nuero lab neurons, neuroglia and dev of NS Flashcards
main difference betw neurons and neuroglia
neurons - excitable cells
neuroglia - non-excitable
these are the functional unit of the NS
neurons
these are the supporting cells of the NS
neuroglia
what are the functions of neurons
they receive and conduct impulses
they can also be electrically excited = action potential
what are the parts of a neuron
dendrites
soma
axon
function of dendrites
receive, process and transmit signal to soma
function of soma
processes and integrates signal and has nucleus and stores DNA
basta CPU ng neurons
function of axons
transmit information between neurons or away to muscles and glands
describe the structure of the axon
initial segment is the first portion then it divides to pre-synaptic terminals which ends at synaptic knobs/terminal buttons
where is impulse transmitted in neurons
along the axis to its termination
what do neurons respond to
electrical, chemical and mechanical stimuli
electrical, chemical and mechanical stimuli produces _____ in neurons
producing local or propagated potentials
how are neurons classified
according to the number of processes attached sa soma
neuroglia comprises _____ of vol of brain and SC
half of total volume - outnumbers neurons by 5-10x
what is the function of neuroglia
binds neurons together and facilitates their functioning
does not conduct AP
relate neuroglia and brain injury
they proliferate after brain injury
which are smaller neurons or neuroglia
glial cells are generally smaller
how are neuroglia classified
according to size - micro/macroglia
what are the types of neurons according to shape
unipolar
pseudounipolar
bipolar
multipolar
describe the structure of unipolar
only one process extends from soma - receiving and transmitting na
the neurite in unipolar divides into ?
2 branches
peripheral - referred as dendrite but not rlly one
CNS
where are unipolar neurons found
pang sensory lang sha pero usually sa insects lang wala sa tao
for muscle and gland stimulation sa insects
describe the structure of pseudounipolar
short branch coming from soma then in divides into two long processes
where does pseudounipolar attach
one end in sensory organ the other in DRG
so sensory neurons sha in humans
describe the structure of bipolar
cell body with 2 processes connected to soma - axon and dendrite
give an example of bipolar neuron
bipolar cell of retina - dendrite receives signals from photoreceptors tas axon will transmit away
retinal bipolar cells, cochlear and vestibular sensory cells
what type of neuron splits its axon into 2
pseudounipolar
where are pseudounipolar seen in the body
most cranial nerves’ sensory ganglia
describe the structure of multipolar
many dendrites and one axon
longest process is axon tas the rest are dendrites
where are multipolar found
sa brain and SC; most common type sa CNS
give an example of multipolar in the body
purkinje cells of cerebral cortex
where can purkinje cells be seen
fiber tracts of brain and SC, spinal nerves and motor cells of SC
what are the types of neurons according to size
golgi type 1 and golgi type 2
describe the structure of golgi type 1
larger in size, long axons usually more than meter tas may dendrites din
what is the function of golgi type I
relay info from one region of the brain to another - dendrites receive tas axons will transmit away from soma
where are golgi type I usually seen
peripheral nerves and tracts of brain and SC
give examples of golgi type I
pyramidal cells of cerebra cortex
purkinje cells of cerebellar cortex
motor cells of SC
describe the structure of golgi type II
smaller bodies with short or no axons at all kc nag tterminate agad sa near by cell
and short dendrites
star shaped
function of golgi type II
small local interactions bet 2 neurons - interneurons sha
and inhib in nature
which is mas madami golgi type I or II
type II outnumbers type I in cerebral and cerebellar cortex
what are they types of neuroglia
astrocytes
oligodendrocytes
Schwann cells
ependymal cells
microglial
what are the function of astrocytes
maintains blood-brain barrier
supports neurons and anchor them to nutrient supp lines
regulate external chemical environment
functions as phagocytes
further exp how astrocytes maintains blood-brain barrier
protective membrane around brain and SC that allows respiratory gasses to pass but block anything larger
also produces substances that are tropic to neurons
helps maintain correct concentration of ions and neurotransmitters
further exp how astrocytes supports neurons and anchor them to nutrient supp lines
supporting framework of neurons; scaffolding of CNS
further exp how astrocytes regulate external chemical environment
removes excess potassium ions and recycling neurotransmitters released during synaptic transmission
further exp how astrocytes functions as phagocytes
di nag rregen and neurons so they take up degenerating parts ganun
what are the two types of astrocytes and their function
protoplasmic and fibrous - stores glycogen and phagocytes for the degenerating synaptic axon terminals
compare the loc of protoplasmic and fibrous
proto - gray matter
fibrous - white matter
what are the functions of oligodendrocytes
myelinate axons in CNS
influence biochem of neurons
further exp how oligodendrocytes myelinate axons in the CNS
lines along the nerve and produces insulating layer of myelin sheath
what is the significance of myelination of axons
allows rapid saltatory conduction of impulses and also contributes to axonal integrity
how many internodal segments can be covered by 1 oligodendrocyte
60 internal segments - kaya pag na damage 1 oligo = 6 0 segments removed and walang propagation
what in the function og schwann cells
myelinates axons all nerve fibers in the PNS
also maintains and regenerates motor and sensory neurons of PNS
how many myelin sheath created w 1 schwann cell
1 schwann = 1 myelin
where are ependymal cells found
lines ventricles or cavities of the brain and central canal of spine
describe the structure of ependymal cells
cuboidal in shape and make up a single layer with microvilli and cilia
what is the function of ependymal cells
secrete and move CSF throughout cavities of CNS
filter mats from nearby bv to create CSF
facilitate flow of CSF by using cilia to circulate it
what are the 2 types of ependymal cells
ependymocytes and
choroidal epithelial cells
what are ependymocytes
circulates and absorb the CSF;
tanycytes which transport substances from CSF to hypophyseal-portal system
what are choroidal epithelial cells
from choroid plexus and the produce and secrete CSF
where is CSF made from
from blood plasma - ultrafiltrate of blood
what is the function of microglial cells
removes cell debris wastes and pathogens from site s of injury via phagocytosis - migrates to site of lesion
immune cells of CNS
what is the significance of microglial cells
can be used to detect injuries to the neuron
if high levels in lab test - presence of nerve tissue damage; may degenerative disease of NS
where can microglial cells be found
scattered in CNS and are active there
inactive in normal brain and SC
what are the phases of nerve AP
resting stage
depolarization
overshoot
repolarization
hyperpolarization
discuss resting stage
may resting potential of -90 mV before start of AP
sodium potassium pump - 3 Na out, 2 K in
and potassium leak channels - maintain RMP
discuss depolarization stage
positive Na ions will diffuse into membrane = depol if na reach yung threshold potential of -55 mV
dahil too positive na yung loob ng cell mag oovershoot are mag ppositive yung mV nya
discuss overshoot
as sodium ions enter eventually mag ccome to a point na it will pass the 0 mark and become positive
discuss repolarization
sodium channels now close and potassium opens so mag kaka potassium efflux - makes membrane negative again
discuss hyperpolarization
since slow closing anf K channels magiging sobrang negative naman due to efflux - absolute refractory period na toh and di na kaya mag stimulate ng nerve
when does anterior and posterior neuropore close
ant - 26th day
post - 28th day
what are the 3 main germ layers
entoderm
mesoderm
ectoderm
discuss the entoderm
innermost and gives rise to lungs, liver, GI tract
discuss the mesoderm
middle layer and gives rise to connective tissues, vascular system and muscles
discuss the ectoderm
outermost and gives rise to entire nervous system
formed by columnar epithelium cells
how is neural plate formed
thickening of ectoderm betw primitive knot and buccopharyngeal memb on dorsal surface of embryo
pear shaped and wider cranially
how is neural groove and folds formed
plate will develop a longitudinal neural groove with elevated folds thus forming neural folds
how is neural tube formed
fusion of neural folds starting cranially-caudally also will form the neuropores
what are neural crest cells
some cells are not incorporated in the neural tube they will from a strip of ectodermal cells betw neural tube and ectoderm
neural crest cells will migrate _____
anterolaterally
what do neural crest cells differentiate into
posterior root ganglia
sensory ganglia of CN
autonomic ganglia
melanocytes
suprarenal medullary cells
what are the 3 dilations formed at the cephalic end of neural tube
forebrain vesicle - prosencephalon
midbrain vesicle - mesencephalon
hindbrain vesicle - rhombencephalon
primary vesicle - primary division
how does the neural tube cells become primary brain vesicles
interaction of cells with one another
what are the subdivision of primary divisions
prosencephalon - telencephalon and diencephalon
mesencephalon - mesencephalon
rhombencephalon - metencephalon and myelencephalon
adult structures derived from telencephalon
cerebral hemispheres, basal ganglia and hippocampus
adult structures derived from diencephalon
thalamus, hypothalamus, infundibulum, pineal body
adult structures derived from mesencephalon
tectum, tegmentum, crus cerebri
adult structures derived from metencephalon
pons, cerebellum
adult structures derived from myelencephalon
medulla oblongata
cavity of telencephalon
lateral vent
cavity of diencephalon
3rd vent
cavity of mesencephalon
CAS
cavity of metencephalon
upper 4th vent
cavity of myelencephalon
lower 4th vent
