Key terms used across this site, defined simply.
Autonomic nervous system
The part of the nervous system that automatically controls body functions like heart rate, breathing, and digestion without conscious thought. Divided into the sympathetic (activating) and parasympathetic (calming) branches.
Cortisol
A hormone released by the adrenal glands, especially in response to stress. It mobilises energy and follows a natural daily rhythm, typically peaking in the morning.
Dopamine
A chemical messenger in the brain involved in motivation, reward, and the anticipation of pleasure. It plays a central role in learning and habit formation.
Encoding
The first stage of memory, when the brain takes in an experience and translates it into a storable form. Poor encoding is a common cause of forgetting.
Fight-or-flight
The body automatic stress response that prepares you to confront or escape a threat. It involves a rapid cascade of physical changes driven by the sympathetic nervous system.
Gut microbiome
The community of trillions of microorganisms living in the digestive tract, which communicate with the brain via the gut-brain axis and influence mood, immunity, and digestion.
Habituation
The brain natural tendency to pay less attention to repeated, unchanging stimuli. It is why a new sound initially grabs attention but quickly fades into the background.
Hippocampus
A brain region essential for forming new memories and connecting experiences to place and context. It is particularly sensitive to chronic stress and sleep deprivation.
Homeostasis
The body ongoing effort to maintain stable internal conditions, such as temperature, blood sugar, and hormone levels, within a healthy range.
Melatonin
A hormone produced by the brain in response to darkness, signalling that it is time to sleep. Bright light at night suppresses its release and can disrupt sleep.
Nervous system
The body vast communication network, made up of the brain, spinal cord, and billions of nerve cells. It controls everything from breathing and movement to thought and emotion.
Neurotransmitter
A chemical messenger that carries signals between nerve cells across tiny gaps called synapses. Well-known neurotransmitters include serotonin, dopamine, and noradrenaline.
Parasympathetic nervous system
The calming branch of the autonomic nervous system, sometimes called rest-and-digest. It slows the heart, aids digestion, and helps the body recover after stress.
Proprioception
The sense of where your body parts are in space without looking. It is sometimes called the sixth sense and underpins coordination, balance, and graceful movement.
Retrieval practice
The act of recalling information from memory rather than simply rereading it. Each successful retrieval strengthens the memory and is one of the most powerful learning strategies known.
Serotonin
A neurotransmitter produced largely in the gut that plays a role in mood regulation, digestion, and sleep. Low serotonin activity is associated with low mood, though the relationship is complex.
Spaced repetition
A learning technique that involves reviewing material at increasing intervals over time. It exploits the forgetting curve to maximise retention with the minimum number of review sessions.
Sympathetic nervous system
The activating branch of the autonomic nervous system, responsible for the fight-or-flight response. It speeds the heart, diverts blood to muscles, and sharpens focus in a perceived emergency.
Vagus nerve
The longest nerve in the body, running from the brainstem to the abdomen. It is a key pathway of the parasympathetic system and plays a central role in the gut-brain connection.
Working memory
A temporary mental workspace that holds and manipulates a small amount of information for immediate use. It is limited in capacity and fades quickly without rehearsal.
For further reading and professional guidance, these organisations publish high-quality, evidence-based health information.
