Brains Divisions Flashcards
two divisions of the nervous system
- central nervous system (brain and spinal cord)
2. periperhsal nervous system (nerves)
change of brain ontogentically
at birth= 4/5 pounds
adulthood= 3 pounds + 100 billion neurons
further divisions of peripheral nervous system
somatic nervous system (SNS)
autonomic nervous system (ANS)
further divisons of SNS
afference nerves
efferent nerves
further divisions of ANS
sympathethic nerves
parasympathethic nerves
how many cranial nerves (leading to brain)
12
what does the SNS do
interacts with external environment (skin, motor system)
what does the ANS do
regulates internal environment (sensory signals, hormones, etc)
the afferent/efferent nerves carry signals to internal organs
what are affterent nerves
carry sensory signals
what do efferent nerves do
carry motor signals from CNS to sekeltal muscles
what are sympathethic nerves
AROUSING (fight/flight)
autonomic motor nerves in the lumbar and thoracic regions of the spinal cord
they project from the CNS onto 2nd-stage neurons FAR from the target organ
what are parasympathethic nerves
CALMING (rest/digest)
project from brain/sacral
project from CNS synapse NEAR the target organ on the second stage nerves
differences between parasympathethic and sympathethic nerves
parasympethic= conserve energy/calming + project near target organ
sympathethic= far from target organs + arousing/threatining situations
what is the brain protected by
bone
3 meninges
cerebrospinal fluid
3 protective membranes
what does cerebrospinal fuid do
supports/cushions the brain
fills the subarachoid space, ventricles and spinal cord
produced by the choroid plexuses in pia matter
can be blocked by tumors in channels linking ventricles
what is the blood brain barrier
a mechanism that impeded passages of toxic substances from blood into brain cells of blood vessels that are tight packed but some large molecules are actively transported
what are the principles of the sympatethic/parasympethihic nerves
2 stage neural pathways; project from CNS toowards organs and synapse with other neurons
target neurons revieve inputs from both PN and SN and are controlled by relative levels of their activiity
what are cranial nerves
12 nerves projecting from brain that are purely sensory and used for diagnosis basis:
i.e. olfatory, optic, etc.
composition of the brain
60% fat needs 20% of al loxygen 2% of all bodyweight 86billoin neruons weights 3lb at adulthood
what are meninges
3 protective membrances encasing the CNS
what do meningnes consists of
- dura matter
- arachonid membrane + sub-arachanoid space
- pia matter
what is dura mater
thick membrane made of dense irregular connective tissue that surrounds the brain and spinal cord
what is the arachonoid membrane
spiderlike web menginge layer
consits of sub-arachoid space where blood vessels/cerebospinal fluid is found
what is pia mater
the delicate, inner-most part that supports CNS and produced cerebrospinal fuid
what are neurons
cells sepcialized for reception, conduction and transmission of electrical signals
types of cells in nervous system
neurons
glial cells
structural elements of a neuron
cell body axon dendrites cell membrane soma axon hillock nodes of Ranvier myselin buttons/axon terminals synapses
nodes of ranvier
gaps between myelin where saltatory conduction occurs
axon
long narrow process projecting from cell body where action potentials travel down
myelin
fatty insulating layer to allow for saltatory conduction
axon hillock
cone shaped region at the junction between the axon and cell body
dendrites
short procesesses from soma that revieve electircl signals from other neurons
soma
cell body of the neuron= metabolic center
axon terminals/buttons
release chemicals into synaps
synapse
gaps between neurons through which chemical signals are transmitted
schwann cells
a glial cell in PNS= myenliate the PNS nerves and can create axonal regrowth post-damage
endoplasimic reticulum
folded membranes in the cell for fat/protein synthesis
synaptic vesicles
membrane pacakges storing neurostransmitter molecules to release them into synapses
neurotransmitters
molecules relesaed from active neurons infleucning the activity of other cells
what is the neuron cell membrane compsoed of
a lipid bilayer with protein molecules for functional properites of the cell
types of neurosn
unipolar
bipolar
multipolar
multipolar interneruon
unipolar neurons
1 axon
bipolar neurons
2 axons
multipolar neurons
2+ axons
multipolar interneruons
have no axons/super short axons
integrate the neural activit within a single brain structure as opposed to conducting signals from one strucutre to anoher
what are neurons specialized for
- recpetion
- conduction
- transmission
distribution of neurons
- compsoed of cell bodies/axons
- IN CNS; found in clusters
- in PNS; found in ganglion/ganglia
what are bundles of axons called?
in cns= tracts
in pns= nerves
what do glial cells do (4)
- control blood brain barrier
- support neurons (nutrition, waste, etc)
- exchange chmicals with neurons and maintain synapses
- modulate neural activity
types of glial cells (4)
- oligodendrocytes
- schwann cells
- microglia
- astrocytes
what are oligodendrocytes
extensions that wrap aroudn axons of some neurons in the CNS
they myenliate the CNS axons
increased speed/effiency of axonal conduction in several segments
what are microglia
respond to injury by multiplying/engulfing cellular debris + triggering inflammatory responses
what are schwann cells
perform simlar function in peripheral nervous system;
each constitute 1 myselin segment as opposed to many
what are astrocytes
cover brain besswels
allow passage of chemicasl from blood into CNS neurons
provide nutrition/clear waste
send and recieve signals form neurons/other glial cells to control, establish and maintain synapses between neurons
what can only schwann cells do
guide axonal regrowth after damage is
challenge of studyign neurons
axons/dendrites are intricately intertwined
what are some neuroanatomical techniques to study neurons
- golgi stains
- nissl stain
- electron microscopy
golgi stain
ability to see individual neurons using Golgi (silver cromate staining them black)
nissl stain
allows for innter strucutre/number of neurons in an area using cresyl violet dye binding to singular neuran cell bodies
electron microscopy
provides details of neuronal structure using electron-subtances that magnify light using photographic film
what are some neuroanatomic tracing techniues
anterograde
retrograde
anterograde
used to trace paths of axons projecting away from a cell body in a particular area
retrogade
axons projecting into a particular area
what 3 axes does the nervous system of a vertebrate have
- anterior posterior
- dorsal ventral
- medial lateral
anterior-posterior
raustral caudal (back of head and forehad)
dorsal ventral
top/bottom of head (think dolphin)
medial lateral
towards/away form midline of body’s lateral surfaces (facing towards you)
anterior
nose end (rostral)
posterior
tail end (caudal)
medial
midline of body
laeral
away from body
proximal
close
distal
far
what 3 planes are there of the vertebrate NS
- saiggital plane (midline)
- horizontal plane
- frontal plane (vertical; center)
and a cross section!
2 areas of the spinal cord
gray matter
white matter
what is gray matter
cell bodies and unmyelinated interneurons with 2 dorsal arms (dorsal/ventral horns)
what is white matter
myenliated axons
what does the dorsal root ganglia consist of
sensory unipolar neurons with grouped cell bodies
ventral root ganglia consits of
multipolar neurons grouped together
label the spinal cord
x
label the 3 axes of the brain
x
label the 3 planes of the brain
x
label a neuron cell
x
what are the 3 first brain divisions that develop during embryological development
- forebrain
- mind brain
- hind brain
what are the final brain divisions you end up with as an adult
forebrain: telencephalon + diecnephalon
midbrain= mesencephalon
hindbrain= metencephalon + myencephalon
forebrain substructures
telencephalon + diecnephalon
mid brain sub structures
mesencephalon
hind brain sub structures
metencephalon
myencephalon
order form anterior to posterior of brain divisions
telencephalon diencephalon mesencephalon metencephalon myelencephalon
telencephalon vs rest of structures
telencehalon= greatest growth (cerebral hemispheres)
other 4 divisions are the brain stem
difference between human and chimps
larger forebrain in humans as hindbrain/midbrain develop first as they are more primitive (for mechanical functions) as opposed to cognitive functions of the forebrain
what is the myenencephalon
the medulla! (hindbrain; posterior division)
for 1. reticular formation (network of nuclei in brian core for consciousness/alertness)
2. tracts that carry signas from brain to body
what is the metencephalon
hind brain
trackts/reticular formation
consits of :
- pons
- cerelbellum
what is the pons
found in metencephalon; a bulge of tracts on brain strems ventral surface that controls bladder, respiration, etc
what is the cerebellum
found in the metencephalon; th ‘little brain’ for motor coordination/cogntiive functions
its a large/convulated structure on DORSAL part of metenchealon for sensoir-motor, decision making, language, movement
what is the mesencephalon
aka the MIDBRAIN
consits of the tectum and the tegmentum
tectum
dorsal surface of the mesencephalon (Roof)
has collicoli pumps
inferior collicllu for auditory function and superior collicoli for visio-motor function
tegmentum
ventral to tectum 3 colourful structures: consits of: 1. periadquductal gray + cerebral aqueduct 3. substancia nigra 4. red nucelaus
periaqueductal gray + cerebral aqueduct
part of tegmentum: gray matter which mediates analgesic/pain-reducing effects of opiate drugs
substancia nigra/red nucleus
part of the sensorimotor system
what is the diencephalon
part of the forebrain; consists of 2 structures (thalamus + hypothalamus)
thalamus
2 lobed stucutre joined by mass indermedia with many nuclei
contains: sensory relay nuclei, laternal geniculauate + medial + ventral posterior nuclei
the ‘switchboard between subocrotical strucutures and the cortex’
hypothalamus
regulates unmotivated bheaviours (hormones; sleep, temperature, sex, thirst)
affects pituitary gland (hormon release, optic chiasm and mamilary body)
telencephalon structures
- cerebral cortex
- major fissures
- major gyri
- four lobes
- libmic system
- basal ganglia
- cerelbral commisures
what is the telencephalon responsible for
the limbic system that mediates compex functions:
1. intiates involuntary movement
- interprets sensory input
- mediates complex cognitive proceseses (learning, speaking, problem solving)
amygdala
for emotional learning
hippocampus
consolidation of memory
how do the cerebral hemispheres communicate
via the corpus callosum
cerebral cortex
outer layer of grey matter of cerebrum
composed of unmyenliated neurons, fissures and sulci
deeploy conulated to increase brain volume
grey matter
soma + unmyenliated axons
white matter
myenliated axons
fissures
large furrow on wrinkled skin surface of cerebral cortex
are:
1. longitutidinal
2. lateral
3. central
sulci
small fissures
what are the gyri
ridges between fissures and sulci
types of sulci
precentral, postcentrla, suprior in respect to frontal, parietal and temporal lobes
what 4 lobes are there
- frontal
- pareital
- temporal
- occipital
(not functional untis but with SETS of functions)
occipital lobe
visual input
pareital lobe
tactile sentation analysis and locations of objects
directs attention
(where post-central gyrus cuts through)
temporal lobe
- superior temporal gyrus= hearing and language
- inferior temporal gyrus= comple visual patterns
- medial position= memory
frontal lobe
precentral gyrus/adjacent frontal cortex= motor function
frontal cortex= complex cognitive functions (planning, evaluating outcomes)
what is the neocortex
6 layeres differ vy size/density in proporistion to the 2 types of cells
long axons and dendrites
columanr organization
90% of human cerebral cotex; higher cognitive function
what does the neocortex consists of
pyramidal cells (multipolar and large)
stellalte cells (small, interneurons)
limbinc system
part of forebrain; circuit of midline srcuturs circiling the thamalus involved in ‘4 fs’ of motivation
4 Fs of motivation
fleeing
feeding
fighting
sexual behaviour (fucking)
limbic ciruirt
starts at amydalda–> posterior to it is the hippocampus which runs beneath hipocampus in medial temporal lobe
then the cignualte corte + fornix
then the septemb
basal ganglia motor system
plays a role in VOLONUTARY motor responses
projects form striatum (from substancia nigra)
what is associated with the basal anglia motor system
parkinsons disease= deterioirtaion of this pathway
nucleus accumens
medial porition of central striatum; plays a role in reward systems
major fissures 3
central fissure
laternal fissure
longitutundal fissure
major gyri 4
precentral gyrus
postecenral gurys
superior temporal cyrus
cingulate curus
limbic system 6
amygalda hippocampus fornix cingulate cortex septum mammilary bodies
basal ganglia 4
amydala
caudate and putamen (striatum)
globus pallidis
cerebra commisures
corpus callosem
crebral cortex
neocortex and hippocampus
what does the diencephalon consits of
thamalus
hypothalamus
optic chiasm
pituitary gland
where is the motor cortex
between frontoal/occopital lobes
where is the somatosensory cortex
next to motor cortex
where are association ares
distributed; inteprret/inlink info form neurons
glial cells function
provide spiderlink suppor tto insulate and nourish cerebral hemispheres
label all the gyrus and fissures
x
types of NT
endorphins dopamine and seratonin
can be exictatory= increase AP (glutamate)
or inhibitory= prevent PA (gaba, seratonin)
label the functional localization of brain
x
plasticity of brain
brain is malleable and changes always
fire together + wire together
what is ynaptic prunign
less synapses than when born as we lose the synapses we dont’ use for effiency
