12.5 Communication Between Neurons
3 min read•june 18, 2024
Neurons are the building blocks of our nervous system, transmitting signals through a complex dance of electrical and chemical processes. From the arrival of an to the release of , each step is crucial for communication between neurons.
Excitatory and inhibitory signals shape neuronal responses, with spatial and allowing for intricate information processing. Understanding these mechanisms reveals how our brains integrate countless inputs to produce coherent thoughts and actions.
Neurotransmitter Release and Reception
Neurotransmitter release and reception
Top images from around the web for Neurotransmitter release and reception
Communication Between Neurons | Anatomy and Physiology I View original
Is this image relevant?
How Neurons Communicate | BIO103: Human Biology View original
Is this image relevant?
Neurotransmission - Wikipedia View original
Is this image relevant?
Communication Between Neurons | Anatomy and Physiology I View original
Is this image relevant?
How Neurons Communicate | BIO103: Human Biology View original
Is this image relevant?
1 of 3
Top images from around the web for Neurotransmitter release and reception
Communication Between Neurons | Anatomy and Physiology I View original
Is this image relevant?
How Neurons Communicate | BIO103: Human Biology View original
Is this image relevant?
Neurotransmission - Wikipedia View original
Is this image relevant?
Communication Between Neurons | Anatomy and Physiology I View original
Is this image relevant?
How Neurons Communicate | BIO103: Human Biology View original
Is this image relevant?
1 of 3
- Action potential arrives at the and depolarizes the membrane
- open in response to
- () rapidly flow into the axon terminal down their concentration gradient
- Influx of calcium ions triggers containing neurotransmitters to fuse with the presynaptic membrane
- releases neurotransmitters (, ) into the , the space between the presynaptic and postsynaptic neurons
- Released neurotransmitters diffuse across the to reach the
- Neurotransmitters bind to their specific receptors on the postsynaptic membrane
- open or close in response to neurotransmitter binding, allowing ions (, , ) to flow through
- activate second messenger systems (, ) that can modulate cellular processes
- Neurotransmitters are cleared from the to terminate the signal
- Reuptake by the via recycles neurotransmitters
- Enzymatic degradation in the synaptic cleft by enzymes () breaks down neurotransmitters
- Diffusion away from the synapse removes neurotransmitters from the immediate vicinity
Excitatory vs Inhibitory Postsynaptic Potentials
Excitatory vs inhibitory postsynaptic potentials
- (EPSPs) depolarize the postsynaptic membrane
- Caused by neurotransmitters (glutamate) that open ligand-gated cation channels
- Sodium ions () flow into the postsynaptic down their concentration gradient
- Potassium ions () flow out of the postsynaptic neuron along their concentration gradient
- Membrane potential becomes more positive relative to the
- Increases the likelihood of the postsynaptic neuron generating an action potential if the threshold is reached
- Caused by neurotransmitters (glutamate) that open ligand-gated cation channels
- (IPSPs) hyperpolarize the postsynaptic membrane
- Caused by neurotransmitters (, ) that open ligand-gated anion channels
- Chloride ions () flow into the postsynaptic neuron along their concentration gradient
- Membrane potential becomes more negative relative to the resting potential
- Decreases the likelihood of the postsynaptic neuron generating an action potential by moving the membrane potential away from the threshold
- Caused by neurotransmitters (, ) that open ligand-gated anion channels
Spatial and temporal summation
- involves the integration of postsynaptic potentials from multiple synapses on a single postsynaptic neuron
- Occurs when multiple synapses are activated simultaneously or in rapid succession
- EPSPs from different synapses add together, bringing the membrane potential closer to the threshold for an action potential
- IPSPs can counteract EPSPs, reducing the likelihood of reaching the threshold
- Temporal summation involves the integration of postsynaptic potentials from a single synapse over time
- Occurs when a single synapse is activated repeatedly in rapid succession
- EPSPs from the same synapse add together over time, increasing the likelihood of reaching the threshold for an action potential
- Requires the second EPSP to occur before the first EPSP has fully decayed back to the resting potential
- Summation and action potential generation
- If the combined EPSPs reach the , an action potential is generated in the postsynaptic neuron
- propagates along the axon to the next synapse, where the process of neurotransmitter release and reception begins anew
- Summation allows for the integration of multiple signals and the modulation of neuronal activity, enabling complex information processing in the nervous system
Neuronal Structure and Function
Basic structure of a neuron
- Cell body (soma): Contains the nucleus and organelles necessary for cellular function
- : Branched extensions that receive signals from other neurons
- Axon: Long projection that conducts electrical signals (action potentials) away from the cell body
- : Insulating layer that surrounds some axons, speeding up signal transmission
- Axon terminal: End of the axon where neurotransmitters are released
Signal transmission in neurons
- : Small, localized changes in membrane potential that occur in response to stimuli
- Action potentials: All-or-nothing electrical signals that propagate along the axon
- : Brief time following an action potential during which the neuron cannot generate another action potential, ensuring unidirectional signal propagation
Key Terms to Review (61)
Acetylcholine: Acetylcholine is a neurotransmitter that plays a crucial role in the communication between neurons, the activation of muscle fibers, and the regulation of various physiological processes in the body. It is a key player in the functioning of the nervous system, muscle tissues, and the autonomic nervous system.
Acetylcholine (ACh): Acetylcholine is a neurotransmitter in the nervous system that plays a crucial role in stimulating muscle contractions and is involved in various brain functions including memory and learning. In the context of skeletal muscle, it is essential for transmitting nerve signals to muscle cells, leading to muscle movement.
Acetylcholinesterase: Acetylcholinesterase is an enzyme that breaks down the neurotransmitter acetylcholine in the synaptic cleft, ensuring the termination of signal transmission between nerve cells and muscle fibers. By hydrolyzing acetylcholine into acetate and choline, this enzyme plays a crucial role in muscle contraction regulation and communication between neurons, preventing continuous stimulation of muscles or prolonged signaling between neurons.
Action Potential: An action potential is a rapid, transient electrical signal that travels along the cell membrane of excitable cells, such as neurons and muscle cells. It is the fundamental unit of communication in the nervous system, enabling the transmission of information between different parts of the body.
Axon Terminal: The axon terminal is the distal end of an axon, the long projection of a neuron that transmits electrical signals to other cells. It is the site where neurotransmitters are released into the synaptic cleft, facilitating communication between neurons and their target cells.
Biogenic amine: Biogenic amines are organic compounds derived from amino acids that act as neurotransmitters in the nervous system. They play crucial roles in transmitting signals across nerve cells to regulate various physiological functions, including mood, arousal, and blood pressure.
Calcium Ions: Calcium ions (Ca2+) are essential mineral ions that play crucial roles in various physiological processes, including muscle contraction, nerve impulse transmission, and cellular signaling. These positively charged ions are involved in a wide range of functions throughout the body, making them a key topic in the study of anatomy and physiology.
CAMP: cAMP, or cyclic adenosine monophosphate, is a secondary messenger molecule that plays a critical role in cellular signaling pathways. It is synthesized from ATP by the enzyme adenylate cyclase and is involved in the transmission of signals from hormones and neurotransmitters to target cells, influencing various physiological processes. By activating protein kinases, cAMP mediates the effects of many hormones and neurotransmitters, making it essential for communication in both the nervous and endocrine systems.
Chemical synapse: A chemical synapse is a junction between two neurons where information is transmitted from one neuron to another using chemical messengers called neurotransmitters. This process converts electrical signals in the transmitting neuron into a chemical signal that crosses the synaptic gap to trigger an electrical signal in the receiving neuron.
Chloride: Chloride is a negatively charged ion (anion) that is essential for various physiological processes in the human body. It is the second most abundant electrolyte in the body and plays a crucial role in maintaining fluid balance, nerve impulse transmission, and acid-base balance.
Cholinergic system: The cholinergic system is a component of the nervous system that uses acetylcholine as its neurotransmitter to communicate between neurons. It plays critical roles in functions such as muscle movement, heart rate, memory, and the regulation of endocrine system activity.
Dendrites: Dendrites are branched extensions of a neuron that receive signals from other neurons. They are the primary site of communication and information processing within the nervous system, playing a crucial role in the transmission and integration of signals between neurons.
Depolarization: Depolarization is the process by which the electrical potential across a cell membrane, typically a neuron or cardiac muscle cell, becomes less negative. This change in membrane potential is a crucial step in the generation and propagation of electrical signals within the body's nervous and cardiovascular systems.
Effector protein: An effector protein is a molecule within cells that acts to execute the effects of signaling pathways, often as a response to external or internal signals. It translates the signal into a cellular response, such as activating enzymes or opening ion channels.
Electrical synapse: An electrical synapse is a type of neural connection where electrical signals are directly passed from one neuron to another through gap junctions, allowing for rapid and synchronized communication among neurons. These junctions facilitate the direct flow of ions and small molecules, enabling faster signal transmission compared to chemical synapses.
Excitatory postsynaptic potential (EPSP): An excitatory postsynaptic potential (EPSP) is a temporary increase in postsynaptic membrane potential due to the flow of positively charged ions into the postsynaptic cell. This change makes the neuron more likely to fire an action potential.
Excitatory Postsynaptic Potentials: Excitatory postsynaptic potentials (EPSPs) are localized depolarizations that occur in the postsynaptic membrane of a neuron when excitatory neurotransmitters are released into the synaptic cleft. These depolarizations increase the likelihood that the postsynaptic neuron will generate an action potential, facilitating communication between neurons.
Exocytosis: Exocytosis is a cellular process where cells transport molecules out of the cell by vesicles fusing with the plasma membrane and releasing their contents into the extracellular space. This process is essential for the secretion of substances produced by cells, such as hormones and neurotransmitters.
Exocytosis: Exocytosis is the process by which a cell transports and releases substances, such as neurotransmitters, hormones, or other molecules, from the interior of the cell to the extracellular environment. It is a fundamental mechanism for cellular communication and secretion, and is closely linked to the function of the cell membrane and cellular organelles.
G protein: G proteins are molecular switches inside cells that help transmit signals from various stimuli outside the cell to its interior, playing a crucial role in cellular communication and response mechanisms. They are involved in many processes, including hormone signaling, which is essential for neuronal communication and the regulation of physiological functions.
G Proteins: G proteins, also known as guanine nucleotide-binding proteins, are a family of proteins involved in the transduction of signals from cell surface receptors to intracellular effectors. They play a crucial role in the communication between neurons during the process of neurotransmission, as described in the topic 12.5 Communication Between Neurons.
GABA: GABA, or gamma-aminobutyric acid, is the primary inhibitory neurotransmitter in the central nervous system. It plays a crucial role in regulating neuronal excitability, perception, and communication between neurons.
Ganglionic neuron: A ganglionic neuron is a type of nerve cell located in the autonomic ganglia, responsible for transmitting signals from the central nervous system to various targets in the body such as organs, blood vessels, and glands. These neurons play a crucial role in the autonomic nervous system by mediating involuntary functions like heart rate, digestion, and respiratory rate.
Generator potential: A generator potential is a local change in the membrane potential of a sensory receptor that occurs in response to a stimulus, making the neuron more likely to produce an action potential. Unlike action potentials, generator potentials are graded, meaning their magnitude varies with the strength of the stimulus.
Glutamate: Glutamate is a key neurotransmitter in the central nervous system, playing a vital role in neural communication, perception, and response. It is the most abundant excitatory neurotransmitter, responsible for transmitting signals between neurons and enabling various neurological functions.
Glycine: Glycine is the smallest and simplest amino acid found in the human body. It plays crucial roles in various physiological processes, including nervous system function, protein synthesis, and metabolism.
Graded Potentials: Graded potentials are local, non-propagating changes in the membrane potential of a neuron that vary in magnitude depending on the strength of the stimulus. They are an essential part of how neurons communicate information and mediate perception and response in the nervous system.
Hyperpolarization: Hyperpolarization is a process in which the membrane potential of a cell becomes more negative relative to the resting potential, making it more difficult for the cell to reach the threshold for generating an action potential. This term is particularly relevant in the context of understanding the action potential and communication between neurons.
Inhibitory postsynaptic potential (IPSP): An inhibitory postsynaptic potential (IPSP) is a type of synaptic potential that makes a neuron less likely to generate an action potential. It typically results from the flow of negative ions into the neuron or positive ions out of the neuron, increasing the negativity of the neuron's membrane potential.
Inhibitory Postsynaptic Potentials: Inhibitory postsynaptic potentials (IPSPs) are a type of synaptic potential that reduces the likelihood of a postsynaptic neuron generating an action potential. They play a crucial role in the communication between neurons by modulating the overall excitability of the target cell.
Ligand-Gated Ion Channels: Ligand-gated ion channels are a class of transmembrane proteins that open or close in response to the binding of specific signaling molecules, known as ligands. These channels allow the selective passage of ions, such as sodium, potassium, calcium, or chloride, across the cell membrane, triggering changes in the electrical properties of the cell and enabling rapid communication between neurons.
Metabotropic receptor: Metabotropic receptors are a type of receptor on the cell membrane that initiates a series of metabolic steps to modulate cellular activity in response to a neurotransmitter. Unlike ionotropic receptors, they do not form an ion channel pore but activate signal transduction pathways involving G proteins and second messengers.
Metabotropic Receptors: Metabotropic receptors are a class of receptors that indirectly influence the activity of target cells by activating intracellular signaling cascades. These receptors are involved in various aspects of communication between neurons in the nervous system.
Muscarinic receptor: Muscarinic receptors are a type of receptor found in the membranes of certain cells that respond to the neurotransmitter acetylcholine. They play a critical role in the functioning of the autonomic nervous system by mediating slower, longer-lasting synaptic transmission compared to nicotinic receptors.
Myelin sheath: The myelin sheath is a fatty layer that surrounds the axons of many nerve cells, serving as electrical insulation and increasing the speed at which nerve impulses are conducted. It is essential for the proper functioning of the nervous system by facilitating rapid signal transmission.
Myelin Sheath: The myelin sheath is a protective fatty layer that surrounds the axons of certain nerve cells, called myelinated neurons. It acts as an insulator, increasing the speed of electrical impulse transmission along the neuron.
Neuron: A neuron is the fundamental unit of the nervous system responsible for receiving, processing, and transmitting information throughout the body. Neurons are the building blocks of neural networks that mediate perception, response, and communication within the nervous tissue.
Neuropeptide: Neuropeptides are small protein-like molecules used by neurons to communicate with each other. They bind to receptors on the surface of target cells, influencing a variety of physiological processes and behaviors.
Neurotransmitters: Neurotransmitters are chemical messengers that transmit signals between neurons, or nerve cells, in the body. They play a crucial role in the communication and function of the nervous system, including the brain, spinal cord, and peripheral nerves.
Nicotinic receptor: Nicotinic receptors are a type of receptor found in the nervous system that responds to the neurotransmitter acetylcholine as well as nicotine. They play a crucial role in the transmission of signals in both the central and peripheral nervous systems.
Postsynaptic Neuron: A postsynaptic neuron is the receiving neuron at a chemical synapse, where it integrates the signals transmitted from the presynaptic neuron. It plays a crucial role in the communication between neurons, which is essential for the nervous system's ability to perceive and respond to stimuli.
Postsynaptic potential (PSP): Postsynaptic potential is a change in the membrane potential of the postsynaptic terminal of a synapse, following the reception of a neurotransmitter. It can be depolarizing (excitatory) or hyperpolarizing (inhibitory), affecting the likelihood of a neuron firing an action potential.
Potassium: Potassium is an essential mineral that plays a crucial role in various physiological processes within the human body. It is involved in maintaining fluid and electrolyte balance, nerve impulse transmission, muscle contraction, and the regulation of heart function. Potassium is a key player in many of the topics covered in this course, including inorganic compounds, action potentials, neuron communication, nutrition, fluid balance, and acid-base regulation.
Presynaptic Neuron: The presynaptic neuron is the neuron that transmits a signal to another neuron, known as the postsynaptic neuron, across a specialized junction called a synapse. This term is crucial in understanding how neurons communicate and how the nervous system mediates perception and response.
Receptor potential: Receptor potential is the change in membrane potential of a sensory receptor due to the response to a stimulus, leading to the generation of a nerve impulse if the threshold is reached. It represents the initial step in the process of converting an external signal into a neuronal response.
Refractory Period: The refractory period is a crucial concept in various physiological processes, including the function of nervous tissue, cardiac muscle, and the propagation of action potentials. It refers to the time interval during which a cell or tissue is unable to respond to a new stimulus or generate another action potential, even if the necessary stimulus is applied.
Relative refractory period: The relative refractory period is the phase following an action potential during which a neuron can be stimulated to initiate another action potential, but only by a stronger-than-usual stimulus. It occurs right after the absolute refractory period and represents a time of decreased sensitivity to new stimuli.
Resting Potential: The resting potential is the electrical potential difference that exists across the cell membrane of a neuron or other excitable cell when the cell is not actively transmitting an electrical signal. It is a crucial component in the communication between neurons within the nervous system.
Sodium: Sodium is an essential mineral that plays a crucial role in various physiological processes within the human body. It is an electrolyte that helps maintain fluid balance, nerve function, and muscle contraction. Sodium is involved in several key topics in anatomy and physiology, including chemical bonds, inorganic compounds, the action potential, communication between neurons, tubular reabsorption, fluid volume and composition regulation, body fluid compartments, and electrolyte balance.
Spatial Summation: Spatial summation is a phenomenon in neuroscience where the combined input from multiple synapses on a single neuron can lead to the generation of an action potential, even if the individual inputs are not strong enough to do so on their own. This concept is crucial in understanding how neurons communicate and integrate information within the nervous system.
Spontaneous depolarization: Spontaneous depolarization is the automatic and gradual change in membrane potential that occurs in certain cardiac muscle cells, leading them to reach the threshold potential and generate an action potential without external stimulation. It is crucial for initiating and regulating the heart's rhythm.
Summate: Summation is the process by which multiple synaptic potentials combine within one postsynaptic neuron, increasing the likelihood of an action potential. This can occur temporally or spatially, involving multiple signals over time or from different locations on the neuron.
Synapse: A synapse is the specialized junction between two neurons or between a neuron and another cell, where information is transmitted from one to the other through the release of neurotransmitters. It is a critical component in the nervous system's ability to perceive and respond to stimuli, as well as facilitate communication between neurons.
Synaptic cleft: The synaptic cleft is a tiny gap between the axon terminal of one neuron and the dendrite or cell body of another neuron or muscle cell. It facilitates the transfer of chemical signals across neurons or between neurons and muscle cells.
Synaptic Cleft: The synaptic cleft is the small gap or space between the presynaptic terminal of one neuron and the postsynaptic membrane of the next neuron. It is a crucial component in the process of communication between neurons, allowing for the transmission of electrical and chemical signals across the synapse.
Synaptic Vesicles: Synaptic vesicles are small, membrane-bound organelles found within the presynaptic terminals of neurons. They are responsible for storing and releasing neurotransmitters into the synaptic cleft, enabling communication between neurons in the context of neural signaling and synaptic transmission.
Temporal Summation: Temporal summation is a neurophysiological process in which the repeated stimulation of a neuron over time leads to an accumulation of excitatory postsynaptic potentials (EPSPs), resulting in the generation of an action potential. This mechanism allows the nervous system to integrate and respond to multiple, sequential inputs more effectively.
The Action Potential: An action potential is a rapid, temporary change in the electrical membrane potential of a neuron or muscle cell, allowing it to transmit a signal. It involves an influx of sodium ions into the cell followed by an efflux of potassium ions, restoring the original electrical condition.
Threshold Potential: The threshold potential is the minimum electrical charge required to trigger an action potential in a neuron. It represents the critical level of depolarization that must be reached in order to initiate the rapid influx of sodium ions that propagates the nerve impulse.
Transporter Proteins: Transporter proteins are specialized membrane-bound proteins that facilitate the movement of various molecules, ions, and other substances across the cell membrane. They play a crucial role in communication between neurons by enabling the transport of neurotransmitters, ions, and other signaling molecules necessary for neural transmission and synaptic function.
Voltage-Gated Calcium Channels: Voltage-gated calcium channels are specialized ion channels found in the cell membranes of many cell types, including neurons, muscle cells, and endocrine cells. These channels open and close in response to changes in the cell's membrane potential, allowing the controlled influx of calcium ions into the cell, which triggers important physiological processes such as neurotransmitter release, muscle contraction, and hormone secretion.