Download Document

Divisions of the Human Nervous System
Central Nervous System-the brain and the spinal cord
Peripheral Nervous System-the nerves outside the brain and spinal cord
Two Division of the PNS
Somatic Nervous System-the nerves that convey messages from the
sense organs to the CNS and from the CNS to the muscles and
glands
Autonomic Nervous System-a set of neurons that control the heart,
the intestines, and other organs
Figure 4.1 The human nervous system
Both the central nervous system and the peripheral nervous system have
major subdivisions. The closeup of the brain shows the right hemisphere
The Brain: the big picture…
The basic components of
the CNS include the:
• Cerebrum
• Diencephalon
• Cerebellum
• Brain stem
• Spinal cord
The Brain: development…
Our central nervous
system has humble
origins early in our
development (by 3rd wk.)
A plate (neural plate) of
cells develop crests
(neural crests) that rise
and eventually meet and
fuse leaving the hollow
dorsal nerve cord & and
ventricles of our CNS
BI 201 Human Anatomy & Physiology
The Brain: development…
What happens if those
crests DON’T meet and
fuse?
Failure of neural arch
formation can result in Spina
bifida. In mild cases results in
a dimple or discolored spot
(S.b. occulta), severe cases
(S.b. cystica), meninges, CSF
and nervous tissue may
protrude.
The Brain: from the outside in…
The brain and spinal cord are
protected by meninges
3 layers:
Dura mater ~ outermost,
tough, continuous with
periosteum
Arachnoid mater ~ middle
layer, spiderweb appearance
Pia mater ~ innermost layer,
not visible to naked eye
The Brain: from the outside in…
The dura mater helps keep the
brain in position and the
cerebral spinal fluid (CSF)
helps cushion/protect the brain
Where does the fluid come
from?
Choroid plexuses on ventricle
walls
Ependymal cells allow fluids
in from capillaries
The Brain: from the outside in…
The CSF circulates throughout
the ventricles, down the central
canal of the spinal cord and
throughout the subarachnoid
space.
CSF is reabsorbed back into
blood primarily at the venous
sinuses found within the dura
mater.
Cerebral Hemispheres (Cerebrum)
 Paired (left
and right)
superior parts
of the brain
 Include more
than half of
the brain
mass
Figure 7.13a
Slide
Layers of the Cerebrum
 Gray matter
 Outer layer
 Composed
mostly of neuron
cell bodies
Figure 7.13a
Slide
Layers of the Cerebrum
 White matter
 Fiber tracts
inside the gray
matter
 Example:
corpus callosum
connects
hemispheres
Figure 7.13a
Slide
Cerebral Hemispheres (Cerebrum)
 The surface
is made of
ridges (gyri)
and grooves
(sulci)
Figure 7.13a
Slide
The Lobes
The Occipital Lobe-posterior end of cortex
Contains primary visual cortex
The Parietal Lobe-between occipital love the central sulcus
Contains the primary somatosensory cortex-receiving touch sensation,
muscle-stretch information and joint position information
The Temporal Lobe-lateral portion of each hemisphere, near the temples
Contains targets for audition, essential for understanding spoken language,
complex visual processes, emotional and motivational behaviors
The Frontal Lobe-extends from the central sulcus to the anterior limit of the
brain
Contains Primary Motor Cortex-fine movements
Contributes to shifting attention, planning of action, delayed response
tasks as examples
Lobes of the Cerebrum
 Fissures (deep grooves) divide the
cerebrum into lobes
 Surface lobes of the cerebrum
 Frontal lobe
 Parietal lobe
 Occipital lobe
 Temporal lobe
Slide
Lobes of the Cerebrum
Figure 7.15a
Slide
Specialized Areas of the Cerebrum
 Somatic sensory area – receives
impulses from the body’s sensory
receptors
 Primary motor area – sends impulses to
skeletal muscles
 Broca’s area – involved in our ability to
speak
Slide 7.30
Sensory and Motor Areas of the
Cerebral Cortex
Figure 7.14
Slide 7.31
Specialized Area of the Cerebrum
 Cerebral areas involved in special
senses
 Gustatory area (taste)
 Visual area
 Auditory area
 Olfactory area
Slide
Specialized Area of the Cerebrum
 Interpretation areas of the cerebrum
 Speech/language region
 Language comprehension region
 General interpretation area
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
Specialized Area of the Cerebrum
Figure 7.13c
Slide
The Brain: Cerebrum (lobes)
Cerebrum divided into 4
lobes:
Frontal: motor function,
motivation, aggression, smell
and mood
Parietal: reception and
evaluation of sensory info.
Temporal: smell, hearing,
memory and abstract thought
Occipital: visual processing
The Brain: Cerebrum (bumps and grooves)
The sulcus dividing
frontal and parietal lobes
is Central Sulcus.
Ridges on either side are
Pre & Post gyri
Motor
Pre CS ~ motor cortex
Post CS ~ somatic
sensory cortex
Sensory
Layers of the Cerebrum
 Basal nuclei – internal
islands of gray matter
 Regulates voluntary
motor activities by
modifying info sent to
the motor cortex
 Problems = ie unable
to control muscles,
spastic, jerky
 Involved in
Huntington’s and
Parkinson’s Disease
Figure 7.13a
Slide
Figure 4.20 Some major subdivisions of the human cerebral cortex
The four lobes: occipital, parietal, temporal, and frontal.
The Brain: Cerebrum (makin’ waves)
Sum electrical
activity can be
read as waves
with EEG
bio-feedback to
control brain
activity
The Brain: Cerebrum (memories)
3 types:
Sensory ~ less than a second
Short-term ~ seconds to minutes
(about 7 - 12 bits)
Long-term ~ minutes to life time
associated with re-shaping neurons and
formation of memory engrams
(pattern of neurons and their
connections)
1
9
2
1
3
6
0
3
7
8
2
4
3
1
1
3
5
7
9
2
4
6
8
0
1
3
5
7
The Brain: Cerebrum
(memories)
Long term memories are
divided into 2 types:
Declarative memory ~
ability to recall details,
names etc.
Procedural memory ~
ability to repeat behaviors
or actions.
Example: Pavlov and
conditioning
The Brain: Cerebrum (memories in “limbo”)
Deepest portion of
cerebrum and brainstem
associations called the
Limbic system
This is involved with mood,
base emotions and interacts
with hypothalamus to
influence food/H2O
acquisition.
Major input is olfaction
The Brain: Cerebrum (hemispheres)
Not really a “dominant”
side
Hemispheres communicate
via the corpus callosum
Structurally and
functionally different
Right brain -- usually
Representational
Left brain -- usually
Categorical
Anterior
Smell R.
Verb. Mem.
Smell L.
Shape mem.
Musical
Symbolic
Language
Intuitive
Spatial
Posterior