CNS Cellular Organization and Neurotransmitters
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- Neurons communicate primarily through _____.
- axonal firing
- Peripheral neurons (sensory/motor neurons) can regenerate; RECENT animal research suggests that even neurons in ___ and ____ may be able to regenerate to a certain extent
- brain and spinal cord
- Neurons are classified either by ____ or ______.
- morphology (# of of axons coming from cell bodies); function
- Types of CNS cells include ___ and ___.
- neurons; glial
- 6 Functions of the glial cells include:
-
-supply nutrients and oxygen to neurons
-surround neurons to hold them in place
-produce myelin
-help form blood-brain barrier
-act as housekeepers, metabolizing and removing dead neurons
-during development,radial glia’ guide migrating neurons - Glial cells that form myelin of CNS (Schwann cells form myelin in PNS)are called___.
- oligodendrocytes
- Astrocyte glial cells provide multiple support functions, including:
-
1. provide structural support to neurons
2. contribute to metabolism of synaptic transmission
3. regulate ion balance
4. support blood-brain barrier by covering blood vessels in CNS w/ “feet,†which holds the endothelial cells lining the blood vessels in place - _________ epithelial cells line brain ventricles and the central canal of spinal cord and assist in secretion and circulation of ____.
- Ependymal; CSF
- ______ glial cells swell in rx to brain injury, which is responsible for many sxs of TBI
- astrocytes
- Microglia are small cells that proliferate and act as ___ when tissue ______.
- scavengers; are destroyed
- Four common features of the neuron include:
- cell body, dendrites, axon, terminal synaptic buttons
-
__ __come from cell body
some are destined to be secreted as neurotransmitters; others maintain the cell. - axon proteins;
- Cell energy is manufactured by ____, taking up ____ and breaking it down for energy.
- mitochondria; glucose
- Nissl Bodies are part of the _____comprised of groups of ____ used for protein synthesis.
- cell bocy; ribosomes
- Golgi Apparatus is a membrane-bound structure of the cell body important in packaging _______ and _____ (including neurotransmitters) into _____.
- peptides and proteins into vesicles.
- _____ are extensions of cell body that increase surface area and specialized to ___ info from other cells; have the unique feature to _____.
- Dendrites; receive; grown and change.
- The axon originates in cell body at the transition called ____.Each cell has___ axon(s) sending only one message.
- axon hillock; one
- Many axons are surrounded with _____,a _____),giving a whitish appearance.
- myelin sheath; lipoprotein
- degree and integrity of myelinated axons correlates with the speed and efficiency of ______
- action potential propagation
- Increase of neuronal conduction conferred by ___.
- saltatory conduction
- Myelin sheath is interrupted every 1-2 mm by unmyelinated segment called ,____ which permits the action potential to jump from one ___ to the next.
- Node of Ranvier;node
- _______are the presynaptic portion of the synapse where electrical nerve impulses cause release of neurotransmitters
- terminal buttons or axon termials
- Synapse is the site of __ ___, where electrochemical information that travels acorss axon electrically is then transmitted chemically. Synapses can occur on __, __, or___.
-
interneuronal communication;
dendrite, cell body, or axon - Neurons show a __ __ when they are inactive: conssists of a slight __ __between inner and outer surfaces of membrane caused by separation of electrically charged ions
- resting potential; electrical imbalance
-
Ions are defined as ____.
The four important types of ions are: -
atoms or molecules that have acquired electrical charge by gaining or losing one or more electrons.
1. organic ions (symbolized by A-)
2. sodium (Na+)
3. potassium (K+)
4. chloride (Cl-) - Electrical imbalance can occur b/c axon membrane is ___. Molecules including___ and ___ pass thru membrane constantly. Other chemicals including __, __, and ___can’t cross, so they pass through gates.
-
Semipermeable.
oxygen and water; K+, Cl-, NA+ - ___ ____ is the property of two opposing forces: force of ___ and force of ____.
-
membrane potential;
diffusion (molecules distribute themselves equally throughout medium where they’re dissolved);
electrostatic pressure (particles w/ same kind of charge repel; different charge attract) - Transmission of info between cells dependent on chemicals including ___, ___, and ___.
- neurotransmitters, neuromodulators, and hormones
- ____ are released by terminal buttons of neurons and detected by receptors in membrane of another cell located short distance away
- neurotransmitters
- _____ are also released by terminal buttons, but secreted in larger amounts and diffuse for longer distances, modulating activity of many neurons in particular area (most composed of peptides)
- Neuromodulators
- Hormones are most produced in ___ glands; cells that secrete hormones release into extracellular fluid and then distributed to rest of body thru bloodstream; only cells that have target cells for particular hormone respond to its presence.
- endocrine
- Not all communication is mediated at the ___ ___; Other parts of the membrane are sensitive to ___ and hormones
- synaptic juncture; neuromodulators
- Two classes of hormones include ___ and ___.
- Peptides and steroids
- links of amino acids including insulin and pituitary gland hormones are called ____.
- peptides
- small fat soluble molecules, including sex hormones and hormones secreted by adrenal cortexare called ____.
- steroids
- In the brain, most synaptic communication is accomplished by two neurotransmitter substances: one called ___with _____ effects and one with called ____ with ___ effects.
- glutamate, excitatory; GABA, inhibitory
- Name the four classifications of neurotransmitters
-
Acetylcholine
Monoamines
Amnio Acids
Peptides - Acetylcholine stmulates the ______. It has a prominent role in ___, influencing ___control. It is the primary transmitter found at ____ ____ (all ____movement is accomplished by release of Ach)
- parasympathetic nervous system; PNS, motor; neuromuscular juncture, muscular
- ACh is found in the CNS and influences ___, ____. amd ____.
- alertness, attention, memory
-
ACh is located in the PNS in cells of spinal cord and anterior horn and projects to the ____ muscles.
ACh in the CNS starts in the cell bodies of the __ ___(nucleus basalis, medial septal nucleus, and nucleus of diagonal band) and projects to - skeletal; Basal forebrain, cerebral cortex
-
ACh is formed by combination of acetyl CoA + choline; in presence of enzyme ___ ____.
Acetylcholine synthesis:ACh does not undergo ___; action is terminated by _____. -
choline acetyltransferase;
reuptake; cholinesterase - Neurotransmitter _____plays a role in regulation of mood; control of eating, sleep, and arousal; and pain. It is located in the __ __(in brainstem) and projects to the_______.
- serotonin; Raphe Nuclei and projects to the entire CNS
-
Prozac, Paxil, Zoloft, LSD, etc. have effects on ____.
__ ___(eg, imipramine, clomipramine) block both Serotonin and ___ uptake - 5HT; tricyclic antidepressants, NE
-
ACh has two receptor types: ____(movement)and ____(both found in CNS but ______ predominates there).
_____ (Cognex): is reversible anticholinestrase used to enhance ___ functioning.
___ ____ prevents release of Ach; Black widow spider venom sti - nicotinic, muscarinic, muscarinic; Tacrine, cognitive; Botulinum toxin; Curare
- _____ is a NT generally associated with ____ disorders and neuropsychiatric problems (schiz, ADHD, tics), as well as modulation of ____.
- dopamine, motor, reward
-
Conditions due to defects in dopamine synthesis include ___ and ____.
Excessive dopamine produced by coke, amphetamine, L-dopa; can lead to ___ ___ , and ____ movement disorders. - PKU, Parkinson's; visual hallucinations, hyperkinetic
- Dopamine is located in cell bodies of the _____ (substantia nigra, pars compacta, and ventral tegmental) and projected to ___, ___, ___, and ___.
- midbrain; striatum, prefrontal, limbic, amygdala
- Three well known pathways of dopamine include:
- nigrostriatal, mesolimbic, mesocortical
- Most ______ work primarily on _____(eg, Haldol, Thorazine, Clozaril, Risperdal), as does _____.
- antipsychotics, dopamine, L-dopa
-
How is dopamine synthesized?
The termination process includes _____ and ______. -
Phenyalanine to tyrosine to DOPA to Dopamine (tyrosine hydroxylase rate-limiting)
Terminate process: reuptake, monoamine oxidase (MAO), etc. - Functions of NT _____are complex, but probably helps regulate mood, memory, hormones, blood flow, and motor behavior. Also thought to increase ____, role in ___behavior and control of ___.
- norepinepherine;vigilance, sexual, appetite
- Norepinepherine located in the ___ ___ (pons)and projected into ______.
- locus ceruleus; projected to the entire CNS
- Tricyclic antidepressants (eg, imipramine, clomipramine) block both ____ and ___uptake.
- serotonin and NE
- ___ is a hormone produced by adrenal medulla. Also produced in brain, but minor importance compared with NE. Stimulates ____ division of ANS to produce “flight or fight.
- Epinepherine (adrenalin; sympathetic)
- Three amino acids are ___. ___. and ___.
- GABA, glutamate, glycine
-
- Inhibitory neurotransmitter in spinal cord and lower brain
_____ is an amino acid that may play a modulatory role at ___ in cord. It is blocked by ____. - Glycine, interneurons; strychnine.
- ____ project to entire CNS; no mechanism for reuptake once released; deactivated by ____.
- Peptides, enzymes
- Peptide with physiological roles including pain perception, stress, respiratory regulation, temperature control, tolerance development.
- Enkephalin
-
____is an amino acide where cell bodies in entire CNS project to entire CNS. Principal ______ transmitter substance in brain and cord.
Implicated in neural plasticity, ___, and ___.
Excessive activity associated with ____. - glutamate, excitatory, learning, memory;excitotoxicity
- Four types of glutamate receptors, one bing ____ receptor.
- NMDA
- GABA cell bodies in entire CNS project to entire CNS. Principal ____transmitter substance in brain and cord. Enhanced activity produces _____, anxiolytic, and ___ effects. Benzodiazepines (eg, diazepam/valium, xanax, ativan) thought to work by ____GABA.
- inhibitory; sedative, anticonvulsant; stimulating, decreased
- Peptide that is the mediator of inflammation, as well as a neurotransmitter in primary afferent fibers carrying pain signals.
- Substance P
- _____(aka antidiuretic hormone); acts peripherally to facilitate water reabsorption by kidneys; may play a role in ____consolidation.
- Vasopressin; memory
- Somatostatin is a peptide involved in the modulation of ___, ___, and ___. Also reduced in ____ of Alz pts.
- heat, pain, sleep; cortex
- Angiotensin II is a peptide involved in potent _____ activity in periphery; central actions include stimulation of pressor responses and ____.
- vasoconstrictor; drinking