nervous system 2 Flashcards
direction of information flow through neurons
dendrites -> cell body -> axon
types of specialised glial cells
astrocytes, schwann cells
whats the most numerous cell type on the brain?
astrocytes
what is the role of astrocytes
‘housekeeping’ role. regulate chemical content of extracellular space. support structure in spaces between neurons
which type of specialised glial cells myelinate axons
schwann cells
another name for sensory axons in PNS?
afferent axons
another name for motor axons in PNS?
efferent axons
which roots in the spinal cord contain which roots
dorsal roots = afferent axons
ventral roots = efferent axons
what type of axons to spinal nerves contain
afferent and efferent axons (both)
what are the actions of afferent and efferent axons
afferent axons - from skin send info to spinal cord and brain
efferent axons - innervate muscles
what actions do the spinal cord take part in
reflexive actions which are automatic not requiring the brain.
what are excitable cells? function?
electrically charged cells, use electrical currents to sense stimuli, transmit information, and ‘do something’
can ions diffuse through the phospholipid membrane?
no!
how must ions pass through the cell membrane?
through ion pumps or channels
concentrations of sodium, chloride, potassium in the cytoplasm and extracellular fluid?
extracellular - high sodium and chloride, low potassium.
cytoplasm - high potassium, low sodium and chloride
what does the sodium-potassium ATPase do?
used ATP to transfer 3Na+ ions in and 2K+ ions out
what are ion channels
proteins which make pores/gated which allow ions to move across the lipid membrane. can be selective for particular ions
what are leak potassium channels
open at rest, help set the resting membrane potential, selectively permeable to potassium
what are leak potassium channels regulated by
pH, oxygen tension, stretch
what are the two forces determining which side of the membrane potassium goes at rest
concentration gradient - diffuses out of cell as higher concentration inside
electrical force - diffuses into cell as imbalance of potassium and corresponding negative ion
which side of the membrane is positive and which is negative during rest
inside - negative
outside - positive
concentration gradient means more K+ (positive ions) out and more corresponding negative ions inside
what is the resting membrane potential in volts
-65mV
two pumps that bring about the resting membrane potential
potassium leak channels, sodium/potassium ATPase
another name for cell body
soma
how does frequency of action potentials encode information
higher frequency of action potentials can mean greater sensory stimulus
