Neurobiology: Introduction and Nervous System Development - Test 1
contains genetic material (chromosomes) including information for cell development and synthesis of proteins necessary for cell maintenance and survival. Covered by a membrane, about 5-10 um across.
produces ribosomes necessary for translation of genetic information into proteins
Groups of ribosomes used for protein synthesis surrounding nucleus, named after stain.
Endoplasmic reticulum (ER
system of tubes for transport of materials within cytoplasm. Can have ribosomes (rough ER) or no ribosomes (smooth). with ribosomes, the ER is important for protein synthesis.
Specialized cell process for electrical impulse conduction
branched cell processes on which incoming axons terminate
membrane-bound structure important in packaging peptides and proteins (including neurotransmitters) into vesicles.
system of transport for materials within a neuron and may be used for structural support.
produce energy to fuel cellular activities.
Early embryonic stage following blastula where a central cavity forms within the primary germ cell layers
Outermost of the 3 primary germ cell layers in the gastrula. Site of induction of neural tissues
Area of developing cells destined to become a particular structure (from ectoderm)
The process of induction of neural cells from the ectoderm during the mid-gastrula stage of the vertebrate embryo (neural commitment, formation of the neuroectoderm into the neural tube)
Stimulation of internal changes in primitive ectodermal cells by extrinsic signals, such as FGF8
Flat layer of neuroectodermal cells that forms at one pole of the developing gastrula after neurulation (neural induction) from which the nervous system forms.
Formation of a tube of cell layers by invagination of the neural plat and pinching off to form a separate structure. Characterized by an inner ventricular zone, a primitive mantle zone, and an outermost marginal zone.
Innermost ependymal layer of the neural tube containing dividing stem cells.
Middle densely packed layer of the neural tube containing cell bodies; gray matter of CNS.
Outermost layer of the neural tube containing axons of underlying cells and later, cortical plate neurons; white matter of CNS.
Neural crest cells
Population of cells that separates from the edges of the neural fold to lie between the neural tube and overlying ectoderm that will migrate to become the peripheral nervous system (ganglia).
Band of specialized glial cells in the ventral midline of the developing neural tube
Forms separately near the basal neural tube and provides signals to the overlying basal neural tube. Induces formation of floor plate and motor neurons.
Basal neural tube
origin of motor neurons
Dorsal alar region
origin of interneurons
Dorsal most region of neural tube. Provides BMP4, BMP7 and Wnt signals.
Cadherin (E vs N)
Calcium dependent cell surface adhesion proteins that link cells together by homotypic adhesion. E- predominates in the embryonic ectoderm; after neural induction expression changes to N- in neuro-ectodermal cells.
BMP (bone morphogenetic proteins)
Family of -2 and -4 are early signals preventing neural induction in the developing ectoderm which are counteracted by secretion of --- inhibitors (noggin, follistatin) to allow neurulation. Promote the formation of epidermal tissue while suppressing neural differentiation.
The information-processing cell of the nervous system; also called nerve cell. Most neurons use action potentials to send signals over a distance, and all neurons communicate with one another using synaptic transmission.
A support cell in the nervous system, 90% of all brain cells. Classified into four categories: astrocytes, oligodendroglia, Schwann cells, and microglia.
A type of glial cell that regulates the extracellular environment of the brain; make contact with capillaries and neurons. 1) Fibrous: contain filaments and are prevalent in bundles of myelinated nerve fibers in white matter or 2) protoplasmic: contain less fibrous material and are abundant in gray matter around nerve cell bodies, dendrites, and synapses.
Wingless family and associate pathway of signaling proteins which are secreted and diffused to indirectly act by binding to a transmembrane receptor, thereby regulating the cytoplastmic levels of a downstream target in the receiving cell. --- proteins are the ligands whereas Frizzled proteins are the receptors.
Signaling proteins responding to Wnt signaling that transduce signals form the adhesion protein complexes at the inner portion of the plasma membrane to the proliferation machinery genes such as cMyc and D cyclins. Also plays a structural role at the cell surface by interacting with a cell adhesion protein (cadherin).
Sonic Hedgehog (SHH)
-- proteins are growth factors important in the development of the floor plate. Initially produced by the notochord, then by the floor plate cells to create a dorsoventral gradient. The distance from the source influences the pattern of homeotic gene expression. Induces production of motor neurons in the spinal cord, serotonergic and dopaminergic neurons in the hindbrain, and oculomotor neurons in the anterior midbrain.
Sry related HMG box containing gene family with important roles in cell lineage determination. -2 suppresses neuronal differentiation in progenitor cells.
Homeobox gene family in which members are expressed in distinct temporal-spatial pattern in a rostral caudal orientation. Important for inducing segmented rhombomere development of the embryonic hindbrain (rhombencephalon)
Transcription factor that activates genes of terminal neurons in the developing vertebrate cortex. --- is actively repressed by Sox-2 and associated factors. Depression of --- occurs in response to Wnt3a secretion by adjacent newborn astrocytes and resulting activation of b-catenin/LEF transcription.
A protein such as an enzyme that modifies the structure of chromatin (DNA and associated proteins). ---cation is an essential part of silencing or opening areas of the genome for transcriptional activation of genes which are involved in phenotypic changes (cellular programs).
Spherical cell body filled with cytosol, approx 20 um in diameter.
Immature neuron before cell differentiation; develops into a bipolar cell on the mantle layer then becomes a multipolar neuroblast when multiple dendrites form
Region of contact where a neuron transfers information to another cell.
Glial cell in the embryonic brain extending a process from the ventricular zone to the surface of the brain; immature neurons and glia migrate along this process.
Glial cell that provides myelin in the central nervous system; predominant in white matter.
A neuron in the retina of the eye that projects neurites laterally in the inner plexiform layer.
A thin tube extending from a neuronal cell body; the two types are axons and dendrites.
Photoreceptor in the retina containing rhodopsin and specialized for low light levels. Elongated; sensitive to small changes in illumination; function only in dim light after a prolonged period of darkness.
A specialized cell in the retina that transduces light energy into changes in membrane potential.
Satellite glial cell in the retina, analogous to radial glial cells.
Photoreceptor in the retina concentrated in fovea, specialized for daytime vision and responsible for all color vision. Respond to visual stimuli in bright ambient light; subdivided into red-, green-, or blue-sensitive photoreceptors.
Neural stem cell that enters the subepndymal zone which divides, forming immmature neurons that migrate rostrally into the bulb, where they differentiate as interneurons and integrate into existing circuitry.
The expanded tip of a growing axon.
Superficially situated cells in the marginal zone of the cortex that produce reelin, providing a signal that stops migration of neurons.
A large extracellular matrix multi-domain glycoprotein produced by the reeler gene. Signals progenitor cells to exit the glial scaffold and begin to migrate in the local environment.
Line the inner surfaces of the brain, in the ventricles, are usually classified as glial cells.
Symmetrical cell division
production of daughter cells of the same lineage
Asymmetrical cell division
production of daughter cells with one of the same lineage and one becoming another lineage or cell type (ex) intermediate progenitor cells (IPCs) divide into another IPC and a neuron)
Moving of neurons in response to chemical signals; direct their movements according to certain diffused chemicals in their environment.
directional motility or outgrowth of cells, e.g. in the case of axonal outgrowth, usually up a gradient of cellular adhesion sites or substrate-bound** chemoattractants
Signaling molecules called neurotrophins support the survival and maturation of neurons. Neurotrophins are derived from the developing neurons themselves and from other cells in the environment (e.g. muscle cells secrete factors supporting motor neuron survival)
Neural structure of the eye with a highly ordered cellular structure that transmits light signals from the eye (retinal ganglion cells) to the interior brain regions (target neurons of the tectum). Specific innervations are established during development, these form the retinotectal map.
Optic tectum (superior colliculus)
Target region for retinal ganglion cells in mammals
Multiple neurons innervate the same target cell; e.g. motor neurons branch extensively so that each muscle fiber comes to be innervated by axons from several motor neurons
Programmed cell death
Neurons are over-produced and the appropriate number of functional neurons is adjusted by apoptosis, a very clean and efficient means of cell death and removal that does not cause an inflammatory immune response and leaves very little debris. The signaling machinery (proteins) required for apoptosis are induced by the p75NTR receptor.
Active process of removing excess axonal branchings and synaptic connections, ensuring appropriate and complete innervation of a target by a particular population of neurons. In some cases, provides a mechanism for correcting mistakes; in others, reflects a strategy for establishing pathways.
Primitive supporting cell that migrates to the mantle and marginal layers to become astrocytes and oligodendrocytes.
Leading edge of growth cone consisting of flat sheets of membrane that undulate in rhythmic waves.
Thin spikes extending from lamellopodia which constantly probe the environment, contracting and retracting from the lamellopodia.
Outside of the cells, spaces between cells containing important proteins.
Cell adhesion molecules (CAMs)
Transmembrane or membrane-associated glycoproteins that are attracted and bind to others on other axon membranes, causing axons to grown in unison.
Mediate axon outgrowth by cell-cell adhesion (homophilic - same or heterophilic - to other)
Protein secreted by floor plate cells in the ventral midline of the spinal cord. Gradient attracts axons to form the spinothalamic tract.
A diffusible molecule that acts over a distance to attract growing axons to their targets.
A diffusible molecule that chases axons away.
A protein* secreted by midline cells that causes axons to be repelled, when read by the axon receptor*
Axon tyrosine kinase receptor* for repulsive signal* inhibiting further axon growth for temporal retinal axons. -A2 and -A5 expressed in the tectum during the time retinotectal connections are being formed, cause growth cones to detach from substrate and retract; =A3 is expressed on retinal axons in a corresponding nasotemporal gradient.
Protein released from the motor nerve axon as it approaches the muscle fiber, causing postsynaptic structures to be formed and ACh receptors to accumulate at the motor end plate.
Where motor axon growth cones come into contact with muscle fibers (target) and forms synapses.
Transmembrane protein that plays a key role in the functional development of chemical synapses. Presentation induces formation of postsynaptic specializations.
Transmembrane protein that plays a key role in the functional development of chemical synapses. Presented to neurons by expression in non-neuronal cells or linked to beads induces the formation of presynaptic specializations.
Chemorepellant first identified in grasshoppers causing retraction or collapse of growth cones and mediate long range repulsion of axons. Neuropilin is the receptor for this
Family of receptors which span the membrane to link ECM proteins and the intracellular actin cytoskeleton, regulating cell shape and migration. Activation by ECM activates intracellular signaling pathways that control cell growth, proliferation, and differentiation.
Motor end plate
Postjunctional folds or invaginations in the sarcolemma, or cell membrane of a muscle cell, which possess ACh receptors where synapse with neuron is formed.
Family of related trophic proteins acting at specific cell surface receptors, often - activated protein kinases called trk receptors that phosphorylate substrates, stimulating a second messenger cascade that ultimately alters gene expression in the cell's nucleus, saving cells from cell death
Systematic disassembly of the neuron; NOT necrosis (resulting from injury)
Nerve growth factor (NGF)
Produced by the targets of axons in the sympathetic division of the ANS. Stimulates axonal outgrowth; when blocked, neuron dies.
Brain-derived neurotrophic factor (BDNF)
Important for the survival of visual cortical neurons. Required early in development for proliferation, differentiation and survival of neurons. Also potentiates synaptic transmission and increases/decreases neuronal excitability by regulating ion channel expression.
Function as phagocytes to remove debris left by dead or degenerating neurons and glia.
Required early in development for proliferation, differentiation and survival of neurons.
genes that when mutated cause one body part to be change so as to resemble another
Homeodomain & Homeobox
60 AA DNA-binding motif* encoded by a DNA sequence*