Chemical Messengers: Neurotransmitters and Hormones
Neurotransmitters
- Neurotransmitters are chemical messengers that transmit signals across the synapse from one neuron to another.
- Function: They play a critical role in regulating thoughts, emotions , and behaviour.
Example
Serotonin
- Role: Linked to mood regulation, sleep, and appetite.
- Study: Caspi et al. (2003) found that individuals with a short allele of the 5-HTT gene (affecting serotonin transport) were more likely to develop depression after stressful life events.
Example
Dopamine
- Role: Associated with reward, motivation, and pleasure.
- Study: Fisher et al. (2005) demonstrated that dopamine activity increases when individuals view photos of loved ones, explaining feelings of romantic attraction.
Hormones
- Hormones are chemical messengers released by glands into the bloodstream, affecting distant organs and tissues.
- Function: They influence long-term processes like growth , metabolism , and stress responses.
Example
Cortisol
- Role: Known as the stress hormone , it helps the body respond to threats by increasing energy and alertness.
- Study: Newcomer et al. (1999) found that high levels of cortisol impair memory performance , highlighting its impact on cognitive functions.
Mechanisms of Action
Neurotransmitters
- Release: When an electrical impulse reaches the end of a neuron, it triggers the release of neurotransmitters into the synaptic gap.
- Binding: Neurotransmitters bind to receptors on the postsynaptic neuron, causing an excitatory or inhibitory effect.
Analogy
Think of neurotransmitters as keys that fit into locks (receptors) to open or close communication channels.
Hormones
- Secretion: Hormones are released by endocrine glands (e.g., adrenal glands, pituitary gland) into the bloodstream.
- Target Cells: They bind to specific receptors on target cells , triggering physiological changes.
Analogy
Hormones act like broadcast messages, affecting multiple organs simultaneously.
Applications and Implications
- Mental Health: Imbalances in neurotransmitters like serotonin and dopamine are linked to conditions such as depression and schizophrenia.
- Stress Management: Understanding cortisol's effects can inform strategies to reduce chronic stress and improve well-being.
Common Mistake
Avoid assuming that chemical imbalances are the sole cause of psychological disorders. Behaviour is influenced by multiple factors, including genetics, environment, and cognition.
Critical Thinking
Note
Strengths
- Research on chemical messengers has led to effective treatments, such as SSRIs for depression.
Limitations
- The reductionist approach may overlook the complex interplay of biological, psychological, and social factors.
Applications
- Findings have practical implications for medicine, therapy, and stress management.
