AQA GCSE Biology - The Nervous System and Homeostasis

LASIK

Reshapes the cornea surgically- common for myopia.

Cornea

transparent area in front of sclera; can bend light as it enters.

Vasodilation

arterioles dilate, increasing blood flow to surface of skin so more heat is lost through radiation.

Retina

layer at back containing light sensitive cells- rods and cones.

Negative Feedback

Make adjustments to bring body back to bodily norm.

Suspensory Ligament

holds lens in place.

Vasoconstriction

reduces heat loss through radiation.

Stimulus

Change in environment body reacts to.

Contact lenses

Float on the surface of the cornea, focusing and refracting light.

Sensory Neuron

Carry electrical impulse from Receptor to CNS.

Fovea

area of cones where light is bought to focus.

Optic Nerve

sends electrical signal to the brain.

Neurotransmitters

diffuse across the synapse form an area of high concentration to an area of low concentration (down the concentration gradient)

Lens

clear disc that can change shape to focus light on retina.

Motor Neuron

Transmits impulse from CNS to body tissues.

Central Nervous System (CNS)

Made up of brain and spinal cord.

Iris

controls the size of the pupil.

nerve

A(n) ________ is multiple neurons.

Pupil

hole through which light enters.

Sclera

tough, white, outer layer- protects eye.

Relay Neurons

Carry electrical impulse from one part of CNS to another.

Peripheral Nerves

All nerves EXCEPT brain and spine.

convex lens

brings light together before it reaches the eye.

Neuron

specialized cell

nervous system

The ________ is comprised of receptors, nerves, the central nervous system (CNS) and effectors.

Ciliary muscles

change the shape of the lens, which alters the refraction of light.

Neurotransmitter

binds to the receptor on the surface of the post- synaptic neuron.

retina

Light hits the ________ and stimulates the rods and cones.

Homeostasis

Maintenance of constant internal conditions

Relay Neurons

Carry electrical impulse from one part of CNS to another

Nerve

Multiple neurons

Sensory Neuron

Carry electrical impulse from Receptor to CNS

Coordinator

Brain or spine; coordinates response

Peripheral Nerves

All nerves EXCEPT brain and spine

Motor Neuron

Transmits impulse from CNS to body tissues

Stimulus

Change in environment body reacts to

Effector

Muscle or gland that reacts to nerve impulse

Receptor Cells

Specialist cells that detect impulse

Synapse

Gap between two neurons

Cornea

transparent area in front of sclera ; can bend light as it enters

Suspensory Ligament

holds lens in place

Pupil

hole through which light enters

Fovea

area of cones where light is bought to focus

Optic Nerve

sends electrical signal to the brain

Iris

controls the size of the pupil

Ciliary Muscle

contracts and relaxes to change the shape of the lens

Circular Muscles

contract to bring iris further in, opening pupil

Radial Muscles

contract to dilate pupil by pushing pupil further out

Myopia

Short-sightedness

concave lens

spreads light out before it reaches the eye

Hyperopia

Long-sightedness

convex lens

brings light rays together before it reaches the eye

Contact lenses

Float on the surface of the cornea, focusing and refracting light

shivering

muscles contract and relax rapidly with energy from respiration which is exothermic and releases heat