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Chapter 16

The Nervous System and Nervous Tissue

Organisation du système nerveux
Organisation du système nerveux
The nervous system is the primary control and communication center of the body. The nervous system can be divided into two major categories—the ...
Divisions fonctionnelles du système nerveux
Divisions fonctionnelles du système nerveux
The nervous system senses, integrates, and responds to various stimuli. Based on bodily control, the central nervous system cannot be divided ...
Fonctions du système nerveux
Fonctions du système nerveux
The nervous system has three main functions: sensation, integration, and motor output. Sensory functions detect and process stimuli from external and ...
Les neurones : le corps cellulaire et les dendrites
Les neurones : le corps cellulaire et les dendrites
Neurons, excitable nervous system cells, generally consist of three main parts: the cell body, the dendrites, and the axon. The cell body, also known as ...
Neurones : l’axone
Neurones : l’axone
The axon is a long, thin extended portion of the neuron that carries impulses from its cell body toward the effector cell. Axoplasm, the axon's ...
Tissu nerveux : types de neurones
Tissu nerveux : types de neurones
Neurons can be categorized either by their structure or their function. Structurally, neurons are classified by the number of processes emerging from the ...
Tissu nerveux : cellules gliales
Tissu nerveux : cellules gliales
Glial cells or neuroglia are non-neuronal cells in the nervous system that outnumber neurons. These include astrocytes, oligodendrocytes, microglia, and ...
Tissu nerveux : myéline
Tissu nerveux : myéline
Myelin is a protective, multilayered covering around axons, composed of lipids and proteins, that provides electrical insulation. In the PNS, individual ...
Gradient électrochimique et protéines de canal : un aperçu
Gradient électrochimique et protéines de canal : un aperçu
An electrochemical gradient is a fundamental concept in biology and chemistry. It regulates the movement of ions across cell membranes. This movement is ...
Canaux ioniques ligand-dépendants
Canaux ioniques ligand-dépendants
Ligand-gated ion channels are transmembrane proteins with a channel for ions to pass through and a binding site for a ligand. The channel opens only when ...
Canaux ioniques voltage-dépendants
Canaux ioniques voltage-dépendants
Voltage-gated ion channels are transmembrane proteins that open and close in response to changes in the membrane potential. They are present on the ...
Canaux ioniques à portes mécaniques
Canaux ioniques à portes mécaniques
Mechanically-gated ion channels are proteins found in eukaryotic and prokaryotic cell membranes that open in response to mechanical stress. Tension, ...
Potentiel de membrane au repos
Potentiel de membrane au repos
The relative difference in electrical charge, or voltage, between the inside and the outside of a cell membrane, is called the membrane potential. It is ...
Décroissance du potentiel au repos
Décroissance du potentiel au repos
The resting membrane potential of a neuron (-70mV) is sustained due to the selective ion permeability of the membrane. At the resting potential, the ...
Potentiel gradué
Potentiel gradué
The graded potential is a short-lived, localized change in the membrane potential of a neuron. A graded potential occurs in response to a stimulus, ...
Potentiel d’action
Potentiel d’action
Neurons communicate by firing action potentials—the electrochemical signal that is propagated along the axon. The signal results in the release of ...
Potentiel d’action : phases de stimulation
Potentiel d’action : phases de stimulation
An action potential has three main phases: depolarization, repolarization, and hyperpolarization. The depolarizing phase begins after a graded potential ...
Propagation des potentiels d’action
Propagation des potentiels d’action
The Propagation of an action potential is the process by which a nerve impulse is transmitted along the axon. It is a self-propagating process; once ...
Vue d’ensemble des synapses
Vue d’ensemble des synapses
Synapse is a region where communication occurs between two neurons or a neuron and its effector cell. The neuron that carries the impulse toward the ...
Synapses chimiques
Synapses chimiques
Chemical synapses are specialized sites between two neurons or between a neuron and a non-neuronal cell like a muscle, glandular or sensory cell. Because ...
Neuromédiateurs
Neuromédiateurs
Neurotransmitters play a crucial role in the communication between neurons in the autonomic nervous system. Neurons in the autonomic nervous system can be ...
Potentiel postsynaptique (PSP)
Potentiel postsynaptique (PSP)
Postsynaptic potential or PSP refers to a change in the electrical potential of a postsynaptic membrane when neurotransmitters released by presynaptic ...
Intégration d’événements synaptiques
Intégration d’événements synaptiques
The integration of synaptic events involves the summation of multiple graded potentials, such as excitatory and inhibitory postsynaptic potentials, at the ...
Circuits neuronaux
Circuits neuronaux
In the central nervous system, billions of interconnected neurons are organized into specialized functional groups called neuronal pools. Within each ...
Neurogenèse et régénération du tissu nerveux
Neurogenèse et régénération du tissu nerveux
In the CNS, neurogenesis, the birth of new neurons from stem cells, is limited to the hippocampus in adults. In other regions of the brain and spinal ...
Troubles du tissu nerveux
Troubles du tissu nerveux
Nervous tissue disorders are caused by several factors. Homeostatic imbalances include cerebral hypoxia  — or reduced oxygen supply to the ...
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