Download Nervous System PPT C

Nervous Part C
H. Biology II
Adapted 2014-2015
Cerebral Cortex
• Thin (2–4 mm) superficial layer of gray matter
• 40% of the mass of the brain
• Site of conscious mind: awareness, sensory perception,
voluntary motor initiation, communication, memory
storage, understanding
• Each hemisphere connects to contralateral side of the
body
• There is lateralization of cortical function in the
hemispheres
Cerebral Hemispheres
• Surface markings
– Central sulcus
• Separates the precentral gyrus of the frontal lobe and
the postcentral gyrus of the parietal lobe
– Longitudinal fissure
• Separates the two hemispheres
– Transverse cerebral fissure
• Separates the cerebrum and the cerebellum
Precentral
gyrus
Frontal
lobe
Central
sulcus
Postcentral
gyrus
Parietal lobe
Parieto-occipital sulcus
(on medial surface
of hemisphere)
Lateral sulcus
Occipital lobe
Temporal lobe
Transverse cerebral fissure
Cerebellum
Pons
Medulla oblongata
Spinal cord
Fissure
(a deep
sulcus)
Gyrus
Cortex (gray matter)
Sulcus
White matter
(a)
Figure 12.6a
Anterior
Longitudinal
fissure
Frontal lobe
Cerebral veins
and arteries
covered by
arachnoid
mater
Parietal
lobe
Right cerebral
hemisphere
Occipital
lobe
Left cerebral
hemisphere
(c)
Posterior
Figure 12.6c
Left cerebral
hemisphere
Brain stem
Transverse
cerebral
fissure
Cerebellum
(d)
Figure 12.6d
Cerebral
hemisphere
Diencephalon
(d) Birth
Cerebellum
Brain stem
• Midbrain
• Pons
• Medulla
oblongata
Figure 12.3d
Functional Areas of the Cerebral
Cortex
• The three types of functional areas are:
– Motor areas—control voluntary movement
– Sensory areas—conscious awareness of sensation
– Association areas—integrate diverse information
• Conscious behavior involves the entire cortex
Motor areas
Central sulcus
Primary motor cortex
Premotor cortex
Frontal eye field
Broca’s area
(outlined by dashes)
Prefrontal cortex
Working memory
for spatial tasks
Executive area for
task management
Working memory for
object-recall tasks
Solving complex,
multitask problems
(a) Lateral view, left cerebral hemisphere
Sensory areas and related
association areas
Primary somatosensory
cortex
Somatic
Somatosensory
sensation
association cortex
Gustatory cortex
(in insula)
Taste
Wernicke’s area
(outlined by dashes)
Primary visual
cortex
Visual
association
area
Auditory
association area
Primary
auditory cortex
Vision
Hearing
Motor association cortex
Primary sensory cortex
Primary motor cortex
Sensory association cortex
Multimodal association cortex
Figure 12.8a
Posterior
Motor
Motor map in
precentral gyrus
Anterior
Toes
Jaw
Tongue
Swallowing
Primary motor
cortex
(precentral gyrus)
Figure 12.9
Posterior
Sensory
Anterior
Sensory map in
postcentral gyrus
Genitals
Primary somatosensory cortex
(postcentral gyrus)
Intraabdominal
Figure 12.9
Motor areas
Central sulcus
Primary motor cortex
Premotor cortex
Frontal eye field
Broca’s area
(outlined by dashes)
Prefrontal cortex
Working memory
for spatial tasks
Executive area for
task management
Working memory for
object-recall tasks
Solving complex,
multitask problems
(a) Lateral view, left cerebral hemisphere
Sensory areas and related
association areas
Primary somatosensory
cortex
Somatic
Somatosensory
sensation
association cortex
Gustatory cortex
(in insula)
Taste
Wernicke’s area
(outlined by dashes)
Primary visual
cortex
Visual
association
area
Auditory
association area
Primary
auditory cortex
Vision
Hearing
Motor association cortex
Primary sensory cortex
Primary motor cortex
Sensory association cortex
Multimodal association cortex
Figure 12.8a
Premotor cortex
Corpus
callosum
Cingulate
gyrus
Primary
motor cortex
Frontal eye field
Prefrontal
cortex
Processes emotions
related to personal
and social interactions
Orbitofrontal
cortex
Olfactory bulb
Olfactory tract
Fornix
Temporal lobe
(b) Parasagittal view, right hemisphere
Uncus
Primary
olfactory cortex
Central sulcus
Primary somatosensory
cortex
Parietal lobe
Somatosensory
association cortex
Parieto-occipital
sulcus
Occipital
lobe
Visual
association
area
Primary
visual cortex
Calcarine sulcus
Parahippocampal
gyrus
Motor association cortex
Primary sensory cortex
Primary motor cortex
Sensory association cortex
Multimodal association cortex
Figure 12.8b
Brain Add in PPT
• Do some clinical connections/disorders with
brain components
Broca’s Area
• Anterior to the inferior region of the premotor
area
• Present in one hemisphere (usually the left)
• A motor speech area that directs muscles of
the tongue
• Is active as one prepares to speak
Anterior Association Area
(Prefrontal Cortex)
• Most complicated cortical region
• Involved with intellect, cognition, recall, and
personality
• Contains working memory needed for
judgment, reasoning, persistence, and
conscience
• Development depends on feedback from
social environment
Limbic Association Area
• Part of the limbic system
• Provides emotional impact that helps
establish memories
Ventricles of the Brain
• Connected to one another and to the central
canal of the spinal cord
• Lined by ependymal cells
• Contain cerebrospinal fluid
– Two C-shaped lateral ventricles in the cerebral
hemispheres
– Third ventricle in the diencephalon
– Fourth ventricle in the hindbrain, dorsal to the
pons, develops from the lumen of the neural tube
Lateral ventricle
Septum pellucidum
Anterior horn
Inferior
horn
Lateral
aperture
Interventricular
foramen
Third ventricle
Inferior horn
Cerebral aqueduct
Fourth ventricle
Central canal
(a) Anterior view
(b) Left lateral
Posterior
horn
Median
aperture
Lateral
aperture
view
Figure 12.5
Regions and Organization of the CNS
• Spinal cord
– Central cavity surrounded by a gray matter core
– External white matter composed of myelinated
fiber tracts
Cortex of
gray matter
Inner gray
matter
Central cavity
Migratory
pattern of
neurons
Cerebrum
Cerebellum
Region of cerebellum
Outer white
matter
Gray matter
Central cavity
Inner gray matter
Outer white matter
Brain stem
Gray matter
Central cavity
Outer white matter
Spinal cord
Inner gray matter
Figure 12.4
Reflex Arc
Spinal Cord Trauma
• Functional losses
– Parasthesias
• Sensory loss
– Paralysis
• Loss of motor function
• Flaccid paralysis—severe damage to the
ventral root or ventral horn cells
– Impulses do not reach muscles; there is no
voluntary or involuntary control of muscles
– Muscles atrophy
Spinal Cord Trauma
• Spastic paralysis—damage to upper motor
neurons of the primary motor cortex
– Spinal neurons remain intact; muscles are
stimulated by reflex activity
– No voluntary control of muscles
Spinal Cord Trauma
• Transection
– Cross sectioning of the spinal cord at any level
– Results in total motor and sensory loss in regions
inferior to the cut
– Paraplegia—transection between T1 and L1
– Quadriplegia—transection in the cervical region
Poliomyelitis
• Destruction of the ventral horn motor neurons
by the poliovirus
• Muscles atrophy
• Death may occur due to paralysis of
respiratory muscles or cardiac arrest
• Survivors often develop postpolio syndrome
many years later, as neurons are lost
Amyotrophic Lateral Sclerosis (ALS)
• Also called Lou Gehrig’s disease
• Involves progressive destruction of ventral
horn motor neurons and fibers of the
pyramidal tract
• Symptoms—loss of the ability to speak,
swallow, and breathe
• Death typically occurs within five years
• Linked to glutamate excitotoxicity, attack by
the immune system, or both
Multiple Sclerosis (MS)
• An autoimmune disease that mainly affects young adults
• Symptoms: visual disturbances, weakness, loss of
muscular control, speech disturbances, and urinary
incontinence
• Myelin sheaths in the CNS become nonfunctional
scleroses
• Shunting and short-circuiting of nerve impulses occurs
• Impulse conduction slows and eventually ceases
Multiple Sclerosis: Treatment
• Some immune system–modifying drugs,
including interferons and Copazone:
– Hold symptoms at bay
– Reduce complications
– Reduce disability
Developmental Aspects of the CNS
• CNS is established during the first month of development
• Gender-specific areas appear in both brain and spinal
cord, depending on presence or absence of fetal
testosterone
• Maternal exposure to radiation, drugs (e.g., alcohol and
opiates), or infection can harm the developing CNS
• Smoking decreases oxygen in the blood, which can lead
to neuron death and fetal brain damage
Developmental Aspects of the CNS
• Age brings some cognitive declines, but these
are not significant in healthy individuals until
they reach their 80s
• Shrinkage of brain accelerates in old age
• Excessive use of alcohol causes signs of
senility unrelated to the aging process