RHPT-354
NEUROPHYSIOLOGY
UNIT 1
INTRODUCTION TO NERVOUS
SYSTEM
Objectives
By the end of this class the students must have
an understanding about
 Definition & function of NS
 Different cells present in NS & their basic
function
 Parts of Brain & its function
 Parts of NS
 Major division of NS & their function.
Nervous System
 The human nervous system consists of the
central nervous system (CNS) and peripheral
nervous system (PNS). The primary functions
of the nervous system are to monitor,
integrate (process) and respond to
information inside and outside the body.
Nervous System
•
•
•
The human nervous
system is comprised of
two kinds of cells:
– Neurons
– Glia
The human brain contains
approximately 100 billion
individual neurons.
BEHAVIOUR depends
upon the communication
between neurons.
The Cells of the Nervous
System
• Neuron cells are similar to other cells of
the body but have a distinctive shape.
• A motor neuron has its soma in the spinal
cord and receives excitation from other
neurons and conducts impulses along it
axon to a muscle.
• A sensory neuron is specialized at one end
to be highly sensitive to a particular type
of stimulation (touch, temperature, odor
etc.)
The Cells of the Nervous
System
• All neurons have the following major
components:
– Dendrites.
– Soma/ cell body.
– Axon
The Cells of the Nervous
System
 Terms used to describe the neuron include
the following:
Afferent axon - refers to bringing
information into a structure.
Efferent axon - refers to carrying
information away from a structure.
Interneurons or Intrinsic neurons are
those whose dendrites and axons are
completely contained within a structure.
Fig. 2-8, p. 34
The Cells of the Nervous
System
• Glia are the other major component of the
nervous system and include the following:
– Astrocytes helps synchronize the
activity of the axon by wrapping around
the presynaptic terminal and taking up
chemicals released by the axon.
– Microglia - remove waste material and
other microorganisms that could prove
harmful to the neuron.
Fig. 2-10, p. 35
Fig. 2-11, p. 36
The Cells of the Nervous
System
 (Types of glia continued)
Oligdendrocytes & Schwann cells- build
the myelin sheath that surrounds the axon
of some neurons.
Radial glia- guide the migration of neurons
and the growth of their axons and
dendrites during embryonic development.
The Nerve Impulse
 A nerve impulse is the electrical message
that is transmitted down the axon of a
neuron.
 The impulse does not travel directly down the
axon but is regenerated at points along the
axon.
 The speed of nerve impulses ranges from
approximately 1 m/s to 100 m/s.
The Nervous System
Major division - Central
vs. Peripheral
Central or CNS- brain
and spinal cord
Peripheral- nerves
connecting CNS to
muscles and organs
Central Nervous System
Peripheral Nervous System
Peripheral Nervous System
 3 kinds of neurons
connect CNS to the body
sensory
motor
interneurons
 Motor - CNS to muscles
and organs
 Sensory - sensory
receptors to CNS
 Interneurons:
Connections Within CNS
Brain
Spinal
Cord
Nerves
Peripheral Nervous System
Peripheral Nervous System
Skeletal
(Somatic)
Autonomic
Sympathetic
Parasympathetic
Somatic System
 Nerves to/from
spinal cord
 control muscle
movements
 somatosensory
inputs
Brain
Sensory
Neuron
 Both Voluntary and
reflex movements
Skin receptors
 Skeletal Reflexes
 simplest is spinal
reflex arc
Motor
Neuron
Interneuron
Muscle
Autonomic System
 Two divisions:
sympathetic
Parasympatheitic
 Control involuntary functions
heartbeat
blood pressure
respiration
perspiration
digestion
 Can be influenced by thought and emotion
Sympathetic
CENTRAL NERVOUS SYSTEM SYMPATHETIC
 “ Fight or flight”
response
 Release adrenaline and
noradrenaline
 Increases heart rate and
blood pressure
 Increases blood flow to
skeletal muscles
 Inhibits digestive
functions
Brain
Dilates pupil
Stimulates salivation
Relaxes bronchi
Spinal
cord
Salivary
glands
Lungs
Accelerates heartbeat
Inhibits activity
Heart
Stomach
Pancreas
Stimulates glucose
Secretion of adrenaline,
nonadrenaline
Relaxes bladder
Sympathetic Stimulates ejaculation
ganglia
in male
Liver
Adrenal
gland
Kidney
Parasympathetic
CENTRAL NERVOUS SYSTEM PARASYMPATHETIC
Brain
 “ Rest and digest ”
system
 Calms body to
conserve and
maintain energy
 Lowers heartbeat,
breathing rate,
blood pressure
Contracts pupil
Stimulates salivation
Spinal
cord
Constricts bronchi
Slows heartbeat
Stimulates activity
Stimulates gallbladder
Gallbladder
Contracts bladder
Stimulates erection
of sex organs
Summary of autonomic
differences
Autonomic nervous system controls physiological arousal
Sympathetic
division (arousing)
Parasympathetic
division (calming)
Pupils dilate
EYES
Pupils contract
Decreases
SALVATION
Increases
Perspires
SKIN
Dries
Increases
RESPERATION
Decreases
Accelerates
HEART
Slows
Inhibits
DIGESTION
Activates
Secrete stress
hormones
ADRENAL
GLANDS
Decrease secretion
of stress hormones
Central Nervous System
Brain
 Brain and Spinal Cord
Spinal
Cord
Brain has 2 Hemispheres
 Left & Right sides are
separate
 Corpus Callosum :
major pathway
between hemispheres
 Some functions are
‘lateralized’
language on left
math, music on right
 Lateralization is never
100%
Corpus Callosum
Right
Hemisphere
Left
Hemisphere
Each hemisphere is
divided into 4 lobes
Frontal
Parietal
Occipital
Temporal
Sensory Information sent
to opposite hemisphere
 Principle is Contralateral
Organization
 Sensory data crosses over
in pathways leading to the
cortex
 Visual Crossover
Left visual Right visual
field
field
Optic
nerves
left visual field to right
hemisphere
right field to left
 Other senses similar
Left Visual Corpus Right Visual
Cortex Callosum
Cortex
Contralateral Motor
Control
 Movements
controled by motor
area
 Right hemisphere
controls left side of
body
 Left hemisphere
controls right side
 Motor nerves cross
sides in spinal cord
Motor Cortex
Somatosensory Cortex
Corpus Callosum
 Major ( but not only)
Medial surface of right hemisphere
pathway between sides
 Connects comparable
structures on each side
 Permits data received on
one side to be
processed in both
hemispheres
 Aids motor coordination
of left and right side
Corpus Callosum
Corpus Callosum
What happens when the corpus
callosum is cut?
Sensory inputs are still crossed
Motor outputs are still crossed
Hemispheres can’t exchange data
Localization of function
Frontal
Parietal
Occipital
Temporal
Occipital Lobe
Input from Optic
nerve
Contains primary
visual cortex
most is on surface
inside central
fissure
Outputs to parietal
and temporal lobes
Occipital
Lobe
Visual
Lobe
Temporal Lobe
 Contains primary
auditory cortex
 Inputs are auditory,
visual patterns
speech recognition
face recognition
word recognition
memory formation
 Outputs to limbic
System, basal Ganglia,
and brainstem
Auditory
Cortex
Temporal
Lobe
Parietal Lobe
 Inputs from multiple
senses
 contains primary
somatosensory cortex
 borders visual &
auditory cortex
 Outputs to Frontal lobe
 hand-eye coordination
 eye movements
 attention
Somatosensory
Parietal
Cortex
Lobe
Frontal Lobe
 Contains primary motor
cortex
 No direct sensory input
 Important planning and
sequencing areas
 Broca’s area for speech
 Prefrontal area for
working memory
Frontal
Lobe
Working
Broca’s
Memory
Area
Motor
Cortex
Frontal Lobe Disorders
Broca’s area
productive aphasia
Prefrontal area
lose track of ongoing context
fail to inhibit inappropriate
responses
Often measured with the
Wisconsin Card Sorting Task
The Nervous System:
Summary
 Major structures of the
nervous
CNS, Somatic, Autonomic
Two hemispheres & 4 lobes
 Organization
contralateral input & output
primary sensory areas
motor areas
Commissure
 Localization of functions
Central Nervous System
Peripheral Nervous System