Traumatic Brain Injury and Strokes

1. Traumatic Brain Injury and Strokes • Concussion- alteration in brain function, usually temporarily • Contusion- bruising of brain, permanent neurological damage • Hemorrhage- bleeding in ruptured vessels in subdural or subarachnoid spaces • Cerebral edema- swelling of brain • Cerebrovascular Accidents (CVAs or Strokes)- blood circulation to brain is blocked, brain tissue dies • Most common cause= blockage of cerebral artery by blood clot, other causes= compression of brain tissue by hemorrhage, edema, narrowing of brain vessels by atherosclerosis (plaque)

2. Degenerative Brain Disorders • Alzheimer’s- plaque litters brain between neurons & neuron fibers tangle • Disrupts transport mechanisms, cells die, brain shrinks • Most vulnerable= hippocampus & basal forebrain- thinking & memory • Symptoms: memory loss, short attention span, disorientation, language loss, moodiness, confusion, and hallucinations • Parkinson’s- degeneration of dopamine-releasing neurons of substantianigra • Deprives basal nuclei of dopamine, become overactive • Symptoms: tremor, bent-walking posture, shuffling gait, stiff facial expression, slow initiating/executing movement • Huntington’s- fatal hereditary disorder • Protein accumulates in brain cells & tissue dies massive degeneration basal nuclei & later of cerebral cortex • Symptoms: wild, jerky, flapping involuntary movements, later- mental deterioration

3. Spinal Cord Trauma • Paralysis- loss of motor function • Flaccid paralysis- damage to ventral root/horn cells, nerve impulses no longer reach skeletal muscles, muscles atrophy • Spastic paralysis- damage to upper motor neurons of primary motor cortex, skeletal muscle movement not under control, but muscles remain healthy • Transection of spinal cord at any level results in total motor & sensory loss in all body regions inferior to site of damage • Paraplegia, Quadraplegia, Hemiplegia (1 side of body) • Spinal shock- period of functional loss that follows a traumatic injury to spinal cord • Neural function usually returns within a few hours following the injury

4. Spinal Cord Disorders • Poliomyelitis (Polio)- inflammation of spinal cord from destruction of ventral horn motor neurons by poliovirus • Early symptoms: fever, headache, muscle pain and weakness, loss of certain somatic reflexes • Later: paralysis and muscle atrophy • Vaccines have nearly eliminated this disease • Amyotrophic Lateral Sclerosis (ALS or Lou Gehrig’s Disease)- progressive destruction of ventral horn motor neurons and fibers of pyramidal tract • Loose ability to speak, swallow and breathe, death typically occurs in 5yrs of onset

5. Drugs and Drug Abuse • Drug- any substance other than food that changes the structure or function of the body • ALL drugs have the potential to do harm if they are used improperly • Drug abuse- using any drug in a way that most doctors would not approve

6. Stimulants vs Depressants • Stimulants- increase actions regulated by the nervous system (sympathetic, CNS, or both; especially RAS) • Effects- feel energetic but when it wears off brains neurotransmitters are depleted, leads to feeling fatigued and depressed • Long tem can cause circulatory problems, hallucinations, and psychological problems • Depressants- “depress” (slow down) actions regulated by the nervous system (many different parts of brain, especially RAS) • Some prevent nerve cells from starting an action potential • Depressant + alcohol can cause death because nervous system is depressed to the point breathing stops • Hallucinogens (LSD, XTC, Mescaline, )- interfere with sensory blocking of RAS

7. Drugs Associated with Pleasure Centers • Many pleasure systems in the limbic system • Addiction- uncontrollable craving for more of a drug • Cocaine- sudden release of dopamine • Causes intense feelings of pleasure and satisfaction, it also depletes the brain of stored dopamine, causing depression shortly after use and psychological dependence • Very powerful stimulant- can cause heart attack • Crack- potent and dangerous form of cocaine, addictive after only a few uses • Opiates- pain-killing drugs produced from opium poppy- mimic endorphins • 1st use produces strong feelings of satisfaction and security, but the body gets used to the higher levels of endorphins quickly and cannot do without • Depressants • Intravenous drug use

8. Marijuana and Alcohol • Marijuana- Tetrahydrocannabinol (THC) • Most widely abused drug • Can produce temporary feeling of euphoria and disorientation • Bad for lungs • Long-term use can cause loss of memory, inability to concentrate and reduced levels of testosterone in males • Alcohol • Can produce feelings of relaxation and confidence, but even a small amount slows reflexes, disrupts coordination and impairs judgment • One of most dangerous and abused depressants • Alcohol abuse costs the US at least $150 billion per year! • Cirrhosis- scar tissue in liver