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Drugs and Our Society
Drugs and the Brain
Part 6
The Nervous System
1. The nervous system can be divided into two parts:
2.
3.
- 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)
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
4. 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
Nervous system, cont
6. 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
7. The brain
- it is a complicated structure
- made up of nuclei and fiber tracts
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
8. 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
Nervous system, cont
9. The brain has a rich supply of blood from 4
major arteries
- drugs circulating in the blood have a fast
access to the brain
10.Blood-brain barrier
- capillaries in the brain are different
- the cells are tightly joined
- this keeps many drugs from reaching the
brain
11.For a drug to be psychoactive, the molecules
must be capable of passing this barrier
Nervous system, cont
12.Drugs are carried to the brain by the blood
supply
- how do they know where to go
- they don’t
- drugs go everywhere
13.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
Parts of the Brain
1. There are 3 primary parts to the brain:
- the forebrain / midbrain / hindbrain
2. Hindbrain
- controls breathing / heart rate (respiration)
/ and digestion
- it is highly sensitive to opiates / alcohol /
barbiturates / and depressants
3. Midbrain
- sensory and motor reflexes
- processing of pain information
Parts of the brain, cont
4. Forebrain
- feeding / drinking / sexual behavior
- organizing emotional behavior
- visual / auditory / sensory
5. The brain is further broken-down into the:
- cortex
- medulla oblongata
- hippocampus, and
- thalmus