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Small organic molecule that blocks potassium channels, but not sodium channels

Gets activated by alpha-subunits of the G-coupled receptors in the gill-fibre of the sea hare. It produces cAMP from ATP which in turn activates proteinkinase A

1) synaptic vesicles are docked to microfilaments via SYNAPSIN
2) when an action potential arrives, voltage-gated calcium channels open
3) calcium detaches the vesicles from microfilaments
4) attechment by SYNAPTOBREVIN (vesticle), SYNTAXIN (presynapse)
5) fusion by SYNAPTOTAGMIN

1) The leakage along the axonal membrane is reduced
2) The membrane capacitance is decreased

Hence, the electrotonic potentials can spread faster and wider until the next node of ranvier.

Alternating activity of antagonist muscle groups, based on the interaction of calcium-channels calcium-activated potassium channels.

Glial cells:
PNS: Schwann cells each produce one myelin segment
CNS: Oligodendrocytes, send out several cell processes to form a multitude of myelin segments.

Neurotransmitter between the antannae-axon and the gill-axon (there is an axo-axonic synapse).

Weak hitting of the patella with a hammer.
Dislocation activates stretch receptor in the muscle.
Signal enters spinal cord via dorsal roots and is directly transferred onto a motoneuron that activates the extensor muscle in the leg.
To rule out activity of the antagonistic flexor muscle, afferent collateral inhibition is needed.

Possess a specific protein, the glial fabrillary acidic protein (GFAP). They provide nutrients from the blood strom.
Removal of waste (neurotransmitters, potassium)

Enzymes attaching or removing a phosphate residue from their substrate, which induces a conformational change there.
In case of protein substrates: protein kinases.

Phosporylates potassium channels (in the sea hare), which leads to a current reduction there. Hence the repolarization of action potentials arriving at the gill fiber synapse is delayed.

temporal summation
spatial summation

Synaptic Integration

Autoimmune disease - auto-antibodies against myelin specific proteins and the MBP.
Viruses that share structural elements with the MBP cause immune bodies to destroy MBP (leakage of the BBB is fatal!)

Primary: The amino acid sequence (there are 20 different amino acids) -> biochemical methods

Secondary: Polypeptide chain, alpha helix (tubule), beta sheet, random coil -> CD-Spectroscopy, often can be predicted

Tertiary (conformation): 3D-shape, changes of the 3D-shape are also called conformational changes, X-ray crystallography

1) increases linearly to fiber diameter, the potential is decaying exponentially
2) increases with the square root of the fiber diameter

In myelinated fibers there is a LINEAR relationship between axon diameter and conduction velocity!!!

In the Golgi-complex proteins are said the be sorted and packaged into transport vesicles.

Axons (also called Neurites) have a uniform diameter and can branch in various collaterals. Their tips are highly branched, forming up to 1000 nerve endings per axon. They send out electrical signals.

In the mitochondria the energy needed for cell survival is generated by the breakdown of glucose to adenosine-tri-phosphate (ATP). For this process to function properly, oxygen is needed.

Postsynaptic effects: activates enzyme calcium-calmodulin kinase II (CaM-kinase II) Phosphorylates itself -> Remains activated. Induces more non-NMDA receptors in post-synaptic membrane (increase in epsp).
Presynaptic: captivates enzyme which produces nitric oxide (gas), which reaches presynaptic nerve terminal (retrograde messenger). Enhances neurotransmitter release.

CNS: low molecular weight basic proteins (MBP), proteolipid protein (PLP) with 4 transmembrane segments

PNS: low molecular weight basic proteins (MBP), P0-glycoprotein with 1 transmembrane segment

Antagonist of nAChR: curare
Antagonist of mAChR: atropine

solid filaments of 5nm diameter, consisting of the protein actin.
In muscle cells, they support muscle contraction.

injury, they are activated, divide, migrate to the site of injury.
Transform into macrophage-like cells, clear damage cells.
-> involved in immune defense

long unbranched hollow tubes of 20nm diameter, mainly consist of the protein tubulin.

Dendrites are often highly branched and receive electrical signals. They are often covered with small protrusion called dendritic spines.
They are used to receive electrical signals.

Myelination:
- oligodendrocytes: CNS
- Schwann cells: PNS

- Astrocytes
- Microglia

Both: Spinal cord

solid filaments of 10nm diameter formed of three neuro-specific neurofilament proteins.

In the nucleus the complete genetic material is stored by DNA. It is transferred to the ER by messenger RNA.

Here, protein and lipid biosynthesis are taking place - the ribosomes on the ER surface associate with the mRNA produced in the nucleus.

1) ACh fuses with plasma membrane and is released
2) ACh binds to a receptor protein which is a chemically gated ion channel (nAChR)
Cations (sodium) flow into the muscle cell -> small membrane depolarisation
3) Voltage gated sodium channels open and elicit an action potential
4) ACh is degraded by the enzyme acetylcholine-esterase AChE

The poison of the buffer fish - blocks the sodium channels. Action potentials can no longer be generated.

Decreases the level of cAMP

Very fast, direct electrical coupling by CONNEXONS (six subunits, each 4 transmembrane segments)
Current flow in both directions.

Means to synchronize electrical signaling in a network

MAO inactivates dopamine in the pre-synapse and those controls the level of dopamine available.