Nervous System Overview

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Questions and Answers

What is the primary function of the nervous system?

To facilitate blood circulation

To control and communicate body functions (correct)

To provide structural support to the body

To regulate body temperature

Which part of the nervous system serves as the integration and command center?

Central Nervous System (correct)

Peripheral Nervous System

Somatic Nervous System

Autonomic Nervous System

What type of fiber transmits impulses from visceral organs to the brain?

Visceral afferent fibers (correct)

Efferent fibers

Sensory afferent fibers

Skeletal muscle fibers

Which division of the peripheral nervous system controls skeletal muscles consciously?

Somatic Nervous System Signup and view all the answers

What are the two principal cell types of the nervous system?

Neurons and glial cells Signup and view all the answers

What is the role of supporting cells in the nervous system?

To surround and support neurons Signup and view all the answers

Which component of the autonomic nervous system is responsible for the 'fight or flight' response?

Sympathetic division Signup and view all the answers

Which nervous system division carries messages to and from the brain and spinal cord?

Peripheral Nervous System Signup and view all the answers

What primary role do astrocytes play in the nervous system?

Support and brace neurons Signup and view all the answers

Which type of glial cell is responsible for monitoring the health of neurons?

Microglia Signup and view all the answers

What is the primary function of oligodendrocytes?

Wrap CNS nerve fibers with myelin Signup and view all the answers

What structure is primarily associated with the cell body of a neuron?

Nissl bodies Signup and view all the answers

Which glial cell type surrounds neuronal cell bodies in ganglia?

Satellite cells Signup and view all the answers

What is NOT a characteristic of neurons?

Short lifespan Signup and view all the answers

What do ependymal cells primarily do in the central nervous system?

Line the central cavities of the brain and spinal cord Signup and view all the answers

Which of the following glial cells is specific to the peripheral nervous system?

Schwann cells Signup and view all the answers

What is the primary role of dendrites in motor neurons?

Act as input regions for receiving signals Signup and view all the answers

Which structure arises from the axon hillock?

Axons Signup and view all the answers

Which component of the nervous system forms the myelin sheath around axons?

Schwann cells in the PNS Signup and view all the answers

What is the main function of the myelin sheath?

Protect the axon and increase transmission speed Signup and view all the answers

What are Nodes of Ranvier?

Gaps in the myelin sheath between Schwann cells Signup and view all the answers

In which type of matter are dense collections of myelinated fibers found in the brain and spinal cord?

White matter Signup and view all the answers

Which type of cell is responsible for forming myelin sheaths in the central nervous system?

Oligodendrocytes Signup and view all the answers

How do long axons compare to typical axons?

They are referred to as nerve fibers Signup and view all the answers

What is one of the primary roles of astrocytes in the nervous system?

Supporting and bracing neurons Signup and view all the answers

Which characteristic distinguishes oligodendrocytes from Schwann cells?

Oligodendrocytes wrap multiple CNS nerve fibers. Signup and view all the answers

What is the primary function of microglia in the nervous system?

Serve as phagocytes monitoring neuron health Signup and view all the answers

Which structural component of a neuron is responsible for cell-to-cell signaling?

Dendrites Signup and view all the answers

What role do ependymal cells play in the central nervous system?

Producing cerebrospinal fluid Signup and view all the answers

How do satellite cells function in the peripheral nervous system?

Surrounding neuron cell bodies in ganglia Signup and view all the answers

What is a primary characteristic of neurons?

They are amitotic and long-lived. Signup and view all the answers

Which type of cells are primarily responsible for nutrient supply and chemical environment regulation in neural tissue?

Astrocytes Signup and view all the answers

What characteristic allows oligodendrocytes to insulate multiple axons in the central nervous system?

Branching structure Signup and view all the answers

Which function best describes the role of the neuron cell body (soma)?

Synthesize proteins and maintain cell health. Signup and view all the answers

Which statement accurately reflects the structure of dendrites in motor neurons?

They are short, tapering, and diffusely branched processes. Signup and view all the answers

What is a function of the myelin sheath surrounding axons?

To protect the axon and increase the speed of impulse transmission. Signup and view all the answers

Which type of cells are responsible for forming the myelin sheath in the peripheral nervous system?

Schwann cells Signup and view all the answers

What structure describes the gaps in the myelin sheath between adjacent Schwann cells?

Nodes of Ranvier Signup and view all the answers

What is true regarding the axons of the central nervous system compared to those in the peripheral nervous system?

Both myelinated and unmyelinated fibers are present in the CNS. Signup and view all the answers

What distinguishes white matter in the brain and spinal cord?

It consists of dense collections of myelinated fibers. Signup and view all the answers

What role do oligodendrocytes play in the central nervous system?

They form the myelin sheath around axons. Signup and view all the answers

What is the role of the sensory division in the peripheral nervous system?

It monitors and carries stimuli from sensory receptors to the brain. Signup and view all the answers

Which statement best describes the axon in terms of its function?

Axons secrete neurotransmitters and transmit action potentials. Signup and view all the answers

Which function is primarily associated with the integration role of the nervous system?

Interpreting sensory information. Signup and view all the answers

Which of the following statements is NOT true regarding the structure of an axon?

Axons are generally short and heavily branched. Signup and view all the answers

What is the function of the neurilemma in relation to the axon?

It protects the axon and plays a role in its regeneration. Signup and view all the answers

Which part of the autonomic nervous system is primarily responsible for regulating glandular activity?

Parasympathetic division. Signup and view all the answers

What is the primary function of neurons in the nervous system?

To transmit electrical signals. Signup and view all the answers

Which of the following best explains the term 'afferent' in the context of sensory nerves?

Nerves that carry signals toward the central nervous system. Signup and view all the answers

In what way do supporting cells contribute to the function of neurons?

They provide structural support and insulation. Signup and view all the answers

Which statement about the central nervous system (CNS) is accurate?

It consists of the brain and spinal cord. Signup and view all the answers

What is the primary action that occurs in the autonomic nervous system?

Regulation of involuntary body functions. Signup and view all the answers

Which glial cell type is primarily associated with myelination in the peripheral nervous system?

Schwann cells. Signup and view all the answers

What is the primary distinction between the sympathetic and parasympathetic divisions of the autonomic nervous system?

Sympathetic speeds up bodily functions; parasympathetic slows them down. Signup and view all the answers

Study Notes

The Nervous System

The nervous system manages communication and control within the body.
The nervous system carries out three primary functions:
- Sensory input: Detecting internal and external stimuli
- Integration: Interpreting sensory information
- Motor output: Initiating responses to stimuli, often by activating effector organs like muscles or glands

Nervous System Organization

The nervous system breaks down into two main parts:
- Central nervous system (CNS): Consists of the brain and spinal cord, serving as the integration and command center.
- Peripheral nervous system (PNS): Comprises paired cranial and spinal nerves, transmitting messages to and from the CNS.

Peripheral Nervous System (PNS)

The PNS splits into two functional divisions for communication:
- Sensory (afferent) division: Carries signals to the CNS for processing:
  - Sensory afferent fibers: Carry information from skin, muscles, and joints.
  - Visceral afferent fibers: Transmit information from internal organs.
- Motor (efferent) division: Transmits commands from the CNS to effector organs.

Motor Division: Controlling Movement and Function

The motor division branches into two primary parts:
- Somatic nervous system: Responsible for conscious control of skeletal muscles, allowing voluntary movement.
- Autonomic nervous system (ANS): Regulates involuntary functions, controlling smooth muscle, cardiac muscle, and glands. The ANS is divided further into the sympathetic and parasympathetic systems.

Nervous Tissue: Cells of the Nervous System

The nervous system contains two principal cell types:
- Neurons: Specialized cells that transmit electrical signals, enabling communication within the nervous system.
- Supporting cells (neuroglia or glial cells): Cells that provide essential support for neurons:
  - Offer physical scaffolding.
  - Segregate and insulate neurons.
  - Promote neuron health and growth.

Astrocytes: The Most Abundant Glial Cells

Astrocytes, the most numerous and versatile glial cells, perform multiple critical functions:
- Support and anchor neurons.
- Connect neurons to their nutrient supplies.
- Guide the migration of developing neurons.
- Regulate the chemical environment around neurons.

Other Glial Cell Types

Microglia: Small, phagocytic glial cells that monitor the health of neurons, removing cellular debris and pathogens.
Ependymal cells: Line the central cavities of the brain and spinal cord, contributing to the production and circulation of cerebrospinal fluid.

Oligodendrocytes, Schwann Cells, and Satellite Cells

Oligodendrocytes: These cells create the myelin sheath around axons in the CNS, enhancing signal transmission.
Schwann cells: Responsible for myelin sheath formation around axons in the PNS, increasing signal speed and providing insulation.
Satellite cells: Surround neuron cell bodies in ganglia (collections of neuron cell bodies in the PNS), offering supportive functions.

Neurons: Structural and Functional Units of the Nervous System

Neurons, the fundamental units of the nervous system, share a common structure:
- Cell body (soma): Contains the nucleus and is the site of protein synthesis.
- Axon: A long, slender process that transmits electrical signals (action potentials) away from the cell body.
- Dendrites: Short, branching processes that receive incoming signals from other neurons.

Nerve Cell Body (Soma or Perikaryon)

The cell body is crucial for neuron function due to:
- Nucleus: Contains the genetic material for neuronal function.
- Nissl bodies: (rough ER) Responsible for protein synthesis, essential for neuron growth and repair.
- Axon hillock: The cone-shaped region where the axon emerges from the cell body, initiating the action potential.

Neuronal Processes: Extensions of the Cell Body

Tracts: Bundles of axons within the CNS.
Nerves: Bundles of axons within the PNS.
Dendrites: Short, tapering, branching processes that receive incoming signals from other neurons, acting as input regions.
Axon: A long, single process that generates and transmits action potentials away from the cell body.
The axon transmits signals to other neurons or effector organs.

Myelin Sheath: Insulating and Protecting Axons

The myelin sheath is a whitish, fatty (protein-lipoid) layer that surrounds most long axons, providing insulation and increasing signal efficiency.
Functions of the myelin sheath:
- Protects the axon.
- Electrically isolates axons from each other.
- Speeds up the transmission of nerve impulses.

Myelin Sheath Formation in the PNS

Schwann cells: Responsible for formation in the PNS. A Schwann cell wraps its plasma membrane around an axon to form the myelin sheath, leaving gaps called Nodes of Ranvier.
Neurilemma: The remaining cytoplasm and nucleus of the Schwann cell.

Myelination in the CNS

Oligodendrocytes: Form the myelin sheath around axons in the CNS.
Nodes of Ranvier: Widely spaced in the CNS.

White and Grey Matter: Structures of the Brain and Spinal Cord

White matter: Made up primarily of myelinated axons, giving it a whitish appearance.
Grey matter: Mostly consists of neuron cell bodies (soma) and unmyelinated axons, giving it a greyish appearance.

Nervous System Overview

Master controlling and communicating system of the body.
Plays a vital role in monitoring internal and external stimuli, integrating information, and generating responses to activate effector organs.

Nervous System Organization

Central Nervous System (CNS):
- Consists of brain and spinal cord.
- Acts as the integration and command center.
Peripheral Nervous System (PNS):
- Includes paired spinal and cranial nerves.
- Primarily responsible for communication between CNS and the rest of the body.

Peripheral Nervous System Divisions

Sensory (Afferent) Division:
- Carries sensory information from the body (skin, muscles, joints, and internal organs) to the CNS.
- Consists of sensory afferent fibers and visceral afferent fibers.
Motor (Efferent) Division:
- Carries motor commands from the CNS to effector organs (muscles and glands).

Motor Division Subdivisions

Somatic Nervous System:
- Controls voluntary movement of skeletal muscles.
Autonomic Nervous System (ANS):
- Regulates involuntary functions of smooth muscle, cardiac muscle, and glands.
- Divided into sympathetic and parasympathetic divisions.

Nervous Tissue Histology

Composed of two primary cell types:
- Neurons: Excitable cells responsible for transmitting electrical signals.
- Neuroglia (Glial Cells): Supportive cells that create a supportive scaffold, insulate neurons, and promote neuron health and growth.

Neuroglia Types and Functions

Astrocytes:
- Most abundant and versatile glial cells.
- Support and brace neurons, anchor them to nutrient sources, guide neuron migration, and control the chemical environment.
Microglia:
- Small, ovoid cells with spiny processes.
- Act as phagocytes, monitoring neuron health and removing debris.
Ependymal Cells:
- Line the central cavities of the brain and spinal cord.
- Play a role in cerebrospinal fluid production and circulation.
Oligodendrocytes:
- Branched cells that wrap around CNS nerve fibers, forming myelin sheaths.
Schwann Cells:
- Surround PNS nerve fibers, also forming myelin sheaths.
Satellite Cells:
- Surround neuron cell bodies within ganglia, providing support and regulation.

Neuron Structure and Function

Structural units of the nervous system.
Composed of a cell body, axon, and dendrites.
Long-lived, non-dividing cells with a high metabolic rate.
Plasma membrane plays a critical role in electrical signaling and cell-to-cell communication.

Neuron Components

Cell Body (Soma):
- Contains the nucleus, nucleolus, and is the site of protein synthesis.
- Contains Nissl bodies, which are rough endoplasmic reticulum involved in protein production.
- Has an axon hillock, the cone-shaped region from which axons emerge.
Processes:
- Arm-like extensions from the soma.
- Include axons and dendrites.
- Called tracts in the CNS and nerves in the PNS.
Dendrites:
- Short, tapering, and branched processes.
- Receive input from other neurons, acting as the receptive region of the neuron.
Axon:
- Single, slender process arising from the axon hillock.
- Often covered in a myelin sheath.
- Generates and transmits nerve impulses (action potentials).
- Secretes neurotransmitters at the axon terminal, where it communicates with other neurons.

Myelin Sheath

Whitish, fatty sheath that insulates and protects axons.
Functions:
- Protects the axon.
- Electrically insulates fibers from one another.
- Increases the speed of nerve impulse transmission.

Myelin Sheath Formation

In the PNS: Formed by Schwann cells wrapping around the axon.
In the CNS: Formed by oligodendrocytes.
Nodes of Ranvier: Gaps in the myelin sheath between adjacent Schwann cells or oligodendrocytes, where the axon is exposed.

Gray and White Matter

White Matter: Primarily composed of myelinated axons, giving it a whitish appearance.
Gray Matter: Composed of soma, dendrites, and unmyelinated axons, appearing grayish in color.

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Description

Explore the essential functions and organization of the nervous system, including its central and peripheral components. This quiz covers sensory input, integration, and motor output, essential for understanding body communication and control.