The operation of Nervous system depends on what?
The flow of information through chains of neurons
Neurons are functionally connected by ______
Syanpse
What is a Synapses?
A junction that mediate information transfer from one neuron to another or to an effector cell
Where is the Axodendritic?
Related study material: OpenStax Anatomy and Physiology 2E
Between axon terminals of one neuron & the dendrites of others
Where is the Axosomatic?
Between axon terminals of one neuron and soma of others
The neuron conducting impulses toward the synapse is the _______
Presynaptic neuron
The neuron transmitting the electrical signal away from the synapse is the _____
Postsynaptic neuron
The presynaptic neuron ______ the information, and the postsynaptic neuron _______ the information
Sends, Receives
Most neurons function as both presynaptic and postsynaptic….
True of False?
TRUE
What are the 2 types of Synapse?
Chemical & electical
What are the most common type of synapse?
Chemical
What are Chemical Synapse?
Synapse that are specialized for release and reception of chemical neurotransmitters
What 2 parts are the Chemical Synapse made up of?
Synaptic vesicles & Synaptic cleft
A synaptic vesicles are filled with what?
Neurotransmitters
Where is the neurotransmitter receptor region located on the postsynaptic membrane?
On dendrite or cell body
The synaptic cleft is a fluid filled space that separates what?
Presynaptic and postsynaptic membranes
Chemical synapses prevent what?
A nerve impulse from being directly transmitted from one neuron to another
Chemical synapse convert electrical signals to chemical signals that travel across the synapse to the postsynaptic cells, where they are then converted into what?
Back into electrical signals
Electrical Synapse consist of _____ junctions
Gap
What are Electrical Synapse?
Neurons electrically coupled and transmission that occurs here is very rapid
Electrical synapse are joined by gap junctions that connect the ______ of adjacent neurons
Cytoplasm
Communication is Electrical synapse can be either ___________ or __________
Unidirectional, Bidirectional
In adults, Electrical synapses are found where and are responsible for what?
Regions of the brain and responsible for certain stereotype movements
The Synaptic Cleft prevents nerve impulses from _______ passing from one neuron to the next
Directly
Transmission across the synaptic clef depends on what?
Hint: there are 3 things
**- Release
- Diffusion
- Receptor binding of neurotransmitters**
Synaptic clef ensures unidirectional communication between ______
Neurons
In Information Transfer across Chemical Synapses, an Action Potential arrives where?
At the axon terminal of presynaptic neuron
In Information Transfer across Chemical Synapses, it causes _____________ channels to open, therefore….
Voltage gated Ca2+
In Information Transfer across Chemical Synapses, what type of PROTEIN binds Ca2+ and promotes fusion of synaptic vesicles with axon membrane?
Synaptotagmin
In Information Transfer across Chemical Synapses, when Ion channels are open, it causes what kind of event?
Excitatory or inhibitory
Within just a few milliseconds, neurotransmitters effect terminated in one of what 3 ways?
**- Reuptake
- Degradation
- Diffusion**
What is Synaptic Delay?
Time needed for neurotransmitter to be released, diffuse across the membrane, and bind to receptors
What structure joins two neurons at an electrical synapse?
Gap junctions
Chemical synapse are either excitatory or inhibitory depending on what?
How they affect the membrane potential of the postsynaptic neuron
What are the 2 types of postsynaptic potentials?
**- EPSP (excitatory postsynaptic potentials)
- IPSP (inhibitatory postsynaptic potentials)**
At excitatory synapse, neurotransmitters binding depolarizes the _______
Postsynaptic membrane
Neurotransmitters binding open chemically gated channels allows simultaneous flows of?
Na+ and K+ in opposite directions
EPSP can help trigger what?
An action potential is EPSP is of threshold strength
If EPSP helps trigger and Action potential, it can spread to _________, triggering an opening of voltage-gated channels and cause an action potential to be generated
Axon hillock
What is excitatory postsynaptic potentials?
Local graded depolarization events that occur at excitatory postsynaptic membranes
Each EPSP last only a few milliseconds an then the membrane returns to its _________
Resting potential
Inhibitory Synapses ________ postsynaptic neuron's ability to produce an action potential
Reduces
Inhibitory Synapses makes the membrane more permeable to ____ or ____
K+ or CL-
If K+ channels _____, it moves out of the cell
Open
If Cl- channels open, it moves ____ the cell
Into
Hyperpolarizing changes in potential are called?
Inhibitory postsynaptic potentials
If the inner surface of the membrane becomes more negative, what happens to the Action potential?
It becomes less likely to "fired"
True or false, A single EPSP can induce an Action potential?
False
EPSP can add together or _____ to influence the activity of a postsynatic neuron
Summate
IPSP can also summate…
True or False?
TRUE
Most neurons receive both excitatory and inhibitory inputs from thousands of other neurons…
True or False?
True
What are the 2 types of summation that occur?
**- Temporal
- Spatial**
When does Temporal summation occur?
When one or more presynaptic neurons transmit impulses in rapid-fire order
When does Spatial summation occur?
When the postsynaptic neuron is stimulated simultaneously by a large number of terminals at the same time
Why are the most effective synapses those closest to the axon hillock?
Because EPSP and IPSP are graded potentials that decay the farther they spread
What is Synaptic Potentiation?
Repeated or continuous use of a synapse that enhances the presynaptic neuron's ability to excite the postsynaptic neuron, producing a large EPSP
Ca2+ concentrations _____ in presynaptic terminal and postsynaptical neruons
Increases
Chemically gated channels allow _____ to enter
Ca2+
Ca2+ activates ________ that promote more effective responses to subsequent stimuli
Kinase enzymes
When does Presynaptic inhibition occur?
When the release of excitatory neurotransmitters by one is inhibited by another neuron via axoaxonic synapse
The less neurons released, the ______ EPSPs formed
Smaller
50 or more neurotransmitters have been identified….
True or False?
TRUE
Most neurons make two or more neurotransmitters….
True or False?
TRUE
Different neurotransmitters are released at different stimulation frequencies….
True or False?
TRUE
How are Neurotransmitters classified?
By chemical structure and function
Neurotransmitters are grouped into several classes based on _________
Molecular structure
What was the first neurotransmitter identified?
Acetylcholine
Where is Acetylcholine released?
At neuromuscular junctions
Acetylcholine is degraded by what enzyme?
Acetylcholinesterase
Acetylcholine is released by all neurons that stimulate skeletal muscles and by many neurons of the autonomuc nervous system….
True or False?
TRUE
The Biogenic amines includes?
Catecholamines (such as Dopamine)
Biogenic amines are broadly distributed in the _____
Brain
Biogenic amines play a role in ________
emotional behaviours
Amino acids include:
**- Glutamante
- GABA**
Neurotransmitters have a great diversity of ______
Functions
Neurotransmitters can be classified by?
**- Effects
- Actions**
Effects are ______ vs _______
Excitatory, Inhibitory
Actions are ____ vs ____
Direct, Indirect
The effect is determined by?
The receptor to which it binds
ACh is _______ at a neuromuscular junction in skeletal muscle
Excitatory
ACh is ______ inhibitory in cardiac muscle
Inhibitory
Neurotransmitter that act directly are those that….
Bind to and open ion channels
Direct action of a neurotransmitter promotes rapid responses by altering membrane potential….
True or False?
TRUE
What does Neuromodulator mean?
Term used to describe a chemical messenger relased by a neuron that does not directly cause EPSP or IPSP
What are the 2 types of Neurotransmitter receptors?
**- Channel-linked receptors
- G protein-linked receptors**
What are channel-linked receptors?
Ligand-gated ion channels that mediate direct neurotransmitter action
What are G protein-linked receptors?
The responses are indirect, complex, slow
Do Neurons function in groups?
YES
What is Discharge zone?
Neurons most closely associated with incoming fiber
What is Facilitated zone?
Neurons farther away from incoming fiber
What are Circuits?
Patterns of synaptic connections in neuronal pools
What are the 4 types of Circuits?
**- Diverging
- Converging
- Reverberating
- Parallel after-discharge**
What do Patterns of Neural Processing do?
Input travels along one pathway to a specific destination
Why are Patterns of Neural Processing important?
For higher-level mental functioning
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