Nervous System Overview

Nervous System Overview

• The nervous system facilitates rapid communication within the body, controlling and adjusting bodily activities.
• It swiftly responds to stimuli to maintain homeostasis, contrasting with the endocrine system's longer-term regulations.
• It acts as an integration center for reflex arcs (somatic and visceral), interpreting sensory information and handling memory, learning, thought, personality, consciousness, communication, and emotion.

Central Nervous System (CNS)

• The CNS comprises the brain and spinal cord.
• It integrates, processes, and coordinates sensory and motor input.
• It's the seat of higher brain functions.

Peripheral Nervous System (PNS)

• The PNS is the nervous tissue outside the CNS.
• It transmits sensory information to the CNS and carries motor commands away from the CNS.
• Afferent pathways transmit information to the CNS (originating at receptors).
• Efferent pathways carry motor commands away from the CNS to effectors.

Neuron Structure and Function

• Neurons are the fundamental units of the nervous system.
• Sensory neurons transmit information from the PNS towards the CNS.
• Motor neurons carry commands from the CNS to effectors.
• Neuroglia cells support neurons by regulating their extracellular environment, defending against pathogens, and repairing tissue.
• Dendrites receive stimuli from the environment or other cells.
• The axon conducts nerve impulses (action potentials) toward axon terminals.
• Myelin, a membranous wrapping produced by neuroglia, speeds up action potential propagation.

Neuroglia Cells (CNS)

• Astrocytes maintain the blood-brain barrier, providing structural support and regulating ion concentrations, absorbing and recycling neurotransmitters, and forming scar tissue.
• Oligodendrocytes myelinate CNS axons.
• Microglia remove cell debris and pathogens.
• Ependymal cells produce, circulate, and monitor cerebrospinal fluid, lining ventricles and the central canal.

Neuroglia Cells (PNS)

• Satellite cells surround neuron cell bodies; they regulate O2, CO2, nutrient, and neurotransmitter levels around neurons in ganglia.
• Schwann cells surround peripheral axons, myelinate them, and participate in repair processes following injury.

Internodes and Neuronal Types

• An internode is the portion of a myelinated axon between adjacent Schwann cells.
• Anaxonic neurons lack distinguishable axons and dendrites; they are only found in the CNS and special sense organs.
• Bipolar neurons possess two processes separated by the cell body; they're involved in sight, smell, and hearing, and typically lack myelin.
• Pseudo-unipolar neurons have a single, long process with the cell body off to one side; they are often sensory neurons in the PNS and may be myelinated.
• Multipolar neurons have multiple processes; they are typically associated with skeletal motor neurons and the most common type in the CNS.

Neuron Properties

• Individual neurons can repair themselves.
• Adult neurons generally do not divide.
• Astrocytes can limit repair in the CNS through generating scar tissue and secreting chemicals hindering axon regrowth.

Synapses

• Synapses are junctions between neurons or between a neuron and another cell type.
• Chemical synapses use neurotransmitters (e.g., acetylcholine) for one-way transmission, such as in the motor end plate of skeletal muscle.
• Electrical synapses allow two-way transmission between neurons through tightly bound membranes, where the action potential propagates via ion movement.

Neural Pools

• Neural pools are groups of neurons working together, categorized by their functions - divergence, convergence, serial processing, parallel processing, and reverberation circuits.
• Divergence transmits stimulation to multiple neurons or pools.
• Convergence allows signals from multiple sources to influence a single neuron.
• Serial processing involves neurons or pools working sequentially.
• Parallel processing involves simultaneous processing of information by different neurons or pools.
• Reverberation circuits involve positive feedback.

Spinal Cord

• The spinal cord integrates and processes information, functioning in conjunction with the brain, but can also operate independently.
• Growth stops by age 4, terminating at the conus medullaris, followed by the cauda equina.
• Cervical and lumbar enlargements control limb functions.
• 31 spinal segments form the spinal nerves (mixed nerves with sensory and motor fibers).

Spinal Meninges and Spinal Nerves

• Spinal meninges (dura mater, arachnoid mater, pia mater) surround and protect the spinal cord.
• Spinal nerves consist of dorsal and ventral roots, and dorsal root ganglia, collectively providing connection between the spinal cord and the body.

Peripheral Nerves

• Peripheral nerves are composed of epineurium, perineurium, and endoneurium layers.
• Ependyrium is the outer layer that connects to the dura mater.
• A perineurium layer surrounds a fascicle (bundle of axons).
• Endoneurium surrounds individual axons or Schwann cells.

Miscellaneous Anatomical Information (Specific Examples)

• The provided data includes various anatomical structures, their functions, locations, relationships, and identification by letter on diagrams.
• The information covers endocrine glands, specific structures within the body, and various functions. The references to letters on diagrams indicate the location of those elements within the body.
• Additional note: This data is compiled primarily for identifying and locating structures, not necessarily in a logically sequential or comprehensive presentation of all anatomy information.

Explore the intricate workings of the nervous system in this quiz. Understand the roles of the Central Nervous System (CNS) and Peripheral Nervous System (PNS) in controlling and coordinating bodily functions. Dive into topics such as sensory information processing, reflex arcs, and higher brain functions.