Part II Central Nervous System: Brain

Chapter 7 Vocabulary ventricles gyri (gyrus) sulci (sulcus) fissures longitudinal fissure central sulcus Broco’s area speech area cerebral cortex corpus callosum Parkinson’s disease Huntington’s disease Alzheimer’s disease (AD)

II. Central Nervous System (CNS) CNS develops from the embryonic neural tube The neural tube becomes the brain and spinal cord The opening of the neural tube becomes the ventricles Four chambers within the brain Filled with cerebrospinal fluid

Ventricles and Location of the Cerebrospinal Fluid Figure 7.17a–b

A. Four Major Regions of the Brain 1. Cerebrum (Cerebral hemispheres) 2. Diencephalon 3. Brain stem 4. Cerebellum Figure 7.12b

Cerebral Hemispheres (Cerebrum) Paired (left and right) superior parts of the brain Include more than half of the brain mass Figure 7.13a

Cerebral Hemispheres (Cerebrum) The surface is made of ridges (gyri) and grooves (sulci) Gyri (gyrus) – outward folds or ridges on surface of cerebral cortex Sulci (sulcus) – shallow grooves or furrows in cerebral cortex Fissures – the deepest inward folds on the brain Figure 7.13a

Cerebral Hemispheres (Cerebrum) Central Sulcus – divides the cerebral hemisphere into motor and sensory areas; separates the frontal lobe from the parietal lobe Longitudinal Fissure - separates the cerebral hemispheres Figure 7.13a

B. Cerebrum - Four Lobes Fissures (deep grooves) divide the cerebrum into lobes: 1. Parietal lobe – somatic sensory area (post- central sulcus) 2. Frontal lobe – primary motor area (pre-central sulcus), Broca’s area (motor speech) 3. Temporal lobe – auditory area and olfactory area 4. Occipital lobe – visual area

Lobes of the Cerebrum Figure 7.15a

Specialized Areas of the Cerebrum Somatic sensory area – receives impulses from the body’s sensory receptors (parietal lobe) Primary motor area – sends impulses to skeletal muscles (frontal lobe) Broca’s area – involved in our ability to say words correctly; usually in left cerebral hemisphere (frontal lobe) Speech Area – involved in language comprehension (word meanings); located at junction of temporal, parietal, and occipital lobes

Sensory and Motor Areas of the Cerebral Cortex Figure 7.14

Specialized Areas of the Cerebrum Cerebral areas involved in special senses Gustatory area (taste) Visual area Auditory area Olfactory area

Specialized Areas of the Cerebrum Interpretation areas of the cerebrum Speech/language region Language comprehension region General interpretation area

Specialized Areas of the Cerebrum Figure 7.13c

Layers of the Cerebrum Gray matter Outer layer Composed mostly of neuron cell bodies Cerebral cortex – outermost gray matter of the cerebrum; Figure 7.13a

Layers of the Cerebrum White matter Fiber tracts inside the gray matter corpus callosum - connects cerebral hemispheres Figure 7.13a

Corpus Callosum – connects the cerebral Corpus Callosum – connects the cerebral hemispheres; allows the brain stem and cerebral hemispheres to communicate with one another corpus callosum

Layers of the Cerebrum Basal nuclei – internal islands of gray matter; help regulate voluntary motor activities by modifying instructions sent to the skeletal muscles by the primary motor cortex; Located at the base of the brain Composed of 4 clusters of neurons, or nerve cells. This area of the brain is responsible for body movement and coordination. Figure 7.13a

The Terrible Three CNS Degenerative Diseases Parkinson’s disease – degeneration of dopamine-releasing neurons causing basal nuclei to become overactive, causing persistent tremor at rest and trouble initiating movement or getting muscles going Huntington’s disease - genetic disease that leads to massive degeneration of the basal nuclei and later of the cerebral cortex. Symptoms are wild, jerky, and almost continuous flapping movements called chorea and mental deterioration, usually fatal, within 15 years of onset Alzheimer’s disease (AD) – progressive degenerative disease of the brain that ultimately results in dementia (mental deterioration). AD is associated with a shortage of acetylcholine (ACh) and structural changes in the brain, particularly in areas involved with cognition and memory where abnormal proteins are deposited, gyri shrink, and the brain atrophies. Causes are unknown.

Alzheimer’s Disease Progressive degenerative brain disease Mostly seen in the elderly, but may begin in middle age Structural changes in the brain include abnormal protein deposits and twisted fibers within neurons Victims experience memory loss, irritability, confusion and ultimately, hallucinations and death

Alzheimer’s Disease (AD)

Alzheimer’s Disease (AD)

Huntington’s Disease

Huntington’s Disease Huntington's disease is a hereditary disorder caused by a faulty gene for a protein called huntingtin. The children of people with the disorder have a 50% chance of inheriting it. The disease causes degeneration in many regions of the brain and spinal cord. Symptoms of Huntington's disease usually begin when patients are in their thirties or forties, and the average life expectancy after diagnosis is about 15 years. Cognitive symptoms of Huntington's disease typically begin with mild personality changes, such as irritability, anxiety, and depression, and progress to severe dementia. Many patients also show psychotic behavior. Huntington's disease causes chorea - involuntary jerky, arrhythmic movements of the body - as well as muscle weakness, clumsiness, and gait disturbances.

Parkinson’s Disease

Parkinson’s Disease

Imaging Dementia-Mayo Clinic http://www.youtube.com/watch?v=b6iOEeqI27E&feature=player_embedded

C. Diencephalon (Interbrain) Sits on top of the brain stem Enclosed by the cerebral hemispheres Made of three parts: 1. Thalamus – relays sensory impulses 2. Hypothalamus – temperature, thirst, appetite, sex, pain, and pleasure center (limbic center- emotions); regulates pituitary gland and mammillary bodies (sense of smell) 3. Epithalamus – contains pineal body (sleep/wake cycle) and choroid plexus (makes CS fluid)

Diencephalon Figure 7.15

Ventricles and Location of the Cerebrospinal Fluid Figure 7.17a–b

Diencephalon: Thalamus Surrounds the third ventricle The relay station for sensory impulses Transfers impulses to the correct part of the cortex for localization and interpretation

Diencephalon: Hypothalamus Under the thalamus Important autonomic nervous system center Helps regulate body temperature Controls water balance Regulates metabolism An important part of the limbic system (emotions) The pituitary gland is attached to the hypothalamus

Diencephalon: Epithalamus Forms the roof of the third ventricle Houses the pineal body (an endocrine gland) Includes the choroid plexus – forms cerebrospinal fluid

D. Brain Stem Attaches to the spinal cord Parts of the brain stem: 1. Midbrain – contains cerebral aqueduct, cerebral peduncles, and corpora quadrigemina; reflex centers for vision and hearing 2. Pons – “bridge”; controls breathing 3. Medulla oblongata – merges with spinal cord; vital centers control heart rate, blood pressure, breathing, swallowing and vomiting 4. Reticular formation – motor control of organs, RAS controls awake/sleep cycle and consciousness

Brain Stem Figure 7.15a

Brain Stem: Midbrain Mostly composed of tracts of nerve fibers Has two bulging fiber tracts – cerebral peduncles Has four rounded protrusions – corpora quadrigemina Reflex centers for vision and hearing

Brain Stem: Pons The bulging center part of the brain stem Mostly composed of fiber tracts Includes nuclei involved in the control of breathing

Brain Stem: Medulla Oblongata The lowest part of the brain stem Merges into the spinal cord Includes important fiber tracts Contains important control centers Heart rate control Blood pressure regulation Breathing Swallowing Vomiting

Brain Stem: Reticular Formation Diffuse mass of gray matter along the brain stem Involved in motor control of visceral organs Reticular activating system plays a role in awake/sleep cycles and consciousness

Brain Stem: Reticular Formation Figure 7.15b

E. Cerebellum Two hemispheres with convoluted surfaces Provides involuntary coordination of body movements Precise timing for skeletal muscle activity Controls balance and equilibrium

Cerebellum Figure 7.15a

Traumatic Brain Injury Videos Effects of damage to different lobes http://www.youtube.com/watch?feature=player_detailpage&v=wlYiDxNcMdc

Chapter 7 Vocabulary ventricles gyri (gyrus) sulci (sulcus) fissures longitudinal fissure central sulcus Broco’s area speech area cerebral cortex corpus callosum Parkinson’s disease Huntington’s disease Alzheimer’s disease (AD)