06 - Drugs and the Mind

Two major divisions of the nervous system

Central nervous system (CNS)

Peripheral nervous system (PNS)

Central nervous system (CNS)

▪ Consists of the brain and spinal cord

▪ Integrates incoming information and coordinates all voluntary and involuntary nervous functions

Peripheral nervous system (PNS)

▪ Consists of ganglia and the nerves that branch from the CNS

▪ Keeps the CNS in contact with the rest of the body

cns vs pns: protection

cns: brain and spinal chord is protected by bones

pns: nerves + cells of peripheral sre not protected by bones thus more susceptible to damge

structure of a neuron

cell body, dendrite, axon

What is a neuron? (or nerve cell)

▪ Fundamental unit of the nervous system

• responsible for receiving sensory input from the external world

• sending motor commands to our muscles

• transforming and relaying the electrical signals at every step in between

cell body

The main part of a neuron that contains the nucleus and organelles; it integrates signals and keeps the neuron alive.

dendrite

Branch-like extensions from the cell body that receive signals from other neurons and transmit them toward the cell body.

myeline sheath

A fatty layer that wraps around the axon, acting as insulation to speed up the transmission of electrical signals.

axon

A long, thin projection that carries electrical impulses away from the cell body to other neurons or muscles.

synapse

The junction between two neurons where chemical or electrical signals are transmitted from one neuron to another.

axon terminal

The endpoint of an axon where neurotransmitters are released to communicate with the next neuron or target cell.

How do neurons communicate?

▪ communicate with each other via electrical events called ‘action potentials’ and chemical neurotransmitters

▪ At the junction between two neurons (synapse or synaptic cleft), an action potential causes neuron A to release a chemical neurotransmitter.

▪ The neurotransmitter can either help (excite) or hinder (inhibit) neuron B from firing its own action potential.

How Neurotransmission Works

• Signal Starts at the Neuron:
  A neuron receives a signal through its dendrites from another neuron or sensory input. This signal is an electrical impulse.

• Electrical Impulse Travels Along the Axon:
  The impulse moves down the axon, sometimes sped up by the myelin sheath, which acts like insulation.

• Reaches the Axon Terminal:
  When the impulse reaches the axon terminal, it triggers tiny sacs called vesicles to release neurotransmitters (chemical messengers).

• Crosses the Synapse:
  The neurotransmitters travel across the synapse, the small gap between neurons.

• Binds to the Next Neuron:
  The neurotransmitters attach to receptors on the dendrites of the next neuron, passing along the signal.

• Signal Continues or Stops:
  Depending on the type of neurotransmitter and receptor, the signal can either excite the next neuron to fire its own impulse or inhibit it from firing.

• Neurotransmitters Cleared:
  After transmitting the message, neurotransmitters are either broken down by enzymes or reabsorbed by the sending neuron (reuptake) to reset the system for the next signal.

Psychoactive Drugs

Drugs/substances that affects how the brain works and causes changes in mood, awareness, thoughts, feelings, or behavior

Ways in which psychoactive drugs alter communication between neurons

• Stimulate release of neurotransmitter

• Inhibit release of neurotransmitter

• Prolong effects of the neurotransmitter

Tolerance

• Occurs when higher and higher doses of a drug are needed to generate a response

• Develops because the body steps up production of enzymes that break down the drug

Tolerance happens when two biological events occur:

Cross-tolerance

• Occurs when tolerance to one drug results in a lessened response to another, usually similar, drug

eg. morphine → tolerance to codeine

dependance

▪ Occurs when someone can no longer function normally without the drug

▪ The drug is needed for physical or psychological wellbeing

▪ Certain drugs stimulate the “pleasure centers” in the brain and encourage continued use

addiction

▪ Different than tolerance, dependence

▪ “Behaviour”

▪ Certain drugs stimulate the “pleasure centers” in the brain and encourage continued use

Substance Use Spectrum

non use

beneficial use

lower risk use

higher risk use

addiction (substance use disorder )

a person may move back and forth between the stages over time

non use

avoiding use of substances (abstinence)

eg: no drugs, tobacco or alcohol

beneficial use

use that can have positive health, social, or spiritual effects

example: taking meds as prescribed, ceremonial/religous use of tobacco (such as smudging )

lower risk use

use that has minimal impact to a person, their family, friends and other

example: drinking following the low-risk alcohol drinking guidelines, cannabis use according to the lower risk cannabis use guidleines

higher risk use

use that has a harmful and negative impact to a person, their family, friends and other

example: use of illegal drugs, impaired driving, binge drinking, combining multiple substances, increasing frquency, increasing quantity

addiction (substance use disorder )

a treatable medical condition that affects the brain and involves compulsive and continous use despite negative impacts to a person their family, friends and others

example: when somoene can not stop using drugs, tobacco, or even alcohol even if they want to

classes of drugs

▪ Alcohol

▪ Marijuana

▪ Stimulants

▪ Hallucinogens

▪ Opiates

types of Stimulants

• Cocaine

• Amphetamines

• Nicotine

types of Opiates

• Prescription painkillers

• Heroin

The effects of alcohol on a person’s behavior depend on the

blood alcohol level

• Grams of alcohol per 100 ml of blood

• Example: 1 g alcohol/100 ml blood = blood alcohol level of 1%

The blood alcohol level is affected by

• How much alcohol is consumed

• How quickly it is consumed

• The rates of absorption, distribution, and metabolism of the consumed alcohol

Alcohol: Absorption and distribution

• The intoxicating effects of alcohol begin when it is absorbed from the digestive system into the blood and reaches the brain

• 20% of alcohol is absorbed at the stomach

this is related ro negative effects

The effects of alcohol are felt in about

15 minute

_____ in the stomach slows alcohol absorption

Food

thats why its told to eat food if you are gunna drink

Does one’s overall body size affect one’s blood alcohol level and degree of intoxication?

yes, but not the only factor, multiple factors

eg. biological sex (women → high be than men cuz they have less of a certain enzyme hormone levels too)

Effects of Alcohol on the Body

Nervous system

Alcohol is a depressant and slows neurons’ activity

Excessive amounts of alcohol can cause unconsciousness, coma, and death from respiratory failure

Effects of Alcohol: Areas of the brain are affected in sequence

▪ Higher cortical (“thinking”) centers

▪ Balance and coordination centers

▪ Regions responsible for consciousness

Factors that Affect Intoxication

▪ Food

▪ Strength of Drink

▪ Mood

• ppl who are depressed before drinking, this can worsen effects, even stress can change how an process alchohol

▪ Rate of consumption

• faster = quicker rise

▪ Medications

• drug interactions can have effect with certain meds

Marijuana

Principal psychoactive ingredient in the leaves, flowers, and stems is delta-9- tetrahydrocannabinol (THC)

▪ Binds to receptors in brain regions involved in thinking, memory, and motor control

▪ May regulate mood, memory, pain, appetite, and movement

ways you can use Marijuana

Marijuana: Health-related effects of long-term use:Respiratory system

▪ Experiences the most harmful effects

▪ Caused by residual material in the smoke; not caused by THC

• Carbon monoxide prevents red blood cells from carrying oxygen

Marijuana": Health-related effects of long-term use: Circulatory system

• Causes an increase in heart rate and blood pressure

Marijuana:Health-related effects of long-term use: Reproductive systems

• THC is structurally similar to estrogen

Marijuana Use in Canada (2013-2017)

Data from the 2019/2020 Canadian Community Health Survey

Cocaine (stimulant)

• Extracted from leaves of the coca plant

Cocaine Methods of intake

▪ Inhalation into nasal cavity (powder)

▪ Smoking (freebase and crack)

Cocaine Interferes with

the reuptake of dopamine

▪ Causes a rush of intense pleasure, a sense of self-confidence and power

Cocaine Increases the effects of

norepinephrine

▪ Prepares the body systems for emergency

Amphetamines (stimulant)

Synthetically produced; closely resemble dopamine and norepinephrine

Amphetamines Example

• Example: methamphetamine (“crystal meth”)

Amphetamines Effects

▪ Cause user to feel exhilarated and confident

▪ Suppress appetite and need for sleep

▪ Last longer than those produced by cocaine

Nicotine (stimulant)

• Psychoactive ingredient in tobacco products

• Highly addictive

Nicotine Activates ____ receptors

Activates acetylcholine receptors

▪ facilitates release of dopamine and serotonin, which creates pleasurable feelings of relaxation

Nicotine health effects

• CVD risk: Increases heart rate and stickiness of platelets, constricts blood vessels

Hallucinogens

▪ Act by augmenting the action of serotonin, norepinephrine, or acetylcholine

Hallucinogens effects

• Alter sensory perception

• Produce unusual changes in thought and emotions

Hallucinogens examples

• Natural: mescaline and psilocybin

• Synthetic: LSD and MDMA, ecstasy

Opiates

▪ Natural or synthetic drugs that are medically important but have high potential for abuse

• Reduce pain and anxiety; produce a sense of euphoria

Opiates: examples

• Morphine and codeine (from the opium poppy)

• Heroin (synthetic derivative of morphine)

Opiates mode of action

opiates bind to the receptors of the body’s natural opiates

• E.g. Endorphins and other natural chemicals

Opiates health effects

▪ Slow the breathing rate

• Overdose may cause coma or death

▪ If injected, inflame the veins and promote the spread of pathogens that cause diseases such as AIDS, hepatitis, and syphilis

What led to the opioid crisis

1995: introduced as a breakthrough for chronic pain

2000: reports of OxyContin abuse surfaced

“smooth and sustained pain control all day and all night.

Opioid Epidemic in the Media

Fentanyl

▪ A synthetic opioid that is 50-100 times stronger than morphine.

▪ Originally developed for pain management treatment of cancer

patients, applied in a patch on the skin

Narcan

(naloxone) is a drug that can reverse effects by binding to receptors and displacing the opioid

Naloxone is a medicine that rapidly reverses an opioid overdose

• It is an opioid antagonist