뒤로Anatomy & Physiology: Nervous Tissue and Physiology
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The brain, spinal cord, and nerves make up the nervous system.
The Central Nervous System (CNS) and the Peripheral Nervous System (PNS).
The CNS acts as the integrating and control center for processing sensory input and coordinating responses.
The sensory (afferent) division that receives information and the motor (efferent) division that sends commands to effectors.
The somatic nervous system (voluntary control of skeletal muscles) and the autonomic nervous system (ANS) (involuntary control of smooth muscle, cardiac muscle, and glands).
Sensory input, integration, and motor output.
A neuron has a cell body with nucleus, dendrites for receiving signals, and a single axon for transmitting impulses.
Dendrites receive signals and generate local potentials but do not produce action potentials.
The axon hillock is the junction between the cell body and axon where action potentials are initiated.
The myelin sheath insulates axons and increases the speed of electrical signal transmission.
Oligodendrocytes form myelin in the CNS; Schwann cells form myelin in the PNS.
Gaps between myelin sheath segments where action potentials are regenerated to speed conduction.
Multipolar (most common), bipolar (rare, e.g., retina), and unipolar (sensory neurons in PNS).
Sensory neurons transmit impulses to CNS, motor neurons carry impulses away from CNS, and interneurons connect sensory and motor neurons.
Neuroglia support neurons by maintaining the extracellular environment, assisting neural function, and repairing tissue.
Astrocytes: support and blood-brain barrier; Oligodendrocytes: myelinate CNS axons; Microglia: phagocytize debris; Ependymal cells: produce and circulate cerebrospinal fluid.
Schwann cells form myelin sheaths; Satellite cells surround and support neuron cell bodies.
Process where the part of an axon distal to injury degenerates and is cleared by phagocytes.
In the PNS, axon regeneration is possible if the cell body and part of the myelinated axon remain; in the CNS, regeneration is limited due to scar tissue formation by astrocytes.
Movement of materials along the axon: slow transport moves cytoskeletal proteins anterogradely; fast transport moves vesicles and organelles both anterogradely and retrogradely.