meneghini 3-4 Flashcards
two portions of the nervous system
central: brain and spinal cord
peripheral: nerves (spinal nerves, cranial nerves and ganglia cells)
the PNS has the function to connect the CNS to sensory organs and other peripheral organs of the body
why does the grey matter have a brownish appearance?
due to the fact that contain the cell bodies (somas) of the neurons
what is contained in the white matter?
axons of the neurons, enriched in oligodendrocytes (mielinating cells)
what are the names of the 3 layers of connective tissue that cover the brain ?
meninges, located under the skull
-pia mater
-dura mater
-arachnoid mater
they protect the brain and recycle cerebrospinal fluid
what are the cells that lead to the formation of the peripheral nervous system from the neural tube?
neural crest cells
CNS cell types
- neurons
- glia cells
-oligodendrocytes, astrocytes, ependymal cells (all of them derive from the neural stem cells or also called radial glia cells) and microglia (derive from the hematopoietic lineage)
each neuron is composed of
soma (cell body)
multiple dendrites (that receive infos)
one single axon for each neuron that has multiple terminals->that give infos to target cells
types of neurons
multipolar
one axon, multiple dendrites
(common in CNS)
bipolar
one axon, one dendrite (ex: in the olfactory mucosa)
pseudounipolar
only one axon and peripheral branches as a T shape (connect CNS with peripheral NS)
Nissl bodies
aggregate of free ribosomes and rough ER
can be present in the soma and in the dendrites
not present in the axons
can be visualized with basic dies
what dictates the shape of the neuronal cells?
the neurofilaments
generated thanks to the production of structural proteins
what part of the dendrites receive the signal from the axon of the neighboring neurons?
spiny processes of the dendrites
where does the axon originate?
at the axon hillock, a region in the soma of neurons
what is the resting membrane potential of a neuron?
-60mV
what is the event that generates a depolarization in the membranes of neurons?
when an input arrives, voltage gate sodium channels open causing an influx of sodium ions that will change the neuronal resting potential from -60mV to +40mV (depolarization).
the depo. generates an electrical stimulus that is then transmitted along the axon
which of the 2 types of synapses (electric and chemical) is the one more common in mammals?
chemical one
neurotransmitters are used to communicate the electrical impulse between neurons
what is the most common inhibitory neurotransmitter?
GABA
what is the most common excitatory neurotransmitter?
glutamate
what are the myelinating cells of the CNS?
olygodendrocytes
what are the myelinating cells of the peripheral nervous system?
Schwann cells
which are the glia cells directly involved in the formation of the blood brain barrier?
astrocytes
3 types of astrocytes
protoplasmic
fibrous
intralaminar
tripartite synapsis comprehend:
- pre synaptic neuron
- post synaptic neuron
- astrocyte
astrogliosis
when astrocytes change their shape in response to injuries/diseaes of the CNS
glial fibrillary acidic protein (GFAP)
express by astrocytes
over expressed during astrogliosis
GLIAL BARRIER
formed by the foot processes of astrocytes between the CNS and the connective tissue (that can be found both at the meninges or sorrounsign big blood vessels)
this barrier avoids that the cells of the connective tissue invade the CNS and vice versa
BLOOD BRAIN BARRIER
made by
astrocyte processes
pericytes
endothelial cells
a barrier that regulates the passage of substances between blood and the CNS.
do microglia cells originate from neural stem cells like all the other glia cells?
no
they derive from the hematopoietic lineage
microglia in the homeostatic brain express 2 markers that can be used to distinguish them from boarder associated macrophages, which 2 markers?
PTY12, SALL1
what’s the name of the microglia in the homeostatic brain?
shape?
resting microglia with a very branched shape
ependyma
ciliated simple columnar epithelium made by ependymal cells that surround the ventricular system in the brain and the central canal in the spinal cord.
which are the cells that produce the cerebrospinal fluid?
ependymal cells
fluid rich of ions and proteins essential for the survival of the cells of the CNS
what is the name of the capsule that surrounds each nerve?
epineurium
what is the name of the specialized connective tissue that is in between the bundle of axons?
perineurium, highly vascularized
what is the name of the connective tissue inside each bundle of axons?
endoneurium
enriched of Schwann cells
Glia limitans barrier
Formed by the foot processes of Astrocytes
To divide the CNS tissue from the connective tissue present either at the level of the meninges or at the level of big blood vessels
Amoeboid microglia
Phagocytose the debris at the inflammatory site
We have 3 ventricles
3rd, 4th and lateral ventricle
Sensory ganglia
Dorsal root of spinal nerve, in the spinal cord
Contain sensory (afferent) neurons
Motor ganglia
Involved in autonomic nervous system
Which type of neurons we have in the sensory ganglia? In the motor ganglia?
Pseudounipolar neurons in the sensory ganglia
Multipolar neurons in the motor ganglia
NB:higher number of neurons and of satellite cells in the sensory ganglia
