Chapter 2: Structure And Functions Of Cells Of The Nervous System Flashcards
Central nervous system
Brain and spinal cord
Peripheral nervous system
Part of nervous system outside brain and spinal cord, including nerves attached to brain and spinal cord
Nerves
Bundles of individual neurons contained within protective membrane
- relay sensory to CNS from body and motor info from CNS —> rest of body
Sensory Neurons
Neuron that detects changes in external or internal environment and sends info about these changes to CNS
Motor Neuron
Neuron located within CNS that controls contraction of muscle or secretion
Interneuron
Neuron located in CNS in between sensory and motor neurons
Nucleus
Structure in central region of cell, containing chromosomes
Soma
Long, thin, cylindrical structure that conveys info from soma of neuron to its terminal buttons
Dendrite
Branched, treelike structure attached to soma of a neuron
- receives info from terminal buttons of other neurons
Axon
Long, thin, cylindrical strcuture that conveys info from soma of neuron to its terminal buttons
Myelin Sheath
Sheath that surrounds axons and insulates them, preventing messages from spreading between adjacent axons
Terminal Button
Bud at end of branch of an axon
- sends info to that neuron
Synapse
Junction between terminal button of an axon and membrane of another neuron
Axoplasmic Transport
Active process by which substances are propelled along microtubules that run the length of axon
*anterograde and retrograde
Anterograde Transport
In direction along an axon from cell body toward terminal buttons
- remarkably fast (500mm per day)
Retrograde Transport
In direction along an axon from terminal buttons toward cell body
- half as fast as anterograde transport
Neurotransmitter
Chemical that is released by terminal button
- can be + or - to another neuron
Membrane
Structure consisting principally of lipid molecules that defines outer boundaries of a cell and constitutes many of cell organelles
Cytoskeleton
Formed of microtubules and other protein fibers, linked to each other and forming cohesive mass that gives cell its shape
Microtubule
Long strand of bundles of protein filaments arranged around hollow core
- involved in transporting substances from place to place within cell
Cytoplasm
Viscous, semiliquid substance contained in interior of cell
Chromosome
Strand of DNA, with associated proteins, found in nucleus
Gene
Functional unit of the chromosome, which directs synthesis of one or more proteins
Enzyme
Molecule that controls chemical reaction, combining or breaking substances
Mitochondria
Organelles that are responsible for extracting energy from nutrients
- Produces ATP
Glia
Supporting cells of CNS
Astrocytes
Provides support for neurons in CNS, provides nutrients and other substances, and regulates chemical composition of ECF
- can have aquaporin
- “neuron glue”
- surround and isolate synapses, limiting dispersion of NTs
- phagocytosis
Phagocytosis
Process by which cells engulf and digest other cells or debris caused by cellular degeneration
Oligodendrocytes
Type of glial cell in CNS that form myelin sheath
- Node of Ranvier
- one oligodendrocyte can produce up to 50 segments of myelin
Node of Ranvier
Nakes portion of myelinated axon between adjacent oligodendroglia or Schwaan cells
Microglia
Smallest of glial cells
- act as phagocytes and protect brain from invading microorganisms
- involved in inflammatory reaction following brain trauma
Schwaan Cells
Cell in PNS that is wrapped around myelinated axon, providing one segment of its myelin sheath
- each PNS myelin segment consists of a single Schwann cell
- chemical composition of myelin differs between CNS and PNS
- MS is autoimmune attack of myelin in CNS
Blood-Brain Barrier
Semipermeable barrier between blood and brain produced by cells in the walls of brain’s capillaries
- not uniform throughout nervous system
- regulates composition of ECF
- made up of astrocyte feet and tight junction layer
- lipid soluble go through, water- soluble don’t
Ex. Area postrema
Membrane Potential
electrical charge across cell membrane
- difference in electical potential inside and outside cell
Resting Potential
membrane potential of neuron when it is not being altered by excitatory or inhibitory postsynaptic potentials
- about 70mV in many neurons