The Nervous System

A change in the surroundings that can be detected.

It detects a stimulus and changes it into an electrical impulse.

A muscle or a gland that carries out a response.

The brain and the spinal cord.

Carries impulses from a receptor to the central nervous system.

Carries impulses inside the central nervous system.

Carries impulses from the central nervous system to an effector.

The long fibre that carries the impulse away from the cell body.

Insulates the axon and makes the impulse travel faster.

Short branches that receive impulses.

A small gap between two neurones.

Neurotransmitters diffuse across the gap and start a new impulse.

The neurotransmitter is released from one side only.

Muscles and glands.

Nerves reach every part of the body, with many links and many types of receptor.

Name the part of the neurone marked X.

The myelin sheath. It insulates the axon and speeds up the impulse.

Name the three types of neurone and label the parts of one.

Sensory, relay and motor neurones. The parts are the cell body, dendrites, axon, myelin sheath and nerve endings.

Name each stage from stimulus to response.

Stimulus, receptor, central nervous system, effector, response. A sensory neurone joins the receptor to the central nervous system, and a motor neurone joins it to the effector.

A rapid, automatic response that protects the body.

The pathway is short, with few neurones and synapses.

It does not need conscious thought.

Receptor, sensory neurone, relay neurone, motor neurone, effector.

In the spinal cord.

It carries the impulse from the spinal cord to the effector.

A muscle.

Neurotransmitter diffuses across the gap and binds to receptors.

The neurotransmitter is released from one side only.

A reflex is faster and automatic; a voluntary action is chosen and involves the brain.

Pulling a hand away from a hot object, or blinking.

By a ruler drop test.

A faster reaction time.

To calculate a mean and reduce the effect of anomalies.

It speeds up the impulse.

Name the neurone marked X and say what it does.

The relay neurone. It links the sensory neurone to the motor neurone inside the spinal cord.

Label the parts of this reflex arc.

Stimulus, receptor, sensory neurone, relay neurone, motor neurone and effector. The relay neurone is in the spinal cord, and synapses join the neurones.

Describe what happens at the gap between the neurones.

The impulse makes the nerve ending release neurotransmitter. It diffuses across the gap and binds to receptors on the next neurone, starting a new impulse.

It refracts light and does most of the focusing.

It controls the amount of light entering the eye.

The hole in the iris that lets light in.

It changes shape to focus light on the retina.

Light receptor cells, rods and cones.

It carries impulses from the retina to the brain.

They connect the lens to the ciliary body and hold it in place.

It becomes smaller.

It becomes larger.

The ciliary muscles contract, the ligaments slacken and the lens becomes thicker.

The ciliary muscles relax, the ligaments are pulled tight and the lens becomes thinner.

The lens is too strong or the eyeball too long, so light focuses in front of the retina.

With a concave lens.

With a convex lens.

Faulty cone cells.

Name the part of the eye marked X and say what it does.

The retina. It contains the light receptor cells, the rods and cones.

Label the eye.

Cornea, iris, pupil, lens, ciliary body, suspensory ligaments, retina and optic nerve.

Describe what happens to the lens in each eye.

Near object: the ciliary muscles contract, the ligaments slacken and the lens is thick. Distant object: the ciliary muscles relax, the ligaments are taut and the lens is thin.

Conscious thought, memory, language and voluntary movement.

Coordination of movement and balance.

Automatic actions such as heart rate and breathing.

Body temperature and water balance.

A gland attached to the hypothalamus that releases hormones.

It releases hormones that control other glands.

The medulla.

The cerebellum.

A case study, a scan or electrical stimulation.

It is complex and hard to reach, and there are ethical issues.

Each injury is different, and it is hard to be sure which region is responsible.

Neurones repair poorly and the damage is often irreversible.

Parts are hard to reach and surrounding tissue can be damaged.

Impulses cannot cross, so movement and feeling are lost below the injury.

The pituitary gland.

Name the part of the brain marked X and say what it controls.

The cerebellum. It coordinates movement and keeps balance.

Name each part of the brain and what it controls.

Cerebrum: thought, memory, language, movement. Cerebellum: coordination and balance. Medulla: heart rate and breathing. Hypothalamus: temperature and water balance. Pituitary gland: hormones.