Neuroscience Chapter on Sensation and Synapses

The point where a nerve cell (neuron) communicates with another cell.

A specialized junction where a neuron communicates with another cell, such as a nerve, muscle, or gland.

The gap separating the presynaptic and postsynaptic cells in a chemical synapse.

Direct contact between the membranes of two cells, allowing rapid and reliable transmission of nerve impulses.

More complex synapses where a chemical messenger called a neurotransmitter is released to transmit the signal.

The process by which a neurotransmitter is released from the presynaptic cell and binds to receptors on the postsynaptic cell, triggering a response.

A chemical messenger that transmits signals between neurons at synapses.

A type of neurotransmitter that increases the likelihood of an action potential in the postsynaptic cell.

A type of neurotransmitter that decreases the likelihood of an action potential in the postsynaptic cell.

A local change in the membrane potential of a neuron, making it more positive, increasing the likelihood of an action potential.

A neurotransmitter that binds to receptors on the postsynaptic cell, causing the opening of ion channels and allowing the influx of positive ions, leading to depolarization.

The main excitatory neurotransmitter in the central nervous system (CNS).

A neurotransmitter that binds to receptors on the postsynaptic cell, causing hyperpolarization, making it less likely to fire.

The process by which neurotransmitters are taken back up into the presynaptic terminal after being released, ending their action.

A neurotransmitter that is involved in mood regulation, sleep, appetite, and other functions.

The ability to sense touch, pressure, vibration, tickle, and itch.

The ability to sense changes in temperature, both hot and cold.

The ability to sense pain, a protective mechanism that alerts the body to potential harm.

The ability to sense the position and movement of body parts, even with eyes closed.

Senses that provide information about conditions within internal organs, like fullness, pain, and pressure.

The spread of information from one neuronal pool to multiple pools, enabling broad distribution of a specific input.

Multiple presynaptic neurons synapse onto a single postsynaptic neuron, allowing various patterns of input to influence the same output.

Information is relayed in a step-by-step manner from one neuronal pool to the next, like a chain reaction.

Multiple neurons or pools process the same information simultaneously, allowing for a variety of responses.

A neural circuit that utilizes feedback to sustain or inhibit its own activity, creating a loop.

A conscious or unconscious awareness of internal or external stimuli.

The conscious awareness and interpretation of a sensation, involving localization and identification.

The property that distinguishes one type of sensation from another, such as sight, hearing, touch, smell, and taste.

The process of information being distributed to different areas of the brain through divergence, allowing for multiple simultaneous actions or responses.

A neural circuit involving feedback that helps maintain consciousness, such as the reticular activating system (RAS).

A neural circuit involving feedback that regulates breathing, ensuring proper oxygen intake.

The functional organization of neurons within the central nervous system (CNS).

A visual representation of the connections and interactions between neurons.

A complex reflex involving areas of the brain stem, controlling vital functions like heart rate and breathing.

The ability of the conscious brain to precisely identify and locate specific sensations.

The afferent limb of a reflex is comprised of sensory neurons that carry information from the periphery to the central nervous system (CNS).

The efferent limb consists of motor neurons that transmit signals from the CNS to muscles or glands.

Neurons in the spinal cord that receive input from sensory neurons and project to motor neurons.

The principle that the activation of a muscle is accompanied by the simultaneous inhibition of its antagonist muscle.

The distribution of sensory information to multiple areas of the brain.

Endorphins are naturally occurring neuropeptides that mimic the effects of opioids. They are produced by the body in response to pain, stress, or exercise, and they help to reduce pain and promote feelings of well-being.

Endorphins exert an inhibitory effect, meaning they decrease the activity of neurons that transmit pain signals.

Endorphins are primarily found in the brain and spinal cord, the central nervous system.

Endorphins help to reduce stress by calming the nervous system and promoting feelings of relaxation.

Endorphins act as natural painkillers by blocking pain signals in the brain and spinal cord.

Nicotine, a stimulant found in tobacco, activates nicotinic acetylcholine receptors, primarily in the brain. This activation leads to the release of dopamine, a neurotransmitter associated with pleasure and reward. This process can contribute to the addictive nature of nicotine.

Curare is a poison traditionally used by South American indigenous people for hunting. It acts as an antagonist of acetylcholine receptors, blocking the neurotransmitter at the neuromuscular junction. This blockage prevents muscle contraction, causing paralysis.

Morphine and heroin are both opioids that act on opioid receptors in the brain and spinal cord. These receptors are involved in pain perception and reward pathways. Opioids can effectively reduce pain but also lead to addiction due to their rewarding effects.

Cannabis, which contains the psychoactive compound THC, exerts its effects by activating cannabinoid receptors in the brain. These receptors are involved in various processes, including mood, memory, and appetite.

Cocaine acts by blocking the reuptake of dopamine in the synaptic cleft. This prevents dopamine from being removed from the synapse, prolonging its effects and leading to increased dopamine signaling. This increased dopamine signaling is responsible for the stimulating effects of cocaine.

Sarin, a nerve gas, works similarly to cocaine by blocking the removal of acetylcholine at nerve-muscle synapses. This disruption leads to a buildup of acetylcholine, causing continuous muscle contraction and spastic paralysis.

Myasthenia gravis is an autoimmune disorder that affects the neuromuscular junction. The body produces antibodies that bind to acetylcholine receptors on muscle fibers, blocking them and reducing the number of functional receptors. This disrupts neurotransmission, leading to muscle weakness and fatigue.

Graves' disease is an autoimmune disorder that affects the thyroid gland. The body produces antibodies that bind to receptors on the thyroid gland, stimulating the release of thyroid hormone. This excessive production of thyroid hormone leads to hyperthyroidism.

Epilepsy, a neurological disorder characterized by seizures, is sometimes linked to a decrease in the efficiency of inhibitory transmission in the brain, particularly involving GABA (gamma-aminobutyric acid). This imbalance between excitation and inhibition can lead to excessive neuronal activity and seizures.

Depression and schizophrenia, two major psychiatric disorders, are thought to involve disruptions in synaptic function related to specific neurotransmitters. Depression is often linked to low serotonin levels, while schizophrenia is associated with excess dopamine signaling.

The process of converting energy from stimuli into electrical signals in neurons.

Electrical signals produced by sensory receptors that vary in amplitude depending on the intensity of the stimulus.

Electrical signals produced by neurons that travel along the axon, maintaining a consistent amplitude and speed.

Sensory neurons that transmit signals from the peripheral nervous system (PNS) to the central nervous system (CNS).

The process of interpreting and integrating sensory information in the central nervous system.

Sensory receptors that respond to physical deformation, such as touch, pressure, and vibration.

Sensory receptors that respond to changes in temperature.

Sensory receptors that detect pain caused by tissue damage.

Sensory receptors that detect chemicals, such as those found in taste and smell.

Sensory receptors that detect light.

A type of graded potential produced by free nerve endings, encapsulated nerve endings, and olfactory receptors.

A type of graded potential produced by specialized sensory cells involved in vision, hearing, equilibrium, and taste.

Sensory receptors located near the surface of the body that detect external stimuli.

Sensory receptors located within internal organs and blood vessels that detect internal stimuli.

The process of transmitting pain signals from the periphery to the brain, and the factors that can modify this transmission.

Receptors that adapt slowly to a stimulus and continue firing action potentials for the duration of the stimulus. They convey information about the duration of the stimulus.

Receptors that adapt rapidly to a stimulus and stop firing when the stimulus is constant. They convey information about changes in stimulus intensity and rate.

The tendency of sensory receptors to decrease their response to a constant stimulus over time.

Receptors located in muscles, tendons, and joint capsules that provide information about body position and movement. They are also tonic receptors.

Neurotransmitters that make the postsynaptic cell less likely to generate an action potential, rendering it less excitable.

The main inhibitory neurotransmitter in the central nervous system, playing a critical role in regulating neuronal activity.

A neurotransmitter that is involved in movement, motivation, and reward.

Receptors that are not conscious except for pain or pressure.

The part of the brain involved in maintaining alertness and consciousness, regulated by reverberation.

A class of drugs that inhibit the activity of monoamine oxidase (MAO), an enzyme that breaks down neurotransmitters like dopamine, serotonin, and norepinephrine in the brain. MAOIs are used to treat depression by increasing the levels of these neurotransmitters.

A type of neurotransmitter action that is longer-lasting and slower-acting than typical neurotransmitters. Modulators often influence intracellular processes like gene expression, leading to wider and more lasting effects.

A potent neurotransmitter known for its role in pain perception and reward. It binds to opiate receptors in the brain, producing analgesic and euphoric effects.

The process of blocking or inhibiting the action of a neurotransmitter at its receptor. Antagonists can reduce or completely prevent the effects of a neurotransmitter.

The process of enhancing or mimicking the action of a neurotransmitter at its receptor. Agonists can increase the effects of a neurotransmitter.

A debilitating neuromuscular disorder that occurs when the immune system attacks and destroys acetylcholine receptors at neuromuscular junctions. This disrupts communication between nerves and muscles, leading to muscle weakness and fatigue.

A disorder characterized by excessive thyroid hormone production due to autoimmune activity. The immune system attacks and stimulates the thyroid gland, leading to hyperthyroidism.

Sensory neurons that transmit impulses from the peripheral nervous system (PNS) to the central nervous system (CNS).

Specialized structures that detect specific types of stimuli, such as touch, pressure, temperature, or light.

Increased sensitivity to pain following an initial painful stimulus.

Suppression of pain signals by descending pathways in the nervous system.

Pain felt in a location different from the actual source of injury.

Theory suggesting that stimulating non-painful sensory fibers can block the transmission of pain signals.