3.4 The Cells of the Nervous System and Neurotransmitters at Synapses (2)

Question 1

State how endorphin production is increased.

Answer 1

Endorphin production is increased as a response to :

· Severe injury

· Prolonged and continuous exercise

· Stress

· Eating certain spicy foods containing capsaicin

· Sexual orgasm

Question 2

State the function of endorphins.

Answer 2

Endorphins are neurotransmitters that stimulate the neurons involved in reducing the intensity of pain. Endorphins are part of the brain’s pain control system.

Question 3

State the function of dopamine.

Answer 3

Dopamine is a neurotransmitter that induces feelings of pleasure and reinforces particular behaviour by activating the reward pathway in the brain.

Question 4

Describe what is meant by the term ‘reward pathway’.

Answer 4

A reward pathway involves neurons which secrete or respond to dopamine.

A reward pathway is activated when an individual engages in a behaviour that is beneficial to their survival e.g. eating when hungry

Question 5

Describe the treatment of neurotransmitter-related disorders

Answer 5

Some of the drugs that are used to treat neurotransmitter-related disorders are classified as either agonists or antagonists.

Question 6

Agonists

Answer 6

Agonists – These are chemicals that bind to and stimulate specific receptors, mimicking the action of a neurotransmitter at a synapse

e.g. curare – a muscle relaxant

Question 7

antagonists

Answer 7

Antagonists – These are chemicals that bind to specific receptors blocking the action of a neurotransmitter at a synapse

e.g. strychnine – a poison

Question 8

Other drugs used to treat neurotransmitter-related disorders act by :

Answer 8

inhibiting the enzymes that degrade neurotransmitters e.g. use of cholinesterase inhibitors in the treatment of Alzheimer’s disease

· inhibiting the reuptake of the neurotransmitter e.g. serotonin reuptake inhibitors in the treatment of depression

Question 9

Describe the mode of action of recreational drugs

Answer 9

Recreational drugs affect neurotransmission at synapses in the brain which alters an individual’s mood, cognition, perception and behaviour.

Many recreational drugs affect neurotransmission in the reward pathway where they can act as either agonists or antagonists.

Question 10

State the cause of drug addiction

Answer 10

Drugs that act a antagonists block specific receptors, this can cause the nervous system to respond by increasing both the number and sensitivity of these receptors. This sensitisation leads to the symptoms of drug addiction where the individual craves more of the drug.

Question 11

State the cause of drug tolerance

Answer 11

Drugs that act as agonists stimulate specific receptors, this can cause the nervous system to respond by decreasing both the number and sensitivity of these receptors. This desensitisation leads to drug tolerance where the individual must take more of the drug to get an effect.