Compendium 8

A neuron is the basic structural and functional unit of the nervous system, responsible for transmitting electrical signals throughout the body.

Neuroglia are supporting cells that maintain homeostasis, provide support and protection for neurons.

An action potential is an electronic signal that propagates along the axon of a neuron, transmitting information through the nervous system.

<p>Sensory receptors are specialized cells that detect various stimuli such as temperature, pain, and light, converting them into sensory input for the nervous system.</p> Signup and view all the answers

<p>A synapse is the junction between a neuron and another cell, facilitating the transmission of signals through neurotransmitters.</p> Signup and view all the answers

<p>The central nervous system processes sensory input to interpret and decide on appropriate responses, which may be immediate or delayed.</p> Signup and view all the answers

<p>The central nervous system consists primarily of the brain and spinal cord.</p> Signup and view all the answers

<p>The nervous system maintains homeostasis by regulating bodily functions through sensory input, integration of information, and motor output.</p> Signup and view all the answers

<p>A reflex arc is the anatomical pathway of a reflex. Its components include a sensory receptor, sensory neuron, interneuron, motor neuron, and effector organ.</p> Signup and view all the answers

<p>Somatic reflexes involve skeletal muscles, such as the patellar reflex, while autonomic reflexes involve smooth muscles or glands, like the pupillary reflex.</p> Signup and view all the answers

<p>Monosynaptic reflexes involve a simple pathway with one synapse between sensory and motor neurons, whereas polysynaptic reflexes have multiple synapses with interneurons.</p> Signup and view all the answers

<p>After a reflex response, the brain receives a signal informing it of the reflex action that has taken place.</p> Signup and view all the answers

<p>Sensory neurons carry messages toward the CNS, while motor neurons send messages away from the CNS toward muscles or glands.</p> Signup and view all the answers

<p>The parasympathetic nervous system promotes rest and digestion, stimulating processes like digestion and urine production while relaxing the body.</p> Signup and view all the answers

<p>Neuroglial cells support and protect neurons, while neurons are the primary cells responsible for transmitting electrical impulses.</p> Signup and view all the answers

<p>Dendrites are highly branched extensions of the neuron that collect stimuli and generate electrical currents to transmit information to the cell body.</p> Signup and view all the answers

<p>The myelin sheath insulates axons, speeding up the transmission of electrical impulses along the neuron.</p> Signup and view all the answers

<p>The three structural types are multipolar (many processes), bipolar (two processes), and unipolar (one process) neurons.</p> Signup and view all the answers

<p>Astrocytes provide structural support, maintain blood-brain barrier integrity, regulate ion balance, and contribute to the repair of nervous tissue.</p> Signup and view all the answers

<p>Oligodendrocytes insulate axons in the CNS, while Schwann cells form myelin sheaths around axons in the PNS.</p> Signup and view all the answers

<p>The node of Ranvier allows for the rapid transmission of electrical impulses by facilitating saltatory conduction.</p> Signup and view all the answers

<p>Sensory neurons conduct impulses toward the CNS from sensory receptors, whereas motor neurons transmit impulses away from the CNS to muscles or glands.</p> Signup and view all the answers

<p>Microglial cells act as the immune cells of the CNS, patrolling for injury or pathogens and phagocytosing debris.</p> Signup and view all the answers

<p>It maintains the differential levels of Na+ and K+ by pumping three Na+ out of the cell in exchange for two K+ into the cell.</p> Signup and view all the answers

<p>All gated Na+ and K+ channels are closed, while K+ leak channels are open, allowing K+ to move out of the cell.</p> Signup and view all the answers

<p>Depolarization is initiated by a stimulus strong enough to meet the threshold of around -55mV, causing Na+ voltage-gated channels to open.</p> Signup and view all the answers

<p>K+ voltage-gated channels are closed during the initial depolarization phase.</p> Signup and view all the answers

<p>During repolarization, Na+ voltage-gated channels close and K+ voltage-gated channels open, allowing K+ to exit the cell and making the intracellular environment more negative.</p> Signup and view all the answers

<p>The afterpotential is a phase where the membrane potential becomes very negative (around -75mV) due to the slow closure of K+ channels that continue to allow K+ to leave the cell.</p> Signup and view all the answers

<p>The sodium potassium pump actively redistributes ions by pumping three Na+ out of the cell in exchange for two K+ entering, re-establishing the resting membrane potential of -70mV.</p> Signup and view all the answers

<p>The negative intracellular change is essential for generating action potentials and maintaining the electrical excitability of the neuron.</p> Signup and view all the answers

<p>Gated channels regulate the flow of Na+ and K+ ions, opening and closing at specific phases to produce the changes in membrane potential that characterize action potentials.</p> Signup and view all the answers

<p>During resting membrane potential, Na+ concentration is higher outside the cell while K+ concentration is higher inside the cell; this is reversed during depolarization.</p> Signup and view all the answers

<p>The two main types are electrical synapses and chemical synapses. Electrical synapses transmit signals via gap junctions, while chemical synapses use neurotransmitters to convey signals across a synaptic cleft.</p> Signup and view all the answers

<p>Neurotransmitters are chemical messengers that transmit action potentials across the synapse by binding to receptors on the postsynaptic membrane.</p> Signup and view all the answers

<p>Voltage gated Ca2+ channels open, allowing Ca2+ to diffuse into the cell, triggering the exocytosis of synaptic vesicles.</p> Signup and view all the answers

<p>The components of a synapse include the presynaptic terminal, presynaptic membrane, postsynaptic membrane, synaptic cleft, neurotransmitters, and synaptic vesicles.</p> Signup and view all the answers

<p>Acetylcholinesterase breaks down acetylcholine into choline and acetic acid, preventing continuous stimulation of receptors.</p> Signup and view all the answers

<p>The spinal cord is a crucial part of the CNS, extending from the brain to the lower back and facilitating communication between the brain and the body.</p> Signup and view all the answers

<p>Depolarization occurs when neurotransmitters bind to receptors, causing ligand gated Na+ channels to open and Na+ to diffuse into the cell.</p> Signup and view all the answers

<p>The spinal cord is protected by the vertebral column and the meninges, which comprise several layers of connective tissue.</p> Signup and view all the answers

<p>Neurotransmitters unbind from their receptors, are broken down by enzymes like acetylcholinesterase, and can be reabsorbed or diffuse away from the synaptic cleft.</p> Signup and view all the answers

<p>Dendrites are important for neurons as they collect sensory information and synapse with many other cells, enhancing communication.</p> Signup and view all the answers

<p>Sensory neurons collect input from sensory receptors and transmit it to the CNS, while motor neurons transmit signals from the CNS to effectors like muscles and glands.</p> Signup and view all the answers

<p>The somatic nervous system is voluntary and controls skeletal muscles, while the autonomic nervous system is involuntary and regulates smooth and cardiac muscles as well as glands.</p> Signup and view all the answers

<p>Ganglia are collections of neuron cell bodies outside the CNS that play a crucial role in relaying signals between neurons.</p> Signup and view all the answers

<p>The sympathetic division has a shorter preganglionic neuron and a longer postganglionic neuron, while the parasympathetic division has longer preganglionic and shorter postganglionic neurons.</p> Signup and view all the answers

<p>The enteric nervous system is a complex network of neurons located in the walls of the digestive tract that controls digestive processes including muscle contraction and gland secretion.</p> Signup and view all the answers

<p>An action potential arriving at the presynaptic terminal causes voltage-gated Ca2+ channels to open, allowing Ca2+ to diffuse into the cell.</p> Signup and view all the answers

<p>The sensory (afferent) division detects stimuli and transmits information to the CNS, while the motor (efferent) division transmits signals from the CNS to effectors.</p> Signup and view all the answers

<p>Acetylcholine unbinds from its receptors and is broken down by acetylcholinesterase into choline and acetic acid.</p> Signup and view all the answers

<p>The shorter neuron pathways lead to faster responses, allowing the body to quickly prepare for physical activity in threatening situations.</p> Signup and view all the answers

<p>Electrical synapses use gap junctions for direct electrical communication, while chemical synapses use neurotransmitters to transmit signals across a synaptic cleft.</p> Signup and view all the answers

<p>The pre-synaptic membrane releases neurotransmitters, while the post-synaptic membrane contains receptors that bind these neurotransmitters.</p> Signup and view all the answers

<p>The PNS detects stimuli through sensory receptors, sends this information to the CNS, which processes it and sends a motor response back via the PNS.</p> Signup and view all the answers

<p>The spinal cord is protected by the vertebral column and meninges, which consist of multiple layers of connective tissue.</p> Signup and view all the answers

<p>Myelinated axons conduct impulses faster due to saltatory conduction, while unmyelinated axons conduct impulses more slowly as a continuous wave.</p> Signup and view all the answers

<p>Grey matter is located on the periphery of the brain and in the center of the spinal cord, while white matter lies deeper in the brain and on the outer part of the spinal cord.</p> Signup and view all the answers

<p>The Na+/K+ pump actively transports Na+ out of the cell and K+ into the cell, helping to establish and maintain the differences in ionic concentration across the membrane.</p> Signup and view all the answers

<p>Depolarization is the process where the membrane potential becomes less negative, leading to the opening of voltage-gated Na+ channels and the rapid influx of Na+ into the cell.</p> Signup and view all the answers

<p>The Nodes of Ranvier are important for facilitating saltatory conduction, allowing electrical impulses to jump between nodes, which increases the speed of conduction.</p> Signup and view all the answers

<p>The extracellular environment has higher concentrations of Na+ and Cl-, while the intracellular environment has higher concentrations of K+ and proteins.</p> Signup and view all the answers

<p>Ion channels are selectively permeable based on factors such as size, solubility, polarity, and the specific needs of the cell.</p> Signup and view all the answers

<p>During repolarization, K+ channels open allowing K+ to flow out of the cell, while Na+ channels close, returning the membrane potential back toward resting levels.</p> Signup and view all the answers

<p>Grey matter is composed of neuronal cell bodies, dendrites, unmyelinated axons, and glial cells, and is mainly found in the outer cortex of the brain and the 'H' shaped area in the spinal cord.</p> Signup and view all the answers

<p>Unmyelinated axons are thinner and rest within the invaginations of Schwann cells or oligodendrocytes, lacking a myelin sheath.</p> Signup and view all the answers

<p>The sodium potassium pump maintains resting membrane potential by pumping three Na+ ions out of the cell and two K+ ions into the cell, creating a negative charge inside the cell.</p> Signup and view all the answers

<p>An action potential occurs when a stimulus depolarizes the neuron to reach a threshold of about -55mV.</p> Signup and view all the answers

<p>During depolarization, the membrane potential becomes more positive as Na+ ions rush into the cell, exceeding 0mV.</p> Signup and view all the answers

<p>During repolarization, Na+ voltage-gated channels close and K+ voltage-gated channels open, causing K+ to exit the cell and membrane potential to become more negative.</p> Signup and view all the answers

<p>The afterpotential occurs due to the slow closure of K+ channels, allowing K+ to continue exiting the cell, leading to a more negative membrane potential.</p> Signup and view all the answers

<p>After an action potential, the sodium-potassium pump re-establishes the resting membrane potential by restoring the original distribution of Na+ and K+ ions.</p> Signup and view all the answers

<p>K+ leak channels contribute to resting membrane potential by allowing K+ to move out of the cell, which creates a negative charge inside.</p> Signup and view all the answers

<p>The concentration gradient drives Na+ to move into the cell during depolarization, making the intracellular environment more positive.</p> Signup and view all the answers

<p>During depolarization, the inside of the neuron becomes positive while the outside becomes more negative.</p> Signup and view all the answers

<p>At the end of repolarization, Na+ channels are closed and K+ channels eventually close, stabilizing the membrane potential back to resting levels.</p> Signup and view all the answers

<p>Non-gated ion channels are always open, while gated channels require specific signals to open.</p> Signup and view all the answers

<p>In a resting neuron, K+ ions diffuse out due to a higher concentration inside, while Na+ ions diffuse in due to a higher concentration outside.</p> Signup and view all the answers

<p>Negatively charged proteins, which remain inside the cell, contribute to the overall negative charge of the intracellular environment.</p> Signup and view all the answers

<p>The resting membrane potential is around -70mV because of the unequal distribution of Na+ and K+ ions across the membrane and the permeability of the membrane to K+.</p> Signup and view all the answers

<p>More K+ leak channels facilitate greater diffusion of K+ out of the cell, which is vital for maintaining the negative resting membrane potential.</p> Signup and view all the answers

<p>Ligand-gated ion channels open when a specific chemical, or ligand, attaches to the channel.</p> Signup and view all the answers

<p>Voltage-gated ion channels are crucial as they open in response to changes in membrane potential, allowing for rapid depolarization during action potentials.</p> Signup and view all the answers

<p>The Na+/K+ pump maintains resting membrane potential by actively transporting 3 Na+ ions out and 2 K+ ions into the cell.</p> Signup and view all the answers

<p>Other gated ion channels open in response to specific physical stimuli, such as temperature changes or mechanical pressure.</p> Signup and view all the answers

<p>The resting membrane potential can vary in different cell types due to differences in ion channel composition and ion concentrations.</p> Signup and view all the answers