Brain and mind Flashcards
Why do multicellular organisms need communication systems?
So that the body works as a whole
What are the two communication systems?
Nervous system, hormone system.
What are the organs that make up the nervous system?
Brain and spinal cord.
What sort of response is produced by the nervous system?
A quick and short response.
What sort of response is produced by the hormone system?
A slower response, but longer lasting.
In vertebrates, what does the CNS (central nervous system) consist of?
Brain and spinal cord.
In mammals, what is the CNS connected to?
The PNS (peripheral nervous system).
What does periphery mean?
The outskirts, or edges; the external boundary
What is the PNS made up of?
Neurons.
What would you call a neuron that is detecting changes in the environment?
A sensory neuron.
What would you call a neuron that is responsible for communicating a response?
A motor neuron
What do sensory neurons connect?
A receptor (eg in the eye) with the CNS
What do motor neurons connect?
The CNS to effectors.
What is the name given to changes in the environment that are detected by an organism?
Stimuli
What are hormones?
Chemical messengers
Where are animal hormones produced?
In glands
How are hormones transported?
In the bloodstream
How do hormones only affect the target cells?
The genes controlling the proteins required for the response are switched off in other cells.
Where is insulin produced?
The pancreas.
What is controlled by the use of insulin?
Blood sugar
How does insulin act on body cells?
It enables them to take in glucose from the blood.
Where is oestrogen produced?
Ovaries (and a little in the testes)
What does oestrogen do during puberty?
It controls the development of secondary sexual characteristics, eg breasts, body shape.
What does oestrogen do in all women?
Controls the menstrual cycle
What sort of messages does the nervous system send?
Electrical
What sort of messages does the hormonal system send?
Chemical
What are neurons specialised to do?
Carry nerve impulses
What is the shape of a neuron?
Looooooooooooooooooooooooooooooong
What do neurons consist of?
A cell body, that contains the nucleus, and the long axon. It also has branches on the cell body called dendrites.
Where would you find the longest axon?
In the blue whale, running from tail to brain, so about 25 metres.
What is the direction of the impulse along the axon?
It runs away from the cell body
What is the axon a long extension of?
The cytoplasm
What are some axons covered in?
A myelin sheath.
What is the speed of nerve impulse affected by?
Temperature; diameter of the axon; the myelin sheath
How does temperature affect the speed of nerve impulses?
It is faster in warm blooded animals than cold blooded animals.
How does the diameter of the axon affect the speed of nerve impulses?
It is faster as the diameter goes up.
How does the myelin sheath affect the speed of nerve impulses?
It speeds the nerve impulse up as it “jumps” from gap to gap.
What does the myelin sheath do, apart from speeding the nerve impulse up?
It insulates the neuron from neighbouring cell.
What is there between two neurones who want to have a little gossip?
A small gap called the synapse.
What happens when the electrical nerve impulse gets to the end of the axon?
It is changed to a chemical signal.
What happens when the chemical signal has crossed the synapse?
It is changed to an electrical signal.
How many synapses per neuron?
There can be many, so one neurone can communicate with many neurons.
What is the chemical that crosses the synapse called?
The transmitter substance.
What happens when the transmitter substances is released into the synapse?
It diffuses across the gap, and then binds with receptor molecules on the the neuron.
What happens to the transmitter substance after the next neuron has sent the electrical impulse?
It is either taken back up by the neuron, or broken down by enzymes.
Why is there more than one type of transmitter molecule?
They work on different nervous pathways.
Name a transmitter molecule that is important in the brain
Serotonin
Some transmitters do not work by exciting the next nerve. What else can they do?
They can inhibit the next nerve, or work on muscles instead of nerves.
How many different transmitters fit one receptor?
One - again, lock and key idea.
What does the nervous system respond to?
Stimuli (one stimulus)
Stimuli are detected by?
Receptors
How can receptors be organised?
They can be part of organs, or organised into groups, or spread over large areas.
What coordinates the response to a specific stimulus?
The CNS
What is the response to a stimulus made by?
An effector
What effectors are there?
eg glands; muscles
What do glands do?
Release chemicals such as hormones and enzymes.
When is the hormone insulin released?
After eating, when blood sugar rises.
What do we use muscles for?
Movement
On a basic level, what movement does an organism need to do?
It needs to move away from dangerous, unpleasant stimuli and towards pleasant ones (eg food).
Do any of our muscles move in ways that we can’t control?
Yes, eg the heart, the gut walls, the muscles associated with breathing, the bladder
What is a reflex?
A simple response to a stimulus
Give an example of a reflex.
eg Dropping a hot cup of tea.
What is the pathway of a reflex through the nervous system called?
Reflex arc
The reflex arc is?
stimulus->receptor->sensory neuron->relay neuron in CNS->motor neuron->effector (often muscle)
When would you learn a simple reflex?
You don’t, they are present from birth
Why do we have reflexes?
They enable us to respond quickly to stimuli that could harm us.
Name some of your reflexes
dropping a hot object, the knee jerk reflex, the pupil reflex
What is the pupil reflex?
Pupils contract when light is shone into them
How many reflexes does the human baby have, compared to the adult?
More
Name some new born reflexes
Stepping (the baby walks when held upright), grasping (if you put something against the palm of the babies hand); sucking (when something is placed in the babies mouth).
Why are reflexes rapid?
If the stimulus is below the neck the brain is not involved at all, only the relay neurons in the CNS).
What do the relay neurons connect to, as well as the reflex arc?
Neurones that run to the brain.
What do the relay neurons’ connection to the brain permit us to do?
To know about the reflex action; to inhibit the reflex action if we anticipate it.
Why can we only inhibit a reflex action if we anticipate it?
The brain will only find out after the reflex has occurred, due to the speed of the reflex.
What name is given to the ways that an animal acts?
Behaviours
How does an animal acquire behaviours?
They can be instinctive, or learned.
Instinctive behaviours are controlled by…
reflex responses.
Can simple animals learn?
Very simple animals can’t - however, even insects can.
How can an animal gain a reflex response to a stimulus?
Conditioning. (Learning, effectively)
Give examples of conditioning
Pavlov’s dogs, John B Watson’s study with eight month old Albert.
What was the conditioning shown by Pavlov’s dogs?
After learning to associate the sound of a bell with food, they started salivating at the sound of the bell even without food.
What was the conditioning shown by Albert?
He learned to fear a rat because a loud noise was associated with it. Note - this sort of reflex does go through the brain.
With Pavlov’s dogs, what is the name given to the bell?
It is the secondary stimulus.
What is the value of a conditioned reflex?
It has survival value, in that the animal does not need to think about what to do, it responds quickly. eg - a small gnu learns to associate the sight of a lion with the panic of the herd (unpleasant) so will avoid the lion in future.
When an animal is sick after eating, what happens?
It develops a conditioned reflex against eating that type of food, as it might well have been the food that made it ill. (Raisins, anyone?)
Why do we believe that our brain gave us an advantage?
It enables social behaviour; it enables learning by experience, so we are able to exploit new situations.
What is the thin outer layer of the brain called?
The cerebral cortex.
What is the cerebral cortex involved with?
Intelligence; memory; language; consciousness.
Why is the cerebral cortex folded?
To get more of it into the space allowed by the skull.
Who maps the brain?
Neuroscientists
How do neuroscientists map the brain?
Using invasive, and non-invasive techniques.
what invasive techniques can be used to map the brain?
Observation when a specific part of the brain is damaged; during brain surgery, using electrodes to stimulate the brain and having the patient say what is experienced.
What non-invasive techniques are there for mapping the brain?
eg MRI scans, PET scans. Used for comparing diseased brains with normal brains; looking at the brain when it is stimulated by music, language, etc.
How do we learn?
By forming new paths between neurons (so old pathways may be lost); certain pathways are more likely to be used than others.
What is a pathway formed by learning called?
A neuron pathway.
If an experience is repeated, what happens to the neuron pathway?
It is strengthened.
How else can neuron pathways be strengthened?
By using strong stimuli, eg smell, colour
How does practise improve our ability to do things?
The neuron pathway is strengthened.
Who forms neuron pathways more easily, children or adults?
Children
How many neurons in our brains?
Billions, so the possible number of inter-connections is huge!
What happens to the new-born reflexes?
They are lost as we learn new behaviours.
What happens if a child is not given appropriate stimuli?
They may not progress in their learning.
What does evidence suggest about the ability to learn things, as related to age?
Some skills can only be learned at a certain age, eg language.
What evidence do we have about a “window of opportunity” with language development?
Feral children will learn only very limited language when returned to civilisation (but it does depend on how much language they had when they went feral).
What is memory?
A way of storing, and retrieving, information. Guaranteed to fail in an exam.
What are the two types of memory?
Short term and long term memory
How is it easier to remember information?
If there is a pattern; if you repeat it; if you add a strong stimulus.
What is long term memory?
The experiences we have that are stored for a long time
What is short term memory?
The things we are remembering from now, like a phone number, which may be forgotten.
How can we explain how memory works?
We try to use models of how we think it works.
What is the multi-store model of memory?
Sensory memory; short term memory; long term memory.
Where does an initial stimulus go, in the multi-store model of memory?
Into the sensory memory.
Where does an initial stimulus go after the sensory memory, in the multi-store model of memory?
Into the short term memory
Where does an initial stimulus go after the short term memory, in the multi-store model of memory?
Into the long term memory
What makes the initial stimulus move on from the sensory memory, in the multi-store model of memory?
Paying attention to the stimulus
What makes the initial stimulus move on from the short term memory, in the multi-store model of memory?
Rehearsal
How long does the sensory memory last, in the multi-store model of memory?
1-3 seconds
How long does the short term memory last, in the multi-store model of memory?
15-30 seconds
How long does the long term memory last, in the multi-store model of memory?
1 second-lifetime.
What happens if a memory arrives in a memory store, and it is not passed on, or retrieved (in the multi-store model of memory)?
It is forgotten
Why are models not very good for explaining memory?
Memory is more complicated than the model; no model really explain how long term memory works; the multi-store model is too linear; the multi-store model does not sub-divide short and long term memory; the model does not differentiate between different stimuli, or different people
How do many drugs and toxins work on the nervous system?
Affecting the transmission of impulses across the synapse; stopping the transmission; changing the speed of the transmission; or making the impulse stronger or weaker.
What does the anti-depressant Prozac do?
It increases the levels of the transmitter substance serotonin.
What does Ecstacy (MDMA) do?
It increases the levels of serotonin released.
Why do people feel “down” after ecstacy?
The brain’s serotonin is depleted, so the person feels tired and irritable.
What should happen to the transmitter molecules after the transmission of a nerve impulse?
They should be removed from the synapse.
What does MDMA do to the sites on the neuron where serotonin would be reabsorbed?
It blocks them.
What does MDMA do to the concentration of serotonin in the synapse by blocking the reabsorption sites?
It increases it in the synapse, giving a feeling of well-being, but it also means that the neurones are depleted of serotonin for use later..
What does curare, the South American Indian arrow poison, so?
It blocks a transmitter molecule that is used for movement. A version is used to stop the body moving during surgery.
What are beta blockers?
A prescription drug that blocks the transmitter molecule adrenaline. They can reduce anxiety, which is why BG don’t allow them.
What do the opiates do?
They mimic the effects of some neurotransmitters.
