review of cellular neuroanatomy Flashcards by M K

three roles of glia

physical support

electrical insulation for impulse conductance

metabolic exchange btw the vascular system and the NS

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what is the cell’s supply station? (produces proteins and provides metabolic function)

soma

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what are the cell’s receiver inputs? receive electrial impulses from other axons

dendrites

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how many axons in a neuron?

one

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electrial output of the cell is via the ____

axon

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what are dendritic spines?

functions?

membranous protrusions from the dendrite. spines recieve:

synaptic inputs, transmit electrical signals to the dendrite, serve as an anatomical substrate for synaptic transmission, synaptic plastiticity, and memory storage.

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what is gray matter?

unmyelinated tissue - primarily soma and dendrites

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what is white matter?

tissue containing myelinated axons(myelin = lipid wrapping on axons, appearance = white in unstained tissue)

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what are Nissl bodies? composition? function?

basophillic masses - **primarily of rough ER and ribosomes. function: protein synthesis. **

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what ndoes NIssl stain indicate?

primarily indicates **cell bodies and proximal dendrites (not axons) **

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where does NIssl substance not extend?

does not extend into axon hillock or axons

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where do dendrites originate

the soma

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how do they branch?

branch and form dendritic tree

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what occurs at dendritic spines?

spines = where dendrites receive informatin from other neurons (especially excitatory inputs)

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which type of neuron has a pear shaped soma, and prominent apical dendrites as bell as basal dendrites?

pyramidal cell

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a singel _______ at the soma of a neuron? what does it form? what does it lack?

axon
forms an axon hillock
free of cell organelles

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what is the initial segment of an axon?

the portion of the axon from the hillock to the the beginning of myelination

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when is a neuron called a motor neuron?

when its axon connects to an effector organ (eg muscle, gland)

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why are long axons myelinated?

for electrial insulation resulting in faster nerve impulse conduction.

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what are collaterals?

major branches of an axon

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what is the site of action potential initiation?

axon initial segment (AIS)

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what are three general neuron types?

multipolar neuron

pseudounipolar neurons

bipolar neurons

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unipolar neurons have a single ______. do they exist in mature vertebrae?

have a single neurite(process- axon or dendrite).

do not exist in mature vertebrae(common in insects)

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which type of neurons seen in dorsal root ganglion?

pseudounipolar

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how to Golgi stains (silver stains) stain neurons?

generally stain a random subset of cells but show the enitre morphology of those cells.

what are principal cells? which neuron is an example of a principle cell?

principal cell = projection neuron pyramidal neuron = example of principal cell

what is a function of a principal cell? what type of golgi neuron is a principal cell?

principal cell = projection neuron that integrates ifnormation and sends axons to other brain areas (**a projection i**s the path of an axon from one brain area to another). **Golgi TYPE 1 cells = long projecting axons**

what are interneurons? provide some examples. what type of golgi cells are they?

interneurons = cells that do notsend their axon out of the local brain area (eg chandelier cells, basket cells, double bouquet cells) l**ocal circuit neurons ** **GOLGI type 2 cells b/c either no axon or short, local axon **

what are specialized juctions that alloow neural signals to be communicated from one cell to another( or from neuron to another effector)?

synapses

what are the two types of synapses? how are they different?

electrical and chemical. electrical = formed as direct connections from one cell to another via gap juctions chemical synapses = electrical signal in the presynaptic neuron is transduced into release of a chemical transmiteer that transverse a synaptic cleft btw cells to bind to receptors on postsynaptic neuron (or effector)

where are most(but not all) exictatory synapses in the brain located?

DENDRITIC spines

what is the synapse between a neuron and muscle?

neuromuscular juction

synapses can be classified by subcellular target. what are the four types of major synapses

axodendritic (axon to dendrite. location of most excitatory synapses = **axospinous**= subset of axodendritic) axoaxonic synapse = axon to axon synaptic contact dendrodendritic = dendrite to dendrite

t/f. vertebrate chemical synapses are unidirectional.

TRUE

what does the presynapci (or axonal varicosity) contain?

vesicles called synaptic vesicles that contain the neurotransmitter

on an inocming nerve impulse what does entry of Ca2+ cause synaptic vesicles todo?

Ca2+ --\> release of contents of synaptic vesicles into the synaptic cleft

specialized receptor proteins located in postsynaptic density bind the neurotransmitter and generate anotehr electrical signal in the postsynaptic cell.

excitatory synapses increase the probability that the postsynaptic neuron will fire an action potential. two examples of exciatatory neurotransmistters and their receptors.

acetylcholine - Nicotinic receptor glutamate - AMPA, NMDA receptor

inhibitory synapses reduce the probability that postsynaptic neuron will fire an AP. what are examples of inhibitory neurotranmistters? what are their receptors?

glycine GABA(gamma-aminobutyric acid) - at GABA(a) receptors

modulatory synapses influence how excitatory and inhibitory signals are integrated. Examples are synapses using which four neuro transmitters?

dopamine norepinephirne acetylcholine - muscurinic receptors GABA- at GABA(B) receptors

What are Gray's Type 1 synapses? describe their post-synaptic density

**Gray's type 1 synapses** = **excitatory** (eg excitatory amino acids) and **assymetric** (pronounced post synaptic density)

What are Gray's Type 2 synapse?

**Inhibitory** (GABA, glycine) Symmettrical(thin post-synaptic density- same density as presynaptic membrane)

where are Gray's type I synapses found (excitatory)?

dendrites

where are gray's type 2 synapse(inhibitory) found?

on soma ==\> inhibition of receiving cell's activity

what are electrical synapses composed of?

gap juctions

what are gap junctions composed of?

connexons

function of connexon

a direct, passive flow of electrial current from one cell to the next is achieved via large channels = connexons

what are connexons made up of?

one connexon = 6 connexins when connexon from each cell become opposed, a low resistance pathway (pore) called gap juction is formed btw thetwocells

t/f. electrical synapses can be bidirectional.

TRUE. electrical synapses can be bidirectional (eitehr call can be both pre and post synaptic)

how are protein packaged in soma of axon transported?

microtubules

how does kinesin move cargo vesicles along soma?

kinesin moves cargo **anterograde=** away from soma

dynein moves cargo vesicles \_\_\_\_\_\_\_

retrograde = toward the soma

t/f. glia outnumber neurons 10:1 and make up ~50% of brain volume

true

what are the two major types of astrocytes?

fibrous and protoplasmic

provide myelination in the PNS

schwann cells

provide myelination in the CNS?

oligodendrocytes

two major types: fibrous and protoplasmic general support blood-brain barrier

Astrocytes

they function as astrocytes in the autonomic nervous system?

satellite cells

functions include phagocytosis, inflammation, and "immune cells of the CNS"

microglia

stem cells within the brain

polydendrocytes

line the central canal they form a cubodial to columnar epithelium

ependymal cells

where two Schwann cells meet, they form a \_\_\_\_\_\_(an unmeylinated area). this is where action potential regenerate). synpases are not myelinated.

Node of ranvier

Schwann cells form the _____ between nodes of Ranvier

internodes

what are small folds of Schwann cell cytosol that remain to support the myelin after most of the cytoplasm of a Schwann cell has been squeezed while wrapping around an axon?

Schmidt-Lanterman incisures

t/f. each Schwann cell forms only 1 internode. Schwann cell myelin is in contact with the Schwann cell soma. (vs long process in oligodendrocyte)

true

define endoneurium

the thin layer of connective tusse that surrounds each nerve fiber

define perineurium?

perineurium delimits nerve fasicle itself

how many internodes does an oligodendrocyte from? how are neighboring internodes myelinated?

**one oligodendocyte forms 30-50 internodes (many different axons, 1 internode per axo**n) (many axons in CNS not myelinated) take home: neighboring internodes originate from different oligodendrocytes

astrocytes move metabolites to and from neurons = \_\_\_\_\_

metabolic exchange

t/f. astrocytes maintain constain ionic cncentrations for optimal neuronal function by taking up ions (K+, Ca2+) and transmitters

true

astrocytes radiating processes contact neurons \_\_1\_\_\_\_, endothelial cells of blood vessels\_\_2\_\_ and myeline

1. perineural feet 2. perivascular feet

what do astrocytes facilitate? (3)

angiogenesis synaptogenesis maintenance of the blood-brain barrier

where are fibrous astrocytes found?

in white matter have vascular feet that connect them to outside capillary walls

what are radial glia? when are they present in human life? what aretwo examples of radial glia in adulthood?

radial glia = radial astrocytes (oriented in plane perpendicular to ventricle with one axis towards the pia and the other near the ventricle). mostly present in development and play a role in neuron migration mueller cells(retina) Bergmann glia = cerebellum - examples of radial glia that persist into adulthood

protoplasmic astrocytes

m**ost common and located in grey matter **

what are satellite cells

small cuboidal cells of neural crest origin = modified Scwhann cell or oligodendrocyte they funcion as astrocytes in peripheral ganglia surround entire soma of ganglion cells, but only their nucleus is visible in H+E stains

ependymal cells ? what are they

cuboidal to columnar cells apical surface covered with cilial and microvilli basal surface in close contact with astrocytes lack of tight junctions btw ependymal cells allows a free exchange between cerebrospinal fluid and nervous tissue