Bio 14 Week 2 Nervous System Pt. 3

Synapse

The junction between one neuron and another neuron or effector cell

Electrical Synapses, Chemical Synapses

The types of Synapses

Electrical synapses

Type of synapses with gap junctions which allow ions to flow from one cell to another

Gap junctions

multi-subunit channels that connect the interior of two adjacent cells.

two connexons/six connexons

• A gap junction consists of ________ (each formed from ______ subunits).

one

___ connexon is located in each of the adjacent cells, and when they align, they form a channel allowing ions and small molecules to pass through.

Electrical synpases/rapid

________ allow for extremely _____ signal transmission

invertebrate/vertebrate

Electrical synapses are more common in _____ nervous systems than in ________ nervous systems.

coordination of rhythmic activity

Electrical synapses in vertebrates are involved in the _________ essential for controlling breathing patterns.

Chemical synapses

• Synapses where neurotransmitter release occurs between a presynaptic and a postsynaptic cell.

• Slight delay in the transmission of the action potential from one neuron to another.

Ligand-gated receptors

Chemical synapses utilize _______ while electrical synapses utlilize gap junctions

Voltage-gated Ca2+ channels open

For Chemical Synaptic Transmission, what happens after the action potentials arrive at axon terminal?

Ca2+ enters the cell

For Chemical Synaptic Transmission, what happens after the

voltage-gated Ca2+ channels open?

Ca2+ signals to the vesicles

For Chemical Synaptic Transmission, what happens after Ca2+ enters the cell?

Vesicles move to membrane

For Chemical Synaptic Transmission, what happens after

Ca2+ signals to the vesicles

Docked vesicles release neurotransmitter by exocytosis

For Chemical Synaptic Transmission, what happens after vesicles move to membrane

diffuses/receptors

For Chemical Synaptic Transmission, after the docked vesicles release neurotransmitter by exocytosis, neurotransmitter _____ across the synaptic cleft and binds to _____

signal transduction pathways activated

For Chemical Synaptic Transmission, what happens after the neurotransmitter is bound to the receptors of the postsynaptic cell?

omega shapes

Electron microscopy provides evidence of vesicle fusion (“____________”)

dendritic spines

Synapses are often located on _________

dendritic spines

small, bulbous protrusions on dendrites (the receiving part of a neuron) that serve as the primary location for excitatory synapses

thousands

Neurons have ________ of synapses

Axon hillock

What is another name for the axon initial segment?

Neurotransmitter Synthesis

The process by which neurotransmitters are synthesized in the neuron, typically starting in the soma (cell body) and ending with the transport to the axon terminals for release into the synaptic cleft.

endoplasmic reticulum/golgi network

The _________ is involved in synthesizing neurotransmitter precursors and enzymes in the cell body. It then transports these molecules to the ________

enzymes

After the transport of enzymes/peptide precursors down the microtubule tracks, _______ modify precursors to produce peptide neurotransmitter

Ionotropic Receptors

Membrane-bound receptors that, when activated by neurotransmitters, open ion channels to allow ions to flow across the membrane, leading to a rapid change in the membrane potential. These receptors typically result in fast synaptic responses.

Metabotropic Receptors

Membrane-bound receptors, that instead of opening ion channels directly, they initiate signal transduction pathways that often lead to a slower and more complex cellular response. These pathways can alter existing proteins or regulate gene expression, causing a coordinated cellular response.

Glutamate

Most common excitatory neurotransmitter in the brain and is the most abundant neurotransmitter. It plays a crucial role in cognitive functions such as learning and memory.

GABA (Gamma-Aminobutyric Acid)

Most common inhibitory neurotransmitter in the brain. It regulates brain activity, affecting anxiety, concentration, sleep, depression, and other aspects of mental health.

Acetylcholine

Neurotransmitter that regulates the autonomic nervous system. It plays a role in motor functions such as heart rate, blood pressure, gut function, and also impacts muscle contractions, memory, sleep, and learning.

Serotonin

Neurotransmitter that helps regulate mood, sleep patterns, anxiety, appetite, and pain. It is crucial for emotional balance and well-being.

Glycine

inhibitory neurotransmitter primarily found in the spinal cord. It helps in regulating functions related to hearing processing, pain transmission, and metabolism.

spinal cord

Glycine is the most common inhibitory neurotransmitter in your ____

GABA/Glycine

______ are the major Inhibitory neurotransmitters

Glutamate/Acetylcholine

_______ are the major excitatory neurotransmitters

two

Acetylcholine can bind to _____ different receptors

Agonists

substances (such as drugs or neurotransmitters) that bind to a receptor and activate it, mimicking or enhancing the natural biological activity of the receptor. They can increase or facilitate the normal action of the receptor, leading to physiological changes in the body.

Antagonists

substances that bind to a receptor but do not activate it. Instead, they block or inhibit the receptor's normal function by preventing agonists or natural neurotransmitters from binding. Antagonists reduce or block the biological activity of the receptor.

Nicotine

agonist that binds to nicotinic receptors in the body.

Mimics the action of acetylcholine (ACh), activating these receptors and inducing excitatory effects on the nervous system.

Curare

Antagonist of acetylcholine that binds to nicotinic receptors, preventing acetylcholine from activating the receptor. It blocks neuromuscular transmission, which results in paralysis.

Muscarine

Agonist of acetylcholine that binds to muscarinic receptors. It mimics acetylcholine’s effects, activating G-protein-coupled receptors in the body and inducing parasympathetic responses like increased salivation and slowed heart rate.

Atropine

antagonist of acetylcholine that binds to muscarinic receptors and blocks their activation.

Increases heart rate and reduce salivation during surgery

Nicotinic Receptor

• ionotropic receptors that respond to acetylcholine and nicotine.

• Found at neuromuscular junctions and are involved in fast synaptic transmission, allowing for the influx of sodium ions and depolarization of the postsynaptic membrane.

Muscarinic Receptor

metabotropic receptors activated by acetylcholine and muscarine. These receptors are involved in slower, G-protein-coupled signaling pathways, primarily in the parasympathetic nervous system, and control functions such as heart rate and digestion.

Adrenergic

Muscarinic and ________ receptors are both metabotropic (GPCRs)

Excitatory Postsynaptic Potential (EPSP)

graded potentials occurring in the dendrites and cell body of a neuron when excitatory neurotransmitters (like glutamate) bind to receptors on the postsynaptic membrane. This causes positive ions (e.g., Na⁺) to flow into the cell.

hundreds of thousands

Excitatory postsynaptic potentials represent __________ of channels opening

Inhibitory Postsynaptic Potential (IPSP)

Graded potentials that occur in the dendrites and cell body when inhibitory neurotransmitters, such as GABA, bind to their respective receptors.

These lead to the opening of chloride (Cl⁻) channels, allowing chloride ions to enter the postsynaptic cell

Neural output

________ is the sum of excitatory and inhibitory inputs

Hippocampus

The _________ is an important model for neural plasticity

Dentate Gyrus

A part of the hippocampus involved in the formation of new memories and the processing of spatial memory.

Subiculum

The part of the hippocampus that links to other brain regions, facilitating the flow of information.

Entorhinal Cortex

A part of the brain that functions as the main interface between the hippocampus and the neocortex.

Tetanus

A repetitive, high frequency burst of stimuli

Schaffer collaterals

axons of the neurons in the CA3 regions of the hippocampus that form synapses in the CA1 regions

Synaptic plasticity

The functional properties of individual synapses can be modified by a variety of factors, including elevated electrical activity (experience)

Long-Term Potentiation (LTP)

lasting increase in the strength of synaptic transmission, often observed after high-frequency stimulation of a synapse. It's considered a fundamental mechanism for learning and memory.

Perforant Pathway

Critical neural pathway in the brain, particularly in the context of the hippocampus. It connects the entorhinal cortex to the dentate gyrus, which is part of the hippocampal formation.

Perforant Pathway

Entorhinal cortex → dentate gyrus → CA3 → CA1 → subiculum → entorhinal cortex