Cellular organization & neurochemistry Flashcards
Dilated pupils, elevated pulse & BP, dry skin & hyperthermia, delirium are all symptoms associated with an overload of which type of medication?
Anticholinergics
Antipsychotic drugs block DA transmission in which dopaminergic tract?
Mesolimbic
Atrophy of the distal part of neurons after being severed from the proximal part
Wallerian degeneration
Cell bodies of seratonergic neurons are found in & around the
Raphe nuclei
Catecholamines
DA, NE, and epinephrine
Depletion of norepinephrine results in
Decreased sympathetic activity (orthostatic hypotension, sleep disturbances, depression)
Cell death through inflammatory response
Necrosis
Dopamine producing cells are located in the
Midbrain (substantia nigra pars compacta, ventral tegmentum)
Dysfunction of GABA is implicated in which conditions?
Huntington’s (lack of inhibition of BG), tetanus & strychnine poisoning (impair presynaptic GABA release), stiff-person syndrome
Describe the structure of neuronal membranes
Phospholipid membrane bilayer with “head” that contains phosphorus (polar & hydrophilic) & two “tails” that are lipid molecules (nonpolar & hydrophobic)
Enhanced GABA activity produces what kind of effects?
sedative, anxiolytic, anticonvulsant
Excess norepinephrine results in
Increased sympathetic activity (e.g., tremor, bronchodilation)
Endorphins
Peptide hormones synthesized in the brain that bind to opiate receptors; reduce the sensation of pain & affect emotions
Four nucleotide bases
Adenine, thymine, guanine, cytosine
Which neurotransmitter opens Cl- channels & closes CA++ channels, hyperpolarizing cells?
GABA
Excitotoxicity
Cell death by calcium flooding; occurs when concentrations of excitatory amino acids (glutamate) exceed the ability of uptake mechanisms to remove them (e.g., HD, epilepsy, stroke, hypoxia, TBI)
Which neurotransmitter is involved in regulation of mood, memory, hormones, blood flow, new learning, attention switching, & motor behavior?
Norepinephrine
Glutamate is implicated in
Plasticity, learning, & memory
Groups of ribosomes used for protein synthesis
Nissl bodies
Which neurotransmitter is involved in regulating mood, eating, sleeping, temp, sex, aggression, arousal, & pain?
Serotonin
Histamine is concentrated in the
Hypothalamus
How are the catecholamines synthesized?
L-Tyrosine => L-Dopa => dopamine => norephinephrine => epinephrine
How is serotonin involved in sleep?
Activity of serotonin-producing cells reaches highest level during arousal, drops to quiescent levels during slow-wave sleep, & disappears during REM sleep
How is acetylcholine synthesized?
Formed by combo of acetyle CoA + choline, in presence of enzyme choline acetyltransferase, action is terminated by cholinesterase
Low serotonin is associated with
Depression, anxiety, OCD, PD, AD
Solvents that readily permeate the nervous system & damage lipid-rich myelin, causing neuropathy & encephalopathy, are called
Lipophilic
Membrane potential is the property of what 2 opposing forces?
- Force of diffusion - molecules distribute themselves equally throughout the medium in which they’re dissolved 2. Force of electrostatic pressure - particles with the same kind of charge repel; different charges attract
Membrane-bound structures important in packaging peptides & proteins (including NTs) into vesicles
Golgi apparatus
Mesolimbic pathway
Ventral tegmental area => amygdala/limbic system
Which type of glial cells undergo rapid proliferation in response to tissue destruction, act as scavengers & metabolize tissue debris?
Microglia
Nigrostriatal pathway
Substantia nigra => D2 receptors of striatum Decreased DA here = rigidity, tremor, akinesia Excess => dyskinesia
Pathway of norepinephrine
Locus ceruleus (pons) & lateral tegmentum => cerebral cortex, limbic system, RAS, spinal cord
Physiological roles of endorphins
Pain perception, stress, respiratory regulation, temp control, tolerance development (opioids)
Relatively refractory period
State in which axon membrane is hyperpolarized, and a new action potential can be induced by only if the intensity of the stimulus is higher than that which initiated the 1st action potential
Removal of dead cells by mitochondria, microglia, & astrocytes
Phagocytosis
Programmed gene-directed cell death
Apoptosis
Serotonin is increased by what drugs?
SSRIs, tricyclics, MDMA (ecstacy), LSD
Scarring associated with hyperplasia glial overgrowth/replacement of cell bodies by glial cells
Gliosis/sclerosis
Spatial summation
Impulses in 2 excitatory fibers cause 2 synaptic depolarizations at about the same time that together reach firing threshold; they sum over space to fire a target neuron
System of transport for materials within a neuron, may be used for structural support
Microfilaments/neurotubules
Sodium-potassium pump
Continuously pushes Na+ out of the cell, exchanges 3 Na+ for every 2 K+
Serotonin is synthesized from
Tryptophan
Temporal summation
Occurs when a burst of action potentials reaches a nerve fiber terminal; the serious of impulses in one excitatory fiber can sum over time to fire a target neuron, even thought each individual EPSP wouldn’t do it
System of tubes for transport of materials within cytoplasm
Endoplasmic reticulum
Take up glucose & break it down for energy
Mitochondria
What are some of the known functions of glutamate NMDA receptors?
Memory, migration of embryonic neurons, excitotoxic neuron death
What happens during an action potential?
Once the threshold of excitation is reached, Na+ gates open, allowing Na+ into the cell & depolarizing it. K+ gates are then opened, allowing K+ out of the cell and repolarizing it.
What are the main functions of astrocytes?
1) Provide support to BBB 2) Maintain local ionic & pH balance between neurons 3) Deliver energy to neurons 4) Regulate & coordinate neuronal firing
What is acetylcholine’s role in the CNS?
Influences alertness, attention, & memory Decreased acetylcholine fx in AD
What is the average resting membrane potential of neurons?
~ -70mV
What is the only low-molecular-weight amine transmitter substance that is not an amino acid or derived directly from one?
Acetylcholine
What is the principal inhibitory neurotransmitter in the brain?
GABA
What is the principle excitatory neurotransmitter in the brain?
Glutamate
What is the only transmitter to be synthesized in vesicles?
Norepinephrine
When a neuron is at resting potential, what ions are primarily in the intracellular fluid?
K+
When a neuron is at resting potential, what ions are primarily in the extracellular fluid?
Cl- and Na+
Which glial cells form myelin in the CNS? PNS?
CNS - oligodendrocytes PNS - Schwann cells
Where are endorphins found in the brain?
Primarily in the pituitary, lesser amounts also present in the hypothalamus & other regions of the brain involved in pain perception
Which glial cells swell in response to brain injury?
Astrocytes
Which neurotransmitter is found at the neuromuscular junction?
Acetylcholine
Which toxin prevents the release of acetylcholine?
Botulism toxin
Cluster of neurons in the dorsal pons situated on the floor of the 4th ventricle that contains over 1/2 of the norepinephrine neurons in the CNS; neurons are activated during states of heightened vigilance & may be more involved in affective disorders
Locus ceruleus
Which glial cells line the brain ventricles & central canal of the spinal cord, assisting with the secretion/circulation of CSF?
Ependymal cells
Which dopaminergic pathway is implicated in the negative symptoms of psychosis?
Mesocortical
