GCSE Biology: B1.6 - Nervous System & Hormones

Comprehensive vocabulary flashcards covering the human nervous system, the eye, hormonal control of blood glucose, osmoregulation, and plant phototropism based on GCSE Biology lecture notes.

Stimulus

Anything in the environment around us that we respond to.

Receptor

Specialized cells found in sense organs that detect stimuli.

Effector

A muscle or gland that responds to impulses from a motor neurone to produce an action.

Central Nervous System (CNS)

The brain and spinal cord together, which control and co-ordinate responses between receptors and effectors.

Neurones

Specialized cells that carry information in the form of small electrical charges called nerve impulses.

Sensory neurone

A type of neurone that carries impulses from a receptor to the central nervous system.

Association neurone

A neurone that connects the sensory neurone with the motor neurone within the spinal cord.

Motor neurone

A neurone that carries impulses from the central nervous system to the effector.

Synapse

A gap or junction between two neurones where nerve impulses pass due to the diffusion of a transmitter chemical.

Neurotransmitter

A chemical that diffuses across the synapse gap to trigger an electrical impulse in the next neurone.

Accommodation

The process by which the ciliary muscles and suspensory ligaments change the shape of the lens to focus on near or distant objects.

Ciliary muscle

A ring of muscle surrounding the lens that contracts or relaxes to change the lens shape during accommodation.

Suspensory ligaments

Ligaments that attach the lens to the ciliary muscle and tighten or slacken to adjust the lens thickness.

Retina

The part of the eye contains light receptor cells where a focused image is produced.

Voluntary action

An action that is under conscious control and involves the brain, such as reading or talking.

Reflex action

A rapid, automatic response that protects the body and does not involve conscious thinking or the brain.

Reflex arc

The shortest possible nerve pathway involved in a reflex, typically involving a receptor, three neurones, and an effector.

Hormones

Chemical messengers produced by glands and released into the blood to act on specific target organs.

Homeostasis

The maintenance of a constant internal environment for the proper functioning of cells and enzymes.

Insulin

A hormone produced by the pancreas that lowers blood glucose concentration by causing the liver to absorb glucose and convert it to glycogen.

Negative feedback

A mechanism exemplified by insulin where a change in blood glucose levels triggers a response that reverses that change to maintain balance.

Type 1 diabetes

A condition occurring early in life where the pancreas stops producing insulin, requiring lifelong medication via injection.

Type 2 diabetes

A progressive disease linked to obesity and lifestyle where the pancreas produces less insulin or the insulin stops working properly.

Osmoregulation

The homeostatic process of maintaining water balance in the blood and other body fluids.

Excretory system

The system including the kidneys, ureters, bladder, and urethra that removes wastes and regulates water balance.

Antidiuretic Hormone (ADH)

A hormone released by the pituitary gland that causes the kidneys to reabsorb more water, reducing the volume of urine.

Phototropism

The differential growth of plant cells in response to light, causing the stem to bend towards the light source.

Auxin

A plant hormone produced at the tip of the shoot that causes cell elongation and moves towards the shaded side in response to light.