Cytology Flashcards
Golgi I Multipolar Neurons
-long axon that projects from one subsystem to another (eg brain to SC, SC to foot)
Golgi II Multipolar Neurons (Interneurons)
-short axons, make connections in same subsystem
Segmental Interneurons (Types)
- project only to same segment of SC
1. Associative – same side of SC
2. Commussural – crosses sides
Propriospinal Interneurons
-project to other SC segments
Tract Cells
- similar to Golgi I neurons but reside only in CNS
- tracts = collection of fibers sending same information
Excitatory NT’s (3)
AcH, glutamate, Serotonin
Inhibitory NT (1)
GABA
Dopamine
can be BOTH excitatory and inhibitory
Functions of Intracellular Matrix (3)
- gives cell shape, stiffness
- provides mechanisms for growth, motility
- provides internal network for transport of molecules, organelles
Components of Axon (3)
- actin filaments - structural integrity
- neurofilament - mechanical integrity
- microtubules - carry fluids
Glia – functions (4)(MouNDS)
- developmental (scaffold, release GFs)
- support
- nurture
- maintain constant environment
Astrocytes - fibrous
supports axons in white matter
Astrocytes - protoplasmic
supports axons in gray matter
Astrocytes - perivascular
psuedopodial projections onto blood vessel endothelium
Oligodendrocytes
produce myelin in CNS
Microglia
- derived from mesoderm
- clean up debris in CNS (instead of having large WBC’s)
Ependymal cells
- converted neuroepithelial cell
- when stops producing neurons, acts as a limiting membrane to ventricle system & produces CSF
Choroid Plexus
area of ventricle where ependymal cells produce CSF
Schwann Cell
produces myelin in periphery
Satellite glia
- astrocyte-like functions (support)
- supports neurons in periphery (ganglia)
Perineural Glia
structure
Gliosis
proliferation of astrocytes to form plaques of scars
-reaction to injury
Iontotropic receptor
- typical synapse
- gated ion channel
Metabotropic receptor
- receptor activates G protein
- G protein subunit activates ion channel directly or indirectly
Epineurium - types
- Epifasicular - surrounds whole nerve
- Interfasicular - loosely attached to epifasicular, fills in spaces between fasicles, helps disperse compressive forces
Perineurium
- type I & II collagen
- surrounds fasicles
- oriented in oblique, longtitudinal, and circumferential directions
- up to 15 layers thick
- present in tight junctions, BBB
- mechanical strength (primary load bearing portion)
Endoneurium
- surrounds individual axons
- type I & II collagen
Microcirculation of a nerve
- enter epineurium periodically
- divide into arterioles that form anastamosing network in epi/perineurium
- vessels in endoneurium become capillaries, travel longitudinally
Neurolemma
- Schwann cell plasma membrane
- surrounds all peripheral nerves, even unmyelinated
- one schwann for many unmyelinated axons, 1:1 for myelinated
Myelin sheath in PNS
Schwann cell membrane (neurolemma) wraps around axon to form myelin sheath
Myelin sheath in CNS
- no neurolemma sheath, not 1:1 relationship
- oligodendrocytes
Ia
- motor: extrafusal ms fibers (Aalpha)
- sensory: primary afferent of ms spindle
Ib
-sensory: GTO, touch/pressure receptors
II
- motor: both inta/extrafusal ms fibers (Abeta)
- sensory: secondary afferents of muscle spindles, touch/pressure receptors, pacinian corpuscles
III
-sensory: small, lightly myelinated fibers - touch/pressure, pain, temp
IV
- motor: all post ganglionic fibers
- sensory: P&T
SVE
cranial nerves motor to skeletal muscle eg) facial muscles
SVA
visceral sensations - taste & smell
SSA
somatic sensations - vision, hearing, equilibrium
GSA
-conscious sensation (pain, temp, touch, proprioception)
GVA
visceral sensation (ischemia, BP)
GSE
voluntary motor to skeletal muscles
GVE
autonomic motor to smooth/cardiac muscles and glands (PSNS, SNS)
