Neurophysiology

Self-Study Resources

  • Resource folder includes practice tools for students.

    • Full lectures available for neurophysiology.

Introduction to Neurophysiology

  • Topic: Nervous impulse and action potentials.

    • Action potential characterized as an "all or nothing" phenomenon.

    • Travels down the axon to the axon terminal, where neurotransmitter release occurs.

    • Communication at synapse:

    • Can be either excitatory or inhibitory.

    • Excitatory response results in another action potential; inhibitory response does not produce this effect.

Lecture Resources

  • Lecture provided for Chapter 12 (despite mislabeling as Chapter 11).

    • Encouragement to utilize the resources for practice.

    • Reference to an NIH article detailing neurotransmitters.

Overview of Nervous Tissue

  • Composition of nervous tissue:

    • Consists of neurons and neuroglial cells.

    • Types of neuroglial cells play a crucial role in the functioning of nervous tissue.

    • Nervous tissue located throughout the body, divided into:

    • Central Nervous System (CNS): Only includes brain and spinal cord.

    • Peripheral Nervous System (PNS): Encompasses all other nerves and ganglia.

Nervous System Function

  • Rapid communication of messages throughout the body:

    • Sends electrical messages in response to internal and external stimuli.

    • Integration occurs in the brain, processing messages from both internal and external sources.

Types of Neurons and Neuroglial Cells

  • Importance of understanding various types of neurons and neuroglial cells:

    • A chart on Page 425 details differences in types of neuroglial cells.

  • Types of Neurons:

    • Neurons are specialized for various functions, responding to stimuli.

    • Afferent neurons (sensory): Receive signals from the environment; usually unipolar or pseudounipolar.

    • Efferent neurons (motor): Carry signals to muscles or glands; can be somatic or visceral.

  • Note: Somatic relates to voluntary muscle action; autonomic relates to involuntary functions.

Communication Systems

  • Comparison of nervous system and endocrine system:

    • Nervous system relies on electrical signals, endocrine system on chemical signals.

    • The hypothalamus functions as a neuroendocrine organ with secretory properties.

CNS and PNS Key Definitions

  • Central Nervous System (CNS): Contains brain and spinal cord.

  • Peripheral Nervous System (PNS): Includes all nerves beyond the brain and spinal cord.

    • Tracts in CNS: Bundles of myelinated axons.

    • Nuclei in CNS: Clusters of cell bodies or receptive regions.

    • Nerves in PNS: Bundles of myelinated axons.

    • Ganglia in PNS: Clusters of cell bodies or unmyelinated regions.

Neural Communication Dynamics

  • Sensory messages enter CNS:

    • Afferent pathway corresponds to incoming sensory information.

    • Efferent pathway corresponds to outgoing motor commands.

  • Importance of directional flow in nervous physiology:

    • Afferent indicates messages arriving to CNS; efferent indicates messages exiting.

    • Application of terms in blood vessels (afferent and efferent arterioles).

Types of Neurons Based on Function

  • Sensory neurons: Afferent pathways often unipolar or pseudounipolar.

  • Interneurons: Connect sensory and motor neurons; decision-makers located mostly in gray matter of spinal cord.

  • Motor neurons: Efferent pathways, sending commands from CNS.

Reflexes and Neural Integration

  • Reflexes involve spinal cord without higher brain center activation:

    • Example: Knee-jerk reflex, which does not require cognitive processing.

Structure and Function of Neurons

  • Breakdown of neuron structure:

    • Dendrites: Receptive regions; nonmyelinated, where signals are received.

    • Cell body: Contains nucleus, mitochondria, and organelles essential for neuron function.

    • Axon hillock: Initiates action potential; where signals are integrated.

  • Myelination impacts transmission speed:

    • More myelination results in faster impulse conduction.

    • Nodes of Ranvier allow action potentials to skip sections of axon, enhancing speed.

Neuronal Signaling: Action vs. Graded Potentials

  • Graded potentials: Localized changes in membrane potential at the synapse due to neurotransmitter action.

    • Proportional to the strength of the stimulus; may or may not lead to action potential.

  • Action potentials: All-or-nothing response that travels along axon.

    • Initiated at axon hillock if threshold potential is reached.

Neural Communication Mechanisms

  • Neurotransmitters: Chemicals facilitating communication at synapses, categorized as excitatory or inhibitory.

    • Acetylcholine: Example of excitatory neurotransmitter facilitating depolarization.

    • Norepinephrine: Key neurotransmitter for sympathetic nervous response.

  • Excitatory responses lead to action potentials; inhibitory responses prevent them.

Divisions of the Nervous System

  • Distinct divisions in nervous system function:

    • Somatic vs. Autonomic:

    • Somatic: Involves voluntary actions.

    • Autonomic: Involves involuntary actions (e.g., visceral responses, fight or flight vs. rest and digest).

    • Autonomic nervous system divided into sympathetic (fight or flight) and parasympathetic (rest and digest).

    • Neurotransmitters for these systems (Acetylcholine vs. Norepinephrine).

Conclusion and Forward Study

  • Encouragement for students to engage with reading and prepare for future discussion.

  • Requirement to understand neuron types and functional roles for upcoming quizzes and discussions.

The Central Nervous System (CNS) and Peripheral Nervous System (PNS) serve distinct yet interconnected roles in the human body:

Central Nervous System (CNS)

  • Components: Comprises the brain and spinal cord.

  • Function: Acts as the main control center for processing information and coordinating responses.

    • Integration: Processes incoming sensory information.

    • Output: Generates responses and commands to the body based on processed information.

Peripheral Nervous System (PNS)

  • Components: Includes all nerves and ganglia outside the brain and spinal cord.

  • Function: Connects the CNS to the limbs and organs, providing the pathway for communication.

    • Afferent Pathways: Transmit sensory information from the body to the CNS for interpretation.

    • Efferent Pathways: Carry motor commands from the CNS to peripheral organs and muscles to execute responses.