Co-ordination & Response Flashcards
All 41 cards in this deck
What is the function of the cerebellum?
Coordinates muscle movement and balance (fine movement).
What is the function of the medulla oblongata?
Controls unconscious (involuntary) activities such as heart rate and breathing rate.
What is the function of the cerebral hemispheres?
Control conscious thought, memory, language and intelligence.
True or false? The medulla oblongata controls balance and coordinated movement.
False. The cerebellum does that; the medulla oblongata controls unconscious activities such as heart rate.
Why is a brain tumour difficult to treat?
The brain is encased in the skull so it is hard to reach, and surgery or radiotherapy can damage surrounding healthy brain tissue.
Why can damage caused by a spinal injury usually not be repaired?
Neurones of the central nervous system do not repair or regenerate, so the loss of function (e.g. paralysis) is permanent.
Why is brain tissue investigated using scans rather than by examining it directly?
The brain is encased in the skull, so it is difficult to access, and operating on it risks serious damage.
What does a CT scan use, and what does it show about the brain?
Uses X-rays; it shows a detailed image of brain structure (e.g. a tumour or damaged region).
What does a PET scan use, and what does it show about the brain?
Uses an injected radioactive tracer (e.g. radioactive glucose); it shows which areas are active, so gives structure and function in real time.
True or false? A CT scan shows which parts of the brain are active.
False. A CT scan shows structure only; a PET scan shows brain activity.
Give one risk of using CT scanning to investigate the brain.
It exposes the patient to ionising radiation (X-rays).
What makes up the central nervous system (CNS)?
The brain and the spinal cord.
In a neurone, what is the difference between a dendron and an axon?
A dendron carries the impulse towards the cell body; an axon carries it away from the cell body.
What is the function of the myelin sheath on a neurone?
Insulates the axon and speeds up transmission of the electrical impulse.
What is the function of a sensory neurone?
Carries electrical impulses from a receptor to the CNS.
What is the function of a motor neurone?
Carries electrical impulses from the CNS to an effector (a muscle or gland).
True or false? Impulses travel along a neurone as chemical messages.
False. They travel along a neurone as electrical impulses; chemicals are only used at synapses.
What is a synapse?
The junction (small gap) between two neurones.
What is a neurotransmitter?
A chemical released into the synapse that diffuses across the gap and binds to receptors on the next neurone.
What are the steps in transmitting an impulse across a synapse?
e.g. from a sensory neurone to a relay neurone
- The impulse arrives at the end of the sensory neurone and triggers release of neurotransmitter.
- The neurotransmitter diffuses across the gap.
- It binds to receptors on the relay neurone, starting a new electrical impulse.
True or false? The electrical impulse jumps across the gap at a synapse.
False. The impulse cannot cross the gap; a chemical neurotransmitter diffuses across instead.
True or false? A synapse allows impulses to travel in one direction only.
True. Neurotransmitter is released on one side only and receptors are on the other side.
Why does an impulse travel more slowly across a synapse than along an axon?
The neurotransmitter has to diffuse across the gap, which is slower than an electrical impulse.
What is a reflex action?
A rapid, automatic response to a stimulus that does not involve conscious thought.
What is the pathway of a simple reflex arc?
e.g. pulling your hand away from a hot object
- Stimulus detected by a receptor (heat receptor in the skin) → sensory neurone.
- Relay neurone in the CNS (spinal cord).
- Motor neurone → effector (arm muscle contracts and the hand pulls away).
What is the function of a relay neurone?
Connects a sensory neurone to a motor neurone within the CNS.
Why are reflex actions so fast?
The impulse travels a short pathway with few synapses and does not pass through the conscious part of the brain.
True or false? Every reflex arc passes through the conscious part of the brain.
False. Many reflex arcs pass only through the spinal cord, which is why no conscious thought is needed.
What is the function of the cornea?
A transparent layer at the front of the eye that refracts (bends) light to start focusing it on the retina.
What is the function of the retina?
Contains the light receptor cells (rods and cones); light is focused on it and impulses are sent to the brain along the optic nerve.
What happens in the iris reflex in bright light?
e.g. walking outside into bright sunshine
- Receptors in the retina detect the bright light.
- Circular muscles of the iris contract and radial muscles relax.
- The pupil gets smaller, so less light enters and the retina is protected.
How does the eye focus on a near object (accommodation)?
e.g. looking down at a book
- Ciliary muscles contract.
- Suspensory ligaments slacken.
- The lens becomes thicker/more curved, so light is bent more and focuses on the retina.
What is the difference between rod cells and cone cells in the retina?
Rods work in dim light but do not detect colour; cones detect colour but need bright light.
True or false? The lens does most of the refraction of light entering the eye.
False. The cornea does most of the refraction; the lens fine-tunes the focus.
What causes short-sightedness and where does the light focus?
The eyeball is too long or the cornea/lens too curved, so light focuses in front of the retina and distant objects look blurred.
What causes long-sightedness and where does the light focus?
The eyeball is too short or the lens too thin/not curved enough, so light focuses behind the retina and near objects look blurred.
True or false? Long-sightedness is corrected with a concave lens.
False. Long-sightedness needs a convex (converging) lens; a concave (diverging) lens corrects short-sightedness.
What is a cataract and how does it affect vision?
A build-up of protein makes the lens cloudy, so light is dispersed and vision is blurred/cloudy.
How are cataracts treated?
Surgery to replace the cloudy lens with an artificial (plastic) lens.
What causes colour blindness?
Cone cells in the retina are missing or not working (usually red–green cones), so certain colours cannot be distinguished.
What are the steps to plan an investigation to test a hypothesis about eyesight?
e.g. 'People with brown eyes are more likely to be short-sighted than people with blue eyes'
- Choose equal numbers of people in each group: equal numbers with brown eyes and with blue eyes.
- Test each person's vision in the same way: use an optician's eye chart at a set distance.
- Compare the results: if more brown-eyed people are short-sighted, the hypothesis is supported.