Nervous Tissue Lab
BIO 137 Anatomy and Physiology I
Mary Catherine Flath, Ph.D.
Divisions of the
Nervous System
• Central Nervous System
• brain
• spinal cord
• Peripheral Nervous System
• peripheral nerves
• cranial nerves
• spinal nerves
Copyright 2012 Dr. Mary Cat Flath
10-1
Functions of Nervous System
Sensory Function (PNS)
• sensory receptors gather
information (are stimulated)
• information is carried as
sensory impulse on sensory
neurons to the CNS
Integrative Function (CNS)
• sensory information is
integrated. (i.e. used to create
• sensations
• memory
• thoughts
• decisions)
Motor Function (PNS)
• decisions are acted
upon
• motor impulses are
carried on motor
neurons to effectors
(responsive body parts)
Copyright 2012 Dr. Mary Cat Flath
10-6
Divisions of Peripheral Nervous
System
Sensory Division
• picks up sensory information and delivers it to the CNS
Motor Division
• carries information from CNS to effectors:
•muscles and glands
Divisions of the Motor Division
Somatic – carries information to skeletal
muscle
Autonomic – carries information to smooth
muscle, cardiac muscle, and glands
Copyright 2012 Dr. Mary Cat Flath
10-4
Divisions of the Nervous
System

CENTRAL NERVOUS SYSTEM (Brain and Spinal
Cord; Interneurons)

PERIPHERAL NERVOUS SYTEM (Cranial and Spinal Nerves
 SENSORY/AFFERENT NEURONS (INPUT)
 MOTOR/EFFERENT NEURONS (OUTPUT)
 SOMATIC (Effectors: skeletal muscle)
 AUTONOMIC (Effectors: smooth muscle, cardiac
muscle, glands)


PARASYMPATHETIC (maintains
homeostasis; acetylcholine)
SYMPATHETIC (Fight or Fight;
norepinephrine)
Copyright 2012 Dr. Mary Cat Flath
Divisions of the Nervous System
Copyright 2012 Dr. Mary Cat Flath
Nervous Tissue




Neurons with multiple extensions
surrounded by neuroglial cells.
Locations:
 Brain and spinal cord (CNS)
 Nerves (PNS)
Function: Sensory, Integration, and
motor
No reproduction of cells.
Copyright 2012 Dr. Mary Cat Flath
Nervous Tissue
Nervous Tissue is
composed of
• neurons
• neuroglial cells
Copyright 2012 Dr. Mary Cat Flath
10-2
Neuron Structure
Copyright 2012 Dr. Mary Cat Flath
10-7
Neuron Structure
Copyright 2012 Dr. Mary Cat Flath
Neuron Structure
SEM
Copyright 2012 Dr. Mary Cat Flath
Transmission of a Nerve Impulse
within a Neuron (Electrical Impulse)
 Starts
on a Dendrite
 Continues through the Cell
Body
 Continues down the Axon
 And finally into Axonal
terminals/Synaptic Knobs
Copyright 2012 Dr. Mary Cat Flath
LIGHT MICROGRAPHS
OF NERVOUS TISSUE
SLIDE IS LABELED “GIANT
MULTIPOLAR NEURONS”
NERVOUS TISSUE ~HP
NEUROGLIAL CELLS
CELL BODY OF NEURON
Copyright 2012 Dr. Mary Cat Flath
Myelination of Axons
PNS: Schwann cells
(neuroglial cells in PNS)
myelinate axons
TEM
CNS: Oligodendrocytes
(neuroglial cells in CNS)
myelinate axons
Copyright 2012 Dr. Mary Cat Flath
10-8
TEM OF AXONS (CROSS-SECTION)
Copyright 2012 Dr. Mary Cat Flath
Types of Neuroglial Cells
Schwann Cells
• PNS
• myelinating cell
Oligodendrocytes
• CNS
• myelinating cell
Microglia
• CNS
• phagocytic cell
Astrocytes
• CNS
• support and nourish neurons
Ependyma
• CNS
• ciliated
• line central canal of spinal cord
and ventricles of brain
Copyright 2012 Dr. Mary Cat Flath
10-11
Neuroglial Cells
Copyright 2012 Dr. Mary Cat Flath
Copyright 2012 Dr. Mary Cat Flath
Functional Classification of Neurons
Sensory Neurons
• afferent neurons
• carry impulses from sensory receptors to CNS
Interneurons
• link neurons
• multipolar
• in CNS
Motor Neurons
• multipolar
• efferent
• carry impulses away from CNS to effectors
Copyright 2012 Dr. Mary Cat Flath
10-10
Structural Classification of Neurons
(we will consider all as multipolar)
Bipolar
• two processes
• eyes, ears, nose
Unipolar
• one process
• ganglia
MULTIPOLAR
• many processes
• most neurons of
CNS
Copyright 2012 Dr. Mary Cat Flath
10-9
Copyright 2012 Dr. Mary Cat Flath
Nervous Tissue (continued)
Divisions of the Nervous System


CENTRAL NERVOUS SYSTEM (Brain and Spinal
Cord; Interneurons)
PERIPHERAL NERVOUS SYTEM (Cranial and Spinal
Nerves
 SENSORY/AFFERENT NEURONS (INPUT)
 MOTOR/EFFERENT NEURONS (OUTPUT)
 SOMATIC (Effectors: skeletal muscle)
 AUTONOMIC (Effectors: smooth muscle,
cardiac muscle, glands)
 PARASYMPATHETIC (maintains
homeostasis)
 SYMPATHETIC (Fight or Fight)
Copyright 2012 Dr. Mary Cat Flath
A NERVE IS A BUNDLE
OF MYELINATED AXONS
IN THE PNS
Peripheral Nervous System
• Definition
of a nerve: A bundle of
myelinated axons in the PNS
•Cranial nerves arise from the brain
• 12 pairs
• Spinal nerves arise from the spinal cord
• 31 pairs
• All mixed
11-42
Copyright 2012 Dr. Mary Cat Flath
Structure of a Peripheral Nerve
11-43
Copyright 2012 Dr. Mary Cat Flath
Copyright 2012 Dr. Mary Cat Flath
Your peripheral nerve slide
shows both a longitudinal
section (l.s.) and cross section
(c.s.)
The slide is labeled “medullated nerve”.
Peripheral Nerve (Medullated nerve)

Longitudinal Section


You can see myelinated axons and Nodes of
Ranvier
Cross-Section

You can see connective tissue coverings
Copyright 2012 Dr. Mary Cat Flath
Longitudinal Section of a Peripheral
Nerve (LM)
Copyright 2012 Dr. Mary Cat Flath
SEM
Copyright 2012 Dr. Mary Cat Flath
Your third slide in Nervous
Tissue is a “motor unit.”
The slide is labeled “Motor Nerve
Endings.” (You saw this slide when
you studied the muscular system).
Divisions of the Nervous System


CENTRAL NERVOUS SYSTEM (Brain and Spinal
Cord; Interneurons)
PERIPHERAL NERVOUS SYTEM (Cranial and Spinal
Nerves
 SENSORY/AFFERENT NEURONS (INPUT)
 MOTOR/EFFERENT NEURONS (OUTPUT)
 SOMATIC (Effectors: skeletal muscle)
 AUTONOMIC (Effectors: smooth muscle,
cardiac muscle, glands)
 PARASYMPATHETIC (maintains
homeostasis)
 SYMPATHETIC (Fight or Fight)
Copyright 2012 Dr. Mary Cat Flath
STIMULATION OF SKELETAL
MUSCLE FIBERS



EACH SKELETAL MUSCLE FIBER IS
STIMULATED TO CONTRACT BY A BRANCH OF
A MOTOR NEURON
A MOTOR UNIT IS DEFINED AS
 ONE MOTOR NEURON
 MANY SKELETAL MUSCLE FIBERS
A NEUROMUSCULAR JUNCTION IS WHERE THE
MOTOR NERVE ENDING MEETS THE
SARCOLEMMA OF THE SKELTAL MUSCLE
FIBER
Copyright 2012 Dr. Mary Cat Flath
Neuromuscular Junction
Copyright 2012 Dr. Mary Cat Flath
Light Micrographs (LMs)
of Motor Units
MOTOR NERVE ENDINGS (MOTOR UNIT) ~LOW
MUSCLE FIBERS
Copyright 2012 Dr. Mary Cat Flath
MOTOR NERVE ENDINGS (MOTOR UNIT) ~LOW~
BRANCHING MOTOR NEURON
Copyright 2012 Dr. Mary Cat Flath
MOTOR NERVE ENDINGS (MOTOR UNIT) ~LOW~
NEUROMUSCULAR JUNCTIONS
Copyright 2012 Dr. Mary Cat Flath
MOTOR NERVE ENDINGS (MOTOR UNIT) ~HIGH~
Copyright 2012 Dr. Mary Cat Flath
Nerve Fiber Classification
Nerves – conduct sensory impulses
into CNS
• Motor Nerves – conduct motor impulses
from CNS to muscles or glands
• Mixed Nerves – contain both sensory nerve
fibers and motor nerve fibers; most
nerves and all spinal nerves
• Sensory
11-44
Copyright 2012 Dr. Mary Cat Flath
Divisions of the Nervous System


CENTRAL NERVOUS SYSTEM (Brain and Spinal
Cord; Interneurons)
PERIPHERAL NERVOUS SYTEM (Cranial and Spinal
Nerves
 SENSORY/AFFERENT NEURONS (INPUT)
 MOTOR/EFFERENT NEURONS (OUTPUT)
 SOMATIC (Effectors: skeletal muscle)
 AUTONOMIC (Effectors: smooth muscle,
cardiac muscle, glands)
 PARASYMPATHETIC (maintains
homeostasis)
 SYMPATHETIC (Fight or Fight)
Copyright 2012 Dr. Mary Cat Flath
Cranial Nerves (studied later)
11-46
Copyright 2012 Dr. Mary Cat Flath
Spinal Nerves (studied later)
• mixed
nerves
• 31 pairs
• 8 cervical (C1 to C8)
• 12 thoracic (T1 to T12)
• 5 lumbar (L1 to L5)
• 5 sacral (S1 to S5)
• 1 coccygeal (Co)
11-54
Copyright 2012 Dr. Mary Cat Flath
See how you do identifying
the following structures.
Copyright 2012 Dr. Mary Cat Flath
Neuron Structure
Copyright 2012 Dr. Mary Cat Flath
10-7
Motor neuron
Copyright 2012 Dr. Mary Cat Flath
Copyright 2012 Dr. Mary Cat Flath
Copyright 2012 Dr. Mary Cat Flath
Longitudinal Section of a Peripheral
Nerve (LM)
Copyright 2012 Dr. Mary Cat Flath
Copyright 2012 Dr. Mary Cat Flath
MOTOR NERVE ENDINGS (MOTOR UNIT) ~LM; LOW~
BRANCHING MOTOR NEURON
Copyright 2012 Dr. Mary Cat Flath
Copyright 2012 Dr. Mary Cat Flath
Copyright 2012 Dr. Mary Cat Flath
Copyright 2012 Dr. Mary Cat Flath
Copyright 2012 Dr. Mary Cat Flath
Good luck studying!!!
Copyright 2012 Dr. Mary Cat Flath