Nervous System Structure and Function.ppt

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1. Anatomy and Physiology I
The Nervous System
Basic Structure and Function
Instructor: Mary Holman

2. Three Basic Functions of the
Nervous System
Sensory Function
Sensory or afferent neurons
Integrative Function
Interneurons
Motor Function
Motor or efferent neurons

3. Fig. 10.2a
Brain
Spinal
cord Spinal nerves (31 pairs)
Cranial nerves (12 pairs)
CNS vs PNS
Central Nervous System Peripheral Nervous System

4. Divisions of the Nervous System
Central Nervous System CNS
Brain
Spinal Cord
Peripheral Nervous System PNS
Cranial Nerves
Spinal Nerves
Ganglia
Sensory Receptors

5. Divisions of the PNS
Somatic Nervous System
Sensory neurons
Motor neurons to skeletal muscle only
Autonomic Nervous System
Autonomic sensory neurons - visceral
Motor neuron impulses to smooth & cardiac muscle,
glands and adipose tissue
Sympathetic vs. Parasympathetic Motor Divisions
Enteric Nervous System
Enteric complexes of the gut

6. Fig. 10.7
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Central nervous system Peripheral nervous system
Cell body
Interneurons
Dendrites
Axon
Axon
Sensory (afferent) neuron
Motor (efferent) neuron
Cell body
Axon
(central process)
Axon
(peripheral process)
Sensory
receptor
Effector
(muscle or gland)
Axon
terminal

7. Cells of Neural Tissue
• Neurons
The electrically excitable nerve cells
responsible for the functions of the
nervous system
• Neuroglia (glia, neuroglia, glial)
Support, nourish, & protect neurons

8. Fig. 10.1
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Dendrites
Cell body
Axon
Nuclei of
neuroglia
© Ed Reschke
The Neuron
600x

9. Fig. 10.3
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cell body
Neurofibrils
Nucleus
Nucleolus
Dendrites
Impulse
Nodes of Ranvier
Myelin (cut)
Axon
Axon
Chromatophilic
substance
(Nissl bodies)
Axonal
hillock
Portion of a
collateral
Schwann
cell
Nucleus of
Schwann cell
Synaptic knob of
axon terminal
Neuron with
Myelinated
Axon

10. Fig. 10.6
Dendrites
Axon Axon
Axon
Direction
of impulse
(a) Multipolar
Central
process
Peripheral
process
(c) Unipolar(b) Bipolar
(eyes,nose,ears)

11. Neuroglia of the PNS
• Schwann Cells
Produce myelin sheath
• Satellite Cells
Support neuronal clusters in
ganglia

12. Fig. 10.4a
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Dendrite
Node of Ranvier
Myelinated region of axon
Axon
Unmyelinated
region of axon
Neuron
cell body
Neuron
nucleus
Medullated or Myelinated Axon
Schwann cells
Neurolemma
containing nucleus

13. Fig. 10.4b
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Neurilemma
Myelin sheath
Neurofibrils
Axon
Axon
Node of Ranvier
Myelin
Schwann cell
nucleus
© Biophoto Associates/Photo Researchers, Inc.
650x
Schwann Cell

14. Fig. 10.4c
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Enveloping
Schwann cell
Schwann
cell nucleus
Unmyelinated
axon
Longitudinal
groove
Schwann Cell with non-myelinated Axons
A
x
o
n

15. Fig. 10.5
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Schwann
cell cytoplasm
Myelin
sheath
Myelinated
axon
Unmyelinated
axon
© Dennis Emery
30,000x

16. Neuroglia of the CNS
• Astrocytes
major support cells
provide nutrients, monitor metabolism etc
• Oligodendrocytes
myelinate axons in CNS
• Microglia
phagocytic
• Ependymal
line ventricles & central canal
produce cerebrospinal fluid (CSF)

17. Fig. 10.8
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Microglial cell
Axon
Oligodendrocyte
Astrocyte
Capillary
Neuron
Myelin
sheath (cut)
Node of
Ranvier
Ependymal
cell
Fluid-filled cavity
of the brain or
spinal cord
Neuroglia of CNS

18. Fig. 10.9
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Neuroglia
Neuron
cell body
Tissues and Organs: A Text-Atlas of Scanning Electron Microscopy, by R.G. Kessel and R.H. Kardon. ©1979 W.H. Freeman and Company
SEM 10,000x

19. Fig. 10.10
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Axon
Site of injury Schwann cells
(a)
(b)
(c)
(d)
(e)
Changes over
time
Motor neuron
cell body
Former connection
reestablished
Schwann cells
Form new myelin sheath
Schwann cell tube
extends distal to injury
Proximal end of injured axon
regenerates into tube of Schwann cells
Distal portion of
axon degenerates
Skeletal
muscle fiber
Axonal Repair