intro to nervous system david kachlík a petr zach
TRANSCRIPT
Nervous tissue cells parcellationNervous tissue cells parcellation
Two types of cells:• neurons – cells transmitting informations• Glial cells (neuroglia, glia) (neuroglia) –
neuronal support, protection and participation in their nutrition and work– astrocytes (astrocytus)– oligodendrocytes (oligodendrocytus)– microglia (microgliocytus)– ependymal cells (ependymocytus)
NervesNerves• Are formed by clusters of nervous fibers• Nerve fibers have covering similarly to muscular
tissue:– endoneurium
• Layer of reticular fibers around individual nerve fibers
– perineurium• „sleeve“ containing bundles of nerve fibers formed by
layers of epiteloid cells• Numerous zonulae occludentes – non-passable
barrier shielding nerve fibers
– epineurium• Fibrous covering of whole nerve
GangliasGanglias• Nerve ganglias are accumulation of pericaryons in PNS• They have ovoid shape and their surface is covered by
capsule from thick non-organized fibrous tissue• Typical are satellite cells (gliocyti ganglionici) – small
cuboid cells surrounding perikarya of neurons
http://en.wikipedia.org/wiki/Dorsal_root_ganglion http://www.pharmainfo.net/introduction-autonomic-nervous-system/classification
Ganglias - dichotomizationGanglias - dichotomization
• Spinal ganglia (ganglion spinale)– sensory (ganglion sensorium)
– In posteroir roots of spinal nerves and in the course of cranial nerves (V, IX, X)
– Contain typical pseudounipolar neurons
– Carry sensory impulses from periphery into CNS
• autonomous (vegetative) ganglias (ganglion autonomicum)– In the course of autonomic nerves
– Contain multipolar neurons
– Layer of satellite cells is incomplete
– Intramural ganglias• Parasympatetic ganglias in the wall of hollow organs
Development of neural tubeDevelopment of neural tube
Nervous tissue develops from neuroectoderm
• Neuroectoderm originates from ectoderm by notochord induction
neural plate in the neurulation process creates neural tube=foundation of CNS
• Remnant of neuroectoderm separates neural crest (crista neuralis) = foundation of PNS and other structures (ectomezenchyme of the head etc.)
Development of neural tubeDevelopment of neural tube
• Primary neurulation– Separates ectoderm into three cell types
• Inside oriented neural tube• epidermis externally• Cells of neural crest
• Secondary neurulation – Cells of neural plate create chorda dorsalis
• In the course of 35th somite formation
Development of neural tubeDevelopment of neural tubeEpitelium of neural tube soon changes into multi layer
neuroepitelium in which are created 3 layers:• internal (germinal) zone (zona ventricularis; matrix
germinalis)– Until half of intrauterine life fast proliferating (origination of
neuroblasts)– Then reduction into ependyme
• Middle (shell) zone (zona intermedia; zona pallii)– Formed mostly by migrating neuroblasts– Grey matter originates from it
• External (marginal) zone (zona marginalis)– Formed by extenstions of neuroblasts– White matter originates from it
Somite (Somite (somitussomitus))• somitomers around 3rd week• At the end of 5th week 42-44 somites
http://www.aps.uoguelph.ca/~swatland/HTML10234/LEC5/LEC5.html
http://www.uprightape.net/Image_Pages/UA_Fig7-4_SomiteDevel.html
MyotomeMyotome
• Central part of primitive segment
• Starting 4th week during differentiation it retains lastly epiteloid organization
• Foundation of skeletal muscles
SclerotomeSclerotome
• Dorzomedial part of primitive segment
• At the 4th week gains chars of mesenchyme
• Getting thicker around chorda dorsalis
• Creates foundation of axial skeleton (vertebras, costas, sternum) and base of skull
• Ventrolateral part of primitive segment
• During differentiation from start of 4th week of development gains mesenchyme char
• Migrates into somatopleura• Give foundation to fibrous
part of skin (dermis and tela subcutanea)
• Parts originating from the same dermatome have nerve supply from one spinal root
DermatomeDermatome
Composition of brain tissueComposition of brain tissue• Grey matter (substantia grisea)
– pericarya of neurons, mostly non myelinated nerve fibers
– Protoplazmic astrocytes, oligodendrocytes and microglia
• White matter (substantia alba)– Mostly myelinated fibers– Fibrilary astrocytes, oligodendrocytes and
microglia
http://library.med.utah.edu/WebPath/HISTHTML/NEURANAT/CNS230A.htmlhttp://fuckyeahnervoussystem.tumblr.com/post/1276369326/spinal-cord-light-micrograph-of-a-cross-section
CNS description- partsCNS description- parts
• Spinal cord (Medulla spinalis)• Brain stem (Truncus encephali)
– Oblongate (Medulla oblongata)– Pons (Pons) – formerly pons Varoli– Midbrain (Mesencephalon)
• Small brain (Cerebellum)• Diencephalon (Diencephalon)• Forebrain (Telencephalon)
– Basal ganglia (nuclei basales)– Brain cortex (cortex cerebri)
CNS descriptionCNS description• Inside CNS cavities
– 4th ventricle, 3rd ventricle and two lateral ventricles
• CNS covered by meninges:– Hard meninge (pachymeninx = dura mater)– Soft meninge (leptomeninx)
• arachnoid (arachnoidea mater)• pia (pia mater)
• Inside ventricles is cerebrospinal fluid (liquor cerebrospinalis = CSF)
http://faculty.irsc.edu/FACULTY/TFischer/AP1/AP%201%20resources.htm
http://mortdev.blogspot.cz/2008/09/brain-autopsy.html
CNS functionsCNS functions• Spinal cord – reflexes, ascending and
descending tracts• Brain stem – vitally important reflexes
(respiratory, cardiovascular, vomiting, coughing, synchronization of eyeball movement)
• diencephalon – hormonal production, circadian rhytms, termoregulation, food intake, autonomic regulation
• Terminal brain– cortex: functional cortical areas– Basal ganglia: movement patterns
• limbic system – behavior, emotions, memory
Brain stemBrain stem
• Converting all ascending and descending nerve tracts (tractus)
• Reticular formation (RF; formatio reticularis)– Vital reflex centers
• Cardiac activity, respiration, vazomotorics, consciousness
• Nuclei of cranial nerves– n. III - XII
Truncus encephali• Medulla oblongata = oblongate• Pons (Varoli) = pons• Mesencephalon = mid brain
Cavities of brain stem• ventriculus quartus = 4th ventricle
– fossa rhomboidea = bottom of 4th ventricle
• aqueductus mesencephali (Sylvii) = for CSF between 3rd and 4th ventricle
Brain stem - Brain stem - compositioncomposition
Medulla oblongataMedulla oblongata
Ventral side:• pyramis
– Fibers of tractus corticospinalis
• oliva
dorsal side:• tuberculum gracile
+ cuneatum
Mesencephalon = Mesencephalon = Mid brainMid brain
• Cranial part of brain stem (2 cm)
Ventral side:• fossa
interpeduncularis (intercruralis) – Exit of n. III
• crura cerebri– Descending motor
systems (tractus pyramidalis)
• fibrae corticospinales• other
Dorzal side:
lamina quadrigemina = lamina tecti
• colliculi superiores– vision
• colliculi inferiores– hearing
• Exit of n. IV
Mesencephalon = Mesencephalon = Mid brainMid brain
Mesencephalon = mid brainMesencephalon = mid brain
Internal structure: 3 parts on section• tectum mesencephali (mesencephalic tectum)
= dorzal thin plate with two pairs of tubers
- aqueductus mesencephali Sylvii
• pedunculus cerebri (brain pedicle)
= ventral most of midbrain– tegmentum mesencephali
• nucleus ruber – motor nucleus of stem• substantia nigra – motor nucleus – basal ganglion• Ascending and descending tracts
– crus cerebri – contains only descending tracts
Formatio reticularisFormatio reticularis (reticular formation) RF (reticular formation) RF
• Fylogenetically oldest part of brain• Maintains basic stereotypes (walk, sleep)• Influences wake, tiredness and motivation• Morphologically ill defined• Centrall and dorsally in brain stem,
especially in the pons• Ascending activation systém → talamus,
hypotalamus, cortex• Descending inhibitory systém →
cerebellum, sensory nerves
RF functionRF function• Seat of reflexes
– nutrition– self defense
• respiratory• pneumotactic center• vazomotor center• center for heart beat rate regulation• center for vomiting• Pain• Body temperature maintenance
Cerebellum = small brainCerebellum = small brain
• vermis (worm) – midline non paired• hemispheria (cerebellar hemispheres) – paired• cortex x corpus medullare• 3 lobes
– lobus anterior– lobus posterior– lobus flocculonodularis
• 4 nuclei cerebelli (small brain nuclei)– nucleus dentatus– nucleus emboliformis– nucleus globosus– nucleus fastigii
Cerebellum – three pediclesCerebellum – three pedicles
• pedunculus cerebellaris inferior = corpus restiforme + juxtarestiforme
• pedunculus cerebellaris medius= brachium pontis
• pedunculus cerebellaris superior= brachium conjunctivum
DiencephalonDiencephalon
• thalamus
• metathalamus
• subthalamus
• hypothalalmus
• epithalamus
• thalamus opticus
Thalamus Thalamus (thalamus dorsalis)(thalamus dorsalis)
• „brain secretary“ all except for smell• Nuclei parcellated according to position
or connection– nuclei anteriores, dorsales, intralaminares,
mediani, mediales, posteriores, ventrales, reticularis
– specific • ncl. ventralis posterolateralis, posteromedialis (VPL,
VPM) – hmat, bolest, proprioception• ncl. ventralis anterior, lateralis (VA, VL) - motoric
– Non specific nuclei - (? function)– Association nuclei
Parcellation of thalamic nuclei Parcellation of thalamic nuclei according to positionaccording to position
nucleinuclei anteriores, dorsales, anteriores, dorsales, intralaminares, mediani, mediales, intralaminares, mediani, mediales, posteriores, ventrales, reticularisposteriores, ventrales, reticularis
MetathalamusMetathalamus• Lateral geniculate body (corpus geniculatum
laterale) – vision center• Medial geniculate body (corpus geniculatum
mediale) – hearing center
SubthalamusSubthalamus
• zona incerta= unsure region)– Function similar to
ncll. reticulares thalami
– Making difference of other impulses that regularly enter into talamus
• nucleus subthalamicus= corpus Luysi– Connected with basal
ganglia
HypothalamusHypothalamus
Highest autonomic center• nuclei x transversal and longitudinal zones• Crossing of optic nerve (chiasma opticum)• hypophysis• Mammillary bodies (corpora mamillaria)
Hypothalamus – fyziologyHypothalamus – fyziology
Hormones (blood), nerves, CSF
HYPOTHALAMUS
Endocrine + autonomic system
HOMEOSTASIS emotions (= LIMBIC SYSTEM)
Telencephalon = CerebrumTelencephalon = Cerebrum
• Pallium (pars pallialis; pallium) cerebrum (= hemispheres)
• Basal part (pars basilaris) nuclei basales = bazal ganglias
• Septal part (pars septalis) septum
PalliumPallium
• Paired hemispheres (hemishperia)
• 5 lobes (lobi)– frontal (lobus frontalis)– parietal (lobus parietalis)– occipital (lobus occipitalis)– temporal (lobus temporalis)– insular (lobus insularis) =
inzula
• gyr) x sulci – basic description unit
Cortical parcellationCortical parcellation (Areae Brodmanni) (Areae Brodmanni)
• primary – for one modality
• association– secondary– terciary
• example:– area 4 – primary motoric– area 17 – primary visual– area 18,19 – association visual
bazal ganglia; bazal ganglia; nuclei basalesnuclei basales
• Striated body (corpus striatum)– Caudate nucleus (nucleus caudatus)– putamen
• globus pallidus
• substantia nigra – in mid brain
• ncl. subthalamicus – in diencephalon
Basic function: motor patterns formation
Limbic systemLimbic system
• „visceral brain“• Around brain stem (= “collar“)• emotions, memory, smell• Connected with emotional reactions, sexual
behavior and offspring care, social behavior, memory and regulation of many autonomic function
• Cortical and subcortical parts• hippocampus• corpus amygdaloideum = amygdala• other