Talk Eleven:

Drugs and Addiction

NOT IN BOOK

Biology Today (BIOL 109)

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 drug-seeking 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 Environmental DamageDamage

• 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?