Neurology Flashcards
Permanent Nerve Cell
Neuron
Non-permanent Nerve Cell
Neuroglia/Glial Cells/Supporting Cells
More numerous: Neurons or Glial Cells?
Glial Cells (10:1 ratio)
Produces CSF
Ependymal Cells
Macrophage of the Brain
Microglia
Regulate ECF ion levels; Provide mechanical support; Part of BBB
Astrocyte
Creates myelin in the CNS
Oligodendrocytes
Creates myelin in the PNS
Schwann Cells
Brain tumors from non-mature neurons
NeuroblastomaRetinoblastoma
Receiving portion of the Neuron
Dendrites, Cell Body
Where Action Potential is initiated
Axon Hillock
Function of Myelin Sheath
Insulator
Unmyelinated portions of the axon
Nodes of Ranvier
Branches of the Axons
Neural Fibrils
Terminal portion of a neural fibril that contains NT-containing vesicles
Axon Terminal (Boutons/End Feet)
Space between two Neurons
Synapse
Soma to Axon Terminal; Replenishes synaptic vesicles and enzymes for NT synthesis
Anterograde Axonal Transport
Axon Terminal to Soma; Recycles synaptic vesicle membrane for lysosomal degradation
Retrograde Axonal Transport
Protein responsible for Anterograde Axonal Transport
Kinesin
Protein responsible for Retrograde Axonal Transport
Dynein
Diseases utilizing Retrograde Axonal Transport
TetanusBotulism
Death of the Axon distal to the site of injury after an axon is transected
Anterograde/Orthograde Degeneration
Changes to the soma after an axon is transected
Axonal Reaction/Chromatolysis
Axonal regeneration occurs better in the CNS or PNS?
PNS
Secreted by: Nucleus Basalis of Meynert (Basal Ganglia); Synthesis: uses Acetyl CoA and Choline with enzyme: Choline Acetyltransferase; Degradation: produces Acetate and Choline with enzyme: Acetylcholinesterase (Choline is recycled)
Acetylcholine
Found mainly in the Substantia Nigra Pars Compacta & Ventral Tegmental Area; Removed via reuptake by MAO (in pre-synaptic nerve terminals), COMT (in tissues including liver)
Dopamine
Dopamine deficiency
Parkinson’s Disease
Dopamine excess
Schizophrenia
Secreted by Locus Ceruleus in the pons & post-ganglionic neurons of sympathetic nervous system; Control overall activity and mood of the mind, such as increasing the level of wakefulness; Maybe excitatory or inhibitory
NorepinephrineEpinephrine
Phenylalanine derivatives
PhenylalanineTyrosineL-DopaDopamineNorepinephrineEpinephrineThyroxineMelanin
Secreted mainly by the Median Raphe of the Brain Stem; Inhibitor of Pain Pathways in the Spinal Cord; “Happy Hormones”; From Tryptophan (W); Converted to Melatonin
Serotonin
Secreted in areas of brain responsible for Long-term behavior and Memory; From Arginine; Short-actin neurotransmitter; Not preformed and stored in vesicles
Nitric Oxide
From Histidine; Located mainly within the tuberomammillary nucleus of the Hypothalamus
Histamine
Inhibitory neurotransmitter usually found in spinal interneurons; Increases Chloride influx
Glycine
The number #1 Inhibitory Neurotransmitter in the Brain; Comes from Glutamate; Increases Chloride Influx (GABA-A) or Potassium Efflux (GABA-B)
GABA (Gamma Amino Butyric Acid)
The number #1 Excitatory Neurotransmitter in the Brain
Glutamate
Inhibit neurons in the brain involved in the perception of pain; Enkephalins, Endorphins, Dynorphins
Opioid Peptides
Involved in pain transmission; In specific areas of the brain, primary sensory neurons, GI plexus neurons
Substance P
Neurotransmitter deficient in Alzheimer’s Disease
Acetylcholine
-70mV; Potential difference that exist across the membrane; Exhibited by almost all cells; Refers to Intracellular Charge
Resting Membrane Potential (RMP)
Exhibited by Excitable Cells only (Neurons & Muscle Cells); Stereotypical size and shape; Propagating - non-decremental manner; “All-or-none”
Action Potential
Basis for Resting Membrane Potential (RMP) & Action Potential (AP)
Ion Channels
Making the membrane potential less negative
Depolarization
Making the membrane potential more negative
Hyperpolarization
Positive charges flowing into the cell
Inward current
Positive charges flowing out of the cell
Outward current
Membrane potential in which occurrence of Action Potential is inevitable
Threshold
Portion of the Action Potential where membrane potential is positive
Overshoot
Portion of the Action Potential where membrane potential is more negative than Resting Membrane Potential
Undershoot/Hyperpolarizing afterpotential
Period in which Action Potential cannot be elicited
Refractory Period
Nernst Potential for Na and K diffusion
+61mV and -94mV
Na-K Leak Channels
100x more permeable to K
Na-K-ATPase Pump
-4mV
Opening of Na-Activation gates
Sodium Influx (Depolarization)
Closure of Na-Inactivation gates and Opening of Potassium gates
stop Sodium Influx and Potassium Efflux (Repolarization)
Na-Activation Gates Closed; Na-Inactivation Gates Open; K Gates Closed
Resting state
Na-Activation Gates Open (Some); Na-Inactivation Gates Open; K Gates Closed
Depolarization
Na-Activation Gates Open (All); Na-Inactivation Gates Open; K Gates Closed
Rising phase of Action Potential
Na-Activation Gates Open; Na-Inactivation Gates Closed; K Gates Open
Falling phase of Action Potential
Na-Activation Gates Closed; Na-Inactivation Gates Closed; K Gates Open
Undershoot
Sodium Channel Blockers of Neurons
Tetradotoxin, Saxitoxin
Potassium Channel Blocker of Neurons
Tetraethylammonium
True or False: Na2+ and K+ gated channels are responsible for all types of Action Potential
False (eg: Ca2+ channels seen in muscles)
Stimulates nerve depolarization in the first place
Mechanical disturbance, Chemical, Electricity
Time periods after an Action Potential, during which a new stimulus cannot be readily elicited
Refractory Periods
Another Action Potential cannot be elicited, no matter how large the stimulus; Coincides with almost the entire duration of the action potential
Absolute Refractory Period
No Action Potential can occur until the Inactivation Gates open
Ionic Basis of Absolute Refractory Period
Action Potential can be elicited only if a larger than usual inward current is provided
Relative Refractory Period
Membrane Potential is closer to the K+ equilibrium potential and farther from threshold; More inward current is required to bring the membrane to threshold
Ionic Basis of Relative Refractory Period
When a cell is depolarized so SLOWLY such that the threshold potential is passed without firing an action potential
Accommodation
Effect of Hyperkalemia to heart muscle
Depolarizes the Heart
Effect of Hypokalemia to heart muscle
Hyperpolarizes the Heart (K+ leakage)
Synaptic inputs that depolarize the post-synaptic cell
Excitatory Post-synaptic Potential (EPSP)
Synaptic inputs that hyperpolarize the post-synaptic cell
Inhibitory Post-synaptic Potential (IPSP)
2 or more presynaptic inputs arrive at post-synaptic cell simultaneously
Spatial Summation
2 or more presynaptic inputs arrive at post-synaptic cell in rapid succession
Temporal Summation
Repeated stimulation causes response of post-synaptic cell to be greater than expected
Nerve Facilitation
Increased released of NT and increased sensitivity to the NT
Long-Term Potentiation (Involved in Memory)
Repeated stimulation causes decreased response of postsynaptic cell
Synaptic Fatigue (Due to depletion of NT stores)
Myelinated fiber; For Proprioception and Somatic Motor; Thickest (12-30um) and Fastest (70-120m/s)
Nerve Fiber Type A-alpha
Myelinated fiber; For Touch and Pressure; 5-12um and 30-70m/s
Nerve Fiber Type A-beta
Myelinated fiber; For Motor to Muscle spindles; 3-6um and 15-30m/s
Nerve Fiber Type A-gamma
Myelinated fiber; For Pain, Cold, Touch; 2-5um and 12-30m/s
Nerve Fiber Type A-delta
Myelinated fiber; For Preganglionic autonomic; <3um and 3-15m/s
Nerve Fiber Type B
Non-Myelinated fiber; For Pain, Temperature, some Mechanoreception; 0.4-1.2um and 0.5-2m/s
Nerve Fiber Type C-Dorsal root
Non-Myelinated fiber; For Postganglionic sympathetic; 0.3-1.3um and 0.7-2.3m/s
Nerve Fiber Type C-sympathetic
Vasomotor Center, Resoiratory Center (DRG, VRG), Swallowing, Coughing and Vomiting Centers
Medulla
Micturition Center, Pneumotaxic, Apneustic Centers
Pons
Relay Center for almost all sensations
Thalamus
Contributes to Balance
Cerebellum
Connects the two brain hemispheres
Corpus Callosum, Anterior Commissure
Motor, Personality, Calculation
Frontal Lobe
Somatosensory Cortex
Parietal Lobe
Vision
Occipital Lobe
Hearing, Vestibular processing, recognition of faces, Optic Pathway, (Meyer’s Loop)
Temporal Lobe
Elaboration of thoughts; Plan complex motor movements
Prefrontal Association Area of Cerebral Cortex
Plans and creates motor pattern for speech
Broca’s Area of Cerebral Cortex
Behavior, Emotions, Motivation
Limbic Association Area of Cerebral Cortex
Storage mechanism for learning; A result of previous neural activity
Memory
Seconds-to-minutes memory
Short-term Memory
Days-to-weeks memory
Intermediate-term Memory
Years-to-lifetime memory
Long-term Memory
Conversion of short-term memory to long-term memory; Accelerated an potentiated by Rehearsal
Consolidation
Does NOT store memory; An important output pathway from reward & punishment centers
Hippocampus
Loss of short-term memory; Impairment of the ability to form new memories through memorization
Anterograde Amnesia (Hippocampal Lesion)
Loss of pre-existing memories to conscious recollection; Person may be able to memorize new things but is unable to recall events or identity prior to the onset
Retrograde Amnesia (Thalamic Lesion)
Might play a role in helping a person “search” the memory storehouses and “read-out” the memories
Thalamus
Production of Oxytocin
Paraventricular Nuclei
Production of Vasopressin
Supraoptic Nuclei
Satiety Center
Ventromedial Nuclei
Hunger Center
Lateral Nuclei
Sweating (Heat release)
Anterior Hypothalamic Area
Shivering (Heat conversion)
Posterior Hypothalamus
Reward Center
Medial Forebrain Bundle
Punishment Center
Central Gray Area around the Aqueduct of Sylvius
Social inhibition
Amygdala
Which takes precedence over the other: punishment & fear or pleasure & reward?
Punishment & Fear
Regulate activity of many physiological processes including heart rte, blood pressure, body core, temperature and blood levels of hormones
Biological Clock
Cycles of Periodicity shorter than 24 hours (eg: heart beat, respiratory rhythm)
Ultradian Rhythms
Cycles of Periodicity longer than 24 hours (eg: menstrual cycle, gestation)
Infradian Rhythms
Cycles of Periodicity that approximate Earth’s rotational period (eg: sleep-wake cycle, hormone levels)
Circadian Rhythms
Master clock of all biological clocks in the human body; Destruction causes loss of circadian functions
Suprachiasmatic Nucleus
Implicated in regulation of circadian rhythms; Secretes a hormone called Melatonin that is synthesized from Serotonin
Pineal Gland
Controlled by sympathetic nerve activity which is regulated by light signals from the retina; Increased during darkness; Inhibited by daylight
Melatonin
Also known as Jet-lag; Out of synchronization of body clocks with the destination time; Treated with Melatonin or sunlight exposure
Desynchronosis
Recording of neuronal electrical activity; Important diagnostic tool in Clinical Neurology
EEG
Awake; Eyes Closed (8-13Hz)
Alpha waves
Awake; Eyes Open (13-30Hz)
Beta waves
Brain disorders and degenerative brain states (4-7Hz)
Theta waves
Deep sleep, Organic Brain Disease, Infants (0.5-4Hz)
Delta waves
Clinical assessment of brainstem functions in comatose patients use which evoked potential?
Auditory Evoked Potential
Endogenous periodicity of 25 hours
Sleep-wake cycle
Due to an active inhibitory process; NOT merely due to fatigue of Reticular Activating System (RAS); Secretion of Muramyl Peptide may be involved
Sleep
Usually dreamless or unremembered dreams; 10-30% decrease in blood pressure, heart rate and BMR; Increased in GI motility; Difficult to arouse by sensory stimuli; Alpha, Theta, & Delta waves
Slow-wave Sleep
With Active Dreaming; occurs every 90 minutes of slow-wave sleep; Increased brain metabolism; Decreased muscle tone, pupillary constriction, active body movements, irregular BP, HR, RR; penile erection, rapid eye movements; More difficult to arouse by sensory stimuli; Beta waves
REM Sleep
Who among the following dream the most: newborns, young adults, elderly?
Newborns (50% REM Sleep)
Most metabolic organ
Brain
Source of energy of Brain
Glucose and Ketone bodies only
True or False: Brain requires Insulin
False
Total amount of CSF in the Brain
150ml
Amount of CSF produced per day
500ml
Function of CSF
Cushioning
Consist of Endothelial cells of Cerebral Capillaries, Astrocyte foot processes and Choroid plexus epithelium
Blood-Brain Barrier
BBB exists in all parts of the brain EXCEPT:
Some Areas of HypothalamusPineal GlandArea Postrema
Aka “Visceral Motor System” or “Vegetative Nervous System”; Assists in maintaining Homeostasis (eg: Baroreceptors and Blood pressure)
Autonomic Nervous System
Sympathetic tract: Cell Body of Thoracic and Lumbar segment of Spinal CordParasympathetic tract: Cell Body of Brainstem, Sacral segment of Spinal Cord
Preganglionic Neuron
Sympathetic tract: Cell Body of Paravertebral or Prevertebral GangliaParasympathetic tract: Cell Body in the Ganglia at the walls of target organs
Postganglionic Neuron
Adrenoreceptors on Vascular smooth muscle, skin, renal, & splanchnic, gastrointestinal tract sphincters, bladder sphincter, radial muscle of iris; IP3, increase intracellular Ca2+
Alpha-1 Receptors
Adrenoreceptors on Gastrointestinal tract wall, Presynaptic adrenergic neurons; Inhibition of adenylyl cyclase, decrease cAMP
Alpha-2 Receptors
Adrenoreceptors on Heart, Salivary Glands, Adipose Tissue, Kidney; Stimulation of adenylyl cyclase, increase in cAMP
Beta-1 Receptors
Adrenoreceptors on Vascular smooth muscle of skeletal muscle, gastrointestinal tract wall, bladder wall, Bronchioles; stimulation of adenylyl cyclase, increase in cAMP
Beta-2 Receptors
Cholinoreceptors on skeletal muscle, motor end plate (N1), Postganglionic neurons, SNS and PNS (N2), Adrenal medulla (N2); Opening Na+ and K+ channels (depolarization)
Nicotinic Receptors
Cholinoreceptors on All effector organs, PNS, Sweat glands, SNS; IP3, increase intracellular Ca2+ (M1, M2, M3), decrease adenylyl cyclase, decrease cAMP (M2, M3)
Muscarinic Receptors
Mydriasis
Sympathetic (Alpha-1)
Accommodation (CN III)
Parasympathetic
Sweating
Sympathetic
Mucoid Salivation
Sympathetic
Watery Salivation
Parasympathetic
Glandular Secretion
Parasympathetic
Increased Heart Rate & Cardiac Contractility
Sympathetic (Beta-1)
Bronchoconstriction
Parasympathetic
GI Motility/Peristalsis
Parasympathetic (Rest & Digest)
Increased Blood Glucose, Lipids
Sympathetic
GU & GI sphincter contraction
Sympathetic
Uterine Contraction
Sympathetic (Alpha-1)
Urination and Defecation
Parasympathetic
Vasodilation - Skeletal Muscles
Sympathetic (Beta-2)
Vasoconstriction - Skin, Splanchnic, Renal, Venous
Sympathetic
Piloerection
Sympathetic
Erection
Parasympathetic
Ejaculation
Sympathetic (shoot) & Parasympathetic (point)
