Warm Up 1/21/11 **Reminder: Muscle Quiz #2 (last two pages of packet) next block day 1. What are the main divisions of the nervous system? (be very general) 2. What components make up these two divisions? 3. What is/are the function(s) of ependymal cells? 4. What is the name of the opening where the spinal cord enters/exits the cranial cavity?
Warm Up 1/21/11. **Reminder: Muscle Quiz #2 (last two pages of packet) next block day What are the main divisions of the nervous system? (be very general) What components make up these two divisions? What is/are the function(s) of ependymal cells? - PowerPoint PPT Presentation
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Warm Up 1/21/11
**Reminder: Muscle Quiz #2 (last two pages of packet) next block day
1. What are the main divisions of the nervous system? (be very general)
2. What components make up these two divisions?
3. What is/are the function(s) of ependymal cells?
4. What is the name of the opening where the spinal cord enters/exits the cranial cavity?
Central Nervous System
Chapter 13
CNS Coverings
• Bone• Meninges
– Dura Mater: white fibrous tissue– Arachnoid membrane: cobweb-like layer– Pia Mater: adheres to outer surface of brain & cord;
– Spinotectal: touch that triggers visual reflexes
Spinal Cord – Conduction Routes
• Descending tracts – conduct motor impulses down from the brain– Lateral corticospinal: voluntary movement, contraction
of small muscle groups (hands, fingers, feet, toes of opposite side)
– Anterior corticospinal: same as above but affect muscles on same side
– Reticulospinal: maintain posture during movement– Rubrospinal: coordination of body movement &
posture– Tectospinal: head and neck movement during visual
reflexes– Vestibulospinal: coordination of posture & balance
Spinal Cord – Reflex Centers
• Center of reflex arc
• Switching from afferent to efferent– 3 neuron arc interneuron– 2 neuron arc synapse btwn afferent &
efferent
• Located in gray matter (“H”)
Brain• Consists of:
– 100 billion neurons– 900 billion glial cells
• Weighs approx 3 lbs in an adult• Mature neurons are incapable of cell
division– Only during prenatal and beginning months of
life– Malnutrition hinders neuron
growth/development
Brain - Divisions• Brainstem
– Medulla oblongata– Pons– Midbrain
• Cerebellum• Diencephalon
– Thalamus– Pineal body– hypothalamus
• Cerebrum– Cortex
Brainstem• Medulla Oblongata
– Enlarged extension of the spinal cord – Located just above the foramen magnum– Contains white matter and a network of gray & white
matter called the reticular formation• Reflex centers: cardiac, vasomotor, respiratory
• Pons– White matter & reticular formation– Reflex centers for CN 5-8
• Midbrain– White matter & reticular formation– Reflex centers for CN 3-4
Cerebellum
• Structure– Lower posterior portion of brain– Outer region cortex gray matter– Internal areas white matter– Grooves sulci; raised areas gyri
• Function– Produce skilled movements by coordinating muscle
groups– Posture (unconscious) – Maintains balance
Cerebellar Disease• Diseases of the cerebellum (tumor,
abscess, trauma, hemorrhage) produce abnormalities in muscle coordination
• Most common – ataxia (muscle incoordination)
• Signs/symptoms: – Hypotonia– Tremors– Disturbances in gait & balance
Diencephalon
• Thalamus– Dumbbell-shaped mass of gray matter– Forms walls of third ventricle– Functions:
• Processes auditory & visual input• Conscious recognition of pain, temperature &
touch• Emotional responses (associates sensory
impulses with pleasantness vs unpleasantness)
Diencephalon• Hypothalamus
– Lie beneath thalamus and forms the floor of the 3rd ventricle
– Functions:• Controls responses made by autonomic effectors• Maintains water balance• Endocrine function – release hormones that
regulate actions of the anterior pituitary gland• Waking state (alert and arousal)• Regulating appetite• Maintaining normal body temperature
Warm Up 1/25/11Announcements:1. You need your book – go get it!2. Muscles quiz this Wednesday or Thursday3. Dissections this Wednesday or Thursday – hair back &
tracts carry ________ information.2. True/False: Conduction routes are symmetrical, meaning
they are found on both sides of the spinal cord.3. Reflex centers can be described as:4. What vital reflex centers are found in the medulla
oblongata?5. Which part of the brain produces emotional responses
associated with sensory impulses?
Diencephalon
• Pineal Body– Located just
above the midbrain
– Functions:• Regulates
biological clock
• Produces melatonin
Cerebrum• Largest, upper division of the brain• Two halves – right & left hemispheres
– Communicate via corpus callosum
• Cerebral cortex – surface of the cerebrum; gray matter– Gyri & sulci (shallow) or fissures (deep)– Frontal lobe, parietal lobe, temporal lobe,
occipital lobe, insula (under lateral fissure)
• Cerebral tracts – white matter beneath the cerebral cortex
Functional Areas of the Cerebral Cortex (fig 13-16)
Functions of the Cerebral Cortex
• Postcentral gyrus – termination area for sensory pathways– Touch,
pressure, temperature, body position
• Precentral gyrus – primary motor area– Neurons in
this area control individual muscles
Functions of the Cerebral Cortex - Consciousness
• Consciousness depends on the proper functioning of the reticular activating system– Reticular formation in the brainstem receives
impulses from the spinal cord – Relays signals to thalamus then to cerebral
cortex– Continual excitement of the neurons in this
system is necessary for a person to remain in a conscious state
Functions of the Cerebral Cortex - Language
• Speech centers are located in frontal, parietal & temporal lobes
• In 90% of the population these areas are found in the left hemisphere
• Aphasia = language defects
• Broca’s area – unable to articulate words; able to make vocal sounds
• Wernicke’s area – deficit in language comprehension
Functions of the Cerebral Cortex - Emotions
• Experiencing and expressing emotions involves the function of the limbic system– Area of the brain that surrounds the corpus callosum – For proper expression the limbic system functions with the
cerebral cortex
Functions of the Cerebral Cortex - Memory
• Temporal, parietal and occipital lobes
• Limbic system also plays a role– Removal of hippocampus inhibits a person
from recalling new information
Disorders of the Central Nervous System
Cerebrovascular Accident (CVA)
• Aka Stroke• Hemorrhage or cessation of
blood flow through cerebral blood vessels
• Lack of oxygen to neurons causes cell damage or death
• If motor areas are affected, patient loses function on opposite site of the body– (motor neurons cross over from
side to side in the brainstem)• Hemiplegia – paralysis (loss
of voluntary muscle control) on one whole side of the body