Transcript CNS - Misericordia University

Central Nervous System (CNS):
Brain and Spinal Cord
Biology 211 A&P 1
Tony Serino, Ph.D.
Biology Dept.
Misericordia University
Central Nervous System (CNS)
• Gray vs. White matter
• Protection of CNS
– Meninges
– CSF flow
• Brain
– Development
– Selected structures
• Spinal cord
– Selected structures
CNS (Central Nervous System)
• Brian and spinal cord
• Displays gray and white matter
– Gray matter are areas of CNS with many cell
bodies of neurons present (little myelinated
nerve fibers)
– White matter are area of CNS with few cell
bodies but many myelinated nerve fibers
• Protected by bone and membranes
Gray and White Matter
• Since the cerebrum and
cerebellum outgrow
their cores, gray matter
ends up on outside of
both structures.
Meninges
• Dura Mater –outermost; tough, fibrous CT
– In brain, divided into two layers (periosteal and
meningeal)
– In spine, only one layer with fat filled space
above the layer called the epidural space
• Arachnoid –middle; web-like appearance
– Potential space between Dura and arachnoid is
the subdural space
• Pia Mater –innermost, delicate membrane
fused with CNS surface
– Space between Pia and Arachnoid is the
subarachnoid space
Meninges of the Spinal Cord
Epidural space
Subdural space
Pia mater
Arachnoid
Dura mater
Meninges
Subarachnoid space
Dorsal Root
Ganglion
Centrum
Brain Meninges
Extensions of Dura Mater
hold brain in cavity
Brain Ventricles
Choroid Plexus
CSF (cerebral-spinal fluid) Flow
Hydrocephalus
• Blockage of CSF flow
can lead to severe
brain and/or head
enlargement.
• In an adult, such
swelling would be
fatal.
Brain Damage due to Pressure
Hematoma
Brain
• Development
• Structures
• Functional Areas
Neural Tube Formation
Brain Vesicles
Flexures and Cerebral Cortex Growth
Major Divisions of Brain
Brain Stem = midbrain + pons + medulla
Brain Anatomy (req’d)
Projections vs. Commissures
Functional Anatomy of Brain
Functional Areas of Cerebrum
Communication
• Note difference in
hearing vs. speaking
words
Male vs. Female processing
during a language task
Electroencephalography (EEG)
The electroencephalograph (EEG) is the printout of an
electronic device that uses scalp electrodes to monitor
the internal neural activity in the brain cortex.
EEG as Clinical Tool
EEGs provide diagnostic information about the
location of abnormal activity in the brain,
such as shown in this record typical of a patient
undergoing an epileptic seizure.
• EEGs record largely the surface electrical activity of
underlying brain areas
• Activity largely due to summated graded potentials
of many neurons
• Amplitude shows how much activity (degree of
summation and/or number of neurons)
Primary Motor and Somatosensory Gyri
Basal Nuclei: cerebral nuclei
Putamen and
Globus Pallidus
Subthalamic nuclei and
the Substantia nigra are
usually included
RAS (Reticular Activating System)
• Brainstem nuclei intermingled
with bundles of axons
• Receives and integrates input
from all regions of CNS
• Involved in motor function,
cardiac and respiratory control,
attention, vasomotor control,
sleep/wakefulness
• Extends along length of brain
stem; used in maintaining
alertness while awake
RAS receives inputs from eye, ear and general
sensation to maintain alertness
Sleep Patterns
• NREM Stage 1 4: decreasing
eye and skeletal muscle
movement, increased threshold
for arousal, increase size but
decrease freq. of EEG
• REM: EEG freq. increases with
less amplitude (alpha like),
increase HR, Resp. Rate, and eye
movement, but still in deep
sleep, high oxygen consumption
in brain; dream sleep
• 4-5 cycles of NREM/REM sleep
each night (every ~90 min)
Importance of Sleep
• Slow wave sleep is thought to be restorative to
brain function (Children have more total sleep
time and are in stage 4 more than adults); Elderly
have about the same total sleep time as adults but
broken into smaller episodes, also spend less time
in REM. Time spent in Stage 4 declines with age.
• Person consistently deprived of REM may become
moody or depressed; may exhibit other personality
disorders
Coma & Brain Death
• Coma is a severe loss in
mental function due to
brain damage; sustained
loss of arousal (even
with heavy stimuli),
behavior response is
lost, no sleep/wake
cycles
• Persistent Vegetative
State –sleep/wake cycles
are present; no sign of
external awareness
Limbic System: functional system;
responsible for emotion and memory
Cingulate Gyrus
Fornix
Mammillary body
Learning & Memory
• Learning –acquisition
and utilization of
information from past
experience
• Memory –relatively
permanent storage of
information
• Declarative memory –retention of conscious
experience, facts, etc.; uses Limbic system & cortex
(amygdala, hippocampus & thalamus)
• Procedural memory –knowledge of how to do
something (skilled behaviors); uses sensory cortex, basal
nuclei, & cerebellum
Memory
Processing
• Automatic long term memory
linked to noxious stimuli.
??
• Many long term memories may
be unretrievable consciously,
but may still exist within the
brain
Spinal Cord
• Receives and
generates signals to
body through the
spinal nerves
Spinal Cord (X.S.)
Cord in Spinal Canal
Posterior Median
Sulcus
Posterior
Root
Denticulate
Ligament
Dorsal Root
Ganglion
Anterior
Root
Spinal Nerve
Spinal Cord Segments
• 4 segments: Cervical,
Thoracic, Lumbar, and
Sacral (only 1
coccygeal nerve)
• 31 pairs of spinal
nerves
Cervical Segment
Thoracic Segment
Lumbar Segment
Sacral Segment
Cauda Equina
Lumbar Puncture
Functional Arrangement of SC