Chapter+10+PPT

Chapter 10: Nervous System Overview

Introduction

• Emphasis on the importance of learning.

• Reference to PowerPoint materials and copyright information.

10.1 General Characteristics of the Nervous System

• Overview of Nervous System Function:

  • Master regulatory system.

  • Sends and receives information.

  • Sensory Input: Detects changes in the environment.

  • Integration and Processing: Responsible for decision-making.

  • Motor Output: Stimulates responses in muscles and glands.

  • Maintains homeostasis.

  • Center for thought, learning, and memory.

• Main Cell Types of the Nervous System:

  • Neurons (Nerve Cells):

    • Respond quickly to changes/stimuli.

    • Conduct electrical impulses through neurotransmitters.

  • Neuroglia:

    • Protect, support, insulate, and nourish neurons.

    • Do not conduct electrical impulses.

10.2 Overview of Nervous System Structure

• Central Nervous System (CNS):

  • Composed of the brain and spinal cord.

• Peripheral Nervous System (PNS):

  • Connects CNS to other body parts.

  • Composed of cranial and spinal nerves.

  • Two subdivisions:

    • Afferent (Sensory): Transmits sensory information to CNS.

    • Efferent (Motor): Sends commands from CNS to muscles/glands.

10.3 Sensory and Motor Divisions

• Sensory Division:

  • Involves sensory receptors that detect changes.

  • Convert information into impulses sent to CNS.

• Motor Division:

  • Transmits impulses from CNS to effectors (muscles/glands).

  • Two Subdivisions:

    • Somatic: Controls voluntary skeletal muscles.

    • Autonomic: Controls involuntary functions (smooth/cardiac muscles and glands).

10.4 Clinical Application: Migraine

• Statistics: Affects 12% of the US population.

• Signs:

  • Pounding head, nausea, aura, light/sound sensitivity.

• Triggers: Bright light, stress, hormonal changes, etc.

• Treatment Strategies: Identify and avoid triggers to reduce attack frequency.

10.5 Treatment Options for Migraines

• Medications:

  • Triptans can stop attacks; they affect blood vessel constriction.

  • Transcranial magnetic stimulation is effective for some patients.

  • Long-term treatments: Botox injections and certain antidepressants.

10.6 Nervous Tissue Cells: Neurons and Neuroglia

• Neurons:

  • Vary in size/shape and have specific structural features such as:

    • Cell Body (Soma): Contains nucleus and organelles.

    • Dendrites: Branched surfaces for receiving signals.

    • Axon: Transmits impulses to other neurons or effectors.

• Axons:

  • Structural features: axon hillock, collaterals, axon terminals, synaptic knobs.

  • Schwann Cells: Neuroglia that insulate axons in PNS (myelin sheath).

  • Nodes of Ranvier: Gaps in myelin sheath that facilitate impulse transmission.

10.7 Classification of Neurons

• By Structure:

  • Multipolar Neurons: Common, many dendrites.

  • Bipolar Neurons: Rare, found in sensory organs (e.g., eyes).

  • Unipolar Neurons: One process, mainly found in ganglia of PNS.

• By Function:

  • Sensory Neurons: Carry impulses to CNS using sensory receptors.

  • Internurons: Link neurons in CNS.

  • Motor Neurons: Relay commands from CNS to effectors.

10.8 Neuroglia of the CNS and PNS

• CNS Neuroglia Types:

  • Astrocytes: Connect neurons to blood vessels; regulate ion concentrations.

  • Oligodendrocytes: Form myelin sheaths for CNS axons.

  • Microglia: Phagocytic cells providing support.

  • Ependymal Cells: Line cavities in CNS; regulate cerebrospinal fluid.

• PNS Neuroglia Types:

  • Schwann Cells: Produces myelin sheath for axons, speeds up transmission.

  • Satellite Cells: Support neuron clusters in ganglia.

10.9 Neuron Regeneration

• PNS Regeneration: Can occur; Schwann cells provide guiding sheath.

• CNS Regeneration: Unlikely because of the lack of neurilemma.

10.10 Cell Membrane Potential

• Resting Membrane Potential: About -70 mV; crucial for impulse conduction.

• Action Potential: Sequence of electrical events from depolarization to repolarization.

10.11 Synaptic Transmission

• Neurons communicate via synapses.

• Process involves neurotransmitter release from presynaptic neuron and reception by postsynaptic neuron.

10.12 Neurotransmitter Types and Functions

• Common Neurotransmitters:

  • Acetylcholine: Involved in muscle contraction.

  • Norepinephrine, Dopamine, Serotonin: Affect mood, cognition, and autonomic functions.

  • GABA, Glutamate: Inhibitory and excitatory neurotransmitter functions.

10.13 Clinical Applications and Neurotransmitter Balance

• Disorders associated with neurotransmitter imbalances (e.g., depression, epilepsy).

• Drug effects on neurotransmission: agonists and antagonists alter neuronal activity.

Conclusion

• Understanding the nervous system's structure and function is crucial for recognizing its impact on overall health.

• Recognition of the importance of neurotransmitters in maintaining balance is vital for neurological health.