Transcript Drugs and Addiction

Biology Today (BIOL 109)
Talk Eleven:
Drugs and Addiction
NOT IN BOOK
Drugs and addiction
• Drug addiction is a condition characterized by
compulsive drug intake, craving and seeking, despite
negative consequences associated with drug use.
• The activity of any drug varies with dose
– The amount of the drug taken over time
• The amount of a drug taken to be toxic or lethal
depends upon the chemical structure of the drug
– Also body size and other physiological variables
Drugs and addiction
• Although being addicted implies drug dependence,
it is possible to be dependent on a drug without
being addicted.
• People that take drugs to treat diseases and
disorders, which interfere with their ability to
function, may experience improvement of their
condition.
Drugs and addiction
• There is an growing consensus that drug addiction
is a form of disfunctional learning.
• Drugs of abuse take over the neuronal circuitry
involved in motivation and reward, leading to
aberrant engagement of learning processes.
• Because of this, drug-associated cues can trigger
cravings as well as unconcious or compulsive drugseeking behavior, with the sense that voluntary
control over drug use is lost.
How drugs enter the body
• The way in which a drug enters the body often
affects its resulting concentration in body tissues.
• Example: Cocaine
– A product of the coca plant – grows in the high Andes
• Cocaine exists in many forms that differ in both
conc of the drug and its molecular form.
• Coca leaves are chewed by South American Indians
– Concentrations absorbed by the gut are low.
How drugs enter the body
• By contrast, when cocaine is purified into a powder
and sniffed the rate and concentration of
absorption is increased many times.
– Cocaine is sometimes further purified into crack
• Whether cocaine is sniffed or smoked, it is inhaled
not as a gas, but as small particles
• For these chemicals to be absorbed they must first
adhere to lung tissue.
How drugs enter the body
• Chemicals can be highly
concentrated within a particle
• Thus these particles cause
substantial damage to lung
tissue
• Sniffing cocaine powder also
causes substantial damage to
cells in the nasal passage and
rot a person nose
• Can also eat away at the roof of
the mouth.
How drugs enter the body
• Other drugs are
injected into the body.
• Can be injected into
veins, or under the skin
• Continued uses always
leads to infection and
amputation of damaged
tissue.
How drugs enter the body
• In the US, most drugs are
inhaled and quickly enter the
blood system and affect the
brain.
• However, it is important to
remember that the most
popular drug in the US is
caffeine!
• The second is alcohol!
• It is important to remember
what is a drug!
So what is the biology
of the Respiratory
System?
The Respiratory System
• During inspiration or inhalation, air is
conducted toward the lungs.
• During expiration or exhalation, air is
conducted away from the lungs.
• Works in conjunction with the cardiovascular
system for RESPIRATION to occur
• Breathing –air in and out of lungs
• External respiration –exchange of gasses between air
&
blood
• Internal respiration – exchange between blood
&tissue fluid
• Cellular respiration –production of ATP in cells
The Respiratory System
• Two parts:
• Upper Respiratory Tract
• Nasal Cavities
– Filter, warm and moisten
air
• Pharynx
– Connection to surrounding
regions
• Glottis
– Passage of air into
larynx
• Larynx
– Sound production
The Respiratory System
• Lower Respiratory Tract
• Trachea
– Passage of air to Bronchi
• Bronchi
– Passage of air to lungs
• Bronchioles
– Passage of air to each
alveolus
• Lungs
– Gas Exchange
The Respiratory System
• As air moves towards the
lungs it is cleansed,
warmed, and moistened.
• As air moves out during
expiration, it cools and
deposits moisture on the
lining of the trachea and
the nose
The Larynx
• This serves as a passageway
for air between the pharynx
and the trachea.
• The larynx houses the vocal
cords
– Mucosal folds suspended by
elastic filaments stretched
across the glottis.
• Air moves through
glottis – vibration sounds
• The trachea is a tube
connecting the larynx to the
primary bronchi.
The Trachea
• Windpipe – connects
larynx to primary
bronchi.
• Held open by cartilage
• Goblet cell
– Makes mucus
• Mucosa contains layer
of pseudostratified
ciliated epithelium
– Sweep dirt and excess
mucus upwards
The Bronchial Tree
• The trachea divides
into L & R primary
bronchi
– eventually branch into
secondary bronchi and
then into bronchioles.
– Each bronchiole leads to
an elongated space
enclosed by alveoli.
The Lungs
• These lie on either side of the heart
within the thoracic cavity.
• Total cross-sectional area of 50 – 70
meter squared (1 ½ Tennis courts)
– Right lung has three lobes and the left lung
has two lobes.
• This allows room for the heart
– Each lobe is divided into lobules, further
divided into bronchioles serving many alveoli.
Alveoli
• There are 300 m alveoli per
set of lungs.
– Each one is made up of
squamous epithelium and
blood capillaries.
• Gas exchange occurs: O2
diffuses across the alveolar
wall and enters blood – CO2
goes in other direction.
• Lined with lipoprotein –
lowers surface tension and
prevents them from closing.
Mechanism of Breathing
• Respiratory Volumes
– Tidal volume is the amount of air that
moves in and out with each breath.
– Vital capacity is the maximum amount of
air that can be moved out in a single
breath.
• Inspiration can be increased by expanding the
chest (inspiratory reserve volume).
– Residual volume is the air remaining in the
lungs after deep exhalation.
Gas Exchanges in the Body
• External respiration refers to gas exchange between air in
the alveoli and blood in the pulmonary capillaries.
– Blood entering the pulmonary capillaries has a HIGHER
partial pressure of CO2 than atmospheric air.
• CO2 diffuses out of the blood into the lungs.
• Carried in blood plasma as bicarbonate ions (HC03
ions)
– Blood entering the pulmonary capillaries has a LOWER
partial pressure of O2 than the avlvoli.
• O2 diffuses into plasma and then red blood cells
• Binds with hemoglobin – forms oxyhemoglobin.
Internal Respiration
• Internal respiration - gas exchange
between the blood in systemic capillaries
and the tissue fluid.
– O2 diffuses out of the blood into the tissue
because the partial pressure of O2 in tissue
fluid is LOWER than that of blood.
• O2 leaves hemoglobin and enters tissue
fluid
– CO2 diffuses into the blood from the tissue
because the partial pressure of CO2 in tissue
fluid is HIGHER than that of blood.
• Internal
Respiration occurs
at systemic
capillaries – that is
in the major organs.
• External
Respiration occurs
at pulmonary
capillaries – that is
in the lungs ONLY
Addiction
• Addiction has been defined as
– “Compulsive physiological and psychological need for a
substance”
• This implies there is both a biological basis and a
mental basis for addiction.
• However, as all brain function is biochemically
based, the distinction between physiological and
psychological addiction is becoming blurred.
Addiction
•
Ventral tegmental area (VTA)
– Thought to be positive enforcement
area (pleasure center).
– Experiments on rats and rhesus
monkeys have show that both would
rather electrically stimulate this area
of the brain than eat – even if near to
starvation
•
Nucleus accumbens (NA)
– joined to the VTA by synaptic
connections
– Interprets the stimulation signal from
the VTA
Addiction
• Frontal cortex (FC)
– Play a part in impulse control,
judgment, language production,
working memory, motor function,
problem solving, sexual behavior,
socialization and spontaneity.
– Assist in planning, coordinating,
controlling and executing
behavior.
– This is why behavioral
changes occur which are
hard to break.
Addiction
• So these positive
reinforcement areas are
affected by drugs
• Amphetamines indirectly
stimulate the neurons of
the VTA
– Used as a treatment for
depression
• Cocaine acts on the brain
cells of the VTA that
secrete dopamine
– Produces euphoria.
Addiction
• Opiates, marijuana, caffeine,
and alcohol all produce VTA
self-reinforcing effects.
• Drugs of abuse take over the
neuronal circuitry involved in
motivation and reward, leading
to altered engagement of
learning processes.
• Because of this, drug-associated
cues can trigger cravings as well
as unconcious or compulsive
drug-seeking behavior, with the
sense that voluntary control
over drug use is lost.
Addiction
• The stages of problematic use could be defined as
Pre-occupation/anticipation, binge/intoxication &
withdrawal/negative effect
• As drugs activate neuronal pathways in the brain
we effectivly learn to use them, these pathways in
the brain not only get 'laid down' stronger and
stronger with sucessive use but also activate
faster
– the quicker the effect or 'high' the stronger this
dysfunctional learning.
Addiction
• Objects, people or places also seem to to be
strongly associated with the drug experience,
making them 'Triggers' to 'Cravings'
– increase the chances of further use.
• Animal studies have shown drug availabilty over and
above the actual effects of the substance) are
associated with stimuli, exposure to objects
associated with use trigger the release of
adrenaline (Fight or flight)
– this excitation can be perceived as a 'need' to use.
Addiction
• Users in addictive
drugs in the US in 1991
• The top three are
widely not considered
drugs by most of the
population
• All of these three
produce addictive
behavior.
METH
• Methamphetamine or “Meth”, a derivative of
amphetamine is an extremely powerful stimulant
that affects the central nervous system.
• Developed in 1919 by Japanese pharmacologist.
• Although its initial uses were for medical purposes,
its ability to increase energy and to enable users to
function without sleep made it attractive for
military purposes during World War II.
METH
• Meth has undergone both legal and illegal uses in
the United States.
– As early as the 1930s it was used therapeutically to
treat asthma and epileptic seizures
– In the 1950s it was given to housewives to cope with
bordem and depression
– During the 1970s meth was a primary appetite
suppressant in prescription diet pills.
• The illicit demand for meth resulted in forged
prescriptions, theft and a black market.
METH labs
• How is Meth Made?
– ephedrine reduction.
• In this process, ephedrine or
psuedoephedrine are
chemically extract from over
the counter cold medicines.
• Red phosphorous (match tips),
iodine (table salt), acetone
(nail varnish remover), and
sulphuric acid (car battery)
are all that is required.
METH labs
• Lastly, drain cleaner,
camping fuel and paint
thinner are used to dry out
the drug into a powder.
• Clandestine labs are often
simple, crude and consist of
common household items.
• Meth can be cooked in
basements, old buildings,
motel rooms, camping
trailers and moving vehicles.
How to tell if Someone is on or
has been using Meth
• Meth affects nerve endings
throughout a user's body.
• Many people feel a sensation of
small bugs, known as "Meth
Mites", moving right under their
skin.
• They scratch, pick and dig the
spots, trying to relieve the
itching.
• The Meth Mites and the
scratching result in sores and
serious infections.
How to tell if Someone is on or has
been using Meth
• The heated substance, when
fully aspirated, swirls
through the users' teeth
and gums, inevitably leading
to sores which never heal Meth Mouth
• Tooth enamel wears away
quickly as entire rows of
teeth dissolve to the gum
line.
• Collects in the nasal
passages which drain in the
back of the throat,
effectively corroding your
entire face.
How to tell if Someone is on or has
been using Meth
• Chronic meth users are
typically gaunt, maintain
poor hygiene.
• Lose interesting in eating
– Digestive system shuts down
due to chemicals used to make
meth
• Kidney and liver shut down
– Due to all the toxic chemicals
• Skin scratched off,
infections
• Blindness.
Environmental Damage
• Each pound of meth produced leaves behind
five-seven pounds of toxic waste.
• Toxic byproduct is often poured down drains or
directly into the ground, creating long term
hazards.
• Mobile labs and meth lab dump-sites are found
threaten our state’s natural resources.
• Clean-up costs range from $5,000 to
$50,000..5,000-$50,000
The End.
Any Questions?