Med Neuro Flashcards
What are 4 types of brain herniations?
- Subfalcine 2. Central 3. Transtentorial 4. Tonsillar
Which type of brain herniation syndrome has no symptoms?
Subfalcine - limbic lobe [emotion] is compressed (sagittal section of brain)
Which type of brain herniation syndrome can result in abducent nerve palsy?
Central - brainstem towards foramen magnum inferiorly - pressure on cranial nerves
What is compressed in a transtentorial herniation?
Medial temporal lobe - uncus [smelling]
Which type of brain herniation syndrome can affect respiratory centers?
Tonsillar - from increased pressure in cranial cavity
What are the only two places the arachnoid mater dips into the sulci and fissures of the brain?
- Falx 2. Tentorium
Where is the CSF located?
In the subarachnoid space
Where does the CSF return to the venous circulation?
Through the arachnoid villi
Arachnoid villi
Projections of arachnoid and subarachnoid space projecting into dural venous sinuses
Pia mater
- Follows contours of brain 2. Covers vessels of brain separates subarachnoid from perivascular space [Virchow-Robin space] 3. 2-3 cells thick; microscopic
What does the interventricular foramen of Monro connect?
The lateral ventricles to the 3rd ventricle
What is the role of the choroid plexus?
Secretes CSF
Septum pelucidum
Separate lateral ventricles
What 3 main functions does the frontal lobe have?
- Higher cognitive function - personality/judgements 2. Primary motor cortex - control of voluntary movements 3. Motor area for speech
What 2 main functions does the parietal lobe have?
- Conscious sensation - pain, pressure, touch 2. Association cortices (associate what sensation is coming from)
What 2 main functions does the temporal lobe have?
- Comprehension of language 2. 1˚ auditory cortex - hearing
Wernicke’s area is located where?
Superior temporal gyrus
What are the 2 main functions of the occipital lobe?
- Vision 2. Processing visual information - motion, edge, color
Where is the 1˚ visual cortex located
Occipital lobe along calcarine fissure - striate cortex - Brodmanns area 17
What are the 5 main functions of the Limbic Lobe?
- Fighting 2. Fleeing 3. Feeding 4. Feeling 5. Fucking
Uncus (Limbic)
Part of 1˚ olfactory cortex
Amygdala
Cluster of grey matter - emotions and memory
Insula
Homeostasis, motor control, emotions, self (deep to temporal lobe)
What are two types of basal ganglia (clusters of neural bodies)?
- Caudate nucleus 2. Lenticular nucleus
_____________ makes up the lateral wall of the lateral ventricle.
Caudate nucleus
What is the role of the basal ganglia?
Motor activity/motor control
What are the two parts of the lenticular nucleus?
- Putamen (L) 2. Globus pallidus (M)
The ________ makes up the lateral wall of the 3rd ventricle.
Thalamus
The ____________ transmits all sensation except _____________ to the cerebral cortex.
- Thalamus 2. Olfaction
Epithalamus
Pineal gland - sleep/wake cycle
Cerebellum
Fine tuning movement/motor control
Vermis
Midline structure of the cerbellum
Brainstem functions (4)
- Maintains homeostasis 2. Sensory 3. Motor 4. ANS innervation of head and neck
The cranial nerves emerge from the ______________.
Brainstem
The ______________ anastomose to form the basilar artery.
Vertebral arteries
What is the DIAPHRAGMA SELLAE?
part of dura mater that surrounds pituitary gland
What is the general venous flow from the SUPERIOR SAGITTAL SINUS?
superior sagittal sinus–>straight sinus–>transverse sinus–>sigmoid sinus (joins superior petrosal sinus)–>IJV
Will arachnoid mater bleed if you cut it?
No–it is avascular
What is in the subarachnoid space?
CSF and vasculature
What is the ATRIUM of the lateral ventricles?
where temporal and occipital horns meet
From what developmental structure are the VENTRICLES in the brain derived?
neural tube lumen
What is the CENTRAL CANAL of the spinal cord?
remaining lumen of the spinal cord at brainstem
What structures are associate with the FOURTH VENTRICLE of the brain?
- Lateral aperature (of Luschka); on on each side of the cerebellopontine angle 2. Medial aperture (of Magendie); in cerebellomedularis cisterna
What two structures define the space in which the FOURTH VENTRICLE lies?
superior/inferior medullary velum
How many types of horns do the LATERAL VENTRICLES have and what are they?
- frontal (anterior) horn 2. Temporal (inferior) horn 3. Occipital (posterior) horn
How is CSF moved throughout the spinal cord?
pulsations of ependymal cells with cilia
What is a CISTERN?
a large area of CSF in the spinal cord
What is the CORPUS CALLOSUM?
nerve fivers connecting cerebral hemispheres
A baby bumped his forehead. He bumped the _____ part of his head.
rostral
A child fell backward and hit his head on the lawn. The child hit the _____ part of his head.
caudal
Where does the rostral/caudal angle change occur?
at the midbrain
What is a SULCUS?
a groove on the surface of the brain
What is a FISSURE?
a deep furrow or cleft
What is a GYRUS?
a prominent, rounded elevation on the surface of the cerebrum, between sulci/fissures
What are BROADMANN’S AREAS?
a map of cell patterns in the cerebral cortex
Which lobes does the SAGITTAL FISSURE separate?
two halves of brain
Which lobes does the SYLVIAN (lateral) FISSURE separate?
temporal lobe from frontal/pariteal
Which lobes does the CENTRAL SULCUS (of Rolando) separate?
frontal and parietal loves
Which sulcus separates the occipital and parietal lobes? Where can it be seen
-PARIETOOCCIPITAL SULCUS -is only seen from a half-brain specimen
Where is the CALCARINE FISSUE located?
seen on a half-brain specimen; located in occipital lobe
What are dysphasias? What lobe is damaged if you have this problem?
-trouble speaking -in Brocha’s area [motor] in frontal lobe
How many gyri does the FRONTAL LOBE have and what are they?
- Precentral gyrus 2. Superior gyrus 3. Middle gyrus 4. Inferior gyrus 5. Gyrus rectus (seen in 1/2 brain specimen) 6. Orbital gyrus (seen in 1/2 brain specimen)
Which gyrus of the FRONTAL LOBE holds the primary motor cortex?
precentral gyrus
Which gyrus of the FRONTAL LOBE holds BROCA’S AREA?
left hemisphere of the inferior gyrus
Which lobe of the brain have you injured if when you close your eyes, you cannot recognize that your left hand is yours?
PARIETAL LOBE
Which gyrus of which lobe did you injure if you cannot comprehend language (aphasia)?
supramarginal gyrus of the parietal lobe
Where is the primary AUDITORY CORTEX located?
superior temporal gyrus
What are the functions of the TEMPORAL LOBE of the brain?
- Hearing 2. Comprehension of language
Which part of the brain is associated with comprehending sounds?
Wernicke’s area of the superior temporal gyrus
What are the functions of the OCCIPITAL LOBE of the brain?
- vision 2. interpretation of visual images
What is it called when you are an epilepsy patient and you smell something bad before a seizure? Where is the seizure affecting in the brain?
-UNCINATE FIT -UNCUS
The hypothalamus has _____ and ______ functions.
-endocrine -ANS
What are MAMILLARY BODIES?
part of limbic system (memory)
What can cause CEREBELLAR TONSILS to herniate through the foramen magnum?
hemorrhage
In the SPINAL CORD, _______ matter is on the inside and ______ matter is on the outside.
-gray (cell bodies) -white
What are the 4 types of brain herniations?
- Subfalcine 2. Central 3. transtentorial 4. tonsillar
What is a SUBFALCINE herniation and what does it affect?
when the cingulate gyrus goes under the falx cerebri; affects the limbic lobe (emotion)
What is a CENTRAL herniation and what does it affect?
when brainstem goes toward the foramen magnum; can cause CN VI palsy–>superior oblique muscle paralysis (eye can’t move down and in)
What is a TRANSTENTORIAL herniation and what does it affect?
when medial temporal lobe (UNCAL area) goes through the tentorial notch; can lose sense of smell
What is a TONSILLAR herniation and what does it affect?
when cerebellar tonsils go through foramen magnum; can cause problems with respiration and other basic functions (of brainstem)
Where is the vasculature that supplies blood to the brain?
in the subarachnoid space
Arachnoid villi return ______ to ______.
-CSF -Venous circulation/sinuses
Where are the only places where the ARACHNOID MATER folds onto itself?
arachnoid trabeculae
PIA MATER separates the ________ from the ________.
-subarachnoid space -perivascular space
What is a VIRCHOW-ROBIN SPACE?
pia mater; covers blood vessels in subarachnoid space where blood vessels go into perivascular space
Name the 3 horns of the LATERAL VENTRICLES.
- anterior/frontal 2. inferior/temporal 3.posterior/occipital
What is the name of the place where the temporal and occipital horns of the LATERAL VENTRICLE meets?
ANTRUM
What is the structure that allows CSF to flow from the 3rd to 4th ventricle?
cerebral aqueduct (of Sylvius)
There are two _______ of the fourth ventricle and one _____ of the fourth ventricle that drain CSF into the spinal cord.
-lateral apertures (foramina of Luschka) -medial aperture (foramen of Magendie)
What is the CENTRAL CANAL of the spinal cord?
remaining lumen of spinal cord
The ventricles were derived from the __________ in embryonic development.
neural tube lumen
Where is the CHOROID PLEXUS located?
in lateral and 3rd ventricles (only a little in 4th in lateral foramen of Luschka)
What is the SEPTUM PALLUCIDUM?
thin, lucid tissue that separates the 3rd ventricles on either side
The _______ connects the cerebral hemispheres.
corpus callosum
What is a cistern?
a large area filled with CSF in spinal fluid
______ moves CSF by pulsations in the SC.
ependymal cells
The change in _________ occurs at the midbrain.
rostral/caudal angle
Which structures make up the LIMBIC LOBE?
- amygdala =emotion; gray matter (more anteriorly) 2. hippocampus = memory (more posteriorly) [both on either side of brainstem, posteriolateral to 3rd ventricle] 3. Uncus (smell) 4. Parahippocampal gyrus 5. cingulate gyrus/sulcus
What is the INSULA and where is it located?
deep part of lateral sulcus; not technically part of any lobes; for olfaction, indiscriminate touch (self-awareness)
The ______ always makes up the lateral walls of the anterior horn of the lateral ventricles.
Caudate nucleus
What does the BASAL GANGLIA consist of? What is its function?
- caudate nucleus 2. lenticular nuclei (putamen, globus pallidus) -precise control of VOLUNTARY MOTOR movement
What makes up the BASAL GANGLIA?
gray matter = neural cell bodies [deep within white matter]
What two areas make up the LENTICULAR NUCLEI?
- putamen (vertical upon coronal section) 2. globus pallidus (horizontal upon coronal section)
The _____ makes up the lateral wall of the 3rd ventricle.
THALAMUS
What is the main function of the THALAMUS?
transmits ALL SENSATION (except olfaction) to cerebral cortex for processing
Do the olfactory bulb neurons pass through the thalamus?
NO!
Which brain region has both endocrine and ANS functions?
HYPOTHALAMUS
The ____________ in the ________ region of the brain is sensitive to light and plays a role in the sleep/wake cycle.
-pineal gland -epithalamus
What is the DIENCEPHALON and what 5 regions are in it?
- region of the embryonic vertebrate neural tube that gives rise to posterior forebrain structures 1. thalamus 2. hypothalamus 3. epithalamus 4. subthalamus 5. mamillary bodies
Which part of the diencephalon deals with memory disturbances?
mamillary bodies
MAMILLARY BODIES are part of the _______.
limbic system
The _________ processes sensory information to regulate smooth movement.
CEREBELLUM
Where is the VERMIS on the cerebellum?
in the midline
What are the two bumps lateral to the vermis called? And what can happen to them due to trauma?
-cerebellar tonsils -herniation through the foramen magnum
What 3 structures does the brainstem consist of?
- midbrain 2. pons 3. medulla
What is the function of the BRAINSTEM?
- homeostasis 2. sensory, motor and ANS innervation of the neck/head (chemoreceptors, pressure receptors, etc.) 3. special senses
Which two structures does the MIDBRAIN consist of? And where are they located?
- Tectum (superior/inferior colliculi); posterior to cerebral aqueduct 2. Tegmentum (cerebral peduncles); between cerebral aqueduct [post] and basal pons [anterior]
What are the 4 parts of the SPINAL CORD?
- cervical 2. thoracic 3.lumbar 4. sacral
What does the inner, H-shaped area of the spinal cord consist of?
gray matter = cell bodies
What does the outer, non-H-shaped area of the spinal cord consist of?
white matter = axons
Which physical structures make up the OCCIPITAL LOBE?
- Preoccipital notch 2. Calcarine fissure 3. Striate cortex 4. Cuneus 5. Lingual gyrus
Which 3 symptoms can tip off a doctor that a patient is having a stroke?
- sudden onset 2. focal, neurologica symptoms = unilateral 3. cerebrovascular cause is a possible explanation
About _____ are ischemic strokes and _______ are hemorrhagic strokes.
-85% -15%
What causes an ISCHEMIC stroke?
blockage in vasculature of brain becomes blocked and then area becomes infarct
What causes a HEMORRHAGIC stroke?
a vessel in the vasculature of the brain ruptures
Does altered consciousness usually indicate a stroke?
NO! not usually, because usually a neurological, unilateral problem
What are some specific symptoms that indicate a patient could be having a stroke?
- hemi-field cut/ monocular blindness 2. aphasia/can’t understand speech (nonsense words) 3. weakness of one side of face 4. numbness on one side
What could cause a hemi-field cut or monocular blindness?
A carotid plaque could block flow to the optic nerve and retina and therefore deplete blood to that area of sight on one side
What is the difference between hemi-field cut and monocular blindness?
-hemi-field = vision loss in both eyes at optic chiasm; can be caused by ACA -monocular blindness = vision loss in one of two optic nerves before it enters optic chiasm
What are the two types of ISCHEMIC STROKES?
- thrombotic (athlerosclerosis; irregularities of surface cause clotting–many clots at bifurcation causes turbulent flow) 2. embolic (traveling particle, like from atrial fibrillation)
What are the 2 types of HEMORRHAGIC STROKES?
- intracerebral (in parenchyma caused by hypertension) 2. subarachnoid (aneurysm due to defect in vessel; can be congenital or trauma)
Which type of HEMORRHAGIC STROKE is the most lethal?
subarachnoid
What does a subarachnoid hemorrhage look like on CAT scan?
blood fills ventricles
What does a intracerebral hemorrhage look like on CAT scan?
only within brain parenchyma; midline shift = squished ventricles
What are the 3 main arterial branches that we can diagnose as causes for ischemic stroke?
- anterior cerebral artery (midline) 2. middle cerebral artery (lat) 3. posterior cerebral artery (midline)
What is ISCHEMIC PENUMBRA?
parenchyma proximal to ischemic area that can be salvaged (time permitting) due to collateral flow and autoregulation (dilation) of nearby blood vessels
CNS axons are myelinated by _______________, while PSN axons are myelinated by ________________.
- Oligodendrocytes 2. Schwann cells
What are the 5 types of glial cells?
- Astrocytes 2. Oligodendrocytes 3. Schwann Cells 4. Microglia 5. Ependymal Cells
What are the two types of astrocytes? Where are they located?
- Fibrous in white matter 2. Protoplasmic in gray matter
One oligodendrocyte can myelinate _________________.
Many CNS axons
One Schwann cell can myelinate _____________________.
One segment of a PNS axon
What causes gliosis?
Proliferation of astrocytes after neuronal damage
What are the functions of astrocytes? (7)
- Structural support and repair (GFAP)
- K+ spatial buffering
- NT and metabolite removal - GLAST
- Contribute to BBB
- Communicate w/ each other via gap junctions
- Glial guide for neuronal migration
- Subset serve as stem cells to generate neurons and glia
Are astrocytes electrically excitable?
No
___________ is a potent inhibitor of axon outgrowth and regeneration.
Central myelin
What are 3 inhibitors of CNS axonal elongation?
- Myelin-associated glycoprotein (MAG) 2. Neurite inhibitor of 35 kDa (NI-35) 3. Nogo gene and proteins NI-220/250
A single axon in the PNS can by myelinated by ___________ Schwann cell.
50-500
Schwann cells provide what 3 types of growth promoting factors? (3)
- Laminin (SC basal lamina)
- Cell adhesion molecules: NgCAM/L1
- Some secrete nerve growth factor
What is the function of microglia?
Function as macrophages - phagocytose debris of CNS
When neurons undergo degeneration microglia increase in ____________________.
Size and number
What are 3 functions of ependymal cells?
- Provide a barrier between brain and CSF 2. Aid in CSF circulation 3. In choroid plexus produce CSF
Where are ependymal cells found?
Lining inside of neural tube - cerebral ventricle and cerebral canal
The outer mesaxon is only present in the _____.
PNS (because the Schwann cell wraps around itself)
Myelin has a high ______ content
Lipid
MBP
Myelin basic protein
- major structural protein of myelin in CNS (also present in PNS)
- basis for autoimmune disease (encephalomyelitis)
- on cytoplasmic face of myeilin membrane (MAJOR dense line)
What is MAG? What is its function?
Myelin-associated glycoprotein - in oligodendrocytes in CNS and PNS; inhibits the initiation of myelination
MOG
Myelin-oligodendrocyte glycoprotein - CNS only - on surface of myelin sheath
_____ is a target antigen in autoimmune aspects of CNS demyelinating disease.
MOG
Nodes of Ranvier have a high concentration of _________________.
Voltage gated Na+ channels
Nodes in the CNS are ___________ and nodes in the PNS are _________.
- Bare 2. Covered by Schwann cell cytoplasm
What is the function of clefts (incisures)
Delivery of cytoplasmic nutrients to inner leaflets of myelin
Schmidt-Lanterman incisures (clefts) are found in the _____. What is their function?
- PNS
- to supply cytoplasmic nutrients to the inner leaflets of myelinated axons
Longitudinal incisures are found in the _____. What is thier function?
- CNS
- to provide nutrients to inner leaflets
What is the peak conduction velocity in myelinated axons?
120 m/s
What is the conduction velocity in unmyelinated axons?
<2 m/sec
Multiple Sclerosis
Chronic demyelinating disease of CNS (antibodies against own myelin) - results in gliosis, slowed conduction, disruption of BBB, paralysis, sensory-motor deficits
Guillain-Barré Syndrome
Acute, autoimmune, inflammatory demyelinating disease of PNS (muscles/skin) - slowed/abnormal conduction results in sensory perception and motor coordination issues
What famous person is thought to have had Guillain-Barré syndrome? Why?
- FDR
- because the symptoms resembled the characteristic GB symptoms: moved from legs upward; also, FDR was documented to have fever before his paralysis
Membrane lipid-bilayer is a diffusion barrier functioning as a ________.
Capacitor
The _______ and _____ are long arteries branch off the internal carotid artery in the base of the brain.
-MCA -ACA
What are the 2 long branches from the ACA?
- Cortical branches to the medial aspect of the frontal/parietal lobes 2. arteries to corpus callosum (callosalmarginal and pericallosal a.)
What are the 2 long branches from the ACA?
- Cortical branches to the medial aspect of the frontal/parietal lobes 2. arteries to corpus callosum
What long branches does the MCA branch into?
cortical (superior) branches to frontal, parietal and temporal lobes
What short branches come off the MCA? What do they supply?
-lenticulostriate arteries -basal ganglia, internal capsule
What short branches come off the MCA?
lenticulostriate arteries
What 2 long branches come off the vertebral arteries?
- PICA (posterior inferior cerebellar a) 2. posterior spinal aa.
What short branches come off the vertebral arteries?
anterior spinal aa
What 4 branches come off the BASILAR artery?
- superior cerebella a. 2. long pontine arteries 3. short pontine arteries 4. anterior inferior cerebellar a. (AICA)
What 2 short branches come off the PCA?
- posterior choroidal a. 2. arteries to thalamus
What 2 short branches come off the PCA?
- posterior choroidal a. 2. arteries to thalamus
What does ACA supply?
anterior, medial as far back as sensorimotor cortex [leg/foot]; cingulate and superior frontal gyri, frontal lobes, paracentral lobules, corpus callosum frontal pole; anterior limb of internal capsule (medial striate artery)
A patient cannot move his leg or foot on his right side. Where could there be a thrombosis?
on left ACA (sensorimotor cortex)
From which artery does the anterior choroidal come? What does it supply?
-ICA - midbrain, basal ganglia, internal capsule, parts of visual pathway
The ______ artery passes through the Sylvian fissure in the temporal lobe.
MCA
What does a lesion in the RIGHT SUPERIOR hemisphere of the MCA of the brain cause?
weakness and/or sensory loss of left FACE, HAND, ARM, TRUNK
What does a lesion in the LEFT SUPERIOR hemisphere of the MCA of the brain cause?
weakness and/or sensory loss of right FACE, HAND, ARM, TRUNK and BROCA’S AREA = APHASIA (cannot move , but can understand)
What does a lesion in the LEFT INFERIOR hemisphere of the MCA of the brain cause?
sensory loss from right face, hand, arm, WERNICKE’S AREA = aphasia (cannot understand but can move); posterior part of superior temporal gyrus
What does a lesion in the RIGHT INFERIOR hemisphere of the MCA of the brain cause?
sensory loss from left face, hand and arm; left hemineglect (proprioception; draw only half a picture)
What is paraphasia?
speech is incomprehensibe
Branches of the _____ causes visual field defects when occluded.
MCA
When the __________ arteries are occluded (they supply blood to the ________), the patient experiences contralateral perisis or paralysis.
-lenticulostriate -internal capsule
The vertebral arteries branch from the _________ artery and pass through the _____ of the cervical vertebrae and enter the cranial cavity through the ______.
subclavian transverse foramina foramen magnum
The ANTERIOR SPINAL ARTERIES, branching off the ____ arteries, supply the ________ of the spinal cord and the _______ medulla.
-vertebral -anterior 2/3 -anterior/medial medulla {including medullary pyramids}
The POSTERIOR SPINAL ARTERIES, branching off the _______ arteries, supply the ________ of the spinal cord and the _______ medulla.
-vertebral -posterior 1/3 -posterior part of medulla
From where do the PCAs come from?
basilar artery
The ANTERIOR INFERIOR CEREBELLAR ARTERIES, branching off the ____ artery, supply the ________ of the cerebellum and the _______ of caudal pons.
-basilar -anterior portions of interior -lateral part
The SUPERIOR CEREBELLAR ARTERIES, branching off the ____ artery, supply the ________ of the cerebellum, the _______ of middle pons and the _____.
-basilar -superior part -lateral part -pineal gland
The ______ arteries, branching off the _____ artery, supply the inner ear.
-labyrinthine -basilar
What deep cortical structure does the PCA supply? The _______ and ________ arteries also supply this structure.
-thalamus -basilar -posterior communicating
What deep cortical structure does the PCA supply? The _______ and ________ arteries also supply this structure.
-thalamus -basilar -posterior communicating
__________ of the brain form a barrier (BBB) between the circulation and the interstitial fluid.
endothelial cells lining the microvasculature
What is the function of the BBB?
maintains stable microenvironment for proper functioning of neurons within CNS
General capillaries have ______ and _____ while brain capillaries have ______ and _____ to provide a physical barrier.
-fenestrae/gaps between adjacent endothelial cells -pinocytotic vesicles -tight junctions (est. polarity) -few pinocytotic vesicles
Most molecular traffic must take a _________ route if it is going to cross the BBB.
intracellular (pinocytosis)
Endothelial cells in BBB surrounded by what 3 structures?
- basal lamina 2. pericytes (smooth muscle-like) 3. astrocyte foot processes (cover abluminal surface)
What is the abluminal surface?
side that faces toward the brain, away from EC
_______ provide the cellular link to neurons.
Astrocytes
What are 5 ways substances can pass between BBB?
- paracellular aqueous (water soluble) through tight junctions 2. transcellular lipophillic (O2, ethanol, CO2, etc.)**** 3. transport proteins (glucose, amino acids, AZT, etc.); lumenal/ablumenal surfaces 4. receptor-mediated transcytosis (insulin, transferrin 5. adsorptive trancytosis
What is the route by which most neurological drugs enter the brain?
trancellular lipophilic pathways
A patient is diagnosed with Parkinson’s Disease. What drug could you prescribe? What mechanism would that drug take?
-L-DOPA -via transport protein
What is the mechanism by which some chemotherapy drugs get through the BBB?
via transport proteins
What is adsorptive trancytosis? Give an example of a protein that is transported across the BBB this way.
-When cations surround and reduce negative charge of a protein and then is pinocytosed -albumin
Enzyme systems specific to BBB regulate the ______ of brain interstitial fluid.
composition
_______ in BBB endothelial cells with inactivate catecholamines.
MAO
Astrocytes are a type of _______ cell. Name their 3 functions.
-glial 1. regulate tight junctions (physical) 2.influence expression/polarization of transporters (transport) 3. influence expression of enzyme systems (metabolic)
Name 4 mechanisms that causes pathology in the BBB.
- downregulating proteins contributing to tight junctions 2. breaking down basil lamina holding capillaries 3. upregulating/downregulating transporter proteins 4. influencing secretions of astrocytes
The BBB is always absent of ________, making them unable to receive ______.
-brain tumors -chemotherapy
Which areas of the brain lack a BBB?
pineal gland, subfornical organ, vascular organ of lamina terminalis, median eminence (sensory), area postrema
The _______ senses hormones in the blood in the brain and sends signals to the pituitary gland.
median eminence
The regions (circumventricular organs) that lack a BBB do not have ________ and have lots of ________.
-tight junctions -pinocytotic vesicles
What are 2 characteristics of veins in the cerebrum? They are divided into _______ and _____ groups.
- thin walls 2. no valves -superficial -deep
What are the 3 types of SUPERFICIAL cerebral veins?
- superior 2. middle 3. inferior
There are 8-10 ______ veins that empty into the ______
-superior cerebral -superior sagittal sinus
SUPERIOR CEREBRAL veins anteriorly enter SUPERIOR SAGITTAL SINUS at _______ whereas posteriorly they enter at ______.
-right angles -oblique angles
Why are the angles in which the superior cerebral veins enter the superior sagittal sinus significant?
blood flows anterior to superior and so pressure from sinus may create pressure and help posterior veins from collapsing when intracranial pressure is raised
The ________ veins are located in the Sylvian fissures and drain the lateral surfaces of cerebral hemispheres.
middle cerebral
Blood from middle cerebral veins drain ______ into the _______.
-anteriorly -cavernous sinus
Inferior cerebral veins located in orbital surface of _______ lobes and inferior surface of _______ lobes.
-frontal -temporal
Inferior cerebral veins from the orbital gyri enter into the _______. Those in temporal lobes drain into ______ to the _______.
-superior sagittal sinus -middle cerebral vein -cavernous sinus
A ________ vein connects the superficial cerebral vein with superior sagittal sinus; an__________ vein connects inferior cerebral vein to ________.
-superior anastamotic -inferior anastamotic -transverse sinus
What is the basal vein formed by?
union of anterior cerebral vein and the deep middle cerebral vein
The __________ drains the deep aspect of the cerebral hemispheres and runs with ________ in longitudinal fissure.
-anterior cerebral vein -ACA
The _________ runs through the Sylvian fissure and drains the ______ and surrounding gyri.
-deep middle cerebral vein -insula
The _______ curves around the cerebral peduncle and empties into _______.
-basal cerebral vein -Great cerebral vein of Galen
What 5 structures are drained by lateral cerebral veins?
thalamus, basal ganglia, choroid plexus, lateral and 3rd ventricles
Which two structures make up the Great cerebral vein of Galen?
- Right ICV 2. Left ICV
Where is the straight sinus located?
in faux cerebri
Where is the straight sinus located?
in faux cerebri
MCA supplies _______ of the brain’s volume.
2/3
Does an MRI use shades of gray according to density? How does an ischemic area appear?
-NO! about rotation of molecules -more white
What is a PERFUSION SCAN?
Shows where there is more blood flow (red) and less blood flow (purple)
How long do you have to salvage the penumbra after a stroke?
minutes to hours
Does a person with recurrent, episodic severe frontal headaches and blurry vision present with stroke symptoms?
No {(1) no acute onset , (2) no focal neurologic deficit and (3) possible cerebrovascular cause; must have all 3!}
A 65 yo coming to the ER with 6 months of postural dizziness DOES/DOES NOT have a stroke.
does not {(1) no acute onset (2) no focal neuro deficit and (3) no possible cerebrovascular}
Which one has the stroke? Why? (A ) 80 yo with gradual lethargy, inattention, global confusion, illogical speech (B) 80 yo with sudden garbled nonsensical speech in isolation
-(B) -because acute onset, L Wernike’s area affected (focal neuro problem), cerebrovascular cause!
Does a 78 yo coming to the ER with sudden vertigo, lateropulsion (ataxia), dizziness and emesis (vomiting) have a stroke?
YES! -because acute onset, focal neuro problem in motor function (parietal lobe), cerebrovascular cause = MCA
What are 4 examples of stroke risk factors that are untreatable?
- age 2. gender 3. race 4. heredity
Which ethnicities have the highest incidence of stroke?
african americans and hispanics
What are some examples of stroke risk factors that are modifiable?
hypertension, hyperlipidemia, HD/A fib, hyperhomocysteinemia, obesity/inactivity, diabetes, smoking, carotid disease, heavy alcohol use
What is the process by which people manage a stroke? (3 things)
- acute therapy 2. recovery 3. prevention of secondary stroke
What is an example of acute stroke therapy? What is it used for?
-Thrombolysis (use Tissue Plasminogen Activator via IV or catheter to dissolve any other clots) -to save penumbra
What is the main goal of recovery? What 3 things can a patient do to recover?
-limit the neurologic damage 1. prevention of complications 2. rehabilitation 3. education
After a stroke you are at increased risk for _______ and ________.
-DVT -pneumonia (iatrogenic/from hospital)
How would you prevent a secondary stroke?
-use risk factor modification based on the mechanism of the stroke (like blood thinners)
A patient with a LEFT PCA stroke could most likely present with what clinical findings?
visual field defects, possible sensory defects on R side (numbness) due to PCA supply to thalamus
What is Homonymous hemianopsia?
visual field defects on one side or with one eye
A patient with a RIGHT MCA stroke would most likely present with what clinical signs?
left motor disabilities in left arm/face, possible Broca’s aphasia (cannot move part of mouth)
A patient comes to the ER presenting of the sudden inability to extend his ankle (foot drop) on his LEFT side. Assuming this is a stroke, which artery is occluded?
RIGHT ACA
A patient comes to the ER presenting of the sudden inability to extend his ankle (foot drop) on his RIGHT side. Assuming this is a stroke, which artery is occluded?
LEFT ACA
Which vessel is occluded?
Vertebrobasilar artery
Which vessel is occluded?
MCA
Which vessel is occluded?
PCA
Which vessel is occluded?
ACA
The ______ stain colors nucleic acids (DNA/RNA). This stain shows cell bodies of _____ and _____.
- Nissl
- neurons (large staining)
- Glia (small staining)
What kind of stain is this and what is stained?
Golgi stain; cell bodies, axons and dendrites are stained
Camillo Golgi thought that all neurons were __________.
connected (syncytium) [eventually proved wrong]
_______ theorized that neurons were individual cells with processes that extended out. This theory was called the ____.
Santiago Cajal (Father of Neuroanatomy)
Neural Doctrine
What is the Neural Doctrine?
neurons function as basic units and receive information through one end (dendrites) and transmit information through the other end (axons); therefore neurons are either in series or in parallel
What 3 special characteristics does a neuronal cell body (soma) have and what functions do they serve?
(1) lots of EUCHROMATIN for increase in transcription
(2) lots of RER for increase translation
(3) special intermediate filament = NEUROFILAMENTS (unique to each type of neuron)
What defines the molecular structure of an AXON HILLOCK?
part of the cell body with an ABSENCE of RER (no Nissl substance)
Dendrites are categorized into different ______ and ________.
- sizes
- shapes
______ increase the surface area of the dendrite. What is the purpose of this structure?
- DENDRITIC SPINES
- receives synapses (especially EPSPs)
What is a DENDRITIC SPINE APPARATUS?
special type of ER in dendritic spine that sequesters/releases calcium based on synaptic response (think smooth muscle ryanodine receptors)
Label the structures, starting from the top of the image:
- axolemma (PM)
- axoplasm (cytoplasm)
- myelinated axon (electron dense)
- unmyelinated axon (electron rich, travel in bundles)
What are the arrows pointing to? What do these do?
- AXON COLLATERALS
- contacts other cells or self
_______ are axon collateral that act on the neuron’s own dendrites.
RECURRENT COLLATERALS
What is a Boutons teminaux? (shown in picture)
somewhat enlarged, often club-shaped endings by which axons make synaptic contacts with other nerve cells or with effector cells; notice the large number of mitochondria (large, dark structures) and vessicles (with NTs)
_______ are swellings along the axon where vesicles can be released to supplement synpases.
Varicosities
This shows what kind of neuron structure?
unipolar neuron
This shows what kind of neuron structure?
bipolar neuron
This shows what kind of neuron structure? Where are these neurons located?
pseudo-unipolar neuron; DRGs of sensory neurons
This shows what general type of neuron structure?
multipolar neuron
What kind of multipolar neuron is each arrow pointing to, starting from the top of the picture? What are the defining characteristics of each?
(1) Golgi Type II = interneurons (short axons)
(2) Golgi Type I = projection neurons (long axons)
Polio and Lou Gehrig’s disease affects ______ neurons and syphilis affects ____ neurons.
- motor
- sensory
The size of the soma is related to the ____ and ______ of neurons.
- length
- number of processes
Somal size of neurons varies from ____ to _____ micrometers in diameter.
- 5
- 150
What structure are the red arrows pointing to? The black?
- axon
- dendrites
A _____ can be a single or multiple extensions of the cell body, whereas a _____ almost always has a single extension from the cell body.
- dendrite
- axon
Dendrites lack which organelles?
Golgi apparatus (especially in proximal dendrites)
Axons lack which organelles?
Golgi apparatus, RER, ribosomes (not synthasizing NTs)
What pathology results when there are thinner and fewer dendrites?
Mental retardation
Dendrites taper in a _______ direction, branch profusely and have ________ with ______ and receive the bulk of synapses.
- proxiomo-distal
- dendritic spines
- spine apparatuses
Axons have a ______ trunk that can branch profusely. Terminals enlarge to form _____ that contain synaptic vesicles ; other areas that contain synaptic vesicles along the axon are called ______.
- cylindrical
- boutons
- varicosities (for en passant synapses)
I see a projection that is myelinated. Is it a dendrite or axon? What about unmyelinated?
- axon
- dendrite OR axon
Only _____ ramify close to the cell body whereas _____ can ramify either far or close to the cell body.
- dendrites
- axons (projection neurons, interneuons–respectively)
Dendrites respond to APs with _________, responding to _____ and ____ stimuli.
- graded depolarization/hyperpolarization
- spatial
- temporal
Dendrites can general APs. True or False?
True!!
__________ are propagated along axonal trunk (up to 100m/s) and transmitted at ______.
- APs
- axon terminal
What kind of receptive sites can dendrites have?
- postsynaptic (receptive)
- presynaptic (dendro-dendritic)
What kind of synapse are the green and blue neurons making with each other?
dendro-dendritic synapses (presynaptic)
What kinds of receptive sites can axons have?
- presynaptic (effector site)
- postsynaptic (axo-axonal synapse in brain)
_______ may be absent in unipolar cells whereas ____ may be absent in amacrine (retina) cells.
- dendrites
- axons
The _______ is the major energy-consuming portion of a neuron, mostly due to _______ of membrane for AP propagation.
- dendrite
- repolarizaton
In a(n) _____, energy consumption is low, but in the _____, it may be low, moderate or high (depending on type of neuron).
- axon
- axon terminal
There are about 50 _________ in lysosomes; this allows for _________.
- acidic hydrolases
- active membrane turnover
What is the mechanism behind a lysosomal storage disease? What is an example of a lysosomal storage disease?
- autosomal recessive; mutation in part of gene coding for hydrolytic enzymes–missing tag for targeting lysosome so that there is no breakdown of waste material
- Tay Sachs (accumulation of gangliosides, causing milky substance in retina)
Name 5 characteristics of a MICROFILAMENT.
- most abundant protein/throughout neuron cytoplasm
- made of actin monomers (polar)
- associated with cell membrane; important in changing/maintaining shape
- ATPase
- 5-8 nm diameter, hollow
Describe the process of TREADMILLING in microfilaments.
(1) G actin binds ATP
(2) G actins polymerize to form F actin (filamentous)
(3) Simultaneously, G actin is being removed from (-) end of MF
[when (-) removing G actin more slowly than (+) adding end = growth]
A type of mushroom poison, ________ depolymerize F actin, blocking the turnover of MFs and threatening cell viability. The remedy is ___________ because ________.
- Cytochalasins
- eat lots of RAW MEAT
- it has lots of actin and will compete with binding
________ stabilize F actin, blocking the turnover of MFs and threatening cell viability.
Phalloidins
Name 5 characteristics of NEUROFILAMENTS.
(1) type of intermediate filament unique to neurons
(2) nonpolar due to antiparallel structure
(3) 10 nm in diameter
(4) polypeptide subunits
(5) in cytoplasm throughout neuron, although mostly in cell body
What are the 3 types of NF polypeptide subunits?
(1) NF-L (low) = 70 kDa
(2) NF-M (middle) = 140 kDa
(3) NF-H (high) = 210 kDa
_________ can aggregate into visible clumps known as __________. These are known as the hallmark of Alzheimer’s Disease.
- neurofibrils
- neurofibrillary tangles
Describe the process of NF formation, including when the non-polarity occurs.
(1) monomers (polypeptide) = central rod domain with N-head and C-tail
(2) monomers form dimer with N-N head and C-C tail
(3) protofilaments = antiparallel tetramers (NONPOLAR!)
(4) protofibrils
(5) Neurofilaments (hollow)
Name 5 characteristics of MICROTUBULES.
(1) made of tubulin alpha/beta heterodimer subunits (polar)
(2) GTPase
(3) In cytoplasm throughout neuron
(4) mainly used for transport of cargo through axons/dendrites
(5) can be in 2 states: polymerization-favored (GTP) or depolymerization-favored (GDP–hydrolyzed)
Describe the process of TREADMILLING in MTs.
(1) GTP-tubulin heterodimer binds 2nd hydrolyzable (GTP) tubulin heterodimer
(2) If add GDP-tubulin dimer, MT is weaker due to more curved structure and will favor depolymerization
(3) enzyme can also cause favoring of depolymerization by hydrolyzing end GTP-tubulin to GDP-tubulin at (-) end
[(+) ends grow rapidly while (-) ends disassemble slowly = overall growth]
_______ is another name for treadmilling in MTs.
Kinetic asymmetry
In axons, ________ ends go away from the soma. In proximal dendrites, ______ is mixed and in distal dendrites _______ ends point toward the postsynaptic sites (away from cell body).
- (+)
- polarity
- (+)
______ and ____ are antimitotic chemotherapeutic drugs. Describe its mechanism of each.
(1) Colchicine depolimerizes MTs by binding tubulin
(2) Taxol stabilizes MT by covalently binding tubulin so that MTs cannot disassemble
MTs form _______ with ______ at inital segments of axons.
- bundles
- cross-bridges
If “m” represents MTs, what are the arrows pointing to? What section of the axon is this?
- cross-bridges
- initial segments of the axon
What do MAPS do?
(1) stabilize MTs against abnormal disassembly
(2) mediate interaction of MTswith other cell components (transporter proteins)
List 3 types of High MW MAPs (200-2000 kDa) and where they are located.
(1) MAP-2 = only in dendrites
(2) Kinesin = in axons/dendrites; going toward (+) end (away from cell body)
(3) MAP-1C (cytoplasmic dynein) =in axons/dendrites; going toward (-) end (toward cell body)
Name a class of low MW MAPs (55-62 kDa) and give an example of pathology.
- Tau proteins
- hyperphosphorylated Tau proteins disrupt MTs and cause neurofbrillary tangles of Alzheimer’s disease
Axons may be up to _______ long. Newly synthesized components, however, always come from the ____.
- 1 meter
- soma
Name the 3 types of axoplasmic transport.
(1) slow
(2) fast anterograde (from cell body to axon terminal)
(3) fast retrograde (from axon terminal to cell body)
There are 2 components that make up SLOW axoplasmic transport. What are they and name a couple of their characteristics.
(1) Slow component = rate of 0.2-0.5 mm/day; MT and NF components and soluble proteins in cytosol
(2) Fast component = rate of 10 mm/day; complex proteins (actin) metabolic enzymes and calmodulin (Ca-binding proteins)
Answer FAST ANTEROGRADE or FAST RETROGRADE axonal transport:
(a) faster (about 410 mm/day compared to 300 mm/day)
(b) ATP-dependent
(c) transport subcellular organelles to axon terminals via kinesins
(d) return cell components for degradation, GFs, viruses (polio), toxins (cholera), experiemental tracers via dyneins
(e) relies on MTs for transport
(f) blocked by colchine
(a) FAST ANTEROGRADE
(b) BOTH
(c) FAST ANTEROGRADE
(d) FAST RETROGRADE
(e) BOTH
(f) FAST ANTEROGRADE
Answer either KINESIN, DYNEIN or BOTH:
(a) moves cargo towards (+) end
(b) High MW MAP protien
(c) subunits have bigger proteins (up to 2,000 kDa)
(d) has 2 heavy and 2 light chains
(e) has 2-3 heavy chains and a variable # light chains/intermediate chains
(f) light chains bind to other cell components (cargo, etc.)
(g) moves in retrograde fashion
(h) heavy chains bind both MTs and ATP
(a) KINESIN
(b) BOTH
(c) DYNEIN
(d) KINESIN
(e) DYNEIN
(f) BOTH
(g) DYNEIN
(h) BOTH
_____ is a protein that is synthesized in the some and transported to the dendrites.
MAP2
What is the watershed area of an artery?
An area that recieves dual blood supply from distal branches of two arteries
True/False:
(i) Glia cells have processes.
(ii) Glia cells have synapses
(iii) Glia cells have APs
(i) true
(ii) false
(iii) false
What is GFAP?
type of intermediate filament that makes up CT of CNS around astrocytes
What is GLAST and what is its function?
it is the glutamate-aspartate transport on astrocytes to take up glutamate, so it can be transformed to glutamine (part of glutamate-glutamine cycle)
Where are astrocyte stem cells located?
subventricular zone and hippocampus
What are 3 characteristics of oligodendrocytes?
- smaller than astrocytes
- fewer processes
- round nuclei
Why can neurons regrow in the peripheral NS but not in the CNS (in general)?
because CNS has central myelin
MAG is ______ in developing CNS and PNS, but falls in mature _____ and is stable in mature _____.
- high
- PNS
- CNS
________ and ______ is expressed by oligodendrocytes ONLY and inhibits axon outgrowth.
- Chondroitin sulfate proteoglycan (neurite inhibitor)
- Nogo gene protein = NI220/250
What kind of cell is surrounding the axon at the top of the picture?
What kind of cell is surrounding the axons at the bottom of the picture?
Both are Schwann cell, but top is myelinated and bottom is unmyelinated
_______ is a type of glial cell that may be activated in MS, Parkinson’s, Alzheimer’s and HIV-related dementia.
microglia
Ependymal cells have mostly ______ junctions, ____ to move CSF through the spinal cord and ____ for absorption.
- desmosomal
- cilia
- microvilli
______ cells are glia that make up the choroid plexus and have _____ junctions; this is the basis of the BBB.
- modified ependymal
- tight
What are the red lines pointing to? What kind of cell is this?
- inner/outer cytoplasmic leaflets (circles showing inner/outer mexaxons)
- Schwann
Why is MOG easily accessible to antibodies in MS?
because it is on the surface of the myeilin sheath and oligodendrocytes
What is the purpose of Nodes of Ranvier?
saltatory conduction for fast propagation
Axon branching of myelinated axons always occurs at ______.
nodes (of Ranvier)
What are the 3 functions of myelin?
- provides insulation
- reduces ionic flux across axolemma
- conserves cellular ATP
Why are not all neurons myelinated in CNS? In PNS?
- In the CNS, you have lots of short axons, so you don’t need to waste energy myelinating them
- In PNS, unmyelinated axons mediate pain and so you would like less firing
What are some genetic risks of MS? Environmental risks?
Genetic = increased risk in identical twins, in certain ethnic groups, 20-40 yo Females (2/1 F/M)
Environmental = colder climates, leading to decreased vitamin D; smoking
What myelin antigens may be involved in MS?
MOG, MBP
What are examples of myelin proteins attacked by Guillian Barré Syndrome?
- P0
- PMP22
_______ ususally triggers Guillain-Barré Syndrome.
viral infection
Electrically, neurons have a very high _________. Therefore they require a high _____ for an AP to occur.
resistance; voltage
Electrically, the plasma membrane of an axon acts like a ______ because it is impermeable to ions with a _____ charge on the inside and ____ charge on the outside.
capacitor; negative; positive
Electrically, ion channels act as resistors, allowing for ________ resistance when they are in the ____ and ___ states (and thus [same first word] current)
- variable
- open
- closed
Ion flow is affected by the ______ and _____ of the ion.
size; charge
Some ion channels have minimal selectivity while others are highly selective. Give examples of each.
- minimal = anions vs. cations
- highly = Na+ preferred over K+
What are the 4 types of gated ion channels?
- voltage gated
- ligand gated
- thermally gated
- mechanically gated
Give the extra cellular concentration of Na+, K+, Cl-, Ca2+ (in mM).
- Na = 140
- K = 4
- Cl = 2.5
- Ca = 120
Give the intracellular concentration of Na+, K+, Cl-, Ca2+ (in mM).
- Na =15
- K =130
- Ca = .0001
- Cl = 5
Which ion contributes the most to the resting membrane potential?
K+ (Ev=-94 mV)
What is the difference between the Goldman equation for resting membrane potential and the Nernst equation? Which one shows a less negative (more positive) potential?
- Goldman takes into account other ions besides K+ wherease Nernst only looks at K+ potential
- Goldman
What is the resting membrane potential of a neuron?
about -65 mV
Which 2 factors influence the net passive diffusion of ions across axon membrane?
- Electrochemical gradient
- Conductance of the channel (flow–>at resting potential, Na+ has low conductance and K+ has higher because of leaky channels)
How is the concentration gradient maintained across axon membranes?
Na+/K+ ATPase pump (3 Na+ out, 2 K+ in)
_______ means changing the membrane potential to a more positive state, whereas _____ means changing the membrane potential to a more negative state.
- depolarization
- hyperpolarization
What is the passive electrical property of neurons called? How is it defined?
- Cable properties
- the amplitutde of the potential change decays exponentially as it moves away from its source (change in Vm passively spreads in both directions along axon/dendrite)
The _______ is the distance over which the membrane potential falls by 63% from its original value.
length constant
The length constant depends on the _______ and the ________.
- resistance of the membrane
- longitudinal resistance (within cell)
What is the active electrical property of neurons called? What is the end product?
- action potential
- release of neurotransmitters
The AP actively propogates over long distances, _________ its height as it goes down the axon.
maintaining
What are the 5 properties of an AP?
- each type of neuron has particular threshold
- all-or-none responce
- latency period
- Refractory period
- propagation
The ________ is the time when you need more stimuli in order to reach the threshold of a neuronal axon for AP because most of the Na+ channels are ________.
- latency period
- inactive
If an AP is not stimulated (not enough EPSP to reach threshold), then a __________ response will occur.
cable
In the ____________ period, there is no way to generate an AP whereas in the ________ period, you can generate an AP, but with a smaller magnitude and increased stimulus.
- absolute refractory
- relative refractory
What is the purpose of the refractory periods of an axon?
to limit the repetition rate of firing
Different types of neurons have different _______ of ion channels, which affect the ________ of APs. The absolute upper limit of AP frequency is ________.
- numbers
- rate of firing
- 1 kHz
How many states do voltage-gated Na+ channels have? What are the properies of each?
- RESTING STATE = during resting membrane potential, channel is closed and no ions flowing through
- OPEN STATE = during depolarization, ions flowing through until VERY DEPLOLARIZED, then….
- INACTIVATED STATE = at highly depolarized membrane potentials, no ions flowing through; must go back to RESTING state before can be reopened (at resting membrane potential)
__________ channels have 2 states: OPEN, during _______ potential and CLOSED, during ______ potential.
- voltage-gated K+ channels
- depolarized membrane (ions flowing)
- resting membrane (no flow)
At the AP peak, what is going on with the Na+ and K+ voltage-gated ion channels?
- Na+ = inactive state (means decrease in conduction)
- K+ = open state (means increase in conduction)
The higher the magnitude of AP peak, the higher the concentration of the _____ ion.
-extracellular Na+
Under normal conditions, ______ ensure that APs are propagated in only one direction, although artifically-induced APs can propagate _______.
- refractory periods
- bidirectionally
How is the rate of AP propagation increased?
length constant = by increasing DIAMETER of neuron and increase INSULATION (myelin) of axonal membrane
An EPSP is sent from axon 1 and an EPSP is sent from axon 2. Axon 2 is closer to the soma than axon 1, but axon 1 has a larger diameter. If they both send a signal at the same time, which one will reach the cell body first? Why?
Axon 1 because it has a greater length constant/conduction due to bigger diameter (diameter trumps proximity)
An EPSP is sent from axon 1 and an EPSP is sent from axon 2. Both are the same distance from the cell body. Axon 2 is myelinated and axon 1 is unmyelinated and has a larger diameter. If they both send a signal at the same time, which one will reach the cell body first? Why?
- Axon 2 (myelinated)
- myelination increases length constant more than axon diameter
These two pictures have the same circular diameter, but one has a giant axon (L) and one has many (about 400) small, myelinated axons (R). What are their relative rates? Explain why.
Giant axon = 20-25m/sec; large diameter travels faster
Many myelinated axons = 90m/sec because myelin trumps diameter in terms of conductance speed (SPACE SAVING!!)
Name 2 ways you can record electrical activity in a neuron.
- sharp, micropipette electrode; can record Vm of one cell
- Fire-polished micropipette electrod; can record Vm of different channels/receptors (more specific)
________ channels are largely responsible for the membrane potential.
K+ leak channels (open!)
Match the neurotoxin [TEA, TTX, intra/extracellular TEA and amino pyridines] to the following:
- Voltage-gated Na+ channels
- Voltage-gated K+ channels
- K+ leak channels
________ channels produce the rising phase of the AP.
Voltage-gated Na+ channels
___________ is a channelopathy that causes episodes of weakness and decreased muscle tone (may follow exercise)
Hyperkalemic periodic paralysis
In Hyperkalemic periodic paralysis, muscle fibers are unable to fire APs because the neurons are ________ and the voltage-gated Na+ channels are in the _________ state.
- depolarized
- inactive
Hyperkalemic periodic paralysis can be caused by a mutation in the _______ that prevents some of these channels from being ______ after depolarization.
- voltage-gated Na+ channels
- returned form inactive state to resting state
This graph, looking at Vm, represents what channelopathy?
hyperkalemic periodic paralysis
________ is a channelopathy in which there is difficulty getting muscles to relax once they have been contracted.
Myotonia
Myotonia is due to a decrease in the conductance of _______ which causes the membrane to _________. Name the animal that is famous for having this channel abnormality.
- Cl- (lower number of Cl- channels)
- depolarized
- FAINTING GOATS!!
What are the 2 types of myotonic diseases?
- Thomsen’s disease
- Becker’s disease
Normal _________ have a relatively high Cl- permeability.
skeletal muscles
This graph of Vm is abnormal. There should only be one AP spike. What kind of channelopathy is this and what is the acossiated ion that helps to cause this reaction?
- myotonia
- Cl-
A diver got a small sting by a puffer fish by accident. What toxin coursed though his body and what happened to the diver? What would a larger sting cause (bigger dose of toxin)?
TETRODOTOXIN
- blocks Na+ channels of the PERIPHERAL nerves, which causes weakness/numbness b/c no APs
- respiratory paralysis and death
Name the 2 classes of nervous tissue.
- neurons
- supporting cells
Which cell is labeled “N”?
oligodendrocyte
What cell is labeled “N”?
-Schwann cell
Is this electron micrograph taken in the PNS or CNS?
PNS (Schwann cells)
Is this electron micrograph taken in the PNS or CNS?
PNS (outer membrane leaflet of Schwann cell)
What is the structure near “D”/”Al”? In PNS/CNS?
- Node of Ranvier
- CNS
What structure is the arrow pointing to on a neuron? What is this structure’s function?
- Node of Ranvier
- Saltatory conduction (increase velocity of signaling)
What structure is the arrow pointing to on a neuron?
Node of Ranvier
This is a picture of the ventral horn of the spinal cord. It is gray/white [choose one] matter and the stained nuclei belong to 4 cells–what are they?
- gray
- astrocytes, oligodendrocytes, microglia or cells that make up the walls of blood vessels (endothelial and smooth muscle)
What is “E” pointing to? What is it and what components are within it?
- epineurium (outermost layer of CT surrounding entire nerve)
- fills spaces between nerve fiber bundles (fascilcles) and contains vascular and adipose tissue
What is the arrow pointing to? What is it made of and what does this structure surround?
- perineurium
- made of CT surrounding fascicles that make up the nerve
What is a fascicle composed of? What is the black staining and what structures are being stained?
- many nerve fibers–axons of nerves traveling together
- heavy metals; lipids/myelin sheaths
What is the light part inside the perineurium called? What does it surround?
- endoneurium
- surrounds individual nerves
A given nerve can contain both myelinated and unmyelinated nerve fibers within it. True/False.
True!
Identify the perineurium. What are the pink dots?
- around fascicle (very outside layer of darker area)
- pink dots = axons (with clear, surrounding myelin)
What are the black, short arrows pointing to at the top of the image?
Terminal boutons
What are the three types of cells that neurons synapse with?
- with another neuron
- with an effector cell (muscle/gland)
- with a sensory receptor cell
What are the 3 types of synapses?
- electrical (gap junction)
- chemical (NTs)
- gaseous
What is the most common type of cell junction?
Gap junction (found in most tissues)
What type of cell-cell connection is this?
Gap junction
In addition to neurons, in what cell types would electrical coupling provide an obvious functional advantage?
cardiac/smooth muscle cells (synchronous contractions)
What is the cross-section showing? What structure is in the middle? What is Mf pointing to?
- a motor endplate
- terminal bouton
- myofibers of skeletal muscle
When a motor nerve reaches its destination, it ______, and at the end of each branch is a ______.
- ramifies
- terminal bouton
What are the dark patches on the muscle fibers? What NT does do these structures release? What stain was used?
- motor endplates
- ACh
- Silver stain (can see neuron fibers and terminal bouton)
These black areas are releasing a NT that is deactivated by __________ in the synaptic cleft. What is this image stained with?
- acetylcholinesterase (ACE)
- copper sulfide precipitate (it indicates the synaptic cleft
When ACh is released from the motor neuron into the terminal bouton, the skeletal muscle _____.
contracts
“Motor endplate” is also known as (name 2 others):
- neuromusclular junction
- myoneuronal junction
The muscle component of the NMJ is called the ________, aka the _______. What stain is this visualized with?
- end plate
- sole plate
- ACE stain (copper sulfide stain)
What are the circular structures in the axon (At1)? What are the electron-dense organelles present within the cytoplasm of the dendrite?
- synaptic vesicles
- mitochondria
If the cell on the left is a dendrite (with post-synaptic density) and the one on the top right an axon (At), what is the projection off the dendrite? What are the small, circular structures inside the dendrite?
- dendritic spine
- microtubules
What is the black arrow pointing to? What are the structures longitudinally in the dendrite?
- postsynaptic density
- microtubules
What are the 2 types of synaptic transmission? What are some characteristics of each?
- BRIDGED JUNCTION (gap junction) = current flow at ELECTRICAL synapses, bidirectional/unidirectional, fast
- UNBRIDGED JUNCTION (synaptic cleft) = unidirectional, definite space between neurons, slow
Electrical transmission is mediated by _________, which are composed of hemi-channels called _______.
- gap junctions
- connexons
Each connexon has ________ and each {same word} has ______ membrane-spanning regions.
- 6 connexins
- four
What is the distance between pre-and postsynaptic cell membranes in electrical, chemical and gaseous synapses, respectively?
- 3.5 nm (small)
- 20-50 nm (big, bigger than just ECM)
- 30-50 nm (big, bigger than just ECM)
_________ have cytoplasmic continuity between pre- and postsynaptic cell membranes.
Electrical synapses
What do chemical synapses consist of (3)?
- presynaptic active zones
- postsynaptic receptors/densities
- axonal varicosities/intervaricose segments
The synaptic delay for _____ synapses is virtually absent whereasthere is a small (0.3 ms) delay for ____ and ____ synapses.
- electrical
- chemical
- gaseous
Which synapses are unidirectional? Bidirectional?
- All 3 = electrical, chemical, gaseous
- electrical
______ synapses are low-resistance, high conductance channels bridging 2 cells.
Gap junctions
What are 6 properties of an electrical synapse?
- fast transmission
- synchronization (for fight/flight in invertebrates and human retina cells)
- all-or-none behavior
- transmission of developmental/regulatory signals
- no inhibitory actions
- no long-lasting (modulation) action
In synapses, ________ transmission is the most common.
chemical
The experiment by Otto Lowei took 2 frog hearts:
- Frog Heart #1 = electrically stimulated the _______, and the heart responded by ________.
- Frong Heart #2 = bathed it in the media of the stimulated 1st frog heart; this heart responded by ________.
The NT that was discovered was _________.
- vagus
- slowing down
- slowing down
- acetylcholine
___________ of the postsynaptic neuron contains proteins like actin, PSD-95, and scaffolding proteins.
Postsynaptic densities
Which type of chemical CNS synapse is this?
Gray’s type I (asymmetric)
Choose [Gray’s Type I] or [Gray’s Type II]:
(a) has oval-shaped, inhibitory vesicles
(b) has round, excitatory vesicles
(a) Gray’s Type II
(b) Gray’s Type I
Choose [Gray’s Type I] or [Gray’s Type II]:
(a) has wide synaptic cleft with prominent postsynaptic densities
(b) has narrow synaptic cleft with less prominent postsynaptic densities
(a) Type I
(b) Type II
Why are Gray’s Type II called Symmetric synapses?
postsynaptic densities are roughly equal to the presynaptic densities (asymmetric synapses have bigger postsynaptic densities)
Name 4 characteristics of monoaminergic synapses:
- dense-core vesicles (Ach, norepinephrine, dopamine, seratonin, GABA, glycine)
- axonal varicosities
- wade synaptic cleft (wider than Gray’s type I)
- no prominent pre/postsynaptic densities
_______ synapses contain large dense-core vesicles, like catecholamines and neurosecretory granules (peptides).
Peptidergic
____________ are invaginations of muscle cell at endplate of the NMJ. They contain ______ receptors closer to the synapse (“active zones”) and ______ receptors along the sides and depths of the folds.
- Junctional folds
- ACh
- Voltage-gated Na+ channel
______ and _____ are present in [secondary] synaptic clefts.
AChE; basal lamina
A NMJ contains lots of ______ channels on its presynaptic membrane.
Ca2+
___________ is a POSTSYNAPTIC disease of chemical transmission at NMJ that causes severe weakness.
Myasthenia gravis
Which type of myasthenia gravis is the most common and what is its mechanism?
Autoimmune = antibodies against own nicotinic AChRs in muscles (mostly in face)
Inhibitors of _________ is the preferred treatment of myasthenia gravis.
acetylcholinesterase (to slow/inhibit the breakdown of ACh)
Name the 6 general steps of presynaptic vessicles to release NTs:
- Contact PM
- Fusion
- Fission (release NTs)
- Collapse [into PM]
- Retrieval [of empty vesicle]
- Recycling (start over!)
Describe the CONTACT with PM step (1) in chemical transmission:
(a) synaptic vesicles wait for AP to travel down to axon terminal
(b) preparation for docking = vesicles anchored to to cytoskeletal proteins via DEPHOSPHORYLATED SYNAPSIN I—>AP causes phosphorylation of synapsin I by CA+/CALMODULIN-DEPENDENT PROTEIN KINASE, which releases vesicle from cytoskeletal network
(c) vesicles move toward active zone via RAB 3A proteins [neuron-specific GTPase]
(d) interaction of vSNARE [synaptobrevin] and tSNARE [syntaxin + SNAP-25]
Describe the FUSION and FISSION stages (2/3) in chemical synaptic transmission.
(a) fusion of vesicle membrane with presynaptic membrane begins when an influx of Ca2+ from AP binds SYNAPTOTAGMIN on vesicular membrane, which binds NEUREXIN and SYNTAXIN on presynaptic PM to trigger fusion
(b) release of NT by fission and diffusion of NT across cleft to postsynaptic membrane/endplate
Descrbe the COLLAPSE, RETRIEVAL and RECYLING steps (4/5/6) in chemical synaptic transmission.
(a) The SNAP/NSF unit diffuses to the site of vSNARE-tSNARE binding and attaches
(b) the NSF hydrolyzes ATP to release (unwind) the SNARE complex
(c) synaptobrevin releases (vSNARE) and causes empty vesice formation and release from PM into cytoplasm
START OVER!!
Name 4 ways NTs are terminated in synaptic cleft:
- diffusion
- enzymatic hydrolysis
- presynaptic autoreceptors (that bind excess NTs)
- reuptake
Postsynaptic _________ determine postsynaptic response. Most have membrane-spanning proteins with _______ for specific NT molecules and a given NT binds to a _______ family of receptors associated with specific _________.
- receptor properies
- external recognition sites
- conserved
- physiological functions
The binding of a NT on a postsynaptic membrane can either _____ or _____ activate the gating of ion channels through ______ and ______, respectively.
- directly
- indirectly
- opening receptor channel
- via secondary messengers
In direct gating, the receptor is part of the ________. Many receptors have _____ subunits, each having ____ transmembrane domains.
- ion channel
- 5
- 4
Nicotinic AChR, GABA receptors and glycine receptors are examples of which kind of postsynaptic receptor?
ionotropic (direct)
In indirect gating, the receptor, also called a _______ receptor, activates _______ that cause a second messenger (cAMP or cGMP) cascade via adenylate cyclase activity.
- metabotropic
- G proteins
_______ have a widespread metabolic effect due to amplification of a signal in the postsynaptic membrane.
metabotropic receptors
Metabotropic receptors typically are composed of _____ subunit with _____ transmembrane domains.
- 1
- 7
What is PLURICHEMICAL CODING?
When a neuron codes for and releases more than one NT
What is CHEMICAL CODING in the postsynaptic response?
the tight correlation of a chemical phenotype on a neuron and the function of that neuron (specificitiy) [similar to an MHC recognition complex in immunity]
A certain NT can bind with many different receptors. This property is called ______.
plasticity
Gaseous transmission is mediated by the ____ and _______ of gaseous messengers (NTs) from presynaptic to postsynaptic cell.
- synthesis
- diffusion
[NO ULTRASTRUCTURE (receptors) FOR MODULATION]
Give two examples of gaseous NTs and their function.
- NO
- CO
- increase the production of cGMP
Describe the gaseous transmission of NO in a neuro-neuronal synapse.
(a) GLUTAMATE released (EPSP) and binds NMDA receptors
(b) Ca2+ influx through NMDA receptors activates neuronal NOS when binds Ca2+
(c) nNOS produces NO (coverts L-arg—>L-citrulline and NO) in postsynaptic cell
(d) diffusion to destination (neighboring cells, glia cells, presynaptic terminal, smooth muscle, etc.)
The NO that diffuses into smooth muscle cells is made by nNOS in the _____________. NO causes the smooth muscle cell to ______.
- PRESYNAPTIC axon varicosities
- relax
What are the cofactors of nNOS?
Ca2+/calmodulin and NADPH
NO as a NT acts by binding to _________ attached to which enzyme?
After NO activates cGMP-dependent protein kinase, what happens to certain transmembrane proteins?
altered gating of ion channels in postsynaptic membrane
The half-life of the NT nitiric oxide is ______.
a few seconds
What is lifetime prevalence of Major Depressive disorder? Name 5 risk factors.
- 15%
1. 2x more common for women
2. potential family history
3. mean age = 40, but can occur at any age
4. increased risk of occurrence after losing close relationship
5. occurs in ALL SOCIOECONOMIC classes/races
Major depression is a greater cause of suffering than ______.
cancer
If MDD is untreated, it can last for ______. If it is treated, it can often resolve within ________.
- 6-12 months
- 2 months
What is the rule of thirds for RECURRENCE of MDD?
1/3 = never have another episode
1/3 = frequent recurring episodes
1/3 = recurring episodes once in awhile
What are some symptoms of MDD? How many of these symptoms do you need for over 2 weeks to be diagnosed?
- change in sleep pattern, change in appetite, decreased energy, suicidal ideation, anhedonia (lack of gaining happiness), decreased concentration/memory, depressed mood, feelings of worthlessness, helplessness, excessive guilt, irritability/tearfulness, psychosis
- 5
In the elderly, sometimes ______ is misdiagnosed as Alzheimer’s disease. What do you look for that would tell you otherwise.
- major depressive disorder
- if they are happy doing other things (not just memory problem)
Define PSYCHOSIS.
loss of being in touch with what’s real and what’s not; the symptoms are “mood congruent”; can have morbid delusions
Bipolar disorder and MDD symptoms are identical, but they are caused by different mechanisms. This is because ______. The major tell of differentiating the two is _______. How would you treat each?
- sometimes bipolar disorder demonstrates depressive mood way before mania starts
- family history of bipolar disorder
- MDD = antidepressents; Bipolar = antidepressents AND mood stabilizers
The major difference between MDD and greif is that in greif you do not have _____.
suicide ideation
What describes someone with DYSTHYMIA?
“Eeyore”-type person; pessimistic
The two NTs that are thought to cause depression are _____ and _____. Are they the only cause?
- seratonin; catecholamines
- no, because otherwise, the antidepressents (to block reuptake/hydrolytic proteins) would work immediately
What is Freud’s psychoanalytic theory in the context of MDD? How would Freud explain suicide?
Depression is anger turned inward; suicide would be anger toward self to alleviate depression
How is SEROTONIN produced? Which class of meds would treat a seratonin-caused depression?
(a) Tryptophan converted to 5-hydroxytryptophan via TRYPTOPHAN HYDROXYLASE
(b) 5-hydroxytryptophan converted to seratonin via amino acid decarboxylase (-COOH)
- SSRIs
A patient was put on an SSRI and then started eating a tryptophan-free diet. Her depressive symptoms got worse! What happened?
Need tryptophan to produce seratonin in the body
How is SERATONIN broken down?
seratonin acted on by MONOAMINE OXIDASE and ALDEHYDE DEHYDROGENASE to produce 5-hydroxyindole acetic acid
If you block MAO, what happens to serotonin levels?
they increase! good antidepressent!
During a single episode of MDD, _______ consider suicide. And now suicide has surpassed _______ as a cause of death.
- 66%
- motor vehicle accidents
What are 4 classes of antidepressent drugs and their mechanisms?
- SSRI = inhibit reuptake of SEROTONIN
- SNRI = inhibit reuptake of SEROTONIN and NOREPINEPHRINE
- Tricyclics = decrease reuptake of NOREPINEPHRINE
- MAOI = increase seratonin/catecholamines by decreasing breakdown
The lifetime prevalence of SCHIZOPHRENIA is ______. Name some risk factors.
- 1-2 %
1. equal prevalence between males/females
2. age of onset for males = late teens, females = early twenties
3. no racial difference
4. possible, but probably no SES correlation
What are some POSITIVE symptoms of SCHIZOPHRENIA?
delusions (falsely held beliefs), paranoia, hallucinations (auditory/visual), disorganized thought process (having problem listening to people)
What are some NEGATIVE symptoms of SCHIZOPHRENIA? How many Szch. symptoms do you need to be classified?
- blunted affect, alogia (isolated words), social isolation, lack of motivation, anhedonia (can’t be happy), poor hygiene
- 2 or more
DSM V no longer categorizes previous ________ of schilzophrenia. ______ is now separate category.
5 symptom subtypes = delusions, hallucinations, catatonia, negative symptoms, etc.
You can take drugs to cure schizophrenia. T/F
False! It’s a lifelong illness
We are better at treating ____ symptoms of schizophrenia than _____ symptoms.
- negative
- psychotic
_____ psychotic disorder is characterized by symptoms that appear like the negative profile of schizophrenia and are usually hermits; _____ pychotic disorder, on the other hand, is characterized by “magical thinking” and then more logical thinking when pressed for answers.
- SCHIZOIDAL
- SCHIZOTYPAL
What is SCHIZOAFFECTIVE disorder?
recurrent episodes of sychosis and also recurrent episodes of mood disorder; similar to bipolar + schizophrendia
What is the DOPAMINE THEORY?
(a) too much dopamine is in the MESOLIMBIC area of the brain, causing psychosis
(b) too little dopamine in the MESOCORTICAL (prefrontal) area of the brain, causing negative symptoms
[also abnormalities with GAGergic/glutamagte systems]
Schizophrenia is a ______ brain illness
whole
Typical antipsychotics are _____ blockers. Describe how they work on schizophrenia.
- dopamine
- block D2 channels, causing bettering of PSYCHOSIS but worsening of negative symptoms in MESOCORTICAL are of the brain
Atypical antipsychotics are _____ blockers. Describe how they work on schizophrenia. What are some side effects?
- 5HT2 = D2/4 blockers [D4 enhances dopamine breakdown in MESOLIMBIC area, so less negative effects.]
- side effects include: metabolic syndrome (weight gain/diabetes, etc.)
What is an example of a TYPICAL antipsychotic drug? ATYPICAL?
typical = Fluphenazine
atypical = Ziprasidone
What 2 structures does the DORSAL COLUMN of the spinal cord contain??
- Fasciulus Gracillus (lateral; sacral, lumbar)
- Fascicuus Cuneatus (medial; cervical, thoracic)
What happens if there is a lesion in the Fasciculus Gracilis (posterior funiculus) at the SC level?
You would lose fine touch, vibration, 2-point discrimination and proprioception in sacral/lumbar areas on the IPSILATERAL side of the body below the level of the lesion.
What are the two parts of the DESCENDING lateral funiculus?
- lateral corticospinal tract = motor (cerebral cortex) and some somatosensory
- rubrospinal tract = contains Red Nucleus and only extends to cervical level, crosses at midbrain (digits!)
What happens if there is a lesion AT or BELOW the level of the spinal cord of the lateral corticospinal tract?
IPSILATERAL spastic paralysis
What happens if you have a lesion at a level ABOVE the SC in the lateral corticospinal tract?
CONTRALATERAL spastic paralysis
What are the two types of ASCENDING lateral funiculus? What do they do?
- anterolateral tract/spinothalamic tract = pain, temperature, crude touch
- posterior spinocerebellar tract = proprioception
If there is a lesion on the ANTEROLATERAL tract at the level of the SC, what would the patient experience?
Loss of pain, temperature and touch on the CONTRALATERAL SIDE
If there was a lesion ABOVE the SC of the POSTERIOR SPINOCEREBELLAR tract, what would the patient experience?
IPSILATERAL loss of proprioception
Which LAMINAE are sensory, motor, or both?
Sensory = Dorsal I–>VI
Motor = Ventral VII, VIII, IX
Both = Dorsal VII
Upper ventral root motor lesions cause ________ paralysis whereas lower motor root lesions cause _____ paralysis.
- spastic
- flaccid
