Central Nervous System

1. Central Nervous System

2. Divisions of the Brain • Brainstem • Medulla oblongata • extension of spinal cord • Contains the cardiac, respiratory and vasomotor centers (control heartbeat, blood vessel diameter) • Consists of white and gray matter intermingled • Pons • Midbrain

3. Diencephalon • Small, located above midbrain, below cerebrum • Consists of 2 major structures: hypothalmus and thalmus • Hypothamus: • Pituitary gland is an extension of hypothalmus • Major control over most major organs • Make hormones secreted by pituitary gland • Secrete releasing hormones into blood to the anterior pituitary gland • Helps regulate water balance, body temperature, sleep cycles and appetite and many emotions

4. Diencephalon • Thalmus • Dumb bell shaped gray matter, above hypothalmus • Axons go into cerebellum • Helps produce sensations, associates sensations with emotions and plays a role in the arousal or alerting mechanism

5. Cerebellum • Second largest part of human brain • Arbor vitae – tree of life, gray matter on outside, white matter inside • Produce smooth, coordinated movements, maintain equilibrium and sustain normal postures.

6. cerebrum • Largest and upper most part of brain • Ridges – convolutions or gyri • Grooves – sulci, deep grooves – fissures • Longitudinal fissure – divides into left and right • Find also the central sulcus, lateral fissure • Corpus callosum – connects left and right hemisphere of the brain

7. cerebrum • 4 major lobes of the brain named for bones • Frontal, Occipital, Temporal, parietal • Cerebral cortex – gray matter, surface of cerebrum • White matter (tracts) makes up most of cerebrum • exception is basal ganglia (produce automatic movements and posture, ex. Parkinson disease

8. Brain disorders • Cerebrovascular accident (CVA) – stroke – hemorrhage or cessation of blood flow through vessels in brain, neurons die • If damage occurs in a motor control section of brain, movement ceases • Cerebral palsy – damage to brain tissue • Prenatal infections, trauma to the head before, during, after birth, reduced oxygen to brain • Spastic paralysis – involuntary contractions of affected muscles • Hemiplegia – 1 side of body • Paraplegia – both legs • Triplegia – both legs, 1 arm • Quadriplegia – all 4 appendages

9. Degenerative brain disorders • Destruction of neurons in the brain • Affects memory, attention span, intellectual capacity, personality and motor control = dementia • Alzheimer Disease (AD) – lesions on cerebral cortex • Huntington disease (HD) – chorea – involutary purposeless movements

10. Seizure • Seizure – sudden bursts of abnormal neuron activity • Range from mild to severe • Epilepsy – recurring or chronic seizures • Can be caused by tumors, trauma, or chemical imbalances, most idiopathic • Medications block neurotransmitters in affected areas of the brain.

11. Spinal cord • Average of 17 – 18 inches • From occipital bone to L1 vertebrae • core is made up of gray matter • Outer part is white matter – spinal tracts

12. Spinal cord • 2 way conduction • Ascending tracts – to brain • Descending tracts – from the brain • Primary reflex center • Cut in the spinal cord results in no communication • Anesthesia – loss of sensation • Paralysis – loss of the ability to make voluntary movements

13. Coverings • Meninges – touch, fluid-containing membrane • 3 layers • Dura mater – tough outer layer • Pia mater – innermost membrane, covers spinal cord • Arachnoid mater – between dura and pia mater, cob web like • Meningitis – infection or inflammation of meninges

14. Fluids • Cerebrospinal fluid (CSF) – fills subarachnoid spaces in brain and spinal cord and ventricles in brain • 2 lateral ventricles and third ventricle • CSF is continuously begin made from fluid filtering out of choroid plexus and into ventricles and continues to circulate around the brain and spinal cord • Hydrocephalus – water on the brain – accumulation of CSF in ventricles