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)

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 substantia nigra 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

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

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

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

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

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

Marijuana and Alcohol Marijuana- Tetrahydrocannabinol (THC) Alcohol 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