12.3 The Function of Nervous Tissue
4 min read•june 18, 2024
Nervous tissue communication is a complex dance of electrical and chemical signals. Neurons generate action potentials, which travel along axons, while neurotransmitters facilitate communication between cells. This intricate system allows for rapid and precise information transfer throughout the nervous system.
The nervous system processes sensory input and generates motor output through a coordinated sequence. Sensory receptors detect stimuli, the processes the information, and motor neurons transmit commands to effector organs. This pathway enables our bodies to respond to environmental changes efficiently.
Nervous Tissue Communication and Function
Communication in nervous tissue
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- Electrical signals
- Neurons generate electrical signals called action potentials
- Brief, rapid changes in the membrane potential of a
- Generated when the neuron's membrane potential reaches a value
- Action potentials propagate along the of the neuron
- Voltage-gated sodium and potassium channels open and close in a coordinated manner
- Allows to travel from the cell body to the axon terminal (synaptic terminal)
- is the baseline electrical state of a neuron when not actively transmitting signals
- Neurons generate electrical signals called action potentials
- Chemical signals
- Neurons communicate with each other and with target cells through chemical signals called neurotransmitters
- Released from the axon terminal of the presynaptic neuron
- Bind to specific receptors on the postsynaptic cell (target cell)
- Binding of neurotransmitters can cause excitatory or inhibitory effects on the postsynaptic cell
- Excitatory neurotransmitters increase the likelihood of the postsynaptic cell generating an (, )
- Inhibitory neurotransmitters decrease the likelihood of the postsynaptic cell generating an action potential (, )
- Neuromodulators are chemicals that can modify the effects of neurotransmitters on target cells
- Neurons communicate with each other and with target cells through chemical signals called neurotransmitters
Sensory input to motor output sequence
- Sensory input
- Sensory receptors detect stimuli from the internal or external environment
- Specialized cells or structures that respond to specific types of stimuli (light, sound, touch, temperature)
- Sensory receptors transduce the stimulus energy into electrical signals (receptor potentials)
- Sensory neurons transmit the electrical signals to the central nervous system CNS (brain and spinal cord)
- Sensory receptors detect stimuli from the internal or external environment
- Processing in the CNS
- Sensory information is processed and integrated in the CNS, particularly in the
- Outermost layer of the brain, responsible for higher-order processing and decision-making
- Neural circuits in the CNS analyze and interpret the sensory information
- The CNS generates an appropriate response based on the processed sensory information
- Sensory information is processed and integrated in the CNS, particularly in the
- Motor output
- The CNS sends motor commands to the appropriate effector organs via motor neurons
- Effector organs include muscles and glands
- Motor neurons transmit electrical signals (action potentials) to the effector organs
- The effector organs respond to the motor commands, resulting in a specific action or response
- Muscle contraction, gland secretion
- The is the specialized synapse where motor neurons communicate with skeletal muscle fibers
- The CNS sends motor commands to the appropriate effector organs via motor neurons
Key structures of nervous system
- Sensory receptors
- Detect stimuli from the internal or external environment
- Transduce the stimulus energy into electrical signals (receptor potentials)
- Initiate the process of sensory transduction and transmission of sensory information to the CNS
- Neurons
- Basic functional units of the nervous system
- Generate and transmit electrical signals (action potentials) along their axons
- Communicate with other neurons and target cells through chemical signals (neurotransmitters)
- Types of neurons:
- Sensory neurons: Transmit sensory information from receptors to the CNS
- Interneurons: Process and integrate information within the CNS
- Motor neurons: Transmit motor commands from the CNS to effector organs
- Synapses
- Functional connections between neurons or between neurons and target cells
- Allow for the transmission of information from one neuron to another or from a neuron to a target cell
- Consist of a presynaptic neuron, a , and a postsynaptic cell
- Neurotransmitters are released from the presynaptic neuron, cross the , and bind to receptors on the postsynaptic cell
-
- Outermost layer of the brain, responsible for higher-order processing and decision-making
- Divided into four main lobes: frontal, parietal, temporal, and occipital
- Each lobe is associated with specific functions:
- : Executive functions, planning, decision-making, and motor control
- : Somatosensory processing, spatial awareness, and attention
- : Auditory processing, language comprehension, and memory
- : Visual processing and perception
- Plays a crucial role in processing and integrating sensory information, generating appropriate responses, and coordinating complex behaviors and cognitive functions
Supporting cells and plasticity
- (glial cells) provide support and protection for neurons in the nervous system
- refers to the brain's ability to change and adapt in response to experience and learning
- Graded potentials are small changes in membrane potential that can summate and lead to the generation of action potentials
Key Terms to Review (69)
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.
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.
Astrocyte: Astrocytes are star-shaped glial cells in the brain and spinal cord that play roles in supporting neurons, maintaining the blood-brain barrier, and regulating nutrient and ion concentrations. They are integral to the repair and scarring process of the central nervous system (CNS) following traumatic injuries.
Astrocyte: Astrocytes are a type of glial cell found in the central nervous system (CNS) that provide essential support and protection for neurons. They play a critical role in the function and maintenance of the nervous tissue.
Axon: The axon is a long, slender projection of a neuron that transmits electrical signals away from the cell body to other neurons, muscles, or glands. It is a critical component of the nervous system, responsible for the rapid and efficient communication between different parts of the body.
Axon segment: An axon segment is a distinct portion of an axon, the long, slender projection of a neuron that conducts electrical impulses away from the neuron's cell body. Each segment is delimited by nodes of Ranvier, which are gaps in the myelin sheath that facilitate rapid signal transmission.
Central Nervous System: The central nervous system (CNS) is the primary control center of the body, consisting of the brain and spinal cord. It is responsible for integrating and coordinating information from the peripheral nervous system to regulate and maintain bodily functions.
Cerebral cortex: The cerebral cortex is the outer layer of neural tissue of the cerebrum in the brain, playing a key role in memory, attention, perception, cognition, awareness, thought, language, and consciousness. It consists primarily of gray matter and is responsible for processing and integrating sensory information and directing voluntary motor functions.
Cerebral Cortex: The cerebral cortex is the outermost layer of the cerebrum, the largest part of the brain. It is responsible for higher-order cognitive functions, such as information processing, decision-making, and conscious awareness. The cerebral cortex plays a crucial role in the central nervous system and is closely tied to the topics of nervous tissue, central nervous system function, central processing, central control, and mental status examination.
Circulation and the Central Nervous System: Circulation in the context of the central nervous system (CNS) refers to the blood flow necessary for delivering oxygen and nutrients to neural tissues and removing waste products. Proper circulation is crucial for maintaining the health and functionality of the brain and spinal cord.
Dendrite: Dendrites are the branched extensions of a neuron that receive signals from other neurons and transmit them toward the cell body. They play a crucial role in integrating neural information received from multiple sources.
Dendrite: A dendrite is a branched projection of a neuron that receives signals from other neurons and transmits them to the cell body. Dendrites are a crucial component of the nervous system, playing a vital role in the perception and response to stimuli, the function of nervous tissue, and the generation of action potentials.
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.
Dopamine: Dopamine is a neurotransmitter that plays a crucial role in the nervous system, influencing perception, motor function, motivation, reward, and various other physiological processes. It is a key component in understanding the function of nervous tissue, the central nervous system, and the autonomic system, as well as the effects of certain drugs on the body.
Frontal Lobe: The frontal lobe is the largest of the four major lobes of the cerebral cortex in the human brain. It is responsible for a wide range of functions, including motor control, decision-making, problem-solving, and higher-order cognitive processes.
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.
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 potential: Graded potentials are changes in membrane potential that vary in size and are localized to a specific part of the cell membrane. These changes can either make the neuron more likely to fire (depolarize) or less likely (hyperpolarize), depending on the stimulus.
Graded Potential: A graded potential is a localized, variable change in the electrical charge across the membrane of a neuron or other excitable cell. It is a transient, non-propagating change in the cell's membrane potential that is proportional to the strength of the stimulus, unlike an action potential which is an all-or-nothing response that propagates along the cell's membrane.
Guillain-Barré syndrome: Guillain-Barré syndrome is an autoimmune disorder in which the body's immune system mistakenly attacks the peripheral nervous system, leading to muscle weakness, numbness, and, in severe cases, paralysis. It is a rare condition that typically occurs after a viral or bacterial infection.
Ligand-Gated Channel: A ligand-gated channel is a type of ion channel that opens or closes in response to the binding of a specific chemical messenger, or ligand, to the channel's receptor site. These channels play a crucial role in the function of nervous tissue by facilitating rapid communication between neurons and their target cells.
Multiple Sclerosis: Multiple sclerosis (MS) is a chronic, autoimmune disease that affects the central nervous system (CNS), including the brain, spinal cord, and optic nerves. In MS, the immune system mistakenly attacks the protective myelin sheath surrounding the nerve fibers, leading to disruption of nerve signal transmission and a wide range of neurological symptoms.
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.
Neuroglia: Neuroglia, also known as glial cells, are non-neuronal cells that provide support and protection for neurons in the central and peripheral nervous systems. These cells play a crucial role in the function and maintenance of nervous tissue.
Neuromodulator: A neuromodulator is a chemical substance released by neurons that alters the function of target cells, typically other neurons, without directly causing an electrical signal or action potential. These substances can have a profound impact on the activity and responsiveness of the nervous system.
Neuromuscular Junction: The neuromuscular junction is the site where a motor neuron from the nervous system connects with and transmits signals to a muscle fiber, enabling muscle contraction. It is a critical interface that facilitates the communication between the nervous and muscular systems, allowing for the voluntary control of skeletal muscle movement.
Neuromuscular junction (NMJ): The neuromuscular junction is a specialized synapse between a motor neuron and a skeletal muscle fiber, facilitating the transmission of electrical signals that result in muscle contraction. It plays a pivotal role in converting neural commands into mechanical movement.
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.
Neuroplasticity: Neuroplasticity refers to the brain's remarkable ability to adapt, change, and rewire itself in response to experience, learning, and environmental demands. It is a fundamental property of the nervous system that allows for the modification of neural pathways and synaptic connections throughout an individual's lifespan.
Neurotransmitter Release: Neurotransmitter release is the process by which neurotransmitters are released from the presynaptic terminal of a neuron into the synaptic cleft, allowing for communication between neurons and the propagation of electrical signals throughout the nervous system. This term is crucial in understanding the function of nervous tissue, the action potential, and central processing.
Nodes of Ranvier: The nodes of Ranvier are regularly spaced gaps or constrictions along the length of a myelinated nerve fiber. They play a crucial role in the rapid and efficient transmission of electrical signals through the nervous system.
Occipital lobe: The occipital lobe is the region of the brain located at the back of the skull, primarily involved in visual processing. It interprets information received from the eyes and is crucial for recognizing shapes, colors, and motion.
Occipital Lobe: The occipital lobe is one of the four major lobes of the cerebral cortex, located at the back of the brain. It is primarily responsible for processing and interpreting visual information, playing a crucial role in the function of the nervous system, the central nervous system, and the neurological exam.
Oligodendrocyte: Oligodendrocytes are a type of glial cell in the central nervous system that forms the myelin sheath around neurons. This sheathing process is crucial for increasing the speed and efficiency of electrical signal transmission along the neuron.
Oligodendrocyte: Oligodendrocytes are a type of glial cell in the central nervous system (CNS) that are responsible for producing the myelin sheath that insulates and enhances the transmission of electrical signals along the axons of neurons. These specialized cells play a crucial role in the nervous tissue's ability to mediate perception and response, as well as the overall function of the nervous system.
Parietal lobe: The parietal lobe is one of the four major lobes of the cerebral cortex in the brain, primarily involved in processing sensory information related to touch, temperature, and pain. It also plays a key role in spatial orientation and navigation.
Parietal Lobe: The parietal lobe is one of the four major lobes of the cerebral cortex, located in the middle region of the brain. It is responsible for integrating sensory information from various parts of the body and plays a crucial role in spatial awareness, attention, and language processing.
Peripheral Nervous System: The peripheral nervous system (PNS) is the part of the nervous system that is outside the central nervous system (CNS), which includes the brain and spinal cord. The PNS is responsible for transmitting information between the CNS and the rest of the body, allowing for communication and coordination of various bodily functions.
Peripheral nervous system (PNS): The Peripheral Nervous System (PNS) is a part of the nervous system that consists of nerves and ganglia outside of the brain and spinal cord. It connects the central nervous system (CNS) to limbs and organs, essentially serving as a communication relay back and forth between the brain and the extremities.
Precentral gyrus of the frontal cortex: The precentral gyrus of the frontal cortex is a prominent structure in the brain's frontal lobe, directly involved in controlling voluntary movements. It contains the primary motor cortex, which maps out areas corresponding to different parts of the body for motor functions.
Prefrontal lobe: The prefrontal lobe is the part of the cerebral cortex that covers the front part of the frontal lobe, responsible for complex behaviors such as decision making, planning, and moderating social behavior. It plays a crucial role in personality development and the management of emotional responses.
Propagation: In the context of the nervous system and nervous tissue, propagation is the process by which an electrical impulse travels along the membrane of a nerve cell. This action allows for the communication of information throughout the nervous system.
Receptor Potential: A receptor potential is the graded electrical response generated in a sensory receptor when it is stimulated. It is the initial step in the transduction of a sensory stimulus into a neural signal that can be interpreted by the central nervous system.
Repolarization: Repolarization is the process during an action potential when a neuron's membrane potential returns to its resting negative state after depolarization. It occurs due to the efflux of potassium ions (K+) through channels in the neuron's membrane.
Repolarization: Repolarization is the process by which the resting membrane potential of an excitable cell, such as a neuron or a cardiac muscle cell, is restored after an action potential has been generated. This crucial phase of the action potential cycle allows the cell to regain its ability to respond to subsequent stimuli.
Resting membrane potential: Resting membrane potential is the electrical charge difference across the neuronal membrane when the neuron is not actively transmitting a signal. It is typically negative, indicating that the inside of the neuron is more negatively charged compared to the outside.
Resting Membrane Potential: The resting membrane potential is the electrical charge difference across the cell membrane when the cell is not actively transmitting an electrical signal. It is a crucial concept in understanding the function of nervous tissue, the action potential, and the electrical activity of cardiac muscle.
Saltatory conduction: Saltatory conduction is the process by which nerve impulses jump between the nodes of Ranvier along myelinated axons, significantly speeding up electrical transmission. This method allows for faster communication between neurons without increasing the size of the axon.
Saltatory Conduction: Saltatory conduction is the rapid transmission of electrical impulses along the length of a nerve fiber by 'jumping' from one node of Ranvier to the next, rather than propagating continuously. This specialized form of signal transmission is a key feature of the nervous system and plays a crucial role in the function of nervous tissue.
Schwann cell: Schwann cells are a type of glial cell located in the peripheral nervous system that wrap around axons, creating a myelin sheath which facilitates faster electrical impulses. They also aid in the regeneration of damaged nerve fibers.
Schwann Cell: Schwann cells are the principal glial cells of the peripheral nervous system. They are responsible for myelinating and supporting the axons of neurons, which is essential for the efficient transmission of electrical signals throughout the body.
Serotonin: Serotonin is a neurotransmitter that plays a crucial role in the nervous system, regulating various physiological and psychological processes. It is involved in the perception and response of the nervous tissue, the function of nervous tissue, and the activity of the pineal gland.
Sodium-potassium pump: The sodium-potassium pump is a protein complex found in cell membranes that moves sodium ions out of and potassium ions into the cell, using ATP for energy. It plays a crucial role in maintaining the cell's electrochemical gradient and volume.
Sodium-Potassium Pump: The sodium-potassium pump, also known as the Na+/K+ ATPase, is a crucial membrane-bound protein that actively transports sodium ions (Na+) out of cells and potassium ions (K+) into cells. This electrochemical gradient created by the pump is essential for a variety of physiological processes, including nerve impulse transmission, muscle contraction, and fluid and electrolyte balance.
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.
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 Transmission: Synaptic transmission is the process by which an electrical or chemical signal is transmitted from one neuron to another across the synaptic cleft, the small gap between the axon terminal of the presynaptic neuron and the dendrite or cell body of the postsynaptic neuron. This process is essential for the communication and coordination of the nervous system.
Temporal lobe: The temporal lobe is one of the four major lobes of the cerebral cortex in the brain, primarily involved in processing auditory information and encoding memory. It is located beneath the lateral fissure on both cerebral hemispheres.
Temporal Lobe: The temporal lobe is one of the four major lobes of the cerebral cortex, located on the sides of the brain above the ears. It is primarily responsible for processing and interpreting auditory information, as well as playing a crucial role in memory, language, and emotional processing.
Thalamus: The thalamus is a small structure within the brain that serves as a relay station for information coming from the senses to the cerebral cortex. It plays a crucial role in processing and transmitting sensory and motor signals, as well as in regulating consciousness, sleep, and alertness.
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.
Thermoreceptor: Thermoreceptors are specialized sensory nerve cells that detect changes in temperature and convey this information to the nervous system. They are essential for maintaining homeostasis by enabling the perception of cold and heat.
Threshold: In the context of nervous tissue function, a threshold is the minimum level of stimulus intensity required to activate or depolarize a neuron, leading to an action potential. It is a critical point that once crossed, results in a significant physiological response within the neuron.
Upper motor neuron: Upper motor neurons are nerve cells in the central nervous system that initiate and regulate voluntary movements by transmitting signals from the brain to lower motor neurons, which then directly innervate muscles. They play a crucial role in the planning, initiation, and modulation of motor movements.