lecture 6: chemical & electrical signal transformation Flashcards by Demond Fleming

neurons are specialized and terminally differentiated _______ cells
- sensory:
- motor:
- interneurons:

epithelial cells
- afferent
- efferent
- integration/coordination

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cellular organs:
- condensed, lost replicative functions, no centriole
- protein/peptide synthesis
- lipid synthesis
- modification of synthesized protein/peptide and lipid for sorting
- degrade metabolic wastes
- power plant
- neurofilaments, unique shape

nucleus
rough ER/ nissl body
smooth ER
golgi apparatus
lysosome and peroxisome
mitochondria
cytoskeletal structures

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what is a nissl body?

helps with protein synthesis in the rough ER

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What is neuron reception and summation of signals?

reception: 1st step in communication, dendrites catch neurotransmitters

summation: neurons sum up all signals received (inhibitory & excitatory)

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MOST neurons have only ______ axon, may or may not be ________

Neurons can have _____ of axon terminals

one; myelinated
hundreds

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What are enzymes for neurotransmitter synthesis and activation:

Mitochondria, lysosome/peroxisome

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Where axon form and extending out, the initiation of AP:

hillock

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What is unique about pseudounipolar neurons:

initiation of action potential by peripheral process (touch, pressure, temp.)

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Neuron axons form synapses with ______ cells through _______

The release of neurotransmitters = transformation from _________ to _______

target; terminals
electrical to chemical

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Which neuron in the cerebellar cortex is the only one providing afferent axons to other brain structures and which neurotransmitter does it release?

Purkinje cell; GABA

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Types of Neurons:
1. multiple dendrites from the soma:
2. dendrites mainly on one end of the soma:
3. one hillock with dendrites on the axon
4. one hillock then divides the axon into 2 branches

multipolar
bipolar
unipolar
pseudounipolar

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Where are MOST of the sensory neurons?

pseudounipolar

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Neurons: dendrites = limited cellular organs like axons but have ______ extension

Golgi apparatus

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Transportation of molecules in the neurons —> rapid delivery = _______
(a) anterograde transportation:
(b) retrograde transportation:

active transportation
(a): from soma to dendrites/axons
(b): from dendrites/axons back to soma

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Transportation of Molecules in the Neurons:
_________ elongating unidirectional to the plus direction (+)
_______ can be either way ( + or -) but only to the terminal in the axon

Tubulins
Dendrites

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Transportation of Molecules in the Neurons:

Golgi apparatus extension directly delivers the ______ proteins in the tip

Differentiation of dendrites and axons:

tubulin

dendrites: both directions (+/-)
axons: uniform only (+) direction

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Kinesin =
Dynein =

anterograde transportion
retrograde transportation (die*)

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Which transportation can be hijacked by virus and bacterial toxins:

retrograde transporttaion, dynein

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Is neuron cellular membrane is selectively permeable?

yes - allows some molecules to pass through while blocking others

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Facilitate the transport of water molecules; maintain water balance________

ion channels: _____ or ______
ion pumps:

water channel: aquaporin
leaking or gated
Na/K, atp dependent

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The ion pumps consists of _______ and _____ dependent

Na+ (sodium) and K+ potassium); ATP

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The polarity of the neuron cell membrane
-Osmotic:
-Electric:

Inside the neuron cellular membrane is more ______ due to the 2 potentials: _____ to _____, rest membrane potential

numbers of ions and molecules- related to movement of water
positive and negative charges- electrical potential for signaling
negative; -40 to -90 mV

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Which cellular organs are located in the axons?

Mitochondria, lysosomes/peroxisomes, and enzymes

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Ligand-gated: Lignad as _________, ion channel as _________ –> change in _________ potential

Voltage-gated: resting membrane potential increased to the _______ no ______ needed. Only opens when membrane potential ________

Modality gated: open or close based receptors such as:

neurotransmitters; receptors; membrane
threshold; ligand; reaches threshold
touch, pressure, heat, cold, light, sound wave

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K+ can freely move cross membrane through _______ channel and is in charge of _______ membrane potential: polarized

leaking resting

List the 5 phases of initiation of AP:

resting potential slow depolarization/graded potential fast depolarization/ action potential repolarization hyperpolarization

-70 mV = > -70mV, ligand/modality gated Na+ = > -55mV, threshold, voltage gated Na+ back to -70mV, voltage gated K+ and pumps

resting potential slow depolarization/graded potential fast depolarization/action potential Hyperpolarization

Is the following statement True or False? The voltage-gated sodium channels 2 gates open and close separately at different phases this means that both gates can close at the same time.

false; BOTH gates CANNOT close at the same time

Resting state = AG: IAG:

below threshold closed open

Activated state = AG: IAG:

fast depolarization both gates are open

Inactivated state = AG: IAG:

repolarization + hyperpolarization open closed

Which proteins oversee anterograde and retrograde transportation along the axons separately?

Anterograde: kinesin Retrograde: dynein

Is the following statement True or False? During the absolute refractory period, voltage-gated sodium channel APs will respond to any stimulus.

False: APs WILL NOT respond to any stimulus no matter how strong

Why can APs be induced in the relative refractory period but not in the absolute refractory period?

The IAG is engaged/closed during the absolute refractory period but is open in the relative.

_______ defines unidirectional conduction of APs by preventing immediate re-excitation

Refractory period

What is the flow of the Na+/K+ pumps during repolarization of neurons:

3 Na+ out and 2 K+ in

Na+/K+ pumps are ________ dependent and ________% of the energy consumed by the brain

ATP; 20-40%

Generally, APs are unidirectional conduction but AP in the middle of axons spreads bidirectionally under experiment. How so?

artificial stimulus- direction electrical stimulation

Axonal reflex: both _______ and ______ on one axon Example:

afferent (skin detecting P! ful stimulus) and efferent (muscles near the site of injury contract) papercut: P! and inflammation but no bleeding

What blocks the backflow of action potentials?

activated and then inactivated voltage-gated sodium channels

True or False: Refractory period = bidirectional spread

False: unidirectional - ensures APs flow in one direction along axon

Which of the 5 phases of AP follows the absolute refractory period?

repolarization *depolarization, absolute refractory period, REPOLARIZATION, end of absolute refractory period

When there are multiple AP along one axon: _____ of stimuli represented by _____ of AP

intensity; frequency

Why is there an absolute refractory period phase for action potential initiation?

Only one AP at a time and backflow prevention

layers of lipid, insulation- small gap, only voltage gated sodium channels -

myelins sheath node of ranvier

Node of Ranvier: no __________ due to outflow of K+

hyperpolarization

Axons only need regeneration AP in the nodes, fast pass in the internodes. How does this happen?

AP conduction jumps from one node to another: known as saltatory conduction

Giant squid axon is myelinated or unmyelinated? How many vertebrae (mammal) myelinated axons can be bundled in a giant squid axon?

unmyelinated 160,000

There are different types of myelin sheath in CNS and PNS:

CNS: oligodendrocytes PNS: Schwann cells

CNS: Oligodendrocytes wrap around ________axons, and some nonmyelinated axons in CNS: get wrapped by ________

multiple astrocytes

PNS: Schwann cells wrap around a _______ axon, and nonmyelinated axons _____ together and wrapped by Schwann cells ________ myelin sheath.

single; bundle without

Communication between myelin layers is located where? Local ions replenish ______ during repolarization.

gap junctions fast

What is repolarization and how does neuron repolarize?

AP returns to its resting membrane potential sodium-potassium pump transports Na+ out and K+ in *(3 Na+ out = 2 K+ in)

What two pathologies affect myelin sheath: CNS (1) PNS (1)

CNS: multiple sclerosis (MS) PNS: Guillan Barre Syndrome

Which pathology is being described: Olfactory bulb/tract, CN II, optical nerve, and diencephalon are impaired/affected?

Multiple sclerosis

Gillian Barre affects Schwann cells or Oligodendrocytes?

Schwann cells

Target cells- neurons can synapse with: (3) Terminal functional cells:

dendrites, soma, or axons/terminals muscles & glands

Components of an electrical synapse: (2)

gap junctions, AP directional conduction (neuron can directly pass through gap junction to connected neuron)

Components of electrical synapse: axon terminal: vesicles with ___________, _________cleft, ________ membrane: receptors, __________ channels and ___ protien.

neurotransmitters, synaptic cleft, postsynaptic, ligand-gated, and G-protein coupled receptors

TRANSFORMATION of ELECTROCHEMICAL SIGNALS: AP arrives at the presynaptic terminal of the chemical synapse Depolarization opens Ca2+ channel: voltage-gated Inflow of Ca2+ facilitates the docking of vesicles on the presynaptic membrane Fuse vesicles with presynaptic membrane Release neurotransmitters Diffusion across the synaptic cleft Bind to receptors on the postsynaptic membrane

Excitation: excitatory postsynaptic potential (EPSP) __________ postsynaptic membrane DOES NOT mean ______ initiation but ________

depolarize AP; more likely

Inhibition: inhibitory postsynaptic potential (IPSP) ________ postsynaptic membrane DOES NOT mean ______ initiation but ________

hyperpolarize AP: less likely

What are the two receptors on the postsynaptic membrane:

ionotropic and metabotropic receptors

Which postsynaptic receptor is being described: -fast: point to point specific -one AP is enough -small vesicles with different neurotransmitters to synaptic gap

ionotropic

Which postsynaptic receptor is being described: -slow: can be point to area, nonspecific -need multiple APs: longer Ca2+ channel -large vesicles release neurotransmitters through exocytosis

metabotropic

Which postsynaptic receptor is associated with ligand-gated ion channels?

ionotropic

Single postsynaptic membrane potential: graded potentials are either _______ or _________. Dissipation (become weaker) due to _________ and _______: spatiotemporal effects.

EPSP or IPSP distance & time

stimuli from the same location or location with different timeframe stimuli from different locations simultaneously

temporal summation spatial summation

If the total summation results are over-resting potential but lower than the threshold can you have AP initiation? If the total summation results are over the threshold can you have AP initiation? What if the total summation results are lower than the resting potential?

No Yes inhibitory, hyperpolarized, and refractory activated

At the neuromuscular junction, __________ is the neurotransmitter responsible for transmitting signals. Nicotinic acetylcholine receptor is a ligand-gated ion channel and the binding site is located on ___________ the of the receptor. It causes the ion channel to open, allowing the influx of sodium ions. The influx of sodium ions ultimately leads to _____________

acetylcholine (ACh) alpha subunit muscle

A synapse contains which components: (3)

presynaptic axon terminal synaptic cleft postsynaptic membrane

A patient is experiencing muscle weakness and flaccidity due to diminished Ca2+, which has impaired fusion of ACh. Antibodies against:

Lambert Eaton Syndrome (LEMS): VGCC

A patient is experiencing muscle spasms due to blocked K+. Antibodies against:

Isaacs' syndrome: VGKC

A patient is experiencing muscle weakness, eye muscles are MOSTLY affected. Antibodies against:

Myasthenia gravis disease MuSK, LRP4, AChR

Fate of neurotransmitters: (4)

reuptake degradation diffusion away endocytosis by postsynaptic membrane

What will happen when multiple depolarization signals arrive at the neuron dendrites and soma at the same time?

spatial summation

What are the two main ACH receptors:

Nicotinic and Muscarinic

Nicotinic (nAChRs) are generally associated with ____________ signaling in both the PNS and CNS.

fast, point-to-point, specific

In the CNS, muscarinic receptors play a role in _________ signaling =

neuromodulation slow, point to area, nonspecific

Muscarinic- PNS: slow IPSP in smooth and caridac muscle= ___________ signaling in both the PNS and CNS.

slow, point to point, specific

Muscarine is an _______ for muscarinic acetylcholine receptors (mAChRs) in the brain. If consumed via mushrooms it can be ________

agonist; deadly

Anterograde Transportation: soma to terminals- for small molecular neurotransmitters

enzymes needed synthesized in the soma transport to terminals synthesize small molecular neurotransmitter in terminals

Anterograde Transportation: soma to terminals- for peptide neurotransmitters

pre-peptide synthesized in the soma transport with enzymes to the terminals degrade to form active neurotransmitter

Retrograde Transportation: terminals to soma-

molecules recovered from terminals transported back to cell body for reuse

Which type of receptors for neurotransmitter are on the postsynaptic membrane?

Ionotropic (fast) and Metabotropic (slow) receptors

Receptors on the postsynaptic membrane define functions: -Fast vs. Slow -Excitatory vs. Inhibitory: depending on both the _______ and _______ -___________ inhibitory and excitatory for different bipolar neurons depending in the visual systems

transmitter and receptor glutamate

Three amines: ARAS =

arousal and alert status of cerebral cortex

Main neurotransmitters: (4)

Amines Amino acids Neuropeptides Other small molecules