Term
|
Definition
Suspend the brain within the skull.
-stabilize
-anchor
-cushion the brain |
|
|
Term
|
Definition
1. dura mater
2. arachnoid
3. pia mater |
|
|
Term
|
Definition
dense and tough
-attached to skull and arachnoid layer
pain sensitive (CNV&CNX) |
|
|
Term
| Outer periosteal layer of dura mater contains what? |
|
Definition
|
|
Term
Where is the epidural space?
Subdural? |
|
Definition
Epidural: between cranium and periosteal layer of dura
Subdural: between dura and arachnoid |
|
|
Term
|
Definition
-traumatic head injury
--often fracture of temporal bone or rupture of middle meningeal artery
(happens slowly because adhesion of dura from inside skull is hard to separate) |
|
|
Term
|
Definition
shearing forces sever VEINS (not arterial) connecting to dural sinuses
--shaken baby syndrome
chronic subdural develops slowly
acute subdural is fast |
|
|
Term
|
Definition
folds of inner layer of dura (aka interal folds)
-lies in longitudinal fissure
(extends from crista gall to tentorium cerebelli) |
|
|
Term
| What does the falx cerebri separate? |
|
Definition
the 2 cerebral hemispheres
-superior sagittal sinus outer border
-inferior sagittal sinus at free border |
|
|
Term
|
Definition
separates the middle cranial fossa from the posterior cranial fossa
--infratentorial compartment contains cerebellum and brainstem |
|
|
Term
| In imaging: what shape is made when there are leaks in the tentorium? |
|
Definition
|
|
Term
|
Definition
|
|
Term
| What connects the arachnoid mater and the pia mater? |
|
Definition
| Connects through arachnoid trabeculae |
|
|
Term
| Subarachnoid space is the ONLY _____. |
|
Definition
| true space (not just potential) |
|
|
Term
| Arachnoid mater controls ____ |
|
Definition
| controls passage of substances. --layers of cells line the dura and are joined by tight junctions |
|
|
Term
| Arachnoid granulations protrude into ____ |
|
Definition
| into the superior sagittal sinus - reabsorb CSF. |
|
|
Term
|
Definition
space between arachnoid and pia
(ONLY true space) |
|
|
Term
| Cerebral arteries and veins travel through ____ and connect with _____. |
|
Definition
| arachnoid and connects with venous sinuses in dura |
|
|
Term
| Subarachnoid space is filled with ____. |
|
Definition
|
|
Term
| Subarachnoid cisterns have ____ |
|
Definition
pools of CSF.
(spinal tap to find RBCs in CSF) |
|
|
Term
|
Definition
"worst headache of my life"
-CT shows blood in subarachnoid space
-Spinal tap shows blood in CSF
-Needs immediate intervention |
|
|
Term
|
Definition
1. hemorrhagic stroke
(means break in vessel and is getting pumped to places it doesn't belong)
2. aneurysm bleed
--both causes associated with high blood pressure |
|
|
Term
|
Definition
delicate connective tissue layer
-tightly adherent to brain and spinal cord surfaces |
|
|
Term
| Pia mater follows _____ and separates brain from ______. |
|
Definition
| gyri (UP) and sulci (DOWN) CSF (the CSF running between pia and arachnoid) |
|
|
Term
| The ventricular network produces _____. |
|
Definition
cerebrospinal fluid in choroid plexus.
The brain floats in CSF.
Reference for structures in imaging.
Virtually every part of brain receives nutrients from ventricles. |
|
|
Term
|
Definition
network of capillaries embedded in connective tissue
3 layers of cells:
capillary wall
connective tissue
epithelium
formed from blood by filtration, active transport, facilitated transport |
|
|
Term
|
Definition
1. clear and colorless
2. regulates extracellular environment
3. supplies water, amino acids, glucose, and ions to extracellular fluid
4. protects CNS (shock absorber)
5. removes metabolites form brain (probable) |
|
|
Term
|
Definition
1. circulates in ventricles
2. enters subarachnoid space
3. absorbed into venous circulation
(goes into circulation, pools at bottom, and eventually goes up to sinus) |
|
|
Term
|
Definition
A pair of C shaped horns
1. anterior/frontal
2. posterior/occipital
3. inferior/temporal
extend into each hemispheric lobe |
|
|
Term
| Later ventricles: location in the brain |
|
Definition
below is thalamus
above is corpus callosum
outside wall is caudate nucleus (part of limbic system)
the two sides connect through third ventricle |
|
|
Term
| Visual cortex has optic radiations. Damage here will lead to _____. |
|
Definition
| visual field loss aka periphery |
|
|
Term
| What happens to lateral ventricles as people age? |
|
Definition
| With old age, brain shrinks, and venrtricles look bigger / fill gap. |
|
|
Term
| Third Ventricle: Location |
|
Definition
in midline of diencephalon
walls are thalamus and hypothalamus
connects to 4th ventricle through midbrain canal (or Cerebral/Sylvian Aqueduct) |
|
|
Term
| Third Ventricle: Location |
|
Definition
in midline of diencephalon
walls are thalamus and hypothalamus
connects to 4th ventricle through midbrain canal (or Cerebral/Sylvian Aqueduct) |
|
|
Term
| Fourth Ventricle: Location |
|
Definition
| between pons and medulla anteriorly cerebellum posteriorly inferiorly continuous with central canal of spinal cord eye movement |
|
|
Term
| Fourth ventricle drains into subarachnoid space via: |
|
Definition
2 Lateral foramina (Luschka)
Midline opening (Magendie) |
|
|
Term
|
Definition
congenital
fairly common 4th ventricle blockage |
|
|
Term
|
Definition
| continuation of subarachnoid space |
|
|
Term
|
Definition
| Lumbar Cistern between L2 and S2 |
|
|
Term
| Area where CSF is drawn during spinal tap? |
|
Definition
Cistern
(pooling point for CSF) |
|
|
Term
|
Definition
1. Adults produce about 1 pint daily (0.5ml/minute)
2. Volume: approx 90ml in subarachnoid space, 30ml in lumbar sac
3. Takes 1-2hrs to get to basal cisterns
4. Takes 3-4 hours to sylvian fissure
5. 10-12hrs to spread over cerebral subarachnoid (whole brain)
6. 24 hrs to clear into superior sagittal sinus |
|
|
Term
| What happens if you have too much CSF (or poor output)? |
|
Definition
| This is rare, but ventricles swell. |
|
|
Term
|
Definition
measure head circumference
-put in a drainage system (shunt) to relieve this |
|
|
Term
| Hydrocephalus: symptoms in children |
|
Definition
1. vomiting
2. failure to thrive
3. delay of developmental milestones
4. irritability |
|
|
Term
|
Definition
1. excessive production of CSF
2. Tumors of choroidal plexus (rare)
3. blockage of CSF circulation
4. poor secretion of CSF into venous sinuses (goes through but doesn't drain out very well)
5. scarring from meningitis or hemmorhage |
|
|
Term
| Hydrocephalus: Causes (general categories) |
|
Definition
structural
bleeding
infection
neoplasm
vascular
trauma |
|
|
Term
|
Definition
enclosed in meninges
dura fuses with the sclera
subarachnoid space surrounds nerve |
|
|
Term
| Increased intracranial pressure will cause loss of _____. |
|
Definition
| spontaneous venous pulsation |
|
|
Term
| Spontaneous venous pulsation: Clinical presentation |
|
Definition
Imbalance between pressure inside and outside vein wall
-seen in 75% of normal eyes (so if the symptom isn't present it doesn't mean there is a blockage)
-is lost when intracranial pressure is over 200mmHg |
|
|
Term
|
Definition
Elevated intracranial pressure compresses CRV
Causes edema and elevation of optic nerve head
Evident with ophthalmoscope |
|
|
Term
| CSF leaves the brainstem in a unidirectional flow: |
|
Definition
| CSF->subarachnoid space->through arachnoid villi->through dura to sagittal sinus |
|
|
Term
| What is another name for pseudotumor cerebri? |
|
Definition
| "benign" idiopathic intracranial hypertension |
|
|
Term
| Idiopathic intracranial hypertension: |
|
Definition
likely a meningeal absorption defect
slow: so no dilation of ventricles |
|
|
Term
|
Definition
Headache
Difficulty with Vertical Gaze
Paranaud's Syndrome (Sylvian Aqueduct Syndrome)
Problems with gait, balance, incontinent |
|
|
Term
|
Definition
| Lateral Recumbant Position |
|
|
Term
|
Definition
|
|
Term
| Lumbar Puncture: Pressure |
|
Definition
CSF exits resulting in movement on pressure gague
CSF flows into manometer until level steadies
Normal value less than or equal to 200mm of water!! **
(may be elevated when unable to relax) |
|
|
Term
| Reasons to do imaging aka why bother? |
|
Definition
improve communications
understand reports
study anatomy and structural relationships
double check
understand limitations |
|
|
Term
|
Definition
| Standard x-ray (radiographs) |
|
|
Term
|
Definition
| Computer Axial Tomography |
|
|
Term
|
Definition
| Magnetic Resonance Imaging |
|
|
Term
|
Definition
angiography (to look @ blood vessels)
CTA
MRA/V |
|
|
Term
| If something is bright on a scan then you call it _____. |
|
Definition
|
|
Term
| Remember, image is like looking at person. Their right is on your ____. |
|
Definition
|
|
Term
|
Definition
Fast and inexpensive.
Good for bone and metal/dense objects.
Air shows BLACK
(air where you don't expect to see it around orbit may indicate a fracture) |
|
|
Term
| Plain films/xray: remember |
|
Definition
2d representation of a 3d object - do at least two views perpendicular to each other
(the body part nearest the film will be visualized better) |
|
|
Term
|
Definition
| process of image getting lighter (muscle will attenuate more than fat) |
|
|
Term
| Increased density, atomic number, and electrons per gram = |
|
Definition
|
|
Term
| Specific good use for plain films? |
|
Definition
| Rule out any foreign bodies before an MRI is taken (look for metal!) |
|
|
Term
| Plain film: false results? |
|
Definition
| High false (+) and high false (-) |
|
|
Term
|
Definition
WAY better clarity
developed by EMI (english music industry) |
|
|
Term
|
Definition
-good for bone/calcium aka fractures
-good for blood (especially leaking blood)
(acute subdural, subarachnoid hemmorrhage)
-good for meningiomas (tumor)
-good for fat and orbital muscles
-even used on mummies |
|
|
Term
|
Definition
| in CT, generalized image aka an overview of where you are "this is the angle we took the scan" |
|
|
Term
|
Definition
| muscles get inflamed and swell the inferior rectus pulls eye down and pt will see double |
|
|
Term
| Muscles in thyroid myopathy |
|
Definition
| (brontosaurs) tendon - fat body - tendon |
|
|
Term
|
Definition
-uses radiation (a LOT)
-available in ER
-fast, no danger from metal
-relatively low cost
-different window widths used
-NO SAGITTAL VIEWS POSSIBLE! but you can take axial and coronal and reconstruct sagittal |
|
|
Term
| What kind of cuts do you need for orbital imaging? |
|
Definition
|
|
Term
|
Definition
Iodine based (so avoid if shellfish allergies!)
-opacifies blood vessels (aka increases attenuation) |
|
|
Term
| Will iodine contrast used in CT scans cross the blood brain barrier? |
|
Definition
| Only if there is disruption / a break in the blood brain barrier. |
|
|
Term
| Where is the iodine contrast used in CT scans metabolized? |
|
Definition
In kidneys.
-avoid if abnormal kidney function
-extra care with diabetics |
|
|
Term
| What special task can CT scans be used for? |
|
Definition
Autopsies!
-Some religious groups opposed to autopsies. |
|
|
Term
| Fat vs. Skinny: Radiation |
|
Definition
| Fatty tissue sucks up radiation and makes them more prone to additional negative responses. |
|
|
Term
|
Definition
| response of tissue to applied magnetic field aka changes polarity of tissue |
|
|
Term
| MR is premiere means for ____. |
|
Definition
intracranial pathology evaluation
-less radiation exposure
-increased soft-tissue contrast with MR |
|
|
Term
| Future cancers will be a result of ____. |
|
Definition
|
|
Term
|
Definition
bulk of signal is by hydrogen atoms
-magnets set H atoms in sync
-then disrupt them and photograph (t1/t2)
-see how long it takes them to go back to normal (aka relaxation rate) |
|
|
Term
| Sagittal MRI sections are particularly useful for viewing (list 4): |
|
Definition
1. pituitary gland
2. corpus callosum
3. cervico-medullary junction
4. pineal gland |
|
|
Term
|
Definition
T1 = time to realign nuclei (relaxation)
High H2O content are DARK!! (hypointense)
-vitreous, CSF |
|
|
Term
| Contrast used in T1 MRI scans? |
|
Definition
Gadolinium - which will show up BRIGHT
(do two scans, a before and after for comparison) |
|
|
Term
| Junction Scotoma (shown on an MRI scan) |
|
Definition
VF: not good vision in one eye and have a visual field cut in the other
-unique to junction scotoma |
|
|
Term
| What would you see in an axial MR of an MS patient? |
|
Definition
| -what parts "sticking out" common in multiple sclerosis known as DAWSONS FINGERS -unique to MS |
|
|
Term
|
Definition
Show up on MRI scans for MS.
white parts "sticking out" |
|
|
Term
|
Definition
-NOT iodine based (less allergic reactions)
-IV administration
-abnormalities are ENHANCED
-crosses disrupted blood brain barrier |
|
|
Term
| When would you use gadolinium in an MRI scan? |
|
Definition
| Use for suspected mass, inflammation, and infiltration. |
|
|
Term
|
Definition
| Time 2 - time for nuclei to realign (aka shot a little bit later) |
|
|
Term
| What are T2 images used for? |
|
Definition
|
|
Term
| What contrast is used with T2 scans? |
|
Definition
| NONE! CSF and vitreous are already white. ALWAYS without contrast. |
|
|
Term
| What color is quick flowing blood on T1 scan? and T2? |
|
Definition
|
|
Term
| CT Scans: Advantages? (list 6) |
|
Definition
| 1. 1st day ischemic stroke 2. 1st day cerebreal or cerebellar hemmorhage 3. initial head injury 4. initial brain abcess 5. with ferrous metal 6. orbital bone fracture |
|
|
Term
| What type of scan would you use to view a 1st day ischemic stroke? |
|
Definition
|
|
Term
| What type of scan would you use to view a 1st day cerebral or cerebellar hemmorage? |
|
Definition
|
|
Term
| What type of scan would you use to view an initial head injury? |
|
Definition
|
|
Term
| What type of scan would you use to view an initial brain abcess? |
|
Definition
|
|
Term
| What type of scan would you use to view ferrous metal? |
|
Definition
|
|
Term
| What type of scan would you use to view an orbital bone fracture? |
|
Definition
|
|
Term
| MRI Scans: Advantages (list 6) |
|
Definition
1. infarcts older than 1 day
2. cavernous sinus
3. brainstem/posterior fossa
4. demyelinating disease
5. chiasmal lesions
6. intracranial tumors |
|
|
Term
| What type of scan would you use to view infarcts older than 1 day? |
|
Definition
|
|
Term
| What type of scan would you use to view cavernous sinus? |
|
Definition
|
|
Term
| What type of scan would you use to view brainstem/posterior fossa? |
|
Definition
|
|
Term
| What type of scan would you use to view a demyelinating disease? |
|
Definition
|
|
Term
| What type of scan would you use to view chiasmal lesions? |
|
Definition
|
|
Term
| What type of scan would you use to view intracranial tumors? |
|
Definition
|
|
Term
|
Definition
-exposure to radiation
-lower resolution?
-poorer visualization of most intracranial tissue (the brain stem is mostly surrounded by bone)
-artifacts like streak, motion |
|
|
Term
|
Definition
-longer scan time
-50% higher cost
-bone or calcium lesions not imaged well
-metallic bodies!
-iron oxide in tattoos interferes
-obesity (aka width of machine)
-claustrophobia |
|
|
Term
| What can be used to help with claustrophobia during MRI scans? |
|
Definition
|
|
Term
| What are open MRIs used for? |
|
Definition
| -useful for obese and claustrophobic patients |
|
|
Term
| What kind of cuts do you need to use to study the orbit? |
|
Definition
| Need many fine CORONAL cuts |
|
|
Term
| What must you do with an MRI scan to study the orbit? |
|
Definition
Must do fat suppression (T2) - you need the computer to subtract out the fat so that you can see the muscles properly.
Gadolinium is usually needed. |
|
|
Term
|
Definition
take a catheter up artery in groin (femoral artery) and inject a dye
-can catch small aneurysms |
|
|
Term
| MRA (Angiography) allows imaging of both ___ and ____. |
|
Definition
|
|
Term
| Do angiographies require contrast? |
|
Definition
| No. Although, newer techniques are using this to enhance images. |
|
|
Term
| Can angiography detect a 2mm aneurysm? |
|
Definition
| No, cannot detect aneurysms smaller than 3mm. |
|
|
Term
| Does a CTA (CT Angiography)require contrast? |
|
Definition
| Yes, IV contrast is injected. |
|
|
Term
| What type of arteries can a CTA image? |
|
Definition
| High-speed spiral CT scanning and computer-assisted generation of images of LARGE to MEDIUM-sized arteries. |
|
|
Term
|
Definition
| The patient is moved at a constant rate through the scanning field during a SINGLE BREATH-HOLD. |
|
|
Term
| What are the 3 developmental stages? |
|
Definition
1. Preembryonic
2. Embryonic
3. Fetal |
|
|
Term
| What age is the preembryonic stage? |
|
Definition
|
|
Term
| What age is the embryonic stage? |
|
Definition
|
|
Term
| What age is the fetal stage? |
|
Definition
|
|
Term
| What 2 layers comprise the embryonic disc? |
|
Definition
|
|
Term
Fertilized egg -> Blastocyst -> Embryonic disc
What will the blastcyst form? |
|
Definition
| Inner cell mass: forms a circle around - circle becomes placenta, body becomes fetus. |
|
|
Term
| What develops during the embryonic stage? |
|
Definition
|
|
Term
| What will the ectoderm give rise to? |
|
Definition
sensory organs
epidermis
nervous system |
|
|
Term
| What will the mesoderm give rise to? |
|
Definition
dermis
muscles
skeleton
excretory and circulatory systems |
|
|
Term
| What will the endoderm give rise to? |
|
Definition
gut, liver, pancreas (aka digestive system)
respiratory system |
|
|
Term
| What develops during the fetal stage? |
|
Definition
the nervous system (becomes more specific)
myelination |
|
|
Term
| When does the neural tube form? |
|
Definition
Days 18-26 (embryonic stage)
-specifically: day 21 |
|
|
Term
| In neural tube formation, the ectoderm thickens to form the ____. |
|
Definition
|
|
Term
| In neural tube formation, the edges of the neural plate fold to form the ______. |
|
Definition
| neural groove (goes from top to bottom of fetus). |
|
|
Term
| What happens once the neural tube is totally formed? |
|
Definition
| It is covered by skin and starts to differentiate (as early as 4 weeks). |
|
|
Term
Neural tube differentiation:
Mantle layer
Marginal layer
Which is inner? Which is outer? And what do they form? |
|
Definition
Mantle = inner -> cell bodies aka gray matter
Marginal = outer -> white matter |
|
|
Term
|
Definition
| nodules of cell clusters within part of mesoderm surrounding the neural tube |
|
|
Term
| What are the 3 parts of somites? |
|
Definition
1. sclerotome
2. myotome
3. dermatome |
|
|
Term
| What does the sclerotome give rise to? |
|
Definition
| Vertebrae and Skull aka BONES |
|
|
Term
| What does myotome give rise to? |
|
Definition
|
|
Term
| What does dermatome give rise to? |
|
Definition
|
|
Term
| What does the neural crest become? (list 4) |
|
Definition
1. sensory neurons
2. autonomic neuron
3. myelin-producing cells
4. parts of endocrine organs |
|
|
Term
| On what day does brain formation begin? |
|
Definition
|
|
Term
| What are the three main portions of the brain called? And what do they contain? |
|
Definition
1. Hindbrain:
-medulla, pons, and cerebellum
-4th ventricle
2. Midbrain:
-midbrain
-cerebral aqueduct
3. Forebrain
-posterior forebrain (diencephalon and third ventricle)
-anerior forebrain (telencephalon and lateral ventricles) |
|
|
Term
|
Definition
During development, cerebral and cerebellar hemispheres are not formed.
Brainstem present but malformed.
Skull does not form. |
|
|
Term
|
Definition
1. chromosomal abnormalities
2. maternal nutritional deficiencies
3. maternal hyerthermia |
|
|
Term
| What causes spina bifida? |
|
Definition
Inferior portion of neural tube does not close.
Vertebrae do not close around the neural tube. |
|
|
Term
| What causes spina bifida? |
|
Definition
| maternal folic acid deficit |
|
|
Term
| What causes chiari malformations? |
|
Definition
| Herniation of the cerebellar tonsils through the foramen magnum. |
|
|
Term
| When do symptoms of chiari malformations present themselves? |
|
Definition
| Often begin in adolescence or early adulthood |
|
|
Term
| What are the symptoms of chiari malformations? |
|
Definition
Head and neck pain
Nystagmus
Double vision
Cranial nerve dysfunction
Poor coordination |
|
|
Term
| How are chiari malformations corrected? |
|
Definition
| They remove part of skull to allow more space for cerebellum. |
|
|
Term
|
Definition
Movement and posture disorder
-Permanent and non-progressive brain damage |
|
|
Term
| What causes cerebral palsy? |
|
Definition
-Abnormal development in utero or after delivery
-Metabolic, immmune, or coagulation disorders
-Infection
-Trauma
-Hypoxia |
|
|
Term
| What are some signs and symptoms of cerebral palsy? |
|
Definition
-Scissor gait
-Motor disorders (poor coordination)
-Cognitive, somatosensory, visual, auditory, and speech deficits
-Strabismus is common.
-May have normal and above normal intelligence (though some present mental retardation) |
|
|
Term
|
Definition
cognitive, movement, and behavioral problems
growth deficiencies
mental retardation |
|
|
Term
| Facial anomalies of fetal alcohol syndrome? |
|
Definition
-small head
-eyes set far apart
-epicanthal folds
-small palpebral fissure
-short nose
-thin upper lip |
|
|
Term
| What is the direct effect of maternal substance abuse? |
|
Definition
| Crosses the placenta, baby gets addicted. |
|
|
Term
| What is the indirect effect of maternal substance abuse? |
|
Definition
| Vasoconstriction, not enough blood supply for fetus to develop correctly. |
|
|
Term
|
Definition
| # of synapses increase, continue to form even after birth |
|
|
Term
|
Definition
| grow from one site to another |
|
|
Term
|
Definition
| once it connects and you start using it, it becomes what it will function as (i.e. vision nerve) |
|
|
Term
|
Definition
| conversion of silent synapses to active synapses |
|
|
Term
|
Definition
| the lifelong ability of a nerve to compensate for injury and adjust its activity in response to the environment |
|
|
Term
| When is the most dramatic period of plasticity? |
|
Definition
The first 2 years of life (but continue to grow in older age).
This is why its important to use both eyes equally. |
|
|
Term
| What is the function of myelin? |
|
Definition
| Speeds up impulse traveling down nerve |
|
|
Term
Regeneration:
Brain and spinal cord?
Peripheral NS? |
|
Definition
No regeneration in brain and spinal cord.
Some in peripheral NS. |
|
|
Term
|
Definition
-distal axon degenerates
-myelin surrounding the distal portion of nerve degenerates
-macrophages phagocytize the myelin
-the cell body and postsynaptic cell may also degenerate |
|
|
Term
| Can a nerve regenerate if there is cell body damage? |
|
Definition
|
|
Term
| What is required for regeneration? |
|
Definition
| There can't be too much distance between new mylein sheet and the old living nerve. |
|
|
Term
| Schwann cells in regeneration |
|
Definition
| form a column along the area where the axon was. The new axon will enter the schwann cell columns. |
|
|
Term
|
Definition
An undamaged neuron branches to make a synapse at a site where a damaged neuron used to synapse
(NOTE: if it connects improperly it will cause different reactions. Example given: turn head yields pupil constriction...not normal!) |
|
|
Term
|
Definition
Occurs when the axon and its target have been damaged
-the injured axon sends out side sprouts to a new target |
|
|
Term
| Since there is NO regeneration in the CNS, what does the brain do to compensate instead? |
|
Definition
Reorganize!
Example: Blind or deaf people using their occipital cortex for reading brail. |
|
|
Term
|
Definition
| designed to receive information, process information, and generate output. |
|
|
Term
| What are functions of dendrites? |
|
Definition
1. receive information from other neurons via neurotransmitters and transmit it to the cell body
2. produce local potentials and if strong enough will lead to an action potential |
|
|
Term
| Where do the axons emerge from the cell body? |
|
Definition
|
|
Term
Axons:
What is the cytoplasm called?
What is the cell membrane called? |
|
Definition
|
|
Term
| How does an axon terminate? |
|
Definition
| By branching into extensions with enlarged ends (terminal boutons or presynaptic terminals) |
|
|
Term
| What are the 3 neuron types? |
|
Definition
1. bipolar
2. unipolar
3. multipolar |
|
|
Term
|
Definition
single dendrite and single axon
-some sensory organs including the retina |
|
|
Term
| Unipolar (pseudounipolar) |
|
Definition
single axon and no dendrites (the axon has dendrite-like processes)
-most sensory neurons |
|
|
Term
|
Definition
several dendrites and a single axon
-most neurons in the CNS and muscle neurons are multipolar |
|
|
Term
| What are the important ions in action potentials? |
|
Definition
Sodium (Na+)
Potassium (K+)
Calcium (Ca+)
Chloride (Cl-)
There are also some negatively charged protein molecules. |
|
|
Term
|
Definition
The membrane potential becomes LESS negative than the resting potential.
Considered excitatory. |
|
|
Term
|
Definition
the membrane potential becomes more negative than the resting potential.
-considered inhibitory |
|
|
Term
| Resting membrane potential |
|
Definition
| exists when the cells are not being stimulated |
|
|
Term
| At rest there are relatively more ____ ions outside the neuron and more _____ inside that neuron. |
|
Definition
sodium and chloride
potassium ions and negatively charged proteins |
|
|
Term
| The concentration differences between the inside and outside of the cell are maintained due to three characteristics: |
|
Definition
1. presence of negatively charged proteins in the cell
2. permeability of the cell membrane to K+
3. sodium-potassium exchange pump |
|
|
Term
| In an action potential, the resting membrane potential occurs when _____. |
|
Definition
| there is an equilibrium (aka very little movement of K+ ions across the cell membrane) |
|
|
Term
| In an action potential, the inside of the neuron is more negative or positive relative to the outside? |
|
Definition
|
|
Term
|
Definition
| a stimulus causes a depolarization or hyperpolariation which is confined to a small region of the cell |
|
|
Term
| Characteristics of local potentials |
|
Definition
Graded
Decreases in magnitude as they spread along the cell membrane
Therefore it only spreads a short distance along the cell membrane |
|
|
Term
| Local potentials can be increased by ____ and ____ summation. |
|
Definition
|
|
Term
|
Definition
| stimuli that occur multiple times within milliseconds are added together |
|
|
Term
|
Definition
| stimuli that occur in different locations are added together |
|
|
Term
| An action potential occurs when a local potential is sufficiently strong to reach a threshold. About ____mV |
|
Definition
|
|
Term
|
Definition
| If the depolarization reaches this threshold level an action potential will occur. If this threshold is not reached, no action potential will occur. The SIZE of the action potential is always the same. |
|
|
Term
| Action potential sequence of events: |
|
Definition
1. depolarization phase
2. Na+ channel opens due to a stimulus
3. The Na+ rushes into the neuron causing a depolarization
4. K+ channels open but more slowly
5. The inside of the cell becomes more positive than the outside of the cell |
|
|
Term
| REMINDER TO SELF: Revisit pages on action potentials to better understand sequence! |
|
Definition
|
|
Term
Which will have a faster action potential?
A) Larger or smaller diameter axons
B) Myleinated or nonmyleinated axons? |
|
Definition
|
|
Term
| Refractory Period (in action potentials) |
|
Definition
| Keeps the action potential from reversing the direction of propagation |
|
|
Term
| Absolute refractory period |
|
Definition
| period of time in which the axon is not sensitive to another stimulus |
|
|
Term
| Relative refractory period |
|
Definition
| only a stronger than normal stimulus can cause another action potential |
|
|
Term
| Clinical application of action potentials: Local Anesthetics |
|
Definition
| blocks Na+ channels which prevents the propagation of action potentials along sensory neurons |
|
|
Term
|
Definition
Extracellular Ca2+ levels cause the Na+ channels to close
Low levels of calcium cause the cellular membrane to become more permeable to Na+ |
|
|
Term
| What are symptoms of hypocalcemia? |
|
Definition
1. nervousness
2. muscular spasm (cramps)
3. tetany (muscles locking up) |
|
|
Term
| What causes hypocalcemia? |
|
Definition
-lack of calcium in diet
-lack of vitamin D
-decreased secretion of parathyroid hormone |
|
|
Term
|
Definition
| support system for the neurons |
|
|
Term
|
Definition
|
|
Term
| What do astrocytes do? (list 6) |
|
Definition
1. provide physical support to neurons
2. role in cell signaling
3. aid in the formation of the blood-brain barrier by releasing chemicals that stimulate tight junctions between endothelial cells (prevents toxic substances from entering brain)
4. regulates content of extracellular space
5. transport nutrients to neurons
6. central nervous system development |
|
|
Term
| What do oligodendrocytes do? |
|
Definition
| 1. protect and insulate neurons in the central nervous system 2. cytoplasmic extensions wrap around axons many times to produce the myelin sheath which allows for efficient conduction of action potentials 3. each can supply myelin to several axons |
|
|
Term
|
Definition
| Specialized macrophages in the CNS (kind of like a macrophage of the CNS) |
|
|
Term
| How many cells can a schwann cell myelinate? |
|
Definition
|
|
Term
|
Definition
| interruptions in the mylein sheath |
|
|
Term
|
Definition
| action potentials jump from one node of Ranvier to the next causing the action potential to travel much faster than in an unmyelinated axon |
|
|
Term
|
Definition
| an autoimmune disease in which antibodies attack myelinated CNS nerves. |
|
|
Term
| What cells are affected in MS? |
|
Definition
All glial cells in the CNS.
Oligodendrocytes destroyed compromising the repair process of the myelin sheath.
Microglial cells are stimulated to feed on the myelin debris.
Astrocytes proliferate causing scarring. |
|
|
Term
| What are the symptoms of MS? |
|
Definition
-weakness
-lack of coordination
-decreased vision
-double vision
-impaired sensation
-bladder and bowel dysfunction
-depression |
|
|
Term
|
Definition
| may be the presenting condition in multiple sclerosis |
|
|
Term
|
Definition
age of onset: 20-50yrs, mean age: 30-35
more common in women
prevalence: 115 per 100,000 |
|
|
Term
|
Definition
-90% of patients have pain or discomfort around the eye with eye movement
-decreased vision (usually monocular)
-flashes of light (photopsias) |
|
|
Term
|
Definition
-afferent pupillary defect
-decreased visual acuity
-acquired color loss
-visual field deficit
-decreased contrast sensitivity |
|
|
Term
| What imaging is preferred for optic neuritis? |
|
Definition
MRI
-determines if retrobulbar optic neuritis is present
-determine the presence of plaques |
|
|
Term
| Treatment of optic neuritis? |
|
Definition
90% of patients spontaneously recover vision to 20/40 or better within 3-5 weeks.
3 day course of IV corticosteroid followed by 15 days of oral prednisone and then interferon beta-1a lowers the risk of developing MS over 3 years to 35% intstead of the 50% risk in untreated patients. |
|
|
Term
| The synapse consists of 3 components: |
|
Definition
1. a presynaptic terminal (terminal bouton)
2. the synaptic cleft
3. the postsynaptic membrane |
|
|
Term
| Sequence of events leading up to the release of the neurotransmitter: |
|
Definition
1. action potential arrives at presynaptic terminal
2. Ca2+ channels are opened and Ca2+ diffuses into the presynaptic terminal
3. Ca2+ ions cause the presynaptic vesicle to fuse with the presynaptic membrane and release the neurotransmitter. |
|
|
Term
| Once the neurotransmitter is finished stimulating the postsynaptic cell, it is quickly removed by one of the 3 following processes: |
|
Definition
1. catabolism (neurotransmitters are broken down)
2. active transport (reabsorbed back into presynaptic terminal and then repackaged)
3. diffusion |
|
|
Term
| What is difference between the mechanism of removal of acetylcholine and norepinephrine at the synaptic cleft? |
|
Definition
| Acetylcholine (either catabolism, active transport or diffusion) Norepinephrine is just transported back into pre-synaptic terminal intact. |
|
|
Term
|
Definition
a chemical released by the presynaptic terminal that causes excitation OR inhibition of the postsynaptic membrane
-released in axo-dendritic |
|
|
Term
|
Definition
Influences that likelihood that an action potential will occur in the postsynaptic cell
-released in axo-axonic |
|
|
Term
| Are action potentials produced in an axo-axonic synapse? |
|
Definition
|
|
Term
|
Definition
| decreases neurotransmitter release from the presynaptic membrane |
|
|
Term
|
Definition
| increases neurotransmitter release from the presynaptic membrane |
|
|
Term
| Where is acetylcholine found and what does it regulate? |
|
Definition
found in neuromuscular junction of skeletal muscle
involved in autonomic regulation
plays a role in the general activity level of the CNS |
|
|
Term
Neurotransmitter:
Acetylcholine has two receptors: |
|
Definition
1) Nicotinic (ALWAYS excitatory)
2) Muscarinic (sometimes excitatory, sometimes inhibitory) |
|
|
Term
| 2 clinical applications of acetylcholine: |
|
Definition
1) botox
2) myasthenia gravis |
|
|
Term
Neurotransmitter:
Glutamate and aspartate |
|
Definition
Gulatamate is widely spread - the primary fast excitatory transmitter in the CNS.
(Asparate is not found often in CNS but is excitatory). |
|
|
Term
|
Definition
-elicits neural plasticity in learning and development
-contributes to cell death after injury to CNS |
|
|
Term
| Clinical applications of glutamate: |
|
Definition
-over activity may cause epileptic seizures
-PCP or angel dust blocks glutamate receptors |
|
|
Term
Neurotransmitter:
Gamma-aminobutyric acid (GABA) |
|
Definition
| The major INHIBITORY neurotransmitter in the CNS. |
|
|
Term
| Clinical applications of GABA: |
|
Definition
-low levels can lead to seizures
-benzodiazepines (anti-anxiety) activate GABA receptors
-barbiturates activate GABA receptors
-baclofen (muscle relaxant) increases the presynaptic release of GABA reducing excessive muscle activity
-alcohol inhibits GABA release |
|
|
Term
|
Definition
in spinal cord
INHIBITORY
similar to GABA - prevents excessive neural activity |
|
|
Term
| Clinical applications of glycine: |
|
Definition
-low levels can lead to seizures
-strychnine inhibits glycine receptors |
|
|
Term
Neurotransmitter:
Norepinephrine |
|
Definition
-found in brain stem
-role in increasing attention to sensory information
-role in the sympathetic ANS system
-can be excitatory or inhibitory |
|
|
Term
| Clinical applications of norepinephrine: |
|
Definition
-panic disorder and post-traumatic stress disorder involve excessive levels of norepinephrine
-cocaine blocks the reuptake of norepinephrine
-amphetamines increase the release and block the reuptake of norepinephrine |
|
|
Term
Neurotransmitter:
Serotonin |
|
Definition
Role in general arousal level, mood, and suppressing sensory information
Generally INHIBITORY. |
|
|
Term
| Clinical applications of serotonin: |
|
Definition
-low levels of serotonin are associated with depression and suicide
-Proxac, Zoloft, and Paxil block serotonin reuptake
-Serotonin levels are increased with schizophrenia |
|
|
Term
Neurotransmitter:
Dopamine |
|
Definition
Has an effect on motor activity, cognition, and motivation
can be excitatory OR inhibitory |
|
|
Term
| Clinical applications of dopamine: |
|
Definition
| -Parkinson's disease results from destruction of dopamine-secreting neurons |
|
|
Term
Neurotransmitter:
Peptides |
|
Definition
-endorphins and enkephalins
-associated with pain perception
generally INHIBITORY |
|
|
Term
| Clinical applications of peptides: |
|
Definition
| Morphine and heroin reduce pain by inhibiting neurons involved in pain perception |
|
|
Term
Neurotransmitter:
Substance P |
|
Definition
associated with pain perception
generally EXCITATORY |
|
|
Term
| Clinical applications of Substance P: |
|
Definition
| Morphine blocks the release of substance P which reduces pain. |
|
|
Term
| What causes Myasthenia Gravis? |
|
Definition
| The body produces antibodies to the nicotinic receptors on the skeletal muscle cells aka attacks itself at nicotinic receptors. |
|
|
Term
Myasthenia Gravis:
Onset?
Prevalence? |
|
Definition
20-30 in women, 60-70 in men
14 per 10,000 |
|
|
Term
| Symptoms of myasthenia gravis: |
|
Definition
muscle weakness with repetitive movements
muscle movements most commonly affected:
-eye movements, eyelids
-facial expression
-swallowing, chewing, and talking
-proximal limb movement
-respiration (can lead to death) |
|
|
Term
| Ophthalmic symptoms of myasthenia gravis: |
|
Definition
-lid droop (in almost ALL MG patients and gets worse throughout the day - asymmetrically)
-double vision (gets worse throughout the day) |
|
|
Term
|
Definition
when the patient looks in downgaze and then to primary position the lids overshoot and then come back to normal position
(in myasthenia gravis) |
|
|
Term
| In office testing for myasthenia gravis: |
|
Definition
Ice test (placed over the ptotic lid for 2 minutes) - ptosis will be greatly improved
Rest test - ptosis improves in MG patient after 20 minutes of keeping their eyes closed |
|
|
Term
| Myasthenia gravis: treatment |
|
Definition
1. anticholinesterase medications
2. removal of thymus gland
3. immunosuppressive drugs
4. plasmapheresis (short term and very expensive) |
|
|
Term
| How many nerves are there in the peripheral nervous system? |
|
Definition
43 pairs of nerves
Spinal nerves:
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal |
|
|
Term
| 2 subdivisions of the PNS: |
|
Definition
1) Afferent or sensory division (to the brain)
2) Efferent division (from the brain) |
|
|
Term
| Cell bodies of the afferent/sensory division are located in ______. |
|
Definition
| the dorsal root ganglia near the spinal cord |
|
|
Term
| What are the two subdivisions of the efferent division? |
|
Definition
1) Somatic nervous system
2) Autonomic nervous system |
|
|
Term
|
Definition
Transmits action potentials from the CNS to skeletal muscle
Cell bodies are located within the CNS
Axons extend from CNS to skeletal muscle |
|
|
Term
| Autonomic Nervous System: |
|
Definition
Transmits action potentials from the CNS to smooth muscle, cardiac muscle, or glands.
Consists of pre and post ganglionic fibers. |
|
|
Term
|
Definition
1) Sympathetic division
2) parasympathetic divions
3) enteric division |
|
|
Term
| The effect of the somatic nervous system on skeletal muscle is always ____. |
|
Definition
|
|
Term
| Preganglionic fibers leave the lateral horn of the spinal cord gray matter between ____ and _____. |
|
Definition
the first thoracic (T1)
second lumber (L2) |
|
|
Term
| The head and neck obtain most of its sympathetic nerve supply from the ______. |
|
Definition
superior cervical chain ganglia
(cervical paravertebral ganglia)
Note: supply the sweat glands of the face, salivary glands, dilator muscle of the iris, Mueller's muscle, and blood vessels that supply the lacrimal gland. |
|
|
Term
|
Definition
| any lesion that affects the sympathetic pathway to the eye can cause Horner's syndrome |
|
|
Term
|
Definition
| Ipsilateral ptosis, miosis, anhidrosis (lack of sweating on that side) |
|
|
Term
Preganglionic Horner's syndrome:
Causes (list 8) |
|
Definition
1) cerebral vascular accident
2) ms
3) pituitary tumor
4) pancoast's tumor (apex of lung)
5) mediastinal mass (between lungs)
6) neck trauma
7) coronary bypass surgery
8) thyroidectomy |
|
|
Term
Postganglionic Horner's syndrome:
Causes (list 5) |
|
Definition
1)head or neck trauma
2) migraine
3) vascular
4) cluster headache
5) herpes zoster |
|
|
Term
Horner's Syndrome:
Diagnosis |
|
Definition
Cocaine applied topically
(another option: apraclonidine)
Non-horner's = dilation of pupil
Horner's = no dilation |
|
|
Term
| Parasympathetic fibers in the oculomotor nerve (CNIII) supply ________. |
|
Definition
| the ciliary muscles and the sphincter muscle of the iris |
|
|
Term
| Parasympathetic fibers in the facial nerve (CNVII) supply the _______ and also supplies _______. |
|
Definition
lacrimal gland
mucus glands in the nasal cavity the submandibular and sublingual salivary glands |
|
|
Term
| Parasympathetic fibers in the glossopharyngeal nerve (CNIX) supply ______ |
|
Definition
| the parotid salivary gland. |
|
|
Term
| Parasympathetic fibers in the vagus nerve (CNX) contribute to the ___ which supplies ___, the ___ which supplies ___, and the ___ which supplies _____. |
|
Definition
cardiac plexus - heart
pulmonary plexus - lungs
esophageal plexus - esophagus |
|
|
Term
|
Definition
| a neuron that secretes acetylcholine |
|
|
Term
|
Definition
| a neuron that secretes norepinephrine |
|
|
Term
| Where are nicotinic receptors located? |
|
Definition
Located on ALL postganglionic cell bodies in the ANS.
Located on skeletal muscle cells. |
|
|
Term
| Where are muscarinic receptors located? |
|
Definition
| On the membrane of the effector organ in the parasympathetic system. |
|
|
Term
| Norepinephrine and epinephrine bind to |
|
Definition
|
|
Term
|
Definition
speech
-hard time producing a sentence |
|
|
Term
|
Definition
speech
-talk fast but it doesn't make sense (they don't realize it) |
|
|
Term
| In cranial circulation, where does the anterior system come from? |
|
Definition
internal carotids
-supplies the majority front part of the brain |
|
|
Term
| In cranial circulation, where does the posterior system come from? |
|
Definition
|
|
Term
| What is the function of the circle of willis? |
|
Definition
| Connects the anterior and posterior circulation |
|
|
Term
| What are the main arteries of the circle of willis? |
|
Definition
Anterior cerebral arteries
Middle cerebral arteries
Posterior cerebral arteries (supplies occipital)
Anterior communicating arteries
Posterior communicating arteries |
|
|
Term
| What are the branches of the internal carotid artery? |
|
Definition
OPAAM
Ophthalmic
Posterior communicating
Anterior choroidal
Anterior cerebral
Middle cerebral |
|
|
Term
| Segments of the internal carotid artery? |
|
Definition
1) Cervical segment
2) Petrous segment
3) Cavernous segment
4) Supraclinoid or inracranial segment |
|
|
Term
| Where is the cervical segment of the internal carotid artery located? |
|
Definition
| vertical portion, in the neck (into the petrous portion of temporal bone) |
|
|
Term
| Where is the petrous segment of the internal carotid artery? |
|
Definition
| sharp horizontal bend, enters the temporal bone |
|
|
Term
| What is the shape of the cavernous segment of the internal carotid artery? |
|
Definition
|
|
Term
| Which direction does the supraclinoid segment of the internal carotid artery bend? |
|
Definition
|
|
Term
| What artery supplies most of anterior medial surface? |
|
Definition
|
|
Term
| Where is the anterior cerebral artery? |
|
Definition
| sweeps back over corpus callosum |
|
|
Term
| What supplies most of the lateral convexity of the brain? |
|
Definition
|
|
Term
| Where is the middle cerebral artery? |
|
Definition
| Travels within sylvian fissure |
|
|
Term
| What supplies the inferior and medial temporal lobe and occipital cortex? |
|
Definition
| Posterior cerebral artery |
|
|
Term
| Location of the posterior cerebral artery? |
|
Definition
| curves back around the brainstem |
|
|
Term
| What supplies the basal ganglia and internal capsule? |
|
Definition
Lenticulostriate arteries
(from middle cerebral artery) |
|
|
Term
| What supplies hippocampus, basal ganglia, thalmus, and posterior internal capsule? |
|
Definition
Anterior choroidal artery
(from internal carotid) |
|
|
Term
| Temporary brain ischemia: |
|
Definition
| not enough blood to brain, usually about 10 minutes (lose vision, double vision) |
|
|
Term
| What kind of signs display during a transient ischemic attack? |
|
Definition
| Positive (flashes of light, tingling) or negative (darkness, numbness, loss of vision) |
|
|
Term
| Transient ischemic attacks can lead to _____. |
|
Definition
| full stroke (usually will happen in 48 hours but could be up to a few months). |
|
|
Term
|
Definition
| inadequate blood supply causes infarction (death) of tissue. causes PERMANENT disability |
|
|
Term
|
Definition
1) hemorrhagic (intracerebral or subarachnoid)
2) ischemic (something cuts blood off to portion of brain) |
|
|
Term
|
Definition
1) embolic infarct (clot in heart, moves up to brain)
2) thrombotic infarct (forms in a blood vessel in the brain) |
|
|
Term
| Clinical Patterns: Stroke - Middle Cerebral Artery |
|
Definition
| 1) Aphasia (L hem.) - can't talk 2) Hemi-neglect (R hem.) 3) Hemianopia 4) Sensory loss in face and arm 5) weakness of face and arm 6) Contralateral deficits (R brain = L body) |
|
|
Term
|
Definition
|
|
Term
|
Definition
| can see on both sides but ignore one side of their whole world (including their body) |
|
|
Term
Clinical Patterns:
Stroke - Anterior Cerebral Artery |
|
Definition
Leak weakness (medial side of brain)
Behavior abnormalities (b/c frontal lobe controls behavior)
Contralateral deficits |
|
|
Term
| Clinical Patterns: Stroke - Posterior cerebral artery |
|
Definition
| hemianopia contralateral deficits NOTE: usually only affects vision |
|
|
Term
|
Definition
| blood pressure drops, can cause stroke because vessels far away are much thinner. if you decrease the blood pressure, it won't reach those vessels. you can wiggle fingers but not lift arms |
|
|
Term
|
Definition
|
|
Term
| Watershed infarcts display ____ |
|
Definition
proximal arm and leg weakness
aphasia |
|
|
Term
| What areas do watershed infarcts affect? |
|
Definition
| Region between cerebral artery territories |
|
|
Term
Carotid stenosis:
general concepts |
|
Definition
-atherosclerotic disease
-thrombi can cause embolus distally
-result in TIA or infarcts
-amaurosis fugax
-bruit, MRA, CTA, or Doppler ultrasound |
|
|
Term
|
Definition
| loss of blood causing loss of vision over a 10 minute period of time |
|
|
Term
| Carotid stenosis: effect on vision |
|
Definition
Sometimes a "curtain" aka half vision.
Not usually permanent but can be.
If cholesterol buildup (plaque) is seen in one eye, get the patient in IMMEDIATELY to prevent stroke. |
|
|
Term
|
Definition
| Dilation of arterial wall |
|
|
Term
| What is the effect of an aneurysm? |
|
Definition
| As it grows, it compresses structures much like a tumor would. |
|
|
Term
| What happens when an aneurysm ruptures? |
|
Definition
| A subarachnoid hemorrhage. -sudden and worst HA of life -sudden death |
|
|
Term
| What is it called when there is a congenital connection between artery and vein? |
|
Definition
| Arteriovenous malformation |
|
|
Term
| Arteriovenous malformation |
|
Definition
"steals" blood from adjacent brain tissue
-may rupture and bleed |
|
|
Term
| What are the superficial structures in venous drainage? |
|
Definition
Superior sagittal sinus (along top of brain)
Cavernous sinus |
|
|
Term
| What are the deep structures of venous drainage? |
|
Definition
| Great vein of Galen (inferior sagittal sinus) |
|
|
Term
| Sagittal sinus thrombosis |
|
Definition
-associated with hypercoagulable state
-obstruction of venous drainage raised ICP
-hemmorhages
-decreased perfusion and infarcts
-seizures
-headaches and papilledema |
|
|
Term
|
Definition
tight junctions between capillary endothelium prevents large molecules from exiting the capillary
(tight junctions in arachnoid cell layer have same function)
excludes many pathogens from the CNS |
|
|
Term
| Necessity of constant blood flow |
|
Definition
-brain cannot store glucose or oxygen efficiently
-oxygen consumption increases from brainstem to cerebral hemispheres
(cerebral cortex is more vulnerable than brainstem) |
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Term
| Can the CNS regulate its own blood supply? |
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Definition
Yes.
-blood pressure
-metabolites |
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