Unit 14: Coordination and Response

A set of vocabulary flashcards covering the key terms and definitions for human coordination, response, nervous system, sense organs, hormones, homeostasis, and plant tropisms.

Central Nervous System (CNS)

The section of the nervous system made up of the brain and spinal cord.

Peripheral Nervous System (PNS)

The section of the nervous system containing nerves outside of the brain and spinal cord that carry nerve impulses to and from the CNS.

Sensory Neurone

A neurone that carries nerve impulses from a receptor to the spinal cord and brain.

Relay Neurone

A connector neurone that carries electrical impulses between different parts of the central nervous system.

Motor Neurone

An effector neurone that carries nervous impulses from the central nervous system to an effector, such as a muscle.

Reflex Action

An automatic, involuntary movement carried out when in danger in order to quickly remove an organism from a hazard.

Reflex Arc

The pathway of a reflex response in which a stimulus is detected by a receptor, sending an impulse along a sensory neurone to the spinal cord, through a relay neurone in the CNS to a motor neurone, and to an effector.

Synapse

A junction between two neurones that forms a gap called a synaptic cleft.

Neurotransmitters

Chemical substances released from vesicles at the presynaptic neurone that diffuse across the synaptic cleft and bind to receptors on the postsynaptic neurone.

Sense Organs

Groups of receptor cells that respond to a specific stimulus, such as light, temperature, touch, sound, and chemicals.

Cornea

A clear layer coating the iris that refracts light into the eye.

Iris

The coloured section of the eye that controls the amount of light entering the eye by contracting and dilating the pupil.

Pupil

The opening in the eye that allows light to enter.

Lens

A structure positioned behind the iris that changes shape to focus light onto the retina.

Retina

The layer at the back of the eye containing photoreceptor cells (rods and cones) sensitive to light of different colours, along with blood vessels supplying nutrients.

Fovea

A section in the middle of the retina containing a high concentration of cone cells, providing the clearest image.

Optic Nerve

A nerve formed by grouped neurones attached to photoreceptor cells that carries electrical impulses to the brain.

Pupil Reflex

An automatic response controlled antagonistically by circular and radial muscles to adjust pupil size and regulate the amount of light entering the eye.

Accommodation

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

Rods

Rod-shaped photoreceptor cells used for monochromatic night vision due to high sensitivity to low light levels, distributed evenly at the periphery of the retina and absent at the fovea.

Cones

Cone-shaped photoreceptor cells concentrated at the fovea used for colour vision in bright light, consisting of three types sensitive to red, green, and blue light.

Hormones

Chemical substances produced in glands that travel in the blood to target organs to signal changes in cells.

Endocrine System

A network of hormone-secreting glands that helps control growth, metabolism, and homeostasis.

Adrenaline

A hormone secreted by the adrenal glands during the 'fight or flight' response that increases heart rate, breathing rate, pupil width, and blood glucose concentration.

Insulin

A hormone secreted by the pancreas that lowers blood-glucose concentration by causing glucose to be converted into glycogen in the liver.

Glucagon

A hormone secreted by the pancreas that increases blood-glucose concentration by activating an enzyme to convert glycogen into glucose.

Testosterone

A hormone produced in the testes that maintains muscle and bone strength and plays a role in reproduction.

Oestrogen

A hormone produced in the ovaries that regulates the female reproductive system.

Homeostasis

The maintenance of a constant internal environment in organisms within set limits, despite external changes.

Type 1 Diabetes

An autoimmune condition where antibodies attack insulin-producing cells in the pancreas, preventing insulin production.

Type 2 Diabetes

A condition in which either not enough insulin is produced by the pancreas or body cells do not respond correctly to insulin.

Vasoconstriction

The narrowing of blood vessels near the skin surface to reduce surface area and blood flow, reducing heat loss when internal temperature is low.

Vasodilation

The widening of blood vessels near the skin surface, increasing heat loss to the environment when internal temperature is high.

Tropisms

Growth movements in plants that occur in reaction to external stimuli.

Auxins

Plant hormones made in shoot tips that promote cell elongation and control growth responses such as phototropism and gravitropism.

Gravitropism

A plant growth response to gravity, where shoots show negative gravitropism (growing upwards) and roots show positive gravitropism (growing downwards).

Phototropism

A plant growth response to light, where shoots show positive phototropism (growing towards light) and roots show negative phototropism (growing away from light).