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Drugs and Our Society

Drugs and Our Society. Drugs and the Brain Part 6. The Nervous System. The nervous system can be divided into two parts: - the peripheral nervous system (PNS) and - the central nervous system (CNS) The peripheral is made up of the somatic nervous system and the autonomic systems

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Drugs and Our Society

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  1. Drugs and Our Society Drugs and the Brain Part 6

  2. The Nervous System • The nervous system can be divided into two parts: - the peripheral nervous system (PNS) and - the central nervous system (CNS) • The peripheral is made up of the somatic nervous system and the autonomic systems • Somatic nervous system - nerve cells that interact with the external environment - consciousness / voluntary reactions - it is made up of sensory nerves (eyes / ears / skin / tongue (vision / hearing / touch / taste)

  3. Nervous System, cont - sends sensory information to the CNS - pinch your skin / speck of dust in the eye - sends movement information back out - twitch of the arm / blink or tearing of eye • Autonomic nervous system - internal environment is monitored and controlled - operates the visceral (involuntary) body functions - it is an unconscious reaction - heart rate / blood pressure / breathing

  4. Nervous system, cont • Central nervous system - consists of the brain and spinal cord - spinal cord functions primarily as a relay station - it transmits information from sensory nerves to the brain - it carries motor commands from the brain to the muscles • The brain - it is a complicated structure - made up of nuclei and fiber tracts

  5. Nervous system, cont - it contains 100 billion neurons - these are the messengers in the brain - they transmit information via chemical and electrical processes - they are considered neurotransmitters, such as serotonin / dopamine / nor epinephrine • It is capable of storing and analyzing more information than today’s supercomputers - it is not as fast, but can deal simultaneously with 1000’s of pieces of input

  6. Nervous system, cont • The brain has a rich supply of blood from 4 major arteries - drugs circulating in the blood have a fast access to the brain • Blood-brain barrier - capillaries in the brain are different - the cells are tightly joined - this keeps many drugs from reaching the brain • For a drug to be psychoactive, the molecules must be capable of passing this barrier

  7. Nervous system, cont • Drugs are carried to the brain by the blood supply - how do they know where to go - they don’t - drugs go everywhere • Certain drugs impact certain neuron cells - LSD acts on serotonin in the brain - where the psychoactive drugs are similar to the molecular structure of neuron chemicals - the drug molecules interact with the brain chemistry

  8. Parts of the Brain • There are 3 primary parts to the brain: - the forebrain / midbrain / hindbrain • Hindbrain - controls breathing / heart rate (respiration) / and digestion - it is highly sensitive to opiates / alcohol / barbiturates / and depressants • Midbrain - sensory and motor reflexes - processing of pain information

  9. Parts of the brain, cont • Forebrain - feeding / drinking / sexual behavior - organizing emotional behavior - visual / auditory / sensory • The brain is further broken-down into the: - cortex - medulla oblongata - hippocampus, and - thalmus

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