Fundamentals of the Nervous System and Nervous Tissue

These flashcards cover key vocabulary and concepts related to the nervous system and nervous tissue as discussed in the lecture.

Neurotransmitter

Chemicals that transmit signals from one neuron to another across a synapse.

Central Nervous System (CNS)

The part of the nervous system consisting of the brain and spinal cord.

Peripheral Nervous System (PNS)

The portion of the nervous system outside the central nervous system.

Sensory Input

Information gathered by sensory receptors about internal and external changes.

Integration

Processing and interpretation of sensory input by the nervous system.

Motor Output

Activation of effector organs (muscles and glands) produces a response.

Astrocytes

The most abundant neuroglia in the CNS, which support and brace neurons.

Microglial Cells

Defensive cells in the CNS that monitor neurons and can phagocytize debris.

Ependymal Cells

Cells that line the central cavities of the brain and spinal column, circulate cerebrospinal fluid.

Oligodendrocytes

Neuroglia that form insulating myelin sheaths around CNS nerve fibers.

Dendrites

Processes of neurons that receive signals and convey incoming messages toward the cell body.

Axon

The long, slender projection of a neuron that conducts electrical impulses away from the neuron's cell body.

Myelin Sheath

A protective covering that surrounds axons and increases the speed of nerve impulse transmission.

Somatic Nervous System

Division of the PNS that controls voluntary movements by activating skeletal muscles.

Autonomic Nervous System

Subdivision of the PNS that controls involuntary actions, regulating smooth and cardiac muscles and glands.

Sensory (Afferent) Division

The branch of the PNS that carries sensory input to the CNS.

Motor (Efferent) Division

The branch of the PNS that carries impulses away from the CNS to effectors.

Ganglia

Clusters of neuron cell bodies located in the peripheral nervous system.

Nuclei

Clusters of neuron cell bodies located in the central nervous system.

Neurons

Excitable cells in the nervous system that transmit electrical signals.

Amitotic

The inability of neurons to undergo mitosis, with few exceptions.

Neurotransmitter

Specialized chemical messengers that transmit signals across a synapse from one neuron (nerve cell) to another target cell. They play a crucial role in communication within the nervous system, affecting various functions like mood, sleep, and learning.

Central Nervous System (CNS)

The major part of the nervous system, comprising the brain and spinal cord. It acts as the command center, integrating incoming sensory information and initiating motor responses.

Peripheral Nervous System (PNS)

The division of the nervous system that extends outside the Central Nervous System (CNS), consisting of all nerves that branch out from the brain and spinal cord to other parts of the body, including muscles and organs. It serves as a communication relay between the CNS and the rest of the body.

Sensory Input

The process by which specialized sensory receptors gather stimuli from the internal (e.g., body temperature) and external environment (e.g., light, sound, touch). This information is then conveyed to the Central Nervous System (CNS) for processing.

Integration

The crucial function of the Central Nervous System (CNS) where sensory input is received, processed, interpreted, and decisions are made on how to respond. It involves analyzing information and forming a coherent picture of body states and external conditions.

Motor Output

The response generated by the nervous system after integration of sensory input. This involves signals being sent from the Central Nervous System (CNS) to effector organs, such as muscles and glands, to initiate a movement or secrete a substance.

Astrocytes

Star-shaped neuroglia (glial cells) found in the Central Nervous System (CNS). They are the most abundant type and provide structural support, regulate the chemical environment, exchange between capillaries and neurons, and help in neural information processing.

Microglial Cells

Small, ovoid neuroglia with thorny processes in the Central Nervous System (CNS). They act as the primary immune defense, monitoring the health of neurons and phagocytizing cellular debris, waste products, and pathogens.

Ependymal Cells

Neuroglia that line the central cavities of the brain (ventricles) and the spinal cord (central canal). They are involved in the production and circulation of cerebrospinal fluid (CSF), which cushions the CNS.

Oligodendrocytes

Neuroglia found in the Central Nervous System (CNS) that form the myelin sheath around multiple axons. This myelin sheath provides electrical insulation, significantly increasing the speed of nerve impulse transmission.

Dendrites

Short, branched processes extending from a neuron's cell body. They are the primary receiving regions for incoming signals from other neurons, conveying these electrical messages (graded potentials) toward the cell body.

Axon

A single, long, slender projection extending from the neuron's cell body that functions to transmit electrical impulses, called action potentials, away from the cell body towards other neurons, muscles, or glands.

Myelin Sheath

A white, fatty insulating layer composed of oligodendrocytes (in CNS) or Schwann cells (in PNS) that surrounds and protects the axon of many neurons. Its main function is to dramatically increase the speed at which electrical impulses are conducted along the axon.

Somatic Nervous System

A division of the Peripheral Nervous System (PNS) responsible for voluntary control of body movements by innervating skeletal muscles. It transmits sensory information to the CNS and motor commands from the CNS to the muscles.

Autonomic Nervous System (ANS)

A subdivision of the Peripheral Nervous System (PNS) that regulates involuntary visceral functions such as heart rate, digestion, respiration, perspiration, and sexual arousal. It controls smooth muscle, cardiac muscle, and glands.

Sensory (Afferent) Division

The division of the Peripheral Nervous System (PNS) consisting of nerve fibers that transmit impulses from sensory receptors (e.g., skin, organs) towards the Central Nervous System (CNS), carrying information about both internal and external stimuli.

Motor (Efferent) Division

The division of the Peripheral Nervous System (PNS) composed of nerve fibers that transmit impulses away from the Central Nervous System (CNS) to effector organs such as muscles and glands, initiating a motor response.

Ganglia

Collections of neuron cell bodies (somas) located outside the Central Nervous System (CNS), specifically within the Peripheral Nervous System (PNS). They typically serve as relay stations or integration centers.

Nuclei

Clusters of neuron cell bodies (somas) found within the Central Nervous System (CNS). These distinct groups of neurons often share a common function or connectivity.

Neurons

The fundamental unit of the nervous system; highly specialized, excitable cells that generate and transmit electrical signals (nerve impulses or action potentials). They are responsible for communication throughout the body.

Amitotic

A characteristic of most mature neurons, meaning they lose their ability to divide (undergo mitosis) once they are fully differentiated. This contributes to the nervous system's limited capacity for repair and regeneration after injury. However, some exceptions exist, such as neural stem cells.