
fight or flight
parasympathetic
brings body back to normal state
neuroglia cell types
neuroglia
neurons
neuroglia of CNS
astrocytes
microglial cells
ependymal cells
oligodendrocytes
astrocytes
controls the environment around neurons
microglial cells
cleans up around the neurons
ependymal cells
line cavities of brain and spinal chord - moves cerebral spinal fluid
oligodendrocytes
insulates nerves in the CNS - provide the myelin sheaths
neuroglial of PNS
satellite cells
Schwan cells
neurons
extreme longevity
amniotic, with few exceptions
high metabolic rate
tracts
bundles of neuron processes in CNS
nerves
bundles of neuron processes in PNS
axon
- starts at axonal hillock
- long axons are called nerve fibers
- far ends are called axon terminals
- secrete neurotransmitters
- myelin sheath
myelin sheath
- protects and electrically insulates the axon
- increases speed of conduction
- gaps - axon colladerals emerge
- white matter - regions of the brain and spinal chord with lots of mylenation
- gray matter - non myelinated fibers
structural classification of dendrites
multipolar
bipolar
unipolar
sensory
sends signals to the brain
motor
sends signals away from the brain
interneurons
almost all are in the CNS; association neurons
Neurons can ______ change their resting membrane potential
Rapidly
Neurons are
Highly excitable
Membrane ion channels are
Large proteins, and specific k+ channels that only allow pass through
leakage/nongated channels
always open
Gated channels
Part of the protein changes shape to open/close channel
Chemically (ligand)
Open only with binding of a specific chemical
Voltage
Open and close in response to changes in membrane potential
Mechanically
Open and close in response to physical deformation of sensory receptors
When channels are open
Ions diffuse quickly from high to low, move towards opposite charges
Resting membrane
- ⭐ Approx: -70 mV ⭐
- Cytoplasmic side
Negatively charged relative to the outside - Range
-40 mV to -90 mV - Is said to be polarized (separation of charges)
Generating membrane potential depends on
- Differences in sodium ion and potassium ion concentration
- Differences in permeability
Membranes are impermeable to
large anionic proteins
Slightly permeable to
Na+ → into cell
25 more permeable to
K+ → out of cell
Quite permeable to
Cl-
More __ diffuses out than __ in
- K+, Na+
- Inside of cell is more negative
Sodium potassium pump stabilizes
Membrane potential
Resting potential change when
- Concentrations change
- Permeability changes
Changes produce 2 types of signals
- Graded potentials
- Action potentials
Graded potentials
- Short distances
- Short lived - localized changes in membrane potential
- Triggered by - stimulus that opens gated ion channels
- Named by location and function
- Current flows quickly but decays, only over short distances
Action potentials
- Long distances
- Brief reversal of membrane potential
- Do NOT decay
- Also called nerve impulse
Principal way neurons send signal, only over long distances
Depolarization
Move toward zero and above, become more positive
Hyperpolarization
Move away from zero, become more negative
Generation of AP
Look at graph on paper
