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Chapter 16

The Nervous System and Nervous Tissue

تنظيم الجهاز العصبي
تنظيم الجهاز العصبي
The nervous system is the primary control and communication center of the body. The nervous system can be divided into two major categories—the ...
التقسيمات الوظيفية للجهاز العصبي
التقسيمات الوظيفية للجهاز العصبي
The nervous system senses, integrates, and responds to various stimuli. Based on bodily control, the central nervous system cannot be divided ...
وظائف الجهاز العصبي
وظائف الجهاز العصبي
The nervous system has three main functions: sensation, integration, and motor output. Sensory functions detect and process stimuli from external and ...
الخلايا العصبية: جسم الخلية والتشعبات
الخلايا العصبية: جسم الخلية والتشعبات
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 ...
الخلايا العصبية: المحور العصبي
الخلايا العصبية: المحور العصبي
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 ...
الأنسجة العصبية: أنواع الخلايا العصبية
الأنسجة العصبية: أنواع الخلايا العصبية
Neurons can be categorized either by their structure or their function. Structurally, neurons are classified by the number of processes emerging from the ...
الأنسجة العصبية: الخلايا الدبقية
الأنسجة العصبية: الخلايا الدبقية
Glial cells or neuroglia are non-neuronal cells in the nervous system that outnumber neurons. These include astrocytes, oligodendrocytes, microglia, and ...
الأنسجة العصبية: المايلين
الأنسجة العصبية: المايلين
Myelin is a protective, multilayered covering around axons, composed of lipids and proteins, that provides electrical insulation. In the PNS, individual ...
التدرج الكهروكيميائي وبروتينات القناة: نظرة عامة
التدرج الكهروكيميائي وبروتينات القناة: نظرة عامة
An electrochemical gradient is a fundamental concept in biology and chemistry. It regulates the movement of ions across cell membranes. This movement is ...
القنوات الأيونية ذات البوابات الترابطية
القنوات الأيونية ذات البوابات الترابطية
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 ...
القنوات الأيونية ذات الجهد الكهربائي
القنوات الأيونية ذات الجهد الكهربائي
Voltage-gated ion channels are transmembrane proteins that open and close in response to changes in the membrane potential. They are present on the ...
القنوات الأيونية ذات البوابات الميكانيكية
القنوات الأيونية ذات البوابات الميكانيكية
Mechanically-gated ion channels are proteins found in eukaryotic and prokaryotic cell membranes that open in response to mechanical stress. Tension, ...
إمكانات غشاء الراحة
إمكانات غشاء الراحة
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 ...
الاضمحلال المحتمل للراحة
الاضمحلال المحتمل للراحة
The resting membrane potential of a neuron (-70mV) is sustained due to the selective ion permeability of the membrane. At the resting potential, the ...
الإمكانات المتدرجة
الإمكانات المتدرجة
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, ...
إمكانات العمل
إمكانات العمل
Neurons communicate by firing action potentials—the electrochemical signal that is propagated along the axon. The signal results in the release of ...
إمكانات العمل: مراحل التحفيز
إمكانات العمل: مراحل التحفيز
An action potential has three main phases: depolarization, repolarization, and hyperpolarization. The depolarizing phase begins after a graded potential ...
انتشار إمكانات الفعل
انتشار إمكانات الفعل
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 ...
نظرة عامة على نقاط الاشتباك العصبي
نظرة عامة على نقاط الاشتباك العصبي
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 ...
المشابك الكيميائية
المشابك الكيميائية
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 ...
العصبيه
العصبيه
Neurotransmitters play a crucial role in the communication between neurons in the autonomic nervous system. Neurons in the autonomic nervous system can be ...
إمكانات ما بعد المشبكي (PSP)
إمكانات ما بعد المشبكي (PSP)
Postsynaptic potential or PSP refers to a change in the electrical potential of a postsynaptic membrane when neurotransmitters released by presynaptic ...
تكامل الأحداث المتشابكة
تكامل الأحداث المتشابكة
The integration of synaptic events involves the summation of multiple graded potentials, such as excitatory and inhibitory postsynaptic potentials, at the ...
الدوائر العصبية
الدوائر العصبية
In the central nervous system, billions of interconnected neurons are organized into specialized functional groups called neuronal pools. Within each ...
تكوين الخلايا العصبية وتجديد الأنسجة العصبية
تكوين الخلايا العصبية وتجديد الأنسجة العصبية
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 ...
اضطرابات الأنسجة العصبية
اضطرابات الأنسجة العصبية
Nervous tissue disorders are caused by several factors. Homeostatic imbalances include cerebral hypoxia  — or reduced oxygen supply to the ...
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