The Nervous System: Neural Tissue

Transcription

1 C h a p t e r 13 The Nervous System: Neural Tissue PowerPoint Lecture Slides prepared by Jason LaPres North Harris College Houston, Texas Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

2 Introduction Nervous system and endocrine system Control and adjust the activities of other systems Shared characteristics: Chemical communication with targeted tissues Nervous system Relatively swift but brief responses Endocrine Slower but they often last much longer

3 An Overview of the Nervous System The nervous system = all of the neural tissue Two anatomical subdivisions: Central nervous system (CNS) Brain and spinal cord Integrating, processing, and coordinating Intelligence, memory, learning, and emotion Peripheral nervous system (PNS) Neural tissue outside the CNS Provides sensory information to the CNS Carries motor commands to peripheral tissues

4 An Overview of the Nervous System

5 An Overview of the Nervous System Figure 13.1 The Nervous System

6 An Overview of the Nervous System The PNS is subdivided into two divisions. The afferent division of the PNS brings sensory information to the CNS. The efferent division carries motor commands to muscles and glands. The efferent division is further divided into two divisions: Somatic nervous system (SNS) Autonomic nervous system (ANS)

7 An Overview of the Nervous System Afferent division Receptors The afferent division carries information from Somatic sensory receptors Skeletal muscles, joints, and the skin Visceral sensory receptors Smooth muscle, cardiac muscle, and glands Special sense organs Eye, nose, tongue, and ear

8 An Overview of the Nervous System The efferent division begins inside the CNS and ends at an effector. The efferent division Somatic nervous system (SNS) Skeletal muscle contractions May be voluntary or involuntary Autonomic nervous system (ANS) Visceral motor system Smooth muscle, cardiac muscle, and glands Involuntary

9 An Overview of the Nervous System Figure 13.2 A Functional Overview of the Nervous System

10 Cellular Organization in Neural Tissue Neural tissue contains two distinct cell types: nerve cells, or neurons, and supporting cells, or neuroglia. Neurons are responsible for the transfer and processing of information in the nervous system. Supporting cells, or neuroglia, isolate the neurons.

11 Cellular Organization in Neural Tissue Figure 13.3 A Review of Neuron Structure

12 MCellular Organization in Neural Tissue Neuron Structure

13 Cellular Organization in Neural Tissue Neuroglia have many functions, including: Provide framework for the neural tissue Maintain the intercellular environment Act as phagocytes 100 billion neuroglia, or glial cells Roughly five times the number of neurons

14 Cellular Organization in Neural Tissue Figure 13.4 The Classification of Neuroglia

15 Cellular Organization in Neural Tissue Figure 13.5 Histology of Neural Tissue in the CNS

16 Cellular Organization in Neural Tissue Astrocytes Largest and most numerous glial cells Variety of functions Controlling the interstitial environment Maintaining the blood brain barrier Creating a three-dimensional framework for the CNS Performing repairs in damaged neural tissue Guiding neuron development

17 Cellular Organization in Neural Tissue Figure 13.6 The Ependyma

18 Cellular Organization in Neural Tissue Figure 13.7 Satellite Cells and Peripheral Neurons

19 Cellular Organization in Neural Tissue Figure 13.8 Schwann Cells and Peripheral Axons

20 Cellular Organization in Neural Tissue Figure 13.9 Anatomy of a Representative Neuron (Diagrammatic)

21 Cellular Organization in Neural Tissue Figure A Structural Classification of Neurons

22 Cellular Organization in Neural Tissue Neurons can be categorized into three functional groups: Sensory neurons Most sensory neurons are pseudounipolar neurons Motor neurons Most motor neurons are multipolar neurons Interneurons, or association neurons Most interneurons are multipolar neurons

23 Cellular Organization in Neural Tissue Receptors are monitored by the sensory neurons Exteroceptors = external environment Touch, temperature, and pressure sensations Special senses of sight, smell, and hearing Proprioceptors = internal environment Position and movement of skeletal muscles and joints Information carried in somatic sensory neurons Interoceptors = internal environment Digestive, respiratory, cardiovascular, urinary, and reproductive systems Sensations of deep pressure and pain as well as taste

24 Cellular Organization in Neural Tissue Figure A Functional Classification of Neurons

25 Neural Regeneration Figure Nerve Regeneration after Injury

26 The Nerve Impulse Excitability is the ability of a plasmalemma to conduct electrical impulses. An electrical impulse, or action potential, develops after the plasmalemma is stimulated to its threshold. Nerve impulse is an action potential traveling along an axion. The rate of impulse conduction depends on the properties of the axon, specifically: Presence or absence of myelin sheath The diameter

27 Synaptic Communication Figure 13.9 Anatomy of Representative Neuron (Synapses Shown)

28 Synaptic Communication Figure 13.13a The Structure of a Synapse (A Vesicular Synapse)

29 Synaptic Communication Figure 13.13b The Structure of a Synapse (On The Surface of a Neuron)

30 Neuron Organization and Processing Figure Organization of Neural Circuits

31 Anatomical Organization of the Nervous System Figure Anatomical Organization of the Nervous System

32 Anatomical Organization of the Nervous System