Week 3: Addiction, Behaviour, and Pharmacodynamics

Philosophy of harm reduction

• Aimed at reducing risks associated with substance use

• Seeks to address the actual and potential harm associated with an individual's substance use

• Involves non-judgmental education and support

• Compatible with abstinence-based approaches

Harm reduction strategies used in canada

Approach 1: Drug Substitution

Approach 2: Substitute route of administration

Approach 3: Safer Use

Approach 1: Drug substitution

• Provide different drug that produces similar effects

• Often from the same drug class

• Often involves changing route of administration

• Eliminates spread of disease

Approach 2: Substitute Route of Administration

• Changes how the drug enters the body

• Eliminates spread of disease

Approach 3: Safer Use

• Use of same drugs, often by the same route of administration, just in a safer way

• Ex: Needle Exchange and Bleach Kits

• Involves instruction in use of drugs

• Administration

• Dosage

• Eliminates spread of disease

Nervous system =

• is like a highway with billions of nerves, which the brain uses to send information throughout the body

• two main divisions:

1. Central Nervous System

2. Peripheral Nervous System

-Somatic

- Autonomic

-Sympathetic and Parasympathetic

Central Nervous System

• Brain and Spinal Cord

What are the two major components (types of cells) of the CNS 

1. Glia 

2. Nerves/Neurons 

Peripheral Nervous System

• carries info to the CNS and outward to muscles and glands,

• brings sensory info from environment to CNS,

• acts in environment through motor responses. (COLLECT and IMPLEMENT)

Two main divisions of the PNS

1. Somatic Nervous System

2. Autonomic Nervous System

Somatic Nervous System (PNS) 

• Voluntary responses of skeletal muscles, e.g. walking

• Brings information in from the senses (external environment)

Autonomic Nervous System (PNS)

• Involuntary responses of smooth muscles (i.e. automatic) 

• Smooth muscles = arteries, veins, organs

• Cardiac muscles = surround heart

Two Main Divisions of the Autonomic Nervous System

1. Sympathetic

2. Parasympathetic

Sympathetic Nervous system (ANS) 

• prepares body for action (fight or flight) 

Parasympathetic Nervous system (ANS)

• relaxes body

• rest and digest

Two primary functions of the nervous system

1.Gather and process information from the environment around us

2.Control bodily responses so we can survive in our environment

* Both of these functions serve the ultimate goal of maintaining HOMEOSTASIS

Homeostasis 

Mechanism or process by which the stability of the body's ‘internal’ environment is maintained in response to changes in ‘external’ conditions

• The body’s efforts to ‘keep things the same’ or ‘restore balance’ as a whole

how do psychoactive drugs influence homeostasis

• May overtax systems required to maintain homeostasis

• May create need for more work to maintain homeostasis

• Body adjusts to presence (tolerance) and absence (withdrawal) of psychoactive drugs, creating a ‘new’ homeostatic process for those drugs

Glia

• More numerous than neurons

• 5 Different types and functions of glia cells

• Provide structure and physical support to CNS

• Clean up debris neurons leave behind

• Provide insulation (myelin) to neurons which help with speed of signal transmission

• They form the blood-brain barrier