Nervous System Overview Quiz

Nervous System Overview

• The nervous system is comprised of two cell types: neurons and glial cells.
• Neurons are the functional units responsible for communication through electrical signals.
• Glial cells are support cells that enable neuron function.
• Neurons are polarized cells with dendrites receiving signals, which are then passed to the cell body and propagated along the axon to terminal ends that synapse with other cells.
• Myelin speeds signal conduction.

Central and Peripheral Nervous Systems

• Central Nervous System (CNS) = brain and spinal cord.
• Peripheral Nervous System (PNS) = nerves.
• The brain is located in the cranial cavity of the skull, and the spinal cord, in the vertebral canal of the vertebral column.
• The peripheral nervous system is so named because it extends beyond the brain and spinal cord.

Functional Classification of Nervous Systems

• Sensory functions receive information from the environment.
• Motor functions react to sensory information.
• Integration functions coordinate between sensory and motor functions.

Types of Neurons

• Sensory (afferent) neurons carry impulses from the periphery to the CNS.
• Motor (efferent) neurons carry signals from the CNS to body systems.
• Interneurons provide connections between afferent and efferent neurons, most abundant.

Sensory Function: The Sensation

• Sensation refers to receiving information about the environment.
• Stimuli (singular = stimulus) are these sensations.
• Sensory information travels to the CNS via afferent (sensory) branches of the PNS.
• Somatic sensory refers to sensations outside the body, while visceral sensory refers to sensations from within the body.

Motor Function: The Response

• Responses occur in effector organs (such as muscles or glands) in reaction to sensory stimuli.
• Motor (efferent) branches of PNS transmit signals from the CNS to effector organs
• Somatic motor neurons control voluntary muscle responses; autonomic motor neurons control involuntary responses in cardiac or smooth muscles or glands.

Integration: Coordination between Sensation and Response

• Stimuli are detected by sensory structures (somatic or visceral sensory).
• Through afferent nerves they are communicated to CNS.
• In the CNS, information from stimuli is integrated.
• A motor neuron in the CNS is stimulated and directs the effector organ.
• The process by which sensory information is processed and a motor response is generated is called integration.

Nervous System Cells

• Neurons are the primary functional units in the nervous system, classified by the direction in which they conduct impulses.
  • They are generators and conductors of nerve impulses.
  • They employ electrochemical processes involving sodium and potassium ions to change the electrical potential of neuron fluid.
• Glial cells provide support to neurons.
  • They have connective tissue supporting functions within the CNS.

Brain Review Parts

• Brain is divided into two hemispheres connected by a bundle of nerves (corpus callosum)
• Each hemisphere controls the opposite side of the body
• The three broad functions of the CNS are to take in sensory information, process the information, and send out motor signals.

Nervous System

• The nervous system is comprised of the central and peripheral nervous systems.
• The central nervous system (CNS) consists of the brain and spinal cord. The peripheral nervous system (PNS) consists of nerves.
• The three broad functions of CNS are to take in sensory information, process the information, and send out motor signals.
• The PNS conveys information between the CNS and the rest of the body..

Spinal Nerves

• Spinal nerves carry information to and from the spinal cord
• 31 pairs (8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal)
• Spinal nerves are named for the vertebra immediately below their exit point from the spinal canal.

Clinical Module: Ischemic CNS Injury

• Ischemia, inadequate perfusion, results in impaired oxygenation and potential tissue death.
• Ischemia is caused by blood vessel occlusion (thrombus or local hemorrhage)
• Brain tissue is quickly damaged as it does not store oxygen or nutrients.

Clinical Module: Hemorrhagic Stroke

• Hemorrhagic stroke is caused by blood vessel integrity disruptions (ruptured aneurysm or arteriovenous malformation, or trauma).
• Blood leaks into the brain tissue or subarachnoid space.
• Intracerebral hemorrhage involves bleeding into brain tissue itself; subarachnoid hemorrhage involves bleeding into the subarachnoid space.

Protective Structures of the CNS: Meninges

• Meninges - layered unit of membranous connective tissue.
• Comprised of three layers; dura mater, arachnoid mater, and pia mater. Cranial nerves are attached to the brain
• Primary sensory and motor functions of the head and neck
• There are twelve cranial nerves.

Test your knowledge on the structure and functions of the nervous system. This quiz covers the differences between the central and peripheral nervous systems, the roles of neurons and glial cells, and the functional classifications of the nervous systems. Enhance your understanding of how the body communicates and reacts to stimuli.