CAMPBELL AND KESSARIS Flashcards
what are the separate parts of the forebrain? (diencephalon and telencephalon)
diencephalon: thalamus and hypothalamus
telecephalon: basal ganglia, hippocampus and cerebral cortex
what are the seperate parts of the midbrain?
superior and inferior colliculus
sunstantia nigra
what are the seperate parts of the hindbrain?
pons, medulla and cerebellum
define ipsilateral and contralateral?
ipsilateral: when two structures are on the same side of the midline
contralateral: when two structures are on opposite sides of the midline
what does csf stand for, what produces it and where is it found?
CSF is the cerebrospinal fluid
it is secreted by choroid plexus
found in the subarachnoid space
what is the CSF flow route?
starts from the paired ventricles of cerebrum
a series of connected and unpaired cavities in the core of brainstem
then exits the ventricular system
enters the suarachnoid space via openings or apertures located near where the cerebrum is attached to the brainstem
it is absorbed by blood vesels via arachnoid villi
what is the meningeal layer?
it is made up of 3 layers: dura mater, arachnoid membrane and the pia maer
what is he dura mater?
its is a tough and inelastic bag that covers the brain and spinal cord
what is the space between the dura mater and the arachnoid membrane?
the space is called the subdural space so if there is rupture to blood vessels, the blood builds up in the subdural space
what is the pia mater sepeated from the arachnoid membrane by?
the subarachnoid space
what is the purpose of the meningeal layers?
to prevent the vertabral column from coming directly in contact with the skull
(ventral surface of medulla) what are the parts of the olivary pyramid of the medulla?
motor cerebellum corticospal tract (a descending pathway) pyrimidal decussation(the crossover)
where is the inferior olivary nucleus found, what is it involved in and what connections does it have ?
it is found in the MEDULLA OBLANGATA
involved in control and coordination of movement
It has connections with the vertal cortex and cerebrum
(dorsal surface of brainstem) what structures are present and what are their functions?
superior colliculus (info about the eye movements) inferior colliculus (auditory info)
what is the basal ganglia and what is its function?
it is a restricted collection of nerve cell bodies and regulation of initiation of movement, eye movements, balance and posture
also important role in reward and reinforcement
where is the substantia nigra located?
in the midbrain
why does some parts of the substantia nigra appear darker?
higher levels of dopamine-(found inpeople with Parkinsons disease)
what is the function of the thalamus?
to relay sensory info between the cortex and brainstem : such as ear, eye, taste buds, skin, muscle BUT NOT SMELL
- role in awareness and alertness
what are the inputs of the cerebellum?
moss fibres(brainstem) & climbing fibres (inferior olivary nucleus)
where are the cell bodies of the primary somatic sensory neurons located ?
dorsal root ganglia
where does the corticospal tract cross the medline?
brainstem
what is the function of the hippocampus and what are the cells involved in this?
act as our spatial awarness
place cells
what are the two cells that the CNS is made of?
neurons or nerve cells
glial cells
what are the four lobes of the brain and their functions?
frontal lobe- thinking,mood and motor
parietal lobe- spatial awareness and coordination of movements
occipital- vision
temporal- hearing and language
what are the two language areas and what happens if these have injuries?
brocas area- you cannot speak
wernickes area- you cannot understand speech
what are the two types of receptors on the postsynaptic neuron?
ionotropic (ions in ligand gated ion channels)
metabotropic (signalling mechanism enzymes- initiates phosphorylation and change of conc)
what do the terms excitatory and inhibitory mean ?
excitatory- increasing the possibility of an action potential to be generated
inhibitory- less likely to generate a action potential
what does the autonomic nervous system involve?
smooth muscle, cardiac muscle and glandular/secretory tissue -NOT BREATHING
name the 31 spinal nerves?
cervical 8 thoracic 12 lumbar 5 sacral 5 coccygeal 1
what roots make up the spinal nerves?
dorsal root(sensory) and ventral root(motor)
what are the direction of dorsal root and ventral roots?
dorsal root carry info away from the spinal cord
ventral root carry info to the spinal cord
define a dermatome?
are of skin supplied by nerves from a single spinal root
what are shingles dormant after and where does the sensory axons travel to?
dormant after chicken pox
sensory axons travel down to one blister dermatome
what do the gray matter and white matter contain?
white matter is predominantly axons
gray matter is mainly made of cell bodies
what is the name of the ganglio thats found at the junction that seperates the CNS and the PNS and hwat does its structure not have?
the dorsal root ganglion
it does not have dendrites
what are the 2 ascending pathways?
dorsal column pathway and the spinothalamic tract
define the spinothalamic tract?
a ascending somatic sensory pathway travelling from the spinal cord to the thalamus via lateral spinal column
mediates info about pain and temp (info ascends contralaterally)
define the dorsal column pathway?
a ascending pathway from the white matter of the dorsal spinal cord
carries info of touch and proprioceptive axons to brainstem
what is the 1 descending pathway and what is its function?
corticospinal tract
crosses and leads to pyrimidal decussation that allows that right motor cortex to directly command the left side of the body
where are the schwann cells found and in which nervous system?
in the neural crest and in the PNS
what organells do the myelinated axons contain?
axolemma
microtubule - bone
neurofilaments- connective tissue
what is the function of fibroblast?
colagen reinforcement
what are the two macroglia?
oligodendrocytes and astrocytes
what is neurulation?
the process of forming the neural tube from the neural plate
location of neuroepithelial cells?
these line the ventricles of CNS froming the ventricular zone
radial glia?
neuroepithelial cells give rise to radial glia
the cell bodies of radial glia remain in the ventricularzone but the processes extends to the pial surface
when do radial glia line the ventricles of CNS?
at later stages
where do some nuerons generated by glial cells migrate ?
along radial glia
what are the subdivions of the neuroepithelial cells called?
progenitor domains
what can be used to identify progenitor domains?
specific marker genes
where do the oligodendrocytes originate from?
from the ventricular zone precursor cells in the ventral spinal cord then migrate away from the vz and populate the remaining developing CNS
what is initiated when oligodendrocytes come in contact with axon?
differentiation
what happens during axon ensheathment?
the initiator process extends and spirals arounf the axon
how many axons do oligodendrocytes myleniate?
multiple axons within close proximity of their cell bodies
what is happening during remodelling?
non ensheathment processes are lost
what is happening during ensheathemt?
the non compact myelin ensheaths the axon
what happens during maturation?
the oligodendrocyte sheath wrap produces a compact myelin
what are the nodes of ranvier and what are found inin them ?
they are the gaps within the myelin sheath
clusters of voltage gated na channels are found
what direction do myelin grow?
longitudinally
what does the myelination prevent?
leakage into internodal membrane so flows farther along the axon
what are the four types of astrocytes and where are they located?
fibrious- predominant in the white matter of cns
protoplasmic- found in the gray matter of cns
bergmann glia- found in the cerebellum
mullar glia- found in the retina
where have astrocytes originate from?
- from the radial glia cells during embryogenesis
- some are produced from the transformation of glial cells during the end of neurogenesis
what are the 6 functions of astrocytes?
-structural support
-metabolic support
-removal of neurotransmitter from extracellular space
-regulation of extracellular ion conc & ph
-involved in synaptic formation and synaptic elimination by releasing cerytain factors
regulation and formation of blood brain barrier
explain the blood brain barrier?
produced by vascular endophelium
allows specific substances to enter the CNS via blood
astrocytes have endfeet with receptors or channels that regulate the interface surface between the brain and the blood
how do astrocytes act as a glutamate sink?
they have receptors that are like the ones on the postsynaptic neuron
converts glutamate into glutamine which is released to be take up by the presynaptic neuron
also produces substances like ATP which help modulate synaptic transmission
where are the adult neural stem cells found?
in the subventricular zone
what does the subventricular zone do?
supplies the olfactory bulb with new neurons throughout life
what is heterogeinity?
stem cells of different regions of the subventricular zone generate a restricted neuronal subtypes
what do microglia originate from?
blood derived macrophages outside the CNS
what are microglia responsible for?
immune system and brain defence
where have the microglia originated and descended from?
originate from the myeloid lineage
descend from feotal macrophages
development pathway of microglia?
the feotal machrophages enter the neural tube t early embyonic stages
transforms into embryonic microglia
in the prenatal brain the amoeboid microglia are found in the white matter the divide rapidly and migrates to the overlying cortex
in adult brain the microglia are distributed everywhere
what do microglia do at resting state?
- scan their territories
- constantly moving to look for damage signals
what are the 3 stages of the activationprocess of microglia?
- ramified state- small cell body, thin and mobile processes, multiple branching
- activated state- enlargement of cell body, refraction and thickening of the processes, damage signals come from neurons, glia or other cells
- phagocytic state- under condition of neuronal or synaptic/terminal degenration(cell death), signals froma dying or dead neuron or glia
where are schwann cells found?
in the neural crest
how is the neural crest formed?
the neural folds come together and a section of the ectoderm comes off to lie laterally to neural tube- this tissue is called the neural crest
how many axons does the schwann cell myelinate and which nervous system is it involved in?
one axon
peripheral nervous system
what are the functions of the non myelinating schwann cells?
- surround the axons
- support and separate the unmyelinated axons
what are the functions of myelinating schwann cells?
to ensheath and myelinate axons in the PNS
what is the schwann cell response during a wallerian degenration (injury)?
- differentiate and take part in phagocytosis of their own myelin sheath
- recruit macrophages to clear up the myelin debris
- successful axon regeneration
- the myelin thats is produced is of reduced thickness
name four of the other glia cells in the pns and where they are located?
- olfactory ensheathing cells- envelop axons of the olfactory nerve
- satellite cells- covers the neuronal cell bodies of the dorsal root ganglion cells
- entric glia- entric system of the PNS
- terminal glia- found in the terminals of skeletol neuromuscular junctions
where do mullar glia originate from?
the retinal neuroepithelial cells
what are the 3 layers of the retina?
- outer nuclear layer: photoreceptors are located here
- inner nuclear layer: mullar glia cells are here
- ganglion cell layer: ganglion cells send signals to the brain
what are the functions of the mullar glia?
-vision: guides photoreceptors to the light
-structural and functional support of retina
regualtion of retinal hemoestasis
-expresses progenitor like genes and generates neurons under special conditions
- supports neurons; by recycling neurotransmitters and controlling the ionic balance in extracellular space
where is the bergmann glia found?
in the cerebellum
which ventricle does the bergmann glia arise from?
the fourth ventricles of the neuroepithelium cells
what does the bergmann glia form intimate relationship with?
the dendrites of the purkinje cells which are inhibitory neurons that are a source of the output for the cerebellar cortex
what 2 transporters does the bergmann glia express?
GABA and glutamate transporters
these are involved in synaptic clearance
what does the photoactivation of bergmann glia activate?
the neuronal activity of purkinje cells by releasing glutamate
why does the bergmann glia have long radial fibres?
to extend towards the pial surface
to guide radial migration of immature neurons
