2 4 co ordination and response

The structures are:

The cerebral hemispheres are responsible for higher brain functions such as consciousness, intelligence, memory and language.

False. The cerebellum in the brain is responsible for the coordination of movement.

The medulla in the brain regulates unconscious functions such as:

It is difficult to study the brain because it is inside the skull and is therefore difficult to access.

Brain function can be investigated using scanning technology, e.g.

Information that can be provided by different types of brain scan includes:

False. Spinal cord injuries are difficult to treat because: It is the brain itself that is difficult to access, due to its location inside the skull.

Brain tumours are difficult to treat because:

Receptors are specialised cells that detect specific stimuli and convert them into electrical impulses, initiating the transmission of signals through the nervous system.

The neurone shown in the image is a sensory neurone. It can be identified by the position of the cell body between a dendron and an axon.

Sensory neurones carry impulses from sense organs to the central nervous system (CNS).

The CNS is made up of the brain and the spinal cord.

The neurone shown in the image is a relay neurone. Relay neurones can be identified because they are short and have a small cell body at one end with many dendrites.

The neurone is a motor neurone, identifiable by its long axon with a large cell body at one end.

False. Motor neurones carry impulses from the CNS to effectors (muscles or glands).

False. A nerve impulse travels towards the cell body in sensory neurones and away from the cell body in motor and relay neurones.

Structures A and B are:

False. The myelin sheath insulates axons in order to increase the speed at which nerve impulses are transmitted.

Dendrons carry impulses towards the cell body (in sensory neurones), while axons carry impulses away from the cell body.

A synapse is a junction between two neurones where a very small gap exists between one neurone and the next.

Neurotransmitters are chemical signalling molecules used to transfer signals between neurones at synapses.

False. Electrical impulses cannot directly jump the gap at synapses. Electrical signals are converted into *chemical signals *in the form of neurotransmitters which diffuse across a synapse gap.

The events at a synapse are as follows:

False. Neurotransmitters move across the gap at a synapse by diffusion from a high concentration to a low concentration.

Reflex actions are automatic, rapid responses to a stimulus that do not involve conscious thought.

A flow diagram that represents a reflex arc would be as follows: receptor → sensory neurone → relay neurone → motor neurone → effector

False. Sensory neurones in a reflex arc connect receptor cells with relay neurones in the CNS. While there are some reflex arcs that involve the brain, the brain regions involved are not connected with conscious thought.

A relay neurone is a neurone within the CNS that connects sensory and motor neurones.

Motor neurones in reflex arcs connect relay neurones with effectors.

The structures labelled A-D are:

The function of the cornea is to refract light into the eye.

False. The function of the iris is to control the amount of light that enters the pupil. It is the cornea and lens that focus light correctly onto the retina.

Cone cells absorb light of different colours/wavelengths, providing colour vision.

True. Rod cells work well in dim light.

Defects that affect the eye and eyesight include:

True. Short sighted individuals are unable to focus on distant objects because the light focuses in front of the retina.

Long sighted individuals cannot focus on near objects.

Long-sightedness occurs when light from near objects focuses behind the retina; this can be due to:

Cataracts are a build-up of protein inside the lens, producing a cloudy effect at the front of the eye.

False. Colour blindness results from incorrectly functioning or absent cone cells.

False. Long-sightedness can be corrected with the use of a converging (convex) lens, which causes the light to bend more and so focus on the retina instead of behind the retina. Diverging (concave) lenses are used to correct short-sightedness.

Cataracts can be corrected by removing the cloudy lens and replacing it with an artificial lens.