B6- Brain And Mind

Question 1

How do single celled organisms respond?

Answer 1

A single celled organism can just respond to its environment.

Question 2

How do multicellular organisms respond?

Answer 2

Cells of multicellular organisms need to communicate with each other so the organism can respond to stimuli.

As Multicellular organisms evolved they developed nervous and hormonal communication systems.

Question 3

Central nervous system (CNS)??

Answer 3

In vertebrates (animals with backbone) this consists of the brain and spinal cord only.

In mammals, the CNS is connected to the body by sensory neurones and motor neurones- this makes up the peripheral nervous system (PNS)

Question 4

Sensory neurones?

Answer 4

The neurones that carry impulses from the receptors to the CNS.

Question 5

Motor neurones?

Answer 5

The neutrons that carry impulses from the CNS to effectors.

Question 6

Effectors?

Answer 6

All your muscle and glands which respond to nervous impulses.

Question 7

Receptors?

Answer 7

Receptors are the cells that detect stimuli.

There are different types of receptors, such as taste receptors on the tongue and sound receptors in the ears.

Receptors can form part of larger complex organs. e.g. The retina of the eye is covered in light receptor cells.

Question 8

What do Effectors do?

Answer 8

Effectors respond to nervous impulses and bring about a change. Effectors can also form part of complex organs.

Question 9

What are the two types of effectors?

Answer 9

Muscle cells- which make up muscles.

Hormonal secreting cells- which are found in glands. e.g. Cells that secrete the hormone ADH are found in the pituitary gland.

Question 10

How do CNS coordinate a response?

Answer 10

The CNS is a processing centre it receives information from the receptors and then coordinates a response.

Question 11

Information transmitted by neurones?

Answer 11

• When stimulated neurones transmit information around the body as electrical impulses.
• The electrical impulses pass along the axon of the nerve cells.
• Axons are made from the nerve cells cytoplasm stretched out into a long fibre and surrounded by a cell membrane.
• Some axons are also surrounded by a fatty sheath that acts as an electrical insulator. Shells the neurone from neighbouring cells and speeding up the electrical impulse.

Question 12

Electrical impulses?

Answer 12

They carry information around the body really quickly so the responses they cause happen fast but they are short lived.

Question 13

Hormones?

Answer 13

They carry information around the body- they are produced in glands and travel around in the blood.

The responses they cause are brought about more slowly and they are longer lasting than the responses caused by nerve impulses.

Question 14

What are synapse?

Answer 14

Neurones aren’t attached to each other- the tiny gap between them is called the synapse.

Question 15

Transmitter chemicals?

Answer 15

• When an electrical impulse reaches the end of a neurone it triggers the release of transmitter chemicals into the synapse.
• The transmitter chemicals diffuse across the gap and bind to receptor molecules on the membrane of the next neurone.
• Only specific transmitter chemicals can bind to the receptor molecules on the neurone.
• When the chemicals bind to the right receptors they trigger a new electrical impulse in the next neurone.

Question 16

What affects the transmission across synapses?

Answer 16

• Many drugs and toxins can interfere with the transmission of impulses across a synapses.
• The drug ecstasy blocks sites in the brains synapses where the transmitter chemical serotonin is removed.
• Serotonin affects things like pain, aggression and appetite. It also affects a persons mood.
• Because Serotonin can’t be removed the concentration increases- this affects mood.
• This is why ecstasy is described as mood enhancing effect because of the increased concentrations of serotonin it causes.

Question 17

What are reflexes?

Answer 17

• Reflexes are rapid, automatic responses to certain stimuli.
• Reflexes are quick because you don’t think about them- they are involuntary.
• The route taken by the information in a reflex is called a reflex arc.

Question 18

The reflex arc goes through CNS?

Answer 18

• The neurones in reflex arcs go through the spinal cord or through an unconscious part of the brain.
• When a stimuli is detected by receptors an impulse is sent along a sensory neurone to the CNS.
• In the CNS the sensory neurone passes on the message to another type of neurone- a relay neurone.
• The relay neurone passes the impulse to a motor neurone.
• The impulse then travels along the motor neurone to the effector. (For example a muscle)
• The muscle then contracts and moves your hand away from the bee.
• An impulse always takes the same direct route through the reflex arc so no information is ever processed. This is why reflexes are involuntary and rapid.

Question 19

What are simple reflexes?

Answer 19

Simple animals such as jellyfish have no brain- they rely entirely on simple reflex actions.

Simple reflexes cause these animals to respond to some stimuli in a way that helps them survive.

Question 20

What are simple reflexes in humans?

Answer 20

• Very bright light can damage the eyes- so muscles in the eye contract making the pupil smaller allowing less light into the eye.
• If a person picks up a hot object then there’s a reflex that makes them drop it.
• The doctor may test your knee jerk reflex by tapping it.

Question 21

What simple reflexes do newborn babies have?

Answer 21

Newborn babies have reflexes that are lost as they develop;

• they’ll automatically suckle from their mothers.
• they’ll grasp when their palms are touched.
• they’ll try to take steps when their feet are put on a flat surface.

Question 22

Can reflexes be modified?

Answer 22

It is possible to modify a natural reflex response.

For example;

• When you pick up a hot object such as a hot plate you would want to drop the plate- this is a reflex response to protect your skin from damage.
• The response can be overridden by a neurone between the brain and the motor neurone of the reflex arc - this results in a bit of pain but you can still have your dinner.

Question 23

What is conditioning?

Answer 23

A stimulus causes a particular reflex response but animals can learn to produce the same response to a new secondary stimulus.

This is called conditioning- the new reflex is called a conditioned reflex.

Question 24

How does conditioned reflexes increase chances of survival?

Answer 24

For example;

• Instead of being camouflaged insects are brightly coloured so they stand out.
• Insects that are brightly coloured are poisonous so this acts as a warning to predators.
• The predators develop a conditioned reflex to the secondary stimulus.
• For example when the predator (the bird) spots a bright insect it eats the insect but it doesn’t taste good and makes the bird ill.
• The bird then associates the bad taste and illness with the colour so next time it faces a bright insect it will avoid it.
• By avoiding poisoning insects the birds are increasing their chances of survival.

Question 25

Describe the brain?

Answer 25

* The brain is a bunch of neurones all interconnected. * It can modify behaviour as a result of experience. ( i.e. Learn stuff) * Coordinate complicated behaviour (e.g. Social behaviour - interacting with other members of the group)

Question 26

The brain develops at an early age?

Answer 26

* The brain of a newborn baby is only partly developed- most of the neurone connections are not yet formed. It becomes more developed with every new experience. * Connections form as the child experiences new things- when a neurone is stimulated by the experience it branches out, connecting cells that were previously unconnected. * By the age of 3 most of the connections that will ever form have been formed- making a huge network of neurones with billions of possible routes for nerve impulses to travel down. * The number of connections remains constant until about age 10.

Question 27

You learn throughout your life?

Answer 27

* When experiences are repeated over and over again the pathways that the nerve impulses travel down become strengthened. * Strengthened pathways are more likely to transmit impulses than others. * After the age of 10 the pathways that aren't used as often die off- this is why it's harder to learn as you get older.

Question 28

Why can you predict simpler animals behaviour?

Answer 28

Complex animals are adaptable because of the variety of potential pathways in the brain. Simpler animals have less flexible nervous systems they do not have as many pathways. Making their behaviour more predictable and less adaptable.

Question 29

Skills are developed at a certain age?

Answer 29

There are stages in the development of a child's brain. As some nerve pathways need to be strengthened at a particular age otherwise it's too late. For example; * The ability to communicate by language (talk) depends on a child hearing other people speak. * It is thought that they must hear this during a certain critical period. * Evidence for this comes from studies of feral children (children who have been raised by animals without human contact)

Question 30

Cerebral Cortex?

Answer 30

* The Cerebral Cortex is the outer part of the brain. * It has a folded structure this makes the brain more wrinkled. * It takes roles in intelligence, memory,language and consciousness.

Question 31

How do scientists study the brain?

Answer 31

They use a variety of methods; * Studying patients with brain damage. * Electrically stimulating the brain. * MRI scans.

Question 32

Studying patients with brain damage?

Answer 32

If a small part of the brain had been damaged the effect this has on the patient can tell you a lot about what the damaged part of the brain does. E.g. If an area at the back of the brain was damaged by a stroke and the patient went blind you know that that area has something to do with vision.

Question 33

Electrically stimulating the brain?

Answer 33

The brain can be electrically stimulated by pushing a tiny electrode into the tissue and giving it a small zap of electricity. By observing what stimulating different parts of the brain does it's possible to get an idea of what those parts do. E.g. When a certain part of the brain (motor area) is stimulated it causes muscle contraction and movement.

Question 34

MRI scans?

Answer 34

A magnetic resonance imaging (MRI) scanner is a tube like machine that can produce a detailed picture of the brains structures. Scientists use it to find out what areas of the brain are active when people are doing things like listening to music or trying to recall a memory.

Question 35

Memory?

Answer 35

To remember something you first have to store the information (learn it) and then you have to retrieve it. Humans are more likely to remember things when they can see a pattern in the information. Humans also remember information that are associated with strong stimuli (noise,smell,taste etc.) It also helps if the information is repeated over a long period of time.

Question 36

What are the two types of memory?

Answer 36

Short term memory- lasts for anything from a few seconds to a few hours. It is used for information that you're thinking about this moment. Long term memory- Memories that were stored days,months or even years ago.

Question 37

Memory models?

Answer 37

Nobody knows for sure how memory works therefore people come up with different models to try and explain it. So far, no model has provided satisfactory explanation of human memory.

Question 38

Multi store model?

Answer 38

* Information that you've paid attention to is temporarily stored in short term memory. * If it's repeated enough it's transferred to long term memory and stored there. * Memories that are never transferred from the short term memory to the long term memory are forgotten, but information can be retrieved from the long term memory and remembered.

Question 39

What is a stimulus?

Answer 39

A change in the environment of an organism is called a stimulus. Organisms need to respond to stimuli in order to survive.