Nervous System Overview Quiz

Image Analysis - Illusions

• The first image displays a person's head with a hat, presenting three faces.
• The second image is an elephant with an unusual number of legs.

Nervous System Overview

• The nervous system (NS) coordinates and controls all body systems.
• It allows communication between different systems for common goals.
• The NS functions at conscious (e.g., playing, reading) and unconscious (e.g., digestion, breathing) levels.
• The NS is divided into four functional systems: nerves, sensory receptors, spinal cord, and brain.

Nervous System Learning Outcomes

• Students will be able to define the functions of the nervous system.
• They will also be able to identify the divisions and organization of the nervous system.
• They can name two types of cells in nerve tissue.
• Students will be able to describe neuron structures and characteristics.
• They will also be able to identify neuroglial cell types and their function.
• They will be able to explain nerve physiology, including generation, conduction, and synaptic transmission of nerve impulses.

Introduction to Nervous System

• The nervous system is the body's control center.
• It responds to changes both inside and outside the body.
• The NS works with the endocrine system to maintain homeostasis.
• It also governs perceptions, behaviors, and memories.
• The NS includes the brain, spinal cord, and peripheral nerves

Divisions of the Nervous System (Diagram 1)

• The central nervous system (CNS) consists of the brain and spinal cord.
• The peripheral nervous system (PNS) encompasses cranial nerves, spinal nerves, ganglia, and sensory receptors.

Divisions of the Nervous System (Diagram 2)

• The CNS is divided into the brain and spinal cord.
• The PNS is divided further into:
  • Automatic nervous system (communicates with internal organs and glands)
  • Somatic nervous system (communicates with sense organs and voluntary muscles)
  • Sensory division (sensory input)
  • Motor division (motor output)
  • Further divisions into sympathetic (arousing) and parasympathetic (calming)

Divisions of the Nervous System (Diagram 3)

• The diagram shows the CNS (brain and spinal cord) as a central hub.
• The PNS (peripheral nervous system) is made up of nerves and ganglia reaching to the extremities and organs.

Divisions of the Nervous System (Diagram 4)

• The diagram defines the Central Nervous System (CNS), and Peripheral Nervous System (PNS)
• The CNS includes the brain and spinal cord.
• The PNS is responsible for communication between the CNS and the rest of the body, encompassing cranial and spinal nerves, ganglia, and sensory receptors.

Functions of the Nervous System

• The nervous system is responsible for maintaining homeostasis.
• It receives sensory input from the environment.
• It integrates the received information.
• It controls muscles and glands.
• It establishes and maintains mental activity.

Functions of the Nervous System

• The nervous system detects and responds to changes inside and outside the body.
• The system works with the endocrine system to maintain homeostasis.
• It is responsible for perceptions, behaviors, and memories.
• The nervous system consists of the brain, spinal cord, and peripheral nerves.

Cells of Nervous Tissue

• The nervous system is composed of neurons (functional cells) and neuroglia (supporting cells).
• Neurons respond to stimuli, converting them into electrical signals (nerve impulses).
• Neuroglia nourish and protect neurons and maintain homeostasis of the surrounding interstitial fluid.

Neurons: Structure and Function

• Neurons are the basic units of the NS.
• They are categorized by structure and function, including:
  • Multipolar, Bipolar, Unipolar neurons.
• Neurons receive stimuli, transmit action potentials (impulses), and communicate with other neurons at synapses.
  • Neurons can receive and transmit signals, are highly specialized, and cannot be replaced.

Neuron Structure

• Neurons have a cell body, dendrites (receiving ends), and an axon (transmitting end).
• Axons can vary in length and end in branched endings called presynaptic terminals.

Neuron Structure (Diagram 1)

• The diagram shows dendrites receiving incoming impulses, the cell body containing the nucleus, and an axon transmitting outgoing impulses.
• The diagram highlights the differing directions of the impulses at different points. 

Neuron Structure (Diagram 2)

• The diagram defines the cell body, dendrites, axon, axon collaterals, and axon terminals.
• Neurons also contain: nuclei, cytoplasm and Nissl substance.

Neuron Structure - Dendrites

• Dendrites are branched structures of neurons that receive incoming impulses. They carry impulses toward the cell body.

Neuron Structure - Axon

• Axons transmit impulses away from the cell body.
• Axons can be myelinated (with a myelin sheath for faster conduction) or unmyelinated.
• Axons end in axon terminals with synaptic vesicles containing neurotransmitters.
• Axons are often clustered into bundles, called nerves (PNS) or tracts (CNS).

Neuron Structure - Myelination

• Myelin sheath insulates the axon and increases the speed of nerve impulse conduction.
• The myelin sheath is formed by Schwann cells in the PNS and oligodendrocytes in the CNS.
• Nodes of Ranvier are gaps in the myelin sheath that facilitate faster conduction.

Neuron Organization

• The nervous system is organized into white matter and gray matter.
• White matter comprises bundles of myelinated axons that appear white due to the myelin sheath.
• Gray matter contains unmyelinated axons and neuron cell bodies, appearing gray.

Neuroglial Cells

• Neuroglia are supporting cells in the nervous system.
• There are four types of neuroglial cells:
  • Astrocytes, oligodendrocytes, ependymal cells, and microglia.
  • Astrocytes regulate the composition of brain fluid.
  • Oligodendrocytes help form myelin sheaths in the CNS.
  • Ependymal cells secrete cerebrospinal fluid.
  • Microglia remove foreign substances from the CNS.

Blood-Brain Barrier (BBB)

• The BBB protects the brain from harmful substances.
• It's formed by astrocytes and the walls of blood vessels, restricting the entry of certain molecules from the bloodstream into the brain tissue.
  • Allows water, oxygen, and some nutrients to pass but prevents other harmful substances from entering the brain.

Organization of Nervous Tissue

• White matter: bundles of parallel axons and myelin sheaths (nerve tracts).
  • Appears whitish due to the myelin.
• Grey matter: groups of neuron cell bodies and unmyelinated axons.
  • Found predominantly in the cortex of the brain and the center of the spinal cord. 

Learning Outcomes Review

• Covering functions, structure and organization of the Nervous System, learning outcomes are covered.
• Including neuroglia, nerve impulse types, and synapses.

Nerve Physiology

• Nerve physiology involves the generation, conduction, and transmission of nerve impulses (signals).
• Nerve impulses travel along a neuron, from dendrites to axon to terminals.

Nerve Impulse Generation

• Excitability is the ability of a nerve fiber to respond to a stimulus and generate a nerve signal.
• Resting membrane potential is the steady state potential difference across the neuron membrane. 
• This difference maintained by ion transport across the neuron membrane.
• Action potential is a brief reversal of the membrane potential. 

Nerve Impulse Conduction

• Nerve impulses travel through the axon, via continuous (unmyelinated) or saltatory conduction (myelinated). Factors affecting nerve conduction speed include myelin sheath, nerve fiber diameter, and temperature.

Synapse

• A synapse is the junction where nerve impulses pass from one neuron to another cell. - Synapses can be categorized as electrical or chemical synapses.

Synaptic Transmission

• Synaptic transmission is the process of conducting a nerve impulse across a synapse.
• The pre-synaptic neuron releases neurotransmitters across the synaptic cleft. 
• Neurotransmitters bind to receptors on the post-synaptic neuron. 

Summary

• The nervous system is the body's control center, divided into central (brain and spinal cord) and peripheral systems(nerves, sensory receptors, etc).
•  It comprises neurons (impulse-transmitting cells) and neuroglia (supporting cells).
• It functions via nerve impulse generation, conduction, and release of neurotransmitters at synapses.

Glossary of terms

• Definitions of key terms will vary between specific contexts.

Test your knowledge on the functions and components of the nervous system, including the peripheral and autonomic nervous systems. This quiz covers essential concepts such as sensory neurons and the roles of myelin sheaths. Challenge your understanding of the fundamental aspects of nerve tissue and responses.