Neurophysiology, Topnotch Flashcards
Functions of astrocytes
1) Regulate ECF ion levels
2) Mechanical support
3) Forms BBB
Creates myelin in CNS
Oligodendrocytes
Creates myelin in PNS
Schwann cells
Brain tumors from immature neurons (2)
1) Neuroblastoma
2) Retinoblastoma
Where action potential in a neuron starts
Axon hillock
Branches of axons
Neural fibrils
Terminal portion of neural fibril that contains NT-containing vesicles
Axon buotons
Part of a synapse where there is a high density of mitochondria
Presynaptic terminal of a cholinergic neuron
Where K channels are highly concentrated
Paranodal axolemma and Schwann cell membrane
Death of axon distal to site of injury
Wallerian degeneration
CNS vs PNS: Where axonal regeneration occurs better
PNS
Sites of ACh secretion (5)
1) Nucleus basalis of Meynert in basal ganglia
2) Large pyramidal cells in motor cortex
3) All preganglionic neurons of ANS
4) Postganglionic PSY neurons and postganglionic SY of sweat glands
5) Skeletal muscles
ACh synthesis
Acetyl CoA + choline catalyzed by choline acetyltransferase
Main neurotransmitter in REM sleep
ACh
ACh degradation
Acetate + choline catalyzed by acetylcholinesterase whereby choline is recycled
ACh is deficient in what disease entity
1) Alzheimer’s disease
2) Huntington’s disease
Dopamine is deficient in what disease entity
1) Parkinson’s disease
2) Depression
Main sites of dopamine (2)
1) Substancia nigra pars compacta
2) VTA
Enzymes that degrade dopamine
1) MAO in presynaptic nerve terminals
2) COMT in tissues
What hormone is in excess in Schizophrenia
Dopamine
Sites of NE and Epinephrine secretion (4)
1) Locus ceruleus in pons
2) Brainstem
3) Hypothalamus
4) Postganglionic SY except sweat glands
Phenylalanine derivatives
1) Tyrosine
2) L-dopa
3) Dopamine
4) NE
5) Epinephrine
6) Thyroxine
7) Melanin
Tryptophan derivatives
1) Melatonin
2) Serotonin
3) Niacin
Tyrosine –> L-dopa enzyme
Tyrosine hydroxylase
L-dopa –> Dopamine enzyme
Dopa decarboxylase
Dopamine –> NE
Dopamine b-hydroxylase
NE –> Epinephrine
Phenylethanolamine-N-methyltransferase
Also known as the happy hormone
Serotonin
Main site of serotonin secretion
Median raphe of brain stem
Where serotonin is secreted to initiate sleep
Median raphe of brain stem
Where serotonin is secreted to inhibit pain pathways
Spinal cord
Degradation of serotonin
5-HIAA catalyzed by MAO + aldehyde dehydrogenase
Conversion of serotonin
Melatonin in pineal gland
NT responsible for long-term memory
NO
NO is synthesized from
Arginine
Stimulatory vs inhibitory: NO
Inhibitory
Difference of NO from other NTs
Not preformed and stored in vesicles
NT involved in ctrl of arousal, sleep, and circadian rhythm
Histamine
From which histamine is synthesized
Histidine
Histamine is secreted mainly in
Tuberomamillary nucleus of hypothalamus
Inhibitory neurotransmitter in spinal interneurons
Glycine
Ion INFLUX increased by Glycine
Cl-
From which GABA is synthesized
Glutamate
Ion INFLUX increased by GABA-A
Cl-
Ion EFFLUX increased by GABA-B
K+
NT involved in SLOW pain transmission
Substance P
RMP contributors (3)
1) Nernst potential for Na (+61) and K (-94) diffusion
2) Na-K leak channels or K-leak channels (100x more permeable to potassium
3) Na-K ATPase pump (-4mV)
Characteristics of an AP
1) Stereotypical size and shape
2) Propagating in a nondecremental manner
3) All-or-none
Threshold for AP
-30mV
Portion of AP where MP is less than RMP
Undershoot
Activation gate
M gate
Inactivation gate
H gate
Na channel gates at rest
Closed M gate, opened H gate
Na channel gates at upstroke
Opened M gate, opened H gate
Na channel gates at repolarization
closed H gate
Gates that contribute to repolarization (2)
1) Closed Na inactivation gate
2) Opened K gates causing K efflux
Responsible for undershoot
Prolonged opening of K gates
Configuration of Na channel gates during undershoot
Closed M gate, closed H gate
Ionic basis of ARP
No action potential can occur until the Na-inactivation gates open
Ionic basis for RRP
Membrane potential is closer to K equilibrium potential and farther from threshold
Happens when cell is depolarized so slowly that threshold potential is passed with firing an AP since critical number of open Na channels os not attained
Accomodation
Effect of hyperkalemia on cardiac muscle
Depolarization
Effect of hypokalemia on cardiac muscle
Hyperpolarization
Synaptic inputs that hyperpolarize the post-synaptic cell
IPSP
Repeated stimulation –> Response greater than expected
Nerve facilitation
Increased NT release and increased sensitivity to NT
Long-term potentiation
Repeated stimulation –> decreased response
Synaptic fatigue
Fibers in order of myelination (greatest to none)
A > B > C
Fibers for proprioception
A alpha
Fibers for touch and pressure
A beta
Fibers that are motor to muscle spindles
A gamma
Fibers for touch, fast pain, and cold
A delta
Extrafusal nerve fibers
A alpha
Preganglionic autonomic fiber type
B fibers
Slow pain, temp, mechanoreception (smell)
C - dorsal root
Postganglionic SY
C - sympathetic
Sodium channel blocker of neurons
1) Tetradotoxin
2) Saxitoxin
Potassium channel blocker of neurons
Tetraethylammonium
Respiratory, swallowing, coughing, and vomiting centers
Medulla
Micturitiom, pneumotaxic, and apneustic centers
Pons
Relay center for almost all sensations except olfaction
Thalamus
Motor, personality, calculation, judgement
Frontal
Somatosensory cortex
Parietal
Hearing, vestibular processing, recognition of faces, Meyer’s loop (optic pathway)
Temporal
Memory
Temporal
Plans and creates motor pattern for speech
Broca’s area
Brodmann’s areas of Broca’s area
1) 44 (pars opercularis)
2) 45 (pars triangularis)
Location of Broca’s area (lobe)
Frontal
Area for behavior, emotions, and motivation
Limbic association area
Broca’s expressive aphasia is aka
Affluent aphasia
Receptive aphasia
Wernicke’s aphasia
Brodmann’s area of Wernicke’s aphasia
22
Location of Wernicke’s area in brain
Superior temporal gyurs in the dominant hemisphere
Conversion of short-term memory to long-term memory
Consolidation
Lesion in this part of the brain will cause anterograde amnesia
Hippocampus
Lesion in this part of the brain will cause retrograde amnesia
Thalamus
Produce oxytocin
Paraventricular nuclei
Produce vasopressin
Supraoptic nuceli
Satiety center
Ventromedial nuclei
Hunger center
Lateral nuclei
Sweating/ heat release
Anterior hypothalamus
Shivering/ heat conservation
Posterior hypothalamus
Reward center
Medial forebrain bundle
Punishment center
Central gray area
Social inhibition
Amygdala
Biologic clock
SCN
Regulates SY activity that controls secretion of melatonin from pineal gland
Light signals from retina
Order of sleep waves
BATS DB
1) beta
2) alpha
3) theta
4) sleep spindles and K complexes
5) delta
6) beta
Waves during St1 sleep
Alpha interspersed with theta
Waves during St2 sleep
Theta inerrupted by sleep spindles and K complexes
Waves during St3
Delta waves interrupted by sleep spindles
Waves during St4
Delta
% REM in NB
50%
BP that is autoregulated in brain
60-140 mmHg
Substance that autoregulates cerebral blood flow
CO2
Effect of CO2 on cerebral blood vessels
Vasodilation
Gray matter vs white matter: More metabolic
Gray
Organs whose blood flow is not affected much by ANS
1) Brain
2) Heart
3) Kidneys
4) Exercising skeletal muscle
The brain is ___% of body weight
2
Sources of energy of brain (2)
1) Glucose
2) Ketone bodies
Order of abundance of ketone bodies
B-hydroxybutyrate > acetoacetate > acetone
Amount of CSF in brain
150mL
Amount of CSF produced per day
500mL
Function of CSF
Cushioning
CSF is produced in which parts of the brain (2)
1) Choroid plexus (70%)
2) Brain parenchyma (30%)
CSF pathway
Lateral ventricles > foramen of monroe > third ventricle > cerebral aqueduct of sylvius > 4th ventricle > foramen of megendie and luschka > subarachnoid space > arachnoid granulations > dural venous sinus blood
Cardiac output of major organs from greatest to least
Liver > Kidneys > Skeletal muscle > brain > skin
Components of BBB
1) Endothelial cells
2) Astrocyte foot processes
3) Choroid plexus
BBB exists in all areas except
1) Some areas of hypothalamus
2) Pineal gland
3) Area postrema
4) Organum vasculosum of lamina terminalis (osmotic sensing)
5) Neurohypophysis (ADH release)
Location of cell body of preganglionic neuron in SY ANS
Thoracolumbar
Location of cell body of preganglionic neuron in PSY ANS
Craniosacral
Location of cell body of postganglionic neuron in SY ANS
Paravertebral or prevertebral ganglia
Location of cell body of postganglionic neuron in PSY ANS
Walls of effector organs
Second msgr of alpha1 adrenoreceptor
IP3
Second msgr of alpha2, beta1, and beta2 adrenoreceptor
cAMP
Mechanism of action of nicotinic cholinoreceptor
Opens Na and K channels for depolarization
Mechanism of action of muscarinic cholinoreceptor
IP3 and cAMP
ANS Receptor stimulatory to vascular smooth muscle
Alpha1
ANS Receptor inhibitory to vascular smooth muscle
Beta2
ANS Receptor stimulatory to the heart
Beta1
ANS Receptor inhibitory to smooth muscles of bronchioles
Beta2
ANS receptor stimulatory to smooth muscles of bronchioles
Muscarinic
ANS Receptor stimulatory to GI sphincter and bladder sphincter
Alpha1
ANS Receptor that is inhibitory to bladder wall (detrussor)
Beta2
ANS receptor that mediates mydriasis by radial muscle contraction
Alpha1
ANS receptor that mediates miosis by circular sphincter muscle contraction
Muscarinic
Kidney function mediated by SY nervous system
Renin secretion by JG cells
ANS Receptor for renin secretion
Beta1
Downstream action of IP3
Mobilizes Ca ions from mitochondria and ER > smooth muscle contraction and cell secretion
Downstream action of DAG
Activates PKC
Second messenger from which arachidonic acid is derived for synthesis of protaglandins and other local hormones
DAG
Lacrimal gland secretion receptor
Muscarinic
SY vs PSY: Mucoid salivation
SY
SY vs PSY: Watery salivation (parotid)
PSY
SY vs PSY: Uterine contraction
SY
SY vs PSY: Penile erection
PSY
SY vs PSY: Penile ejaculation
SY
Organs without PSY innervations
1) Ventricles
2) Gravid uterus
3) Blood vessels
