The human nervous system key terms

nervous system

A complex network of neurones that detects stimuli, coordinates responses, and enables humans to react to their surroundings.

coordination

The process by which the nervous system organizes and integrates sensory information to produce appropriate behavioral responses.

sensory neurone

A type of neurone that carries impulses from receptor cells to the central nervous system (CNS) after detecting stimuli.

motor neurone

A type of neurone that transmits impulses from the central nervous system (CNS) to effectors, such as muscles or glands, to initiate a response.

central nervous system

The part of the nervous system that consists of the brain and spinal cord, responsible for processing information and coordinating responses.

spinal cord

A long, thin bundle of nervous tissue that extends from the brain down the back, transmitting signals between the brain and the rest of the body.

effectors

In Structure and function, effectors means muscles and glands that bring about responses in the body. This matters in The human nervous system because it supports the learning objective to describe muscles and glands as effectors that bring about responses, with muscles contracting and glands secreting hormones. Use effectors only in this subtopic-relevant sense so the definition stays concise, curriculum-specific, and useful for AQA GCSE Biology revision. Students should use this term accurately when they explain the biology, identify symptoms, or justify an answer in GCSE Biology questions.

glands

Glands are effectors that produce and release chemical substances. In the nervous-system reflex pathway, glands are contrasted with muscles: muscles contract, while glands secrete substances such as hormones to bring about a response.

reflex action

An automatic and rapid response to a stimulus that occurs without conscious thought, designed to protect the body.

automatic response

A quick reaction to a stimulus that does not involve conscious decision-making, allowing for immediate protective actions.

reflex arc

The neural pathway that mediates a reflex action, consisting of a stimulus, receptor, sensory neurone, relay neurone, motor neurone, and effector.

motor neurone

A type of neurone that transmits impulses from the central nervous system to effectors, such as muscles or glands, to bring about a response.

synapse

A junction between two neurones where signals are transmitted across gaps through neurotransmitters.

neurotransmitter

A chemical substance released at a synapse that transmits signals from one neurone to another.

reflex arc

A neural pathway that controls a reflex action, consisting of a stimulus, receptor, sensory neurone, relay neurone, motor neurone, and effector.

motor neurone

A type of neurone that transmits impulses from the central nervous system to effectors, such as muscles or glands, to initiate a response.

nervous system

A complex network of neurones that transmits signals between different parts of the body, enabling rapid communication and coordination of responses.

hormonal coordination

A slower form of communication in the body that involves the release of hormones into the bloodstream to regulate various physiological processes.

reaction time

The time taken to respond to a stimulus, often measured in experiments to assess the efficiency of the nervous system.

data interpretation

The process of analyzing and making sense of data collected from experiments, particularly in the context of nervous system responses.

reaction time

In Structure and function, reaction time means the time taken to respond to a stimulus, often measured in milliseconds. This matters in The human nervous system because it supports the learning objective to translate reaction-time information between numerical and graphical forms. Use reaction time only in this subtopic-relevant sense so the definition stays concise, curriculum-specific, and useful for AQA GCSE Biology revision. Students should use this term accurately when they explain the biology, identify symptoms, or justify an answer in GCSE Biology questions.

data representation

The method of displaying information in numerical or graphical formats to facilitate analysis.

reaction time

In Structure and function, reaction time means the duration taken for an organism to respond to a stimulus. This matters in The human nervous system because it supports the learning objective to carry out Required Practical 7 by planning and performing an investigation into the effect of a factor on human reaction time. Use reaction time only in this subtopic-relevant sense so the definition stays concise, curriculum-specific, and useful for AQA GCSE Biology revision. Students should use this term accurately when they explain the biology, identify symptoms, or justify an answer in GCSE Biology questions.

required practical

A structured investigation designed to explore the effect of a specific factor on human reaction time.

control variables

Factors that are kept constant during an experiment to ensure that the results are valid and reliable.

mean values

The average of a set of numbers, calculated by adding them together and dividing by the number of values, used to summarize data in experiments.

neurones

Specialized cells that transmit nerve impulses, forming the basic building blocks of the nervous system.

complex behaviour

Actions or reactions of an organism that involve multiple processes and interactions within the brain.

cerebral cortex

The region of the brain associated with consciousness, intelligence, memory, and language.

brain

In The brain (biology only), brain means an organ made of billions of interconnected neurones that controls complex behaviour. This matters in The human nervous system because it supports the learning objective to identify the cerebral cortex as the brain region associated with consciousness, intelligence, memory and language. Use brain only in this subtopic-relevant sense so the definition stays concise, curriculum-specific, and useful for AQA GCSE Biology revision. Students should use this term accurately when they explain the biology, identify symptoms, or justify an answer in GCSE Biology questions.

cerebellum

The region of the brain responsible for coordinating muscular activity and maintaining balance.

muscular coordination

The ability of the brain and muscles to work together to produce smooth and controlled movements.

medulla

The medulla is the part of the brain that controls unconscious activities such as breathing and heart rate.

unconscious activities

Unconscious activities are functions of the body that occur without conscious thought, including processes like breathing and regulating heart rate.

brain complexity

The intricate structure and function of the brain, which consists of billions of interconnected neurones, making it challenging to study and treat disorders.

delicate nature

The sensitivity of brain tissue, which requires careful handling during investigations and treatments to avoid damage.

brain damage

Injury to the brain that can affect cognitive, physical, and emotional functions, often studied to understand brain function.

neuropsychological assessment

A comprehensive evaluation of cognitive, motor, behavioral, and emotional functions to assess the impact of brain damage.

electrical stimulation

A technique used to study brain function by applying electrical currents to specific brain regions to observe effects on behavior and neural activity.

MRI scanning

A non-invasive imaging technique that uses magnetic fields and radio waves to create detailed images of the brain, allowing for the study of brain structure and function.

brain procedures

Medical interventions performed on the brain to treat disorders or injuries, which can have both benefits and risks.

nervous system risks

Potential negative outcomes associated with procedures on the nervous system, including complications or side effects.

retina

The light-sensitive layer at the back of the eye that contains receptor cells sensitive to light intensity and color.

optic nerve

In The eye (biology only), optic nerve means the structure that carries visual impulses from the retina to the brain. This matters in The human nervous system because it supports the learning objective to identify the retina, optic nerve, sclera, cornea, iris, ciliary muscles, suspensory ligaments and lens in the eye. Use optic nerve only in this subtopic-relevant sense so the definition stays concise, curriculum-specific, and useful for AQA GCSE Biology revision. Students should use this term accurately when they explain the biology, identify symptoms, or justify an answer in GCSE Biology questions.

retina

The light-sensitive layer at the back of the eye that contains receptor cells sensitive to light intensity and color.

receptor cells

Specialized cells in the retina that detect light and convert it into electrical signals for the brain.

optic nerve

In The eye (biology only), optic nerve means the structure that carries visual impulses from the retina of the eye to the brain. This matters in The human nervous system because it supports the learning objective to describe the optic nerve as the structure that carries impulses from the eye to the brain. Use optic nerve only in this subtopic-relevant sense so the definition stays concise, curriculum-specific, and useful for AQA GCSE Biology revision. Students should use this term accurately when they explain the biology, identify symptoms, or justify an answer in GCSE Biology questions.

impulses

Electrical signals transmitted by neurones that convey information from sensory receptors to the brain.

sclera

In The eye (biology only), sclera means the tough supporting outer layer of the eye that provides structure and protection. This matters in The human nervous system because it supports the learning objective to describe the sclera as the tough supporting outer layer of the eye. Use sclera only in this subtopic-relevant sense so the definition stays concise, curriculum-specific, and useful for AQA GCSE Biology revision. Students should use this term accurately when they explain the biology, identify symptoms, or justify an answer in GCSE Biology questions.

eye

The organ that detects light and enables vision, consisting of various structures including the sclera.

cornea

In The eye (biology only), cornea means the transparent outer region of the eye that refracts light entering the eye. This matters in The human nervous system because it supports the learning objective to describe the cornea as a transparent outer region that refracts light entering the eye. Use cornea only in this subtopic-relevant sense so the definition stays concise, curriculum-specific, and useful for AQA GCSE Biology revision. Students should use this term accurately when they explain the biology, identify symptoms, or justify an answer in GCSE Biology questions.

refraction

The bending of light as it passes through the cornea and lens, allowing the eye to focus on objects.

iris

In The eye (biology only), iris means the coloured part of the eye that controls the diameter of the pupil. This matters in The human nervous system because it supports the learning objective to describe the iris as the coloured part of the eye that controls the diameter of the pupil. Use iris only in this subtopic-relevant sense so the definition stays concise, curriculum-specific, and useful for AQA GCSE Biology revision. Students should use this term accurately when they explain the biology, identify symptoms, or justify an answer in GCSE Biology questions.

pupil

The pupil is the adjustable opening in the iris that lets light enter the eye. In the eye subtopic, pupil diameter changes because the iris controls how much light reaches the retina.

ciliary muscles

Muscles that control the shape of the lens during accommodation by contracting or relaxing.

suspensory ligaments

Fibrous strands that connect the ciliary muscles to the lens, helping to change its shape for focusing.

accommodation

The process by which the eye adjusts the shape of the lens to focus on near or distant objects.

ciliary muscles

Muscles that control the shape of the lens in the eye, enabling accommodation for focusing on objects at varying distances.

accommodation

The process by which the eye adjusts the shape of the lens to focus on objects at different distances.

ciliary muscles

Muscles that control the shape of the lens in the eye, allowing for focusing on near and distant objects.

myopia

A vision condition where distant objects appear blurred because they are focused in front of the retina.

retina

The light-sensitive layer at the back of the eye that contains receptor cells and is responsible for converting light into neural signals.

hyperopia

A vision condition where distant objects are seen clearly, but close ones are blurred, caused by light focusing behind the retina.

long sightedness

Another term for hyperopia, indicating difficulty in seeing nearby objects clearly due to improper light focus in the eye.

spectacle lenses

Optical devices worn in front of the eyes to correct vision defects such as myopia and hyperopia by altering the path of light entering the eye.

refraction

The bending of light as it passes through different mediums, which is essential for focusing images on the retina.

myopia

A vision condition where distant objects are focused in front of the retina, causing blurred vision for far away objects.

hyperopia

A vision condition where near objects are focused behind the retina, resulting in difficulty seeing close objects clearly.

contact lenses

In The eye (biology only), contact lenses means thin lenses placed directly on the surface of the eye to correct vision defects. This matters in The human nervous system because it supports the learning objective to evaluate the use of contact lenses, laser surgery and replacement lens surgery to correct vision defects. Use contact lenses only in this subtopic-relevant sense so the definition stays concise, curriculum-specific, and useful for AQA GCSE Biology revision. Students should use this term accurately when they explain the biology, identify symptoms, or justify an answer in GCSE Biology questions.

laser surgery

A medical procedure that uses focused light to reshape the cornea and correct vision problems.

thermoregulatory centre

In Control of body temperature (biology only), thermoregulatory centre means the part of the brain that monitors and regulates body temperature. This matters in The human nervous system because it supports the learning objective to describe body temperature as an internal condition monitored and controlled by the thermoregulatory centre in the brain. Use thermoregulatory centre only in this subtopic-relevant sense so the definition stays concise, curriculum-specific, and useful for AQA GCSE Biology revision. Students should use this term accurately when they explain the biology, identify symptoms, or justify an answer in GCSE Biology questions.

body temperature

An internal condition that is maintained within a narrow range to ensure proper physiological function.

thermoregulatory centre

A part of the brain that monitors and regulates body temperature by receiving signals from temperature receptors.

receptors

Specialized cells that detect changes in temperature and send impulses to the thermoregulatory centre.

temperature receptors

Specialized nerve endings in the skin that detect changes in temperature and send impulses to the thermoregulatory centre.

thermoregulatory centre

A region in the brain that monitors and regulates body temperature by processing signals from temperature receptors.

vasodilation

The widening of blood vessels, which increases blood flow to the skin and helps to dissipate heat when body temperature is too high.

sweating

The process of producing moisture on the skin's surface, which cools the body through evaporation when body temperature rises.

vasoconstriction

The narrowing of blood vessels to reduce blood flow and conserve body heat when the temperature is too low.

shivering

An involuntary muscle contraction that generates heat to help raise body temperature when it is too low.

vasodilation

The widening of blood vessels, which increases blood flow to the skin and helps to dissipate heat when body temperature is too high.

sweating

The process by which the body releases moisture through sweat glands, which cools the body as the sweat evaporates from the skin surface.

vasoconstriction

The narrowing of blood vessels, which reduces blood flow to the skin and helps to conserve body heat when temperatures are low.

shivering

A rapid, involuntary contraction of muscles that generates heat to raise body temperature when it is too low.

thermoregulation

The process by which the body maintains its internal temperature within a narrow range despite external temperature changes.

heat transfer

The movement of thermal energy from one object or substance to another, which can occur through conduction, convection, or radiation.