unit 2: CNS Flashcards
STUDY
development of the human CNS:
4 weeks:
6 weeks:
11 weeks:
birth:
4 weeks:
- anterior neural tube - > fore, mid and hindbrain
- spinal cord
6 weeks:
- Hindbrain -> Medulla oblongata, Cerebellum, Pons
- Forebrain -> Diencephalon, Cerebrum
- spinal cord
11 weeks:
- Growth of cerebrum rapid
Birth:
- Cerebrum cover most of other brain region
what is the reason why we believe the spinal cord to be hollow?
because the central canal is hollow and filled with cerebrospinal fluid
what are the meninges layers?
inner layer: PIA MATER
middle layer: ARACHNOID MEMBRANE
dura matter: DURA MATER
TRUE OR FALSE?
between the meninges layer there is free space
false, its filled with cerebrospinal fluid
Protection and support for CNS (brain, spinal cord)
Bony cage: cranium, vertebrae
3 Layers of connective tissue - meninges
Fluid between layers - cerebrospinal fluid
dura mater is?
outer most layer, how to remember? its something tough and DURAble which is something that is usually located on the outside
true or false?
the arachnoid space is very vascularized?
true
how to remember the arachnoid layer of the meninges
arachnophobia is being scared of spiders and the arachnoid space looks like a spider web
true or false?
the PIA MATER is flat
false, it the brain flat, no? and the inner most layer surrounds the brain so it needs to follow the brains groves as well
(it follows all the groves around the brain)
what do you call a broken blood vessel underneath the dura and coming into the arachnoid area
subdural hematoma
common in elderly
Evolutionary trend in nervous system
nerve net, nerve cord, primitive brain
Ventricles
hollow (CSF-filled) central canal
- 2 lateral, 2 descending into spinal cord
what cells determine the composition of the CSF?
ependymal cells
_______ cells create barrier between compartments
ependymal cells
each ventricle has ___________ ___________
choroid plexus
the choroid plexus produces _______
CSF (cerebrospinal fluid)
purpose of arachnoid villi
helps with the removal of CSF from the subarachnoid space via the dural sinus
the dural sinus allows _______ to get out of the CNS
CSF
what does intestinal fluid, plasma and CSF have in common
all are in the CNS
plasma vs CSF
- what has higher K+, Ca2+, HCO3-, glucose, pH
- higher Na+
- very low protein and no blood cells
- plasma
- none of them they have similar Na+
- CSF
how many times is CSF removed and replaced and why?
4x a day
cleans out metabolites and toxins
- together the choroid plexuses produce how much CSF fluid a day?
- how man choroid plexuses are there
- 500 ml a day
- there are three
- lateral ventricle choroid plexus
- third ventricle choroid plexus
- fourth ventricle choroid plexus
explain the process of removing CSF from the brain (choroid plexuses).
- near the 4th ventricle the CSF can leave via some opening and enter subarachnoid space
- its past the inner most layer and is now in the middle of the meninges. CSF travels around the space and can leave the space via the ARACHNOID VILLI.
- these villi allow the CSF to travel to the outer most layer, the dura mater and CSF is able to leave via the dura sinus (venous)
what is another name for DURAL SINUS
superior sagittal sinus
circulation of CNS:
________ –> ________ –> ___________ –> __________ or ________ –> __________ –> ___________.
lateral ventricles (2) –> third ventricle –> fourth ventricle –> central canal of spinal cord or subarachnoid space –> superior sagittal sinus (dural sinus) via arachnoid villi –> venous return to heart.
true or false?
- the ventricles within the CNS that contain CSF are very narrow and if they get further narrowed it can result in pressure build up and press on brain tissue
- what are some examples of added pressure?
- true
- bleeds, tumours, anything causing added pressure
difference between hydrocephalic vs a normal brain
with hydrocephalic,
- ventricles become huge because of fluid build up
- brain becomes compressed
2 functions of CSF
- Chemical protection - maintains extracellular environment for neuron’s (cleans out metabolites + toxins)
- Physical protection
- protects the brain from hitting the cranium/skull, allows CNS tissues to float which relieves pressure on blood vessels + nerves attached to the CNS
Special features of cerebral vasculature
tight junctions: so that there is great control over what can and can- not enter (selectively permeable barrier)
Astrocyte foot processes: secrete paracrine signals to en- sure the cells remain tightly joined.
What crosses the blood-brain barrier easily?
lipid soluble molecules
ex) O2, CO2, ethanol. only really O2 is helpful
hydrophilic substance only cross if specific transporters/carriers are present
Parkinson’s Disease relate to the blood-brain barrier
This disease results in low dopamine levels. The treatment is to give the patient dopamine but it CANT cross the blood-brain barrier. Dopamine pre- cursor L-dopa CAN cross the barrier as it looks enough like L-tyrosine. Once this enters the brain, neurons metabolize it into dopamine and the symptoms lessened.
neurons need oxygen true or false
true, neurons are ‘obligate aerobes’
O2 readily crosses the blood-brain barrier true or false?
true
true or false?
arteries of the CNS express high levels of glucose transporters to provide adequate levels of glucose
false;
capillaries of the CNS express high levels of glucose transporters to provide adequate levels of glucose
true or false?
the brain is responsible for approx half of body’s glucose consumption
true
the delivery of what is very important for vasculature
oxygen and glucose
lack of oxygen and glucose for vascualture can result in
hypoglycemia –> confussion –> losss of consciousness –> death
describe grey matter in spinal cord (characteristics)
- looks like butterfly structure
- located in the centre
- synapses occur
- integration occurs
describe white matter in spinal cord (characteristics)
- like superhighways of the spinal cord
- no synapses
- quickly moving signals up to the brain or down from the brain
_______ : bulge created from afferent neurons
dorsal root ganglion
dorsal = ________ neurons
afferent
ventral = ___________ neurons
efferent
why is there no bulge on the efferent/ ventral horn but there is a bulge on the dorsal/ afferent pathway?
because the efferent neuron is in the ventral horn. whereas the neuron for the afferent pathway is not in the dorsal horn but rather on its way so it forms a dorsal root ganglion
where does each go dorsal or ventral?
- somatic sensory nuclei
- autonomic efferent nuclei
- visceral sensory nuclei
- somatic motor nuclei
- dorsal –> sensory = afferent = dorsal
- ventral = efferent
- Dorsal= sensory = afferent
- Ventral= motor = response = efferent
which type of neuron has the cell body in the middle w/ dendrites
bipolar neuron
true or false grey matter consists of ascending and descending matter
false, white matter does
which of the following are ascending and which of the following are descending?
- corticospinal tract
- dorsal columns
- spinothalmic
- spinocerebellar
- descending cortex –> spine
- ascending
- ascending spine –> thalamus
- ascending spine –> cerebellum
what does each do?
1. corticospinal tract
2. dorsal columns
3. spinothalmic
4. spinocerebellar
- ‘voluntary’ movement
- touch/pressure, proprioception
- pain, temp ( T as in Thalmic)
- proprioception (posture, coordination) (C as in Cerebellar)
what are the two types of corticospinal tracts and their functions?
- lateral corticospinal tracts: descending info about voluntary movement in LIMBS
- ventro medial corticospinal tract: voluntary movement for axial/ trunk muscles
true or false 80-90% of all corticospinal tract fibres are in the lateral tract?
true because we can do a lot more things with our limbs
what are three things about the brainstem?
1.
2.
3.
4.
- oldest and most primitive part of the brain
- organized like spinal cord
- contains structures from embryonic hind and midbrain
- contains nuclei associated with reticular formation.
what nerve has most of the parasympathetic efferent info for the entire body
cranial nerve X (10) or vagus
_________: ascending somatosensory tracts, descending corticospinal tracts site of decussation (crossing over)
white matter
(superhighways)
________ - __________: involved in control of many involuntary functions - BP, breathing, swallowing, vomiting
medulla - grey matter
what are the lobes of the brain
- frontal
- temporal
- parietal
- occipital
__________ (telencephalon): cortex + subcortical structures
- distinctive part of the brain in higher primates
- have groove + sulci
cerebrum
cerebellum; ________ ______ structure
- coordinates _________
- second largest structure
- movement
true or false less advanced mammals would have smooth less folded brains
true, more SA (surface area) = more processing readily available
study pg 47/63
study page 47 / 63
grey matter of cerebral cortex is on the outside true or false
true for spinal cord it is inside and looks like butterfly but for brain its around the white matter
what is the name for the area of movement
basal ganglia
what allows for the right and Left parts of the brain to be coordinated
corpus callosum
why should basal ganglia be called basal nuclei? in reference to the cerebrum
ganglia is a cluster of cell bodies OUTSIDE the CNS and nuclei is a cluster of cell bodies INSIDE the CNS. because the basal ganglia is INSIDE the CNS and NOT outside then it only makes sense for it to be nuclei
what are the functional areas of the cerebral cortex?
- sensory areas (ascending)
- motor areas (descending)
- association areas (integrating info)
where is the central sulcus
dividing the primary motor cortex and the primary somatic sensory cortex
where is the pre central gyrus
in front of the central sulcus on the primary motor cortex side
true or false association areas are present in all lobes of the brain
true
where is the primary motor cortex? and what is its purpose?
location: just anterior to central sulcus
purpose: cell bodies of descending ‘ upper’ or ‘first order’ motor neurons
where is the primary somatosensory cortex?
what is its purpose?
location: posterior to central sulcus
purpose: ascending info from skin / musculoskeletal system. info about touch/ pressure, pain, temp, body positions.
special sense have ________ __________.
ex:
- visual cortex
- auditory cortex
- olfactory cortex
- gustatory cortex
devoted regions
explain a somatotopic map
where parts of the brain are organized in a way that corresponds to various parts of the body. Specifically, in the somatosensory cortex and motor cortex. The map is not proportional to the body’s size but to the density of sensory or motor receptors. For example, areas like the fingertips and lips, which have more sensory receptors, occupy larger regions on the somatotopic map than less sensitive body parts. The map is also dynamic, meaning it can change based on experience or injury
what are two points about Wilder Penfield?
- founding director of Montreal neurological institute
- pioneer of neurosurgical technique for epilepsy “the Montreal procedure”
study page 60/63
study page 60/63
the direct neural pathway is affected by both the
1.
2.
- basal ganglia
- cerebellum
