Nervous System: Synapses

how are neurons functionally connected?

synapses

what type of junction is found between a neuron and muscle fiber?

neuromuscular junction

what type of junction is found between a neuron and gland?

neuroglandular junction

what type of junctions are found between two neurons?

axodendritic, axosomatic, axoaxonic 

what is an axodendritic junction?

axon to dendrite (most common)

what is an axosomatic junction?

axon to cell body

what is an axoaxonic junction?

axon to axon 

what is A?

presynaptic neuron

what is B?

synapse

what is C?

postsynaptic neuron 

what is D?

neurotransmitter

what is E?

synaptic cleft

what is happening in this image?

action potential is arriving at axon terminal 

what is happening in this image?

voltage gated calcium channels open and calcium enters the axon terminal

what is happening in this image?

calcium entry causes synaptic vesicles to release neurotransmitters by exocytosis

what is happening in this image?

neurotransmitter diffuses across synaptic cleft and binds to specific receptors on the postsynaptic membrane

what is happening in this image?

binding of neurotransmitter opens ion channels, resulting in graded potentials on post synaptic nerve

what are the three ways to stop neurotransmitter effects?

enzyme degradation, uptake back into presynaptic neuron for storage or destruction, and diffusion of neurotransmitter away from synaptic cleft

what are the two types of postsynaptic potentials?

excitatory postsynaptic, inhibitory postsynaptic 

what determines the magnitude of depolarization in excitation postsynaptic potentials

amount of neurotransmitters

what is an excitatory postsynaptic potential?

a local depolarization of the postsynaptic membrane that brings the neuron closer to action potential threshold

what does neurotransmitter binding during the excitatory postsynaptic potential allow for?

chemically gated ion channels open, allowing sodium and potassium to pass through simultaneously 

what is inhibitory postsynaptic potential?

a local hyperpolarization of the postsynaptic membrane that drives the neuron away from action potential threshold

what does neurotransmitter binding during inhibitory postsynaptic potential cause?

potassium and/or chlorine chemical-graded channels open

what is temporal summation:?

one or more presynaptic neurons transmit impulses in rapid-fire order

what is spatial summation?

postsynaptic neuron stimulated by presynaptic neurons at the same time

what is this an image of?

temporal summation

what is this an image of?

spatial summation

how are neurotransmitters classified?

chemical structure and function

where is acetylcholine released?

at neuromuscular junctions

how is acetylcholine degraded?

by enzyme acetylcholinesterase

what is epinephrine important for?

adrenalin, regulates sleep/wake cycle, attention, and feeding behaviors

what is dopamine important for?

movement coordination, emotion, and motivation

what is serotonin important for?

mood regulation, emotions, attention, feeding behaviors, and daily rhytms 

what is the important inhibitory neurotransmitter in the central nervous system?

GABA

what is the important excitatory neurotransmitter in the central nervous system?

glutamate

what is this an image of?

diverging circuits

what do diverging circuits allow for?

single neuron to communicate with multiple parts of brain and body

what is a diverging circuit?

single input neuron axon branches out to make contact with multiple postsynaptic neurons

what is a converging circuit?

axon terminals from multiple input neurons converge onto single postsynaptic neuron 

what do converging circuits allow for?

nervous system to respond to sensory information that it collects and processes

what is this an image of?

converging circuits