NEURO Flashcards
Hydrocephalus
Enlarged ventricles due to increased CSF produced in choroid plexus.
Lateral third and fourth ventricles swell
Hypoxia
The brain becomes acidic. Acidosis in the brain causes necrotic changes secondary to hypoxemia.
Cerebral infarction/Stroke
When I don’t have enough oxygen in the tissues around the brain.
Causes two types of pathologies:
Thombotic from atherosclerosis
Embolic stroke from cardiac thrombi to middle cerebral arteries.
Cranial nerves
Numbers, names, and classification.
CN1 - Olfactory - sensory CN1 - Optic - sensory CN3 - Ocular motor CN4 - Trochlear - motor CN5 - Trigeminal - mixed CN6 - Abducens - motor CN7 - Facial - mixed CN8 - Vestibulocochlear - sensory CN9 - Glossopharangeal - mixed CN10 - Vagus - mixed CN11 - Accessory - motor CN12 - Hypoglossal - motor
What does the olfactory nerve do?
Smell
There are CN2 and CN3 reflexes
Like strikes -> Afferent fibers of CN2 -> Synapse in Edinger-Westphal Nuclei (midbrain) -> Efferent Parasympathetic fibers of CN3 travel to Sphincter Pupillae muscle in the iris, causing contraction.
Remember - visual fields are going to be the inverse retinal fields
When you look at something projected into the retina, it is the opposite of what the person is looking at. When you look at something from in the medial aspect of your nose, it is projected towards the lateral aspect of the eye.
What happens to this information to the retina when it goes to the brain?
The temporal or lateral activity or lateral receptive fibers stay on the same side of the brain. The medial fibers cross. 50% of visual information crosses over at the optic chiasm.
The pituitary gland is below the two fibers that cross medially. If there is a tumor then there is a loss of visual fields.
What are cones for?
COLOR vision. Lower sensitivity, higher activity. The cones make color vision. They have 1:1 with bipolar cells. Cones are tunes into three color categories.
Hence: C for C
What are rods for?
Nigh vision. Higher sensitivity, lower activity.
What is the function of CN4?
Superior oblique = movement of the eye down and out.
CN6 - Abducens
Lateral rectus - abducts the eyes.
What gives sympathetic activity to the ciliary, pterygopalatine, submandibular, and otic muscles?
The superior cervical ganglion.
It gives sympathetic activity to the eyes, nose, ear, and throat area.
Where does the thoracic area get its parasympathetic activity from?
Vagus nerve. Upper portion
When we get to the urogenital and lower digestive part of the body where do we get our innervation?
Sympathetic - inferior mesenteric.
Parasympathetic - pelvic splanchnic nerves.
POINT AND SHOOT
Parasympathetic = arausal Sympathetic = Climax
How is the nervous system divided?
Into the central nervous system and peripheral nervous system.
What makes up the CNS?
Spinal cord and the brain.
What is the peripheral nervous system divided into?
Somatic and autonomic.
Somatic Nervous System
- heavily myelinated
- singular
- acetylcholine
- deliberates motion
- always stimulatory
Autonomic Nervous System
- two neuron chain
- pre and postganglionic ganglions
- acetylcholine or norepinephrine
- Stimulatory and inhibitory
What is the autonomic nervous system divided into?
Sympathetic and parasympathetic nervous systems.
Sympathetic Nervous System
- raising heart rate
- blood vessels constrict
- glucose release
- fight and flight
- fibers originate in the thoracic and lumbar regions of the spinal cord
- Short preganglionic and long postganglionic fibers
- regulates sweating, influences metabolism and kidney activity
Parasympathetic Nervous System
- digestion of food
- expulsion of waste
- general maintenance
- rest and digest
- fibers originate in the brain and sacral region
What are the types of cells in the Nervous System?
Neurons
- main cells of NS
- composed of cell body
- groups of cell bodies in CNS -> nucleus
- group of cell bodies outside CNS -> ganglion
Dendrites and ganglions
Dendrites receive information and axons pass information on
What is it called (space) when two neurons come together
Synapse
What cells are found in the grey matter?
Cell bodies of neurons, neuropils( dendrites and unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capilaries.
How is the cerebral cortex divided?
Into the parietal lobe, temporal lobes, frontal lobe, and occipital lobe.
What does each part of the cortex control?
Frontal lobe - movement and executive function.
Parietal - sensory information, guides movements in 3D.
Temporal lobe - hearing, smell, memory, visual recognition, and languages.
Occipital - vision.
What is the resting membrane potential?
-70 mV
What ions are mostly found outside of neurons?
Sodium, chloride, and calcium ions.
What ions are mostly found inside neurons?
Potassium and negatively charged anions
Polar
Negative
Depolarization
Becoming positive
Repolarization
Becoming negative
What is the threshold potential?
-55 mV
What happens after the threshold potential value is achieved?
The neuron becomes less negatively charged thus causing voltage-gated sodium channels to open at the start of the axon called axon Hillock.
A chain reaction of having multiple voltage-gated sodium channels to open
What is the depolarization value during an action potential?
+40 mV
What unique feature do the voltage-gated sodium channels have?
It has the inactivation gate
Voltage-gated potassium channels
They do not open until sodium channels have opened and are inactivated.
Fatty myelin
Allows action potential to propagate faster.
Where does it come from?
From Schwan cells or oligodendrocytes
Saltatory conduction
Conducting action potential from nodes of Ranvier to the next through the fatty myelin sheath.
What are the impacts of oxygen deprivation on the brain?
Strokes, seizures, coma, or death.
Blood supply to the brain
Aorta - aortic arch
Dual circulation to the brain
Anterior - carotid arteries
Posterior - vertebral arteries
Where does the dual circulation meet?
Circle of Willis
What is the blood-brain barrier’s purpose?
CNS homeostasis
- Providing selective nutrient passage.
- Controlling fluid movement.
- Protecting from toxins, microbes.
How is CSF moved?
By the cilia of ependymal cells.
How many pairs of cranial nerves are there?
12
Where do they originate from?
Brain and brain stem
Precentral gyrus
Responsible for voluntary movements
ANterior to the central sulcus
Proprioceptors
Detect position and movement.
Initiate reflexes.
Prevent damage from overstretching or over-contracting
Type Ia neuron fibers
Central region
How far and how fast muscle is being stretched
Type II
Attaches to the ends of the central region.
How far muscle is being stretched.
gamma motor neurons
Innervate both ends of intrafusal muscle.
cause ends to contract.
What is a muscle spindle?
A bunch of intrafusal fibers
Extrafusal fibers
They connect with tendons.
Generate movement.
Intrafusal fibers
They are proprioceptors.
They tell us the position of our muscles in a 3D space.
They pick up the degree of stretch of the muscle.
The speed at which the muscle is being stretched.
What are the two kinds of intrafusal fibers?
Nuclear bag fibers and nuclear chain fibers.
Nuclear bag fibers
At the central point of this fiber, you find a lot of nuclei.
It looks “baggy”.
They pick up length and velocity.
These are more sensitive than the nuclear chain fibers to length and velocity.
Nuclear chain fibers
Their nuclei are linear.
They are sensitive to length.
Mechanoreceptors are divided in how many classes?
4
What are the 4 mechanoreceptors for touch (mechanosensors)?
Meissner corpuscles, Merkel discs, Ruffini corpuscles, and Pacinian corpuscles.
Meissner (tactile) corpuscles
Touch Encapsulated In fingertips Hair follicle sensors Sense vertical indentations on the skin. Fast adapting Small receptive fields = high resolution
Merkel discs
Pressure
Not encapsulated
Slow adapting
Ruffini (Bulbous) corpuscles
Encapsulated Detect skin stretching In joints for detection of rotation Slow adapting Big receptive fields = low resolution
Pacinian (lamellar) corpuscles
Encapsulated
Sense vibration
Fast adaptive
Big receptive fields
3 types of proprioceptors
Muscle spindle -
Joint Receptors
Muscle Spindle
Detects when a muscle is being stretched
Spindle-shaped
Found on perimysium which surrounds muscle cells
Golgi Tendon Organ
Located in tendons
They sense when a muscle is being stretched (indirectly senses force exerted by muscle).
Inhibits the action so no further damage is caused
Joint Receptors
Ruffini corpuscles in joints
Provide joint position and motion info (senses stretch in articular capsules).
Thermo Receptors
Slow adapting
Detect changes in skin temperature
Transient receptor potential channels
Cholinergic receptors
Classes:
Nicotinic (nicotine stimulation)
. Receptor that operates on acetylcholine as its neurotransmitter.
. Ganglionic antagonist: Hexamethonium.
. Motor antagonist: turbocurarine (Curare).
Muscarinic (muscarine stimulation)
. Antagonist: Atropine (Belladonna).
Adrenergic Receptors
They come in 4 categories. Alpha receptors . Excitatory . Type 1 and 2 . Vasoconstriction Beta receptors . Inhibitory . Type 1 and 2 Vasodilation
What does adrenergic means?
Adrenaline acting or adrenaline liking.
What are the classes of adrenergic receptors?
Alpha receptors -Alpha 1 and alpha 2
Beta receptors - Beta 1 and beta 2
What happens with the vascular system during fight or flight? alpha 1
The vascular system is going to tighten up and contract.
We need TPR and blood flow to go up.
I don’t need to be digesting at this, so it will be inhibitory instead of excitatory,
Alpha 2 receptors
Alpha 2 receptors calm the nervous system down.
When I have ventral horn problems…
I have paralysis usually such as polio.
Where are most amino acids (non-essential) mostly produced in the body?
Liver
What are the excitatory neurotransmitters?
Norepinephrine Dopamine Epinephrine Glutamate Serotonin Acetylcholine Histamine
What are the inhibitory neurotransmitters?
GABA
Glycine
Nitric Oxide
Neurosteroids
What is another term for LIGAND?
Messenger
REMEMBER
Choline acetylase creates acetylcholine
The enzyme that breaks Acetylcholine is called acetylcholine esterase.
Vitamin B3
Niacinamide.
It is very important inside the brain. The bain in a deficit of B3 will make niacinamide out of tryptophan.
What is the amino acid that starts the production of dopamine, norepinephrine, and epinephrine?
It all first starts with phenylalanine, then Tyrosine, then L-dopa, Dopa, NE, and finally E.
What are the co-factors for creating E?
What is the enzyme that converts NE to E?
to go from NE to E, SAMe, B12, and folate are needed,
N-methyl-transferase
Remember
In the CNS most catecholamines remain dopamine and NE.
In the peripheral NS, 80% of the catecholamines are epinephrine.
If there is an issue with the MAO or COMT…
ADH, aggression, anxiety due to catecholamine build up in the brain
Is glutamate excitatory or inhibitory?
Excitatory
What is GABA formed from?
Glutamine and the CNS
What does GABA do?
Causes inhibitory activity in the CNS.
Functions of the cerebellum
Vestibulocerebellum - control of balance and eye movement.
Pontocerebellum - planning and initiation of movement.
Spinocerebellum - synergy, which is control of rate, force, range, and direction of movement
Huntington’s Chorea
Genetic
Age 20-50
Progressive to death
Loss of GAA containing neurons.
Parkinson’s disease
Damage to the substantia nigra dopaminergic system
Idiopathic (autoimmune) or toxic
Festinating gait, cog-wheel rigidity, pill-rolling resting tremor
Ventricular system
Network of communicating cavities within the brain that contains CSF.
There are two lateral, third ventricles, and a 4th ventricle.
The function of these ventricles is to produce CSF, circulate, and reabsorb it.
ALS - Amyotrophic lateral sclerosis
Amyotrophic - No muscle nourishment
Men 50-60
Loss of both lower and upper motor neurons
Muscular atrophy, weakness, hyperreflexia
Death following respiratory complication.
10% dt autosomal dominance.
CNS Infection
Will kill you quickly
Encephalitis
Severe Headache with systemic sn/SX (fever, n/v) Often focal neurological deficit Infection of the brain itself Will kill you quicker
Meningitis
Infection of the meninges
Outside of the brain
Tumors and Myelin diseases
Astrocytoma - categorized by grades 1-4
1 and 2 are benign
3 malignant
Grade 4 astrocytomas = Glioblastoma Multiforme or GBM. Very aggressive
Multiple sclerosis
In CNS
female > males
Autoimmune demyelination
Optic neuritis,
Guillain-Barre Syndrome
Symmetrical ascending paralysis
Imminent respiratory failure - a matter of time for this to happen
Cranial nerve mostly affected is CN7
Remember
Cowdry bodies - inclusions you see in patients that have herpes infections
Remember
Negri bodies - Rabies
Wernicke-Korsakoff syndrome
Nutrition deficiency
Thiamine (B1) deficiency due to alcoholism
ETOH metabolism used B1 (among other nutrients). Vitamin B1 is responsible for dehydrogenase metabolism. If I am doing a lot of this, I am using a lot of B1.
Confabulations/no short term memory
Tx. With B1 IV reverses many Sn/Sx
When I don’t have B1, I do not have short-term memory. People with B1 deficiency make things up due to bad short-term memory - not on purpose
Niacin (vitamin B3) deficiency
Nutrition deficiency
Dementia, dermatitis, diarrhea (death)
Niacin is important to every process in the brain that explains dementia.
Vitamin B12 (cobalamin) deficiency
Macrocytic anemia
degeneration of the spinal cord - does not happen in folate deficiency.
Spasticity weakness, dementia, loss of proprioception.
Some PNS Sx
Not cured by Folate supplementation.
Dementia
It is a clinical sign/symptom
Dementia is a clinical finding that correlates to diseases that causes dementia
Dementia - lost higher activity in the brain
It can be caused by drugs, alcohol, trauma, infections,
Alzheimer’s disease
The most common reason for dementia
Inflammatory change
Tay-Sachs
Lysosomal storage dz
Progressive, neurodegenerative disorder
Cause by an enzymatic deficiency (hexosaminidase A)
Inability to catabolize GM2 gangiosides
AVM
Congenital
May occur anywhere
Causes chronic H/A
Berry aneurysm
Congenital
Happens on the anterior communicating arteries or posterior communicating arteries in the circle of Willis
Hypertensive Encephalopathy
Diastolic blood pressure 120
Grade 4 retinal changes
Confusion, drowsiness, h/a, nausea
may lead to rupture and hemorrhage
What can increased intracranial pressure cause?
It can lead to papilledema (swelling of the disk) and brain herniation
What is the right hemisphere dominant for?
Facial expression, intonation, body language, and spatial tasks
Left hemisphere
language
