Polvie lec # 8 Flashcards
What is a synapse?
Is the specialized junction of a neuron with it’s target cell
What is a presynaptic cell?
Is what conducts the impulse towards the synapse for example a neuron
What is a synaptic vesicle?
stores neurotransmitters in the terminal knobs of axons
What is a neurotransmitter?
Is a chemical that binds to the postsynaptic cell
What is the synaptic cleft?
Is the space that seperates the two cells
What is the postsynaptic cell?
receives the neurotransmitter through channels, can be another neuron or a muscle
How does synaptic transmission occur?
depolarization (influx of Na+ ions) causes voltage gated ca2+ channels to open in the presynaptic cell, this allows calcium from outside the cell to diffuse into it
2. The increased Ca conc in the cell causes synaptic vesicles to fuse with the plasma membrane and release neurotransmitters which bind to receptors in the post synaptic membrane
3. The influx of neurotransmitters can cause influx of Na+ and cause depolarization in the post synaptic cell or it can cause cl- gates to open which are inhibitory and lead to hyperpolarization (negative)
After being released from the pre synaptic cell what can happen to the neurotransmitters?
enzymes destroy the remaining neurotransmitter in the synaptic cleft or it gets reuptaked into the presynaptic cell- both stops over stimulation of post synaptic cell
What drugs mess with neurotransmitters reuptake?
antidepressents: stops reuptake of serotonin
cocaine: stops reuptake of dopamine
What is the endomembrane system?
a system composed of the cytoplasmic membranes found in eukaryotic cells
What three types of transport can an endomembrane system do?
Transport materials from donor compartment to recipent
transport materials out of the cell (through secretory pathway)
transport materials into the cell (through an endocytic pathway)
How do endomembrane systems transport materials from donor compartment to recipient compartment?
vesicles grow from the donor compartment and using motor proteins and the cytoskeleton network get transported to recipient these vesicles have material with sorting signals (such aa sequences or oilgosaccharides which are recognized by receptors in the budding vesicles to direct them to the correct destination), vesicles fuse with recipient, release contents and adds to it’s membrane
How does the endomembrane cell transport materials out of the cell (secretory pathway)?
biomolecules are secreted through constitutive or regulated secretion
In constitutive secretion: Materials are always being secreted via secretory vesicles, these contribute to the formation of the plasma membrane
In regulated secretion: Materials are stored in membrane bound compartments and are only released after certain stimuli
Give examples of regulated secretion?
nerve cells that release neurotransmitters base don increased calcium
endocrine cells that release hormones
pancreatic cells that release digestive enzymes
How does the endomembrane system transport material into the cell? (endocyctic pathway)
materials from outside the cell are taken up during endocytosis and are transported to early endosomes for sorting, late endosomes are more acidic than early ones which the early ones might mature into, then the late endosomes fuse with lysosomes which break down the materials through digestive enzymes and there acidic ph
