Neurotransmitters and mood Part 2 Higher Human Biology Neurotransmitters and mood Part 2

What do I need to know? How many ways can a recreational drug interact with a neurotransmitter? Can you give the examples? What are the possible consequences of consuming a recreational drug? Why are recreati0onal drugs associated with addiction? What is meant by drug tolerance? What is drug desensitisation? What is drug sensitisation?

Recreational Drugs Some people choose to alter their state of consciousness by using recreational drugs that affect the transmission of nerve impulses in the reward circuit of the brain Total drugs market attributed to specific drugs

How Recreational Drugs Work They interact with neurotransmitters in different ways by stimulating the release of neurotransmitters (nicotine, alcohol) imitating the action of neurotransmitters (agonists)-(morphine, heroin), blocking the neurotransmitters binding site (antagonists), inhibiting the re-uptake of neurotransmitters (cocaine, ecstasy) Inhibiting the breakdown of neurotransmitters by enzymes

Effect of Recreational Drugs on Neurochemistry An alteration in a person’s neurochemistry can lead to changes in mood (e.g. happier, more confident, more aggressive) cognition (e.g. poorer at complex mental tasks such as problem solving and decision making) perception (e.g. misinterpretation of environmental stimuli- sounds, colours, sense of time) Behaviour (e.g. stays awake for longer and talks about him/herself endlessly) Many recreational drugs affect neurotransmission in the reward circuit of the brain.

Drug Addiction and Tolerance Drug addiction- is defined as a chronic, relapsing brain disease that is characterized by compulsive drug seeking and use, despite harmful consequences. It is considered a brain disease because drugs change the brain; they change its structure and how it works. These brain changes can be long lasting and can lead to many harmful, often self-destructive, behaviours

Drug Tolerance Tolerance occurs when the person no longer responds to the drug in the way they did initially. E.g. It takes a higher dose of the drug to achieve the same level of response achieved initially.

This illustration shows dopamine levels in a monkey's brain after two identical doses of cocaine. The second dose, taken after the effects of the first dose wore off, produced lower levels of dopamine

Drug Sensitisation Repeated use of a drug that acts as an antagonist (blocking certain neuroreceptors) prevents the normal neurotransmitter from acting on the receptors The nervous system compensates for the reduced stimulation of the receptors by increasing their number The receptors themselves also become more sensitive to the antagonist drug. This leads to addiction

Drug Desensitisation Repeated use of agonistic drugs results in certain neuroreceptors (eg those that promote dopamine release) being repeatedly stimulated Causes increased feeling of wellbeing or euphoria The nervous system responds by reducing the number and sensitivity of these receptors to the agonist drug This leads to drug tolerance as a larger dose of the drug is needed to stimulate the reduced number of less sensitive receptors

Activities Complete research task on one of the following: Cocaine Cannabis MDMA (ecstasy) Nicotine Alcohol Research and produce info leaflet outlining the following: Where drug comes from, what its effects are, what’s its mode of action, side effects

What do I know? How many ways can a recreational drug interact with a neurotransmitter? Can you give the examples? What are the possible consequences of consuming a recreational drug? Why are recreati0onal drugs associated with addiction? What is meant by drug tolerance? What is drug desensitisation? What is drug sensitisation?

Further activities and Homework Testing knowledge Qs p276 No’s 1 and 2 Summary sheet for Chapters 17 and 18 Homework Pre-reading Chapter 19 p278 - 282