II - Neurophysiology Flashcards
Nerve Cell: permanent cell
neurons
Nerve Cell: non-permanent cells
neuroglia/glial cells/supporting cells
Nerve Cell: has malignant potential
neuroglia/glial cells/supporting cells
Nerve Cell: high in number
neuroglia/glial cells/supporting cells (10:1)
Glial Cells: Produces CSF
ependymal cells
Glial Cells: Macrophage of the brain
microglia
Glial Cells: Regulate ECF ino levels, gives mechanical support, forms BBB (foot processes)
astrocytes (nurse cells)
Glial Cells: Creates myelin in the CNS
oligodendrocytes
Glial Cells: Creates myelin in the PNS
Schwann cells
Glial Cells: Brain tumors from non-mature neurons
neuroblastoma, retinoblastoma
Neuron: Receiving portion for neurotransmitter
dendrites, cell body
Glial Cells: Where the action potential actually starts
axon hillock
Glial Cells: Function of the myelin sheath
insulator
Glial Cells: Unmyelinated part of the axon
Nodes of Ranvier
Glial Cells: Branches of axons
neural fibril
Glial Cells: Terminal portion of a neural fibril that contains NT-containing vesicles
axon terminal/boutons/end-feet
Glial Cells: Space between 2 neurons
synapse
Axonal Transport: Soma (Cell Body) to Axon Terminal
Anterograde
Axonal Transport: Replenishes synaptic vesicles and enzymes for NT synthesis
Anterograde
Axonal Transport: Axon terminal to Soma (Cell Body)
Retrograde
Axonal Transport: Recycles synaptic vesicle membrane for lysosomal degradation
Retrograde
The death of the axon distal to the site of injury after an axon is transected
Anterograde/Orthograde Degeneration (Wallerian)
Changes to the soma after an axon is transected
Axonal Reaction/Chromatolysis
Axonal regeneration occurs better in the
PNS
Used by neurons to communicate with other neurons across synapses, may be excitatory, inhibitory or both
neurotransmitters
Acetylcholine: Location
Nucleus Basalis of Meynert, found in many areas
Acetylcholine: Synthesis
acetyl CoA + choline (choline acetyltransferase)
Acetylcholine: Degradation
degradation precedes reuptake, produces acetyl CoA and choline (acetylcholinesterase), choline is recycled
Acetylcholine: Deficiency
Alzheimer’s Disease - most common cause of dementia in the elderly
Dopamine: Location
Substantia Nigra Pars Compacta, Ventral Tegmental Area
Dopamine: Degradation
MAO - presynaptic nerve terminals, COMT - other tissues including the liver
Dopamine: Deficiency
Parkinson’s Disease
Parkinson’s: Findings
Tremors, Rigidity, Akinesia, Postural instability
Dopamine: Excess
Schizophrenia
Norepinephrine & Epinephrine: Location
Postganglionic Neuros of the SNS - Both, Locus Ceruleus of the Pons - Norepinephrine
Norepinephrine & Epinephrine: Functions
control overall activity and mood of the mind such as increasing level of wakefulness
Norepinephrine & Epinephrine: Action
excitatory or inhibitory
Norepinephrine & Epinephrine: Site of Action
adrenergic receptors
Phenylalanine Derivatives
Phenylalanine → Tyrosine → L-Dopa → Dopamine → Norepinephrine → Epinephrine, Tyrosine → Thyroxine and Melanin
Tryptophan Derivatives
Serotonin (5-HT) → Melatonin, Niacin (B3)
Serotonin: Location
Median Raphe of the Brain
Serotonin: Function
inhibitor of pain pathways in the spinal cord (“Happy Hormone”)
Serotonin: Precursor
Tryptophan
Serotonin: Product
Melatonin (pineal gland)
Nitric Oxide: Location
areas of the brain responsible for long-term memory and behavior
Nitric Oxide: Precursor
Arginine
Nitric Oxide: Functions
permeant gas that diffuses towards its target cell, short-acting inhibitory neurotransmitter
Histamine: Location
Tubomammillary Nucleus of the Hypothalamus
Histamine: Precursor
Histidine
Histamine: Functions
arousal, sleep, circadian rhythm
Glycine: Location
Spinal Interneurons
Glycine: Functions
major inhibitory NT in SC, increases Cl influx
GABA: Location
brain - spiny neurons of striate nucleus, Purkinje cells of the cerebellum
GABA: Precursor
Glutamate
GABA: Functions
major inhibitory NT in the brain, increases Cl influx (GABAa) and K efflux (GABAb)
Glutamate: Function
major excitatory NT in the brain
Opioid Peptides: Function
inhibit neurons in the brain involved in the perception of pain
Opioid Peptides: Examples
enkephalins, endorphins, dynorphins
Substance P: Location
brain, primary sensory neurons, GI plexus neurons
Substance P: Function
transmission of slow pain
Potential difference across the membrane, INTRAcellular charge
Resting Membrane Potential
Resting Membrane Potential
-70mV
Resting Membrane Potential: mechanism with the highest contribution
Nernst Potential of Na (+61mV) and K (-94mV) Diffusion
Resting Membrane Potential: 100x more permeable to K
Na-K Leak Channels
Resting Membrane Potential: contributes -4mV
Na-K-ATPase Pump
Exhibited by excitable cells only (neurons, muscle cells)
Action Potential
Characteristics of Action Potentials
Stereotypical size and shape - depolarizes to the same potential and repolarizes to the same RMP, Propagating - nondecremental depolarization in adjacent cells, All-or-None - if the threshold is reached, a full AP is generated, otherwise, none at all
Basis for resting membrane potential and action potential
ion channels
RMP & AP: Makes the membrane less negative
depolarization
RMP & AP: Make the MP more negative
hyperpolarization
RMP & AP: Positive charges flowing into the cell
inward current
RMP & AP: Positive charges flowing out of the cell
outward current
RMP & AP: MP in which AP is inevitable
threshold
RMP & AP: Portion of the AP where MP is poritive
overshoot
RMP & AP: Portion of the AP where MP is < RMP
undershoot (hyperpolarizing afterpotential)
Depolarization opens
Na-Activation Gates - Na Influx
Repolarization closes
Na-Inactivation Gates - stops Na influx
Repolarization opens
K Gates - K efflux
Na-Channel blockers of neurons
Tetradotoxin - puffer fish, Saxitoxin - red tide, dinoflagellates
K-Channel blocker of neurons
Tetraethylammonium - puffer fish
What stimulates nerve depolarization in the first place?
mechanical disturbance, chemicals, electricity
Time periods in an action potential during which a new stimulus cannot be elicited
refractory periods
Refractory Periods: Another AP cannot be elicited no matter how large the stimulus, coincides with almost the entire AP
absolute refractory period
Refractory Periods: Na-inactivation gates are closed when depolarized, no AP can occur until they open
absolute refractory period
Refractory Periods: AP can occur with a larger that usual inward current, occurs from the end of the ARF up to the RMP
relative refractory period
Refractory Periods: K conductance is elevated, MP is closer the K equilibrium and farther from the threshold
relative refractory period
When a cell is depolarized so slowly such that the threshold potential is passed with firing an AP
accomodation
Action Potential: Synaptic inputs that depolarize the post-synaptic cell
Excitatory Post-Synaptic Potential (EPSP)
Action Potential: Synaptic inputs the hyperpolarize the post-synaptic celle
Inhibitory Post-Synaptic Potential (IPSP)
Action Potential: Two or more pre-synaptic inputs arrive at the post-synaptic cell simultaneously
Spatial Summation
Action Potential: Two or more pre-synaptic inputs arrive at the post-synaptic cell in rapid succession
Temporal Summation
Action Potential: Repeated stimulation causes response of the post-synaptic cell to be greater then expected
Nerve Facilitation
Action Potential: Increased release of NT and increased sensitivity to NT
Long-Term Potentiation
Action Potential: Repeated stimulation causes decreased response of the post-synaptic cell
Synaptic Fatigue
Nerve Fibers: Fastest, thickest, most myelinated, most ATP consumed
A Fibers
Nerve Fibers: Slowest, thinnest, least myelinated, least ATP consumed
C Fibers
Brain: Vasomotor center, respiratory center, swallowing, coughing and vomiting centers
medulla
Brain: Micturition center, pneumotaxic and apneustic centers
pons
Brain: Relay center for almost all sensations
thalamus
Brain: Balance
cerebellum
Brain: Connects 2 brain hemispheres
corpus callosum, anterior commisure
Brain: Motor, personality, calculation, judgement
frontal lobe
Brain: Somatosensory cortex
parietal lobe
Brain: Visual cortex
occipital lobe
Brain: Hearing, vestibular processing, recognition of faces, optic pathway (Meyer’s Loop), memory storage
temporal lobe
Cerebral Cortex: Initiation
Primary Areas
Cerebral Cortex: Interpretation
Secondary Areas
Cerebral Cortex: Integration
Tertiary Areas
Cerebral Cortex: Receive and analyze signals simultaneously
Association Areas
Cerebral Cortex: Association Areas
Parieto-Occipitotemporal Area, Prefrontal Association Area, Broca’s Area, Limbic Association Area
Association Areas: Elaboration of thoughts, plan complex motor movements
Prefrontal Association Area
Association Areas: Plans and creates motor patter for speech, damage causes expressive aphasia
Broca’s Area
Association Areas: Behavior, emotions, motivation
Limbic Association Area
Storage mechanism for learning, a result of previous neural activity
Memory
Memory: Seconds to Minutes
Short-Term Memory
Memory: Chemical Changes
Short-Term Memory
Memory: Days to Weeks
Intermediate-Term Memory
Memory: Years to a Lifetime
Long-Term Memory
Memory: Physical/Structural Changes
Long-Term Memory
Conversion of short-term memory to long-term memory, accelerated and potentiated by rehearsal (learning by trauma)
Consolidation
Does NOT store memory, an important outputa pathway from the reward & punishment centers of the brain, damage causes ANTEROGRADE amnesis
Hippocampus
Helps a person search the memory storehouses and read-out the memories, damage causes RETROGRADE amnesia
Thalamus
Limbic System: Produces mainly Oxytocin
Paraventricular Nuclei
Limbic System: Produces mainly Vasopressin
Supraoptic Nuclei
Limbic System: Satiety Center
Ventromedial Nuclei
Limbic System: Hunger Center
Lateral Nuclei
Limbic System: Sweating (heat release)
Anterior Hypothalamus
Limbic System: Shivering (heat conservation)
Posterior Hypothalamus
Limbic System: Reward Center
Medial Forebrain Bundle
Limbic System: Punishment Center
Central Gray Area aroung Aqueduct of Sylvius
Limbic System: Social Inhibition
Amygdala
Regulate the activity of many physiological processesinluding HR, BP, T and hormones
Biological Clock
Master clock in the human body
Suprachiasmatic Nucleus (SCN)
Its neurons retain synchronized, rhythmical firing patterns even though they are isolated from the rest of the brain
Suprachiasmatic Nucleus (SCN)
Destruction causes loss of circadian rhythm
Suprachiasmatic Nucleus (SCN)
Regulates circadian rhythm
Pineal Gland
Secretes a hormone called melatonin that is synthesized from serotonin
Pineal Gland
Melatonin is increased in _____, inhibited by _____ and controlled by _____ which is regulated by light signals form the _____.
darkness, daylight, sympathetic nerve activity, retina
Recording of neuronal electrical activity, diagnostic tool in clinical neurology
Electroencephalogram (EEG)
Brain Waves: Fast, awake, eyes closed, relaxed (8-13Hz)
Alpha
Brain Waves: Fast, awake, eyes open, alert (13-30Hz)
Beta
Brain Waves: Slow, brain disorders, degenerative brain states (4-7Hz)
Theta
Brain Waves: Deep sleep, organic brain disease, infants (0.5-4Hz)
Delta
Sleep is due to an active _____ process of releasing _____.
inhibitory, Muramyl Peptide
Sleep: Dreamless or unremembered dreams
Slow-Wave Sleep
Sleep: Decreased BP, HR, BMR, Increased GI motility
Slow-Wave Sleep
Stages of Slow-Wave Sleep
- Aplha waves interspersed with Theta waves, 2. Theta waves interrupted by Sleep Spindles (12-14Hz) and K complexes (large, slow potentials), 3. Delta waves interrupted by Sleep Spindles, 4. Delta waves alone
Sleep: Active dreaming, every 90 minutes
Rapid Eye Movement (REM) Sleep
Sleep: Increased brain metabolism, Decreased muscle tone, pupillary constriction, active body movements, Irregular BP, HR, RR, penile erection
Rapid Eye Movement (REM) Sleep
Sleep: Very difficult to arouse
Rapid Eye Movement (REM) Sleep
Sleep: Mainly Beta waves
Rapid Eye Movement (REM) Sleep
Who dreams the most?
newborns 50%, adults 25%
There is _____ ANS effect to cerebral blood flow.
little
Cerebral blood flow is highly _____ at _____.
autoregulated, BP 60-140mmhg
Increase in CO2 _____ cerebral blood flow.
increases
Gray matter is _____ metabolic than white matter
more
Most metabolic organ of the body
brain (2% of body mass, 15% of metabolism)
Source of energy for the brain
glucose, ketone bodies
Total amount of CSF in the brain
150mL
Total amount of CSF produced per day
500ml/day
CSF Pathway
Lateral Ventricles → Foramen of Monroe → Third Ventricle → Aqueduct of Sylvius , Fourth Ventricle → Foramen of Magendie (1) & Luschka (2) → Subarachnoid Space over the brain and SC → Arachnoid Granulations → Dural Venous Sinus Blood
CSF: Na+, Protein
148 Na+, 15-45 Protein
Blood: Na+, Protein
136-145 Na+, 6.8 x 10^3 Protein
BBB: Components
endothelial cells of cerebral capillaries (and the tight junctions between them), astrocyte foot processes, choroid plexus epithelium
BBB: Location
all areas of the brain EXCEPT: some areas of the hypothalamus, pineal gland, area postrema
Autonomic Nervous System: Fight or Flight
Sympathetic
Autonomic Nervous System: Rest and Digest
Parasympathetic
Autonomic Nervous System: Functions
assists in maintaining homeostasis, participates in appropriate and coordinated responses to external stimuli
Peripheral NS: Voluntary, 1 motorneuron, ACh → Nm - skeletal muscle
Somatic
Peripheral NS: Involuntary, 2 motorneurons, thoracolumbar preganglionic neurons (ACh → Nn - nerve), paravertebral postganglionic neurons (Adrenergic: NE → α1, α2, β1, β2 - smooth muscle, glands, heart; Muscarinic: ACh → M - sweat glands, piloerector muscles, some skeletal BVs)
Sympathetic
Peripheral NS: Involuntary, 2 motorneurons, craniosacral preganglionic neurons (ACh → Nn - nerve), postganglionic neurons at the walls of effector organs (ACh → M - glands, smooth muscle)
Parasympathetic
Peripheral NS: ACh → Nn releases Epinephrine 80% and Norepinephrine 20%
Adrenal Medulla
Adrenoreceptors: IP3, increased intracellular Ca, contraction
α1
Adrenoreceptors: Inhibition of adenylyl cyclase, decreased cAMP, in presynaptic adrebergic neurons (NE reuptake)
α2
Adrenoreceptors: Stimulation of adenylyl cyclase, increased cAMP
β1
Adrenoreceptors: Stimulation of adenylyl cyclase, increased cAMP, relaxation
β2
Cholinorecetors: Opening of Na and K channels, depolarization
Nicotinic
Cholinorecetors: IP3, increased Ca (M1,3,5), inhibition of adenylyl cyclase, decreased cAMP (M2,4)
Muscarinic
Autonomic Nervous System: Capable of mass discharge
Sympathetic
Adrenoreceptors: Found in adipose for lipolysis and thermogenesis, brown fat in infants
β3
ANS: Mydriasis
Sympathetic - radial muscles
ANS: Accomodation
Parasympathetic
ANS: Sweating
Sympathetic
ANS: Salivation
Sympathetic - mucosal, sticky, Parasympathetic - serous, watery
ANS: Glandular Secretion
Parasympathetic
ANS: Increased HR and cardiac contractility
Sympathetic
ANS: Bronchoconstriction
Parasympathetic
ANS: GI motility/peristalsis
Parasympathetic
ANS: Increased blood glucose, lipids
Sympathetic
ANS: GU/GI sphincter contraction
Sympathetic
ANS: Uterus
Sympathetic: contraction - α1, relaxation - β2
ANS: Urination
Parasympathetic
ANS: Defecation
Parasympathetic
ANS: Vasodilation - skeletal muscle
Sympathetic
ANS: Vasoconstriction - skin, splanchnic, renal, venous
Sympathetic
ANS: Piloerection
Sympathetic
ANS: Erection
Parasympathetic
ANS: Ejaculation
Sympathetic
ANS: Meiosis
Parasympathetic - circular muscles
Sympathetic NS: Increased HR (SA Node)
β1
Sympathetic NS: Increased AV node conduction
β1
Sympathetic NS: Increased contractility
β1
Sympathetic NS: Vasoconstriction - skin, splanchnic
α1
Sympathetic NS: Vasodilation - skeletal muscle
β2
Sympathetic NS: Vasoconstriction - skeletal muscle
α1
Sympathetic NS: Bronchodilation
β2
Sympathetic NS: Smooth muscle, walls relax
α2, β2
Sympathetic NS: Smooth muscle, sphincters contract
α1
Sympathetic NS: Salivation
β1
Sympathetic NS: UB wall, detrusor relax
β2
Sympathetic NS: Ejaculation
α
Sympathetic NS: Mydriasis
α
Sympathetic NS: Ciliary muscle dilation (far vision)
β
Sympathetic NS: Sweat glands, thermoregulatory
M
Sympathetic NS: Sweat glands, stress
α
Sympathetic NS: Gluconeogenesis, glycogenolysis
α1, β2
Sympathetic NS: Lipolysis
β2, β3
Sympathetic NS: Renin secretion
β
