nervous system intro Flashcards

Question

methods for studying neurons and glia: Golgi staining

Answer 1

silver chromate highlights some neurons used to find out neurons aren't fully connected - small gaps (synapses)

Answer 2

used to find locations and densities of different membrane proteins use target proteins e.g. Nav channels specific primary antibodies bind to target proteins secondary antibodies with fluorescent tags bind to primary antibodies and tag changes level of fluorescence when bound therefore can see areas dense with target proteins

Answer 3

can be genetic or injected neurons expressing desired protein will fluoresce and can be tracked and studied

Answer 4

can view synapses and organelles

Answer 5

horseradish peroxidase (HRP) retrograde = moves back to the cell body (backward) anterograde = move away from cell body (forward) retrograde: inject retrograde tracer into neuron and wait for it to reach the brain section brain to find tracer and find where neuron has gone to anterograde: inject anterograde tracer into brain and wait to see where in the body the tracer ends up

Answer 6

soma axon dendrite presynaptic terminal (axons and dendrites are neurites)

Answer 7

aka cell body, perikaryon has the nucleus - organelles for protein synthesis and processing: ribosomes, RER, golgi golgi is stained with silver chromate mitochondria have many more neurons than other cells - energy intensive

Answer 8

cytoskeleton of microtubules, microfilaments, and neurofilaments microtubules = longitudinally down neurites, hollow tube of polymers of tubulin microfilaments = longitudinally and membrane associated, polymers of actin neurofilaments = long protein molecules wound together - very strong microtubules and microfilaments are dynamically regulated -> can change length according to needs - polymerisation (grow) and depolymerisation (shorten)

Answer 9

axon hillock = wide part which connects to soma axon initial segment = just below hillock, action potentials generated here, high density of Nav channels axon collaterals = axon starts to branch axon terminal (terminal bouton) = end of each collateral

Answer 10

no RER or free ribosomes - all required proteins have to be made in the soma and transported (uses lots of energy) membrane composition varies depending on part of axon <1mm to >1m in length e.g. whole length of a leg 1um - 25um in diameter main axon is thickest and may be more myelinated, collaterals are thinner axons with many collaterals = high level of divergence = many cells can be contacted

Answer 11

no microtubules synaptic vesicles specialised proteins - release of vesicles and detection of action potential proteins are made in soma and transported here many mitochondria synaptic cleft - couple of um wide - very small

Answer 12

terminal arbour: one axon split into many terminals boutons en passent: means "buttons in passing" swelling on axon full of vesicles - not at the end of an axon

Answer 13

can be slow or fast carry's a vesicle along an axon travel down microtubules using kinesin which "walks" down using energy from ATP anterograde = moves forward from cell body - kinesin retrograde = moves backward from cell body - dynein (similar to kinesin)

Answer 14

receive messages from other neurons dendritic branches --> dendritic arbors : -- can have thousands of synapses, convergence of different inputs from other neurons e.g. Purkinje cells have many dendrites from many sources and combine these dendritic spines: increases surface area creates space for isolated reactions specific receptors on membrane very plastic - can get rid of spine, or grow new ones cognitive impairment caused by disorders where number of sines is abnormal

Answer 15

number of neurites: unipolar = 1 neurite (rare) -- "pseudo-unipolar" is one neurite from soma which splits into two which have distinct functions, very few purely unipolar neurons example -- dorsal root ganglion - info from skin into spinal cord - myelinated axon comes off from soma and becomes dendritic at the end to sense from skin - performs one specific role bipolar = single axon and dendrite (uncommon) example -- retinal bipolar cells, pass info from sensory cells to retina, very reliable - info from one area passed onto another, specialised function multipolar = many neurites (common) example -- Purkinje cell, 150,000 contacts/synapses, majority of neurons are like this, high level of convergence

Answer 16

arrangement of dendrites stellate = star shaped, e.g. layers of neocortex pyramidal = distinct apical and basal dendritic trees, pyramidal shaped soma e.g. layers of neocortex or hippocampus

Answer 17

sensory = afferent motor = efferent interneuron = largest class - relay or projection neurons connect brain regions, local interneurons have short axons and process info in local circuits axonal length = local or further away connections

Answer 18

underlies structural differences defines neurotransmitter expression - inhibitory or excitatory use fluorescent genes to track these and know which neurons to study

Answer 19

fill space around neurons can proliferate through lift - can always make new ones (neurons only created in specific brain areas)

Answer 20

homeostatic: CNS = astrocytes PNS = satellite cells ENS = enteric glia myelinating: CNS = oligodendrocytes PNS = Schwann cells phagocytic: CNS = microglia PNS = Schwann cells and macrophages

Answer 21

enteric nervous system - related to autonomic just focused on the gut - gastrointestinal tract

Answer 22

homeostatic - control environment surrounding neurons maintain resting potentials spatial domains - main cell body surrounded by processes in a star like way, area doesn't overlap with other glial cells much glial fibrillary acidic protein (GFAP) = unique marker which can be tracked with immunohistochemistry to find astrocytes buffer extracellular potassium form part of the BBB couple neuronal activity to blood supply - more oxygen when more active (homeostatic)

Answer 23

don't need to know them all! fibrous protoplasmic radial glial cells - developmental muller cells - retina Bergmann glia - cerebellum ependymal cells - ventricles and central canal (learn this one)

Answer 24

act as fuel suppliers - glycogen stores of the brain 5-10 minute supply metabolise glycogen and supply lactate (becomes pyruvate) convert glucose to glycogen in low activity times, use the glucose in high activity times astrocytic end feet take up glucose

Answer 25

terminates neurotransmitter activity - instantly stop signal once it has been used recycles neurotransmitters to presynaptic terminals astrocytes have receptors too - can respond to neurotransmitters themselves

Answer 26

macrophages of the CNS phagocytosis - engulf debris, take into cell and process it secrete growth factors, help myelination, and synaptic pruning 3 states = resting --> activated --> phagocytic can have harmful roles in neurodegenerative diseases - become phagocytic on healthy cells

Answer 27

myelinate axons in the CNS can myelinate many axons from one oligodendrocyte - 15-30 processes

Answer 28

myelin sheaths in the PNS provides one myelin segment to one axon per Schwann cell

Answer 29

formation: process of oligo cytoplasm wraps many times around the axon cytoplasm squeezed out of layers by compaction so just the membrane and a few proteins are left maintain contact with glial cells for nourishment function: insulate the axon speed up neuronal conduction with saltatory conduction