neurons and glia Flashcards
gyri
ridges
sulci
grooves
what are the 3 types of glia cells
- astrocytes
- oligodendroglia
- microglia
what are the 2 types of ventricular system cells
- choroid plexus epithelium
- ependymal cells
neurons are derived from:
neuroectoderm
dendrites
recieve stimulus from another neuron in the CNS or from environment in the PNS
cell body (soma)
portion that contains nucleus and integrates information
nissl substance/rough endoplasmic reticulum (RER)
protein synthesis (neurotransmitter factory)
axon
conveys information (nerve impulses and neurotransmitters); can be quite long (meters)
synaptic end bulbs (temrinal boutons)
transmit information to next cell
synaptic end bulbs (temrinal boutons)
transmit information to next cell
microtubules
- tubulin
- present in dendrites and axons
intermediate filaments
- neurofilament
- form matrix with embedded microtubules for axonal transport
microfilaments
- actin
- dendritic spines and growth cone of developing and regenerating neurons
what do glial cells account for
majority of cells in CNS
astrocytes
- help maintain blood brain barrier
- regulate nutrients to neurons
- insulate synapes
- neuroectoderm dervived
- cytoskeleton (tubulin, glial fibrillary acidic protein - GFAP, actin)
oligodendrocytes
- produce myelin
- one cell can insulate many neurons
- neuroectoderm derived
- cytoskeleton (tubulin, no intermediate filaments, actin)
microglia
- resident macrophages of CNS (phagocytosis and antigen presenting)
- help regulate neuron fuction
- yolk sac derived
- cytoskeleton (tubulin, vimentin, actin)
what are ventricles
fluid filled sacs (CSF)
what does CSF do
- circulates in ventricles and subarachnoid space
- shock absorber
- transport of nutrients, wastes, hormones
ependymal cells
- form lining of ventricles
- neuroectoderm derived
- produce, move, and absorb CSF
- regulate fluid homeostasis (between ventricles and brain)
- scavenge (phagocytosis), metabolize, and detoxify substances in CSF
choroid plexus cells
- produce CSF
- neuroectoderm derived
- line the choroid plexus
- epithelial-endothelial border (blood CSF barrier)
meninges
- meningothelial cells
- connective tissue covering of the CNS
- carry blood vessels to cerebral cortex (blood meningeal barrier)
- CSF in subarachnoid space provides cushion and nutrients
what are the 3 layers of the meninges
- dura mater - pachymeninges
- arachnoid and pia mater w/ subarachnoid space inbetween (leptomeninges)
blood brain barrier components
- specialized vascular endothelial cells
- tight junctions and unique basement membranes
- astrocyte foot processes
blood brain barrier
- protects the brain from pathogens and xenobiotics
- regulates diffusion of hormones and cytokines
- contributes to sustain the delicate CNS homeostasis
blood meningeal barrier components
- specialized vascular endothelial cells
- tight junctions and basement membrane
blood meningeal barrier
same properties as BBB bus less restrictive and promote immune responses during injury/infection
blood CSF barrier components
- choroid plexus epithelial cells with tight junctions
- vessels in choroidal stroma are fenestrated
- arachnoid membrane
blood CSF barrier
regulates movement of agents from blood to CSF
what is grey matter comprised of
neuronal cell bodies and dendrities (and thinly myelinated axons) and glia
grey matter is organized into:
laminae
- cerebral cortex & cerebellar cortex
nuclei
- diencephalon (at base of cerebral hemispheres)
- cerebellar and brainstem nuclei
grey matter is ____ of nerve impulses
generation
what is white matter composed of
neuronal axons (myelinated) and glia
how is white matter organized
- centrally in cerebrum : coronal radiata and corpus callosum and internal capsule
- intermixed with grey matter in brainstem
- funiculi and tracts in spinal cord
white matter is ____ of nerve impulses
conduction
all neurons have:
- receptive segment
- conductile segment
- transmissive segment
- cell body
cell body of neuron location differences
- can be in receptive segment (olfactory, motor, interneurons)
- can be in conductive segment (auditory and vestibular afferent)
- can be branched off conductile segment (all other afferent)
afferent neurons
signal moves towards CNS
efferent neurons
signals moves away from CNS
afferent neurons components
- conduct sensory impulses cranially to CNS (each may synapse w/ many reflex pathways & many projections neurons)
- cell bodies in ganglia
- pseudounipolar or bipolar
- branch into: longer cranial branch and many shorter caudal collateral branches that synapse with interneurons
interneurons
- cell bodies and all processes entirely within CNS
- excitatory or inhibatory (dependent upon neurotransmitters released)
projection neurons
- upper motor neurons
- pathway begins in cerebral cortex or nucleus -> ends/synapses in brainstem or spinal cord
- conduct impulses caudally (or cranially)
efferent neurons
- lower motor neurons
- stimulated to generate impulses by neurotransmitters from afferent, interneuron, or projectile neuron
upper motor neurons
- projection neurons
- initiate voluntary movement
- cell bodies in cerebral cortex or brainstem nuclei
- axons do not leave CNS
lower motor neurons
- efferent neurons
- innervate and activate skeletal muscle
- cell bodies in CNS (brainstem gray matter and ventral horn of spinal cord)
- axons leave CNS to PNS
