Lecture 01 - BIOL2230

Introduction

• Overview of the nervous system

• Presented by Kevin Danastas, Macquarie University

Course Materials

• Textbook Reference:

  • Stanfield (2017) Principles of Human Physiology, 6th Edition, Pearson.

  • Relevant chapters:

    • Chapter 7: sections 7.1 – 7.2

    • Chapter 9: section 9.1

Learning Objectives

• LO1: Describe the general divisions of the vertebrate nervous system

• LO2: Describe the different functional types of neurons in the CNS

• LO3: Describe the different functional types of glial cells in the CNS and PNS

• LO4: Describe the structural organization of neurons in the nervous system and how neurons communicate

Vertebrate Nervous System Overview

Major Components

• Central Nervous System (CNS):

  • Comprises the brain and spinal cord

  • Responsible for integrating, processing, and coordinating sensory data and motor commands

  • Information processing includes integration and distribution of information

• Peripheral Nervous System (PNS):

  • Consists of all neural tissues outside the CNS

  • Sensory Division:

    • Brings information to the CNS from periphery

  • Motor Division:

    • Carries motor commands from the CNS to peripheral tissues

  • Further Divided into:

    • Somatic Nervous System (SNS): Controls skeletal muscle contractions

    • Autonomic Nervous System (ANS): Regulates smooth muscle, cardiac muscle, glands, and adipose tissue.

Sensory Receptors

• Somatic Sensory Receptors:

  • Provide sensations like position, touch, pressure, pain, temperature

• Special Sensory Receptors:

  • Provide sensations of smell, taste, vision, balance, hearing

• Visceral Sensory Receptors:

  • Monitor internal organ functions

Effectors

• Organs that respond to neural commands, including:

  • Smooth muscle

  • Cardiac muscle

  • Skeletal muscle

  • Glands

  • Adipose tissue

Neural Tissue Composition

• Composed of two main cell types:

  • Neurons: Excitable cells responsible for transmitting signals

  • Neuroglia (Glial Cells): Non-neuronal cells supporting neuron function

  • Neurons consist of:

    • Cell Body (Soma): Contains nucleus, organelles

    • Dendrites: Receive information from other neurons

    • Axon: Transmits information to other destinations

Neurons

Characteristics

• Excitable Cells:

  • Can rapidly alter voltage across membrane

  • Functions:

    • Transfer information

    • Communicate with other cells

    • Bring physiological changes

Functional Categories

• Sensory Neurons:

  • Detect stimuli; transmit signals to CNS

• Motor Neurons:

  • Efferent signals from CNS to effectors (muscles/glands)

• Interneurons:

  • Connect neurons within CNS; process information

Morphological Diversity

• Neurons show diversity in morphology and physiology reflecting functional differences

Glial Cells in the Nervous System

Main Functions

• Provide physical support for neurons

• Supply nutrients and oxygen

• Offer electrical insulation

• Remove pathogens and dead neurons

• Process information

Types of Glial Cells

1. Astrocytes:

   • Support metabolic functions; regulate environment

2. Oligodendrocytes (CNS) & Schwann Cells (PNS):

   • Form myelin sheaths around axons

3. Microglia:

   • Immune defense; cleanup in CNS

4. Ependymal Cells:

   • Line ventricles; assist CSF production

Neural Communication

Mechanisms

• Neurons communicate via synapses

• Axonal transport mechanisms include:

  • Anterograde transport: Cell body to axon terminals

  • Retrograde transport: Axon terminals to cell body

Circuit Organization

• Neurons organized into circuits

• Complexity varies, e.g., reflex loops vs. pain processing circuits

Structural Organization of the CNS

Grey and White Matter

• Grey Matter:

  • Contains cell bodies, dendrites; site of synaptic connections

• White Matter:

  • Comprised of axons; myelin gives white appearance

Neuronal Layers

• Cerebral Cortex:

  • Outer grey matter, inner white matter

• Spinal Cord:

  • Inner grey matter, outer white matter

Conclusion

• Nervous system divided into CNS and PNS

• Neurons are key for communication; glial cells support function

• CNS structure varies in grey and white matter

• Neurons communicate across synapses, organize into circuits for processing information.