14/09/2015 OCR Additional Science Brain and Mind W Richards The Weald School A slideshow that covers the entire OCR 21 st Century 2006 Syllabus “Brain.

19/04/23

OCR Additional ScienceOCR Additional ScienceBrain and MindBrain and Mind

W Richards

The Weald School

A slideshow that covers the entire OCR 21st Century 2006 Syllabus “Brain and

Mind” Module

19/04/23

The Nervous SystemThe Nervous SystemThe CENTRAL NERVOUS SYSTEM (CNS) enables us to react to our surroundings. It consists mainly of the brain, the spinal chord, nerve cells (“neurones”) and receptors.

Types of receptor:

1) Light receptors in the eyes

2) Sound receptors in the ears

3) Taste receptors on the tongue

4) Smell receptors in the nose

5) Touch, pressure and temperature receptors in the skin

6) Changes of position receptors in the ears (balance)

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Nervous ReactionsNervous ReactionsWhen we react to a stimulus our bodies use the following pattern:

Stimulus Receptor Coordinator Effector Response

For example, consider a man and a camel: Oh

No!

What are the stimulus, receptor, coordinator, effector and response in this situation?

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Examples of reactionsExamples of reactionsStimulus Receptor

(i.e. the thing that detects the stimulus)

Effector (i.e. the thing that will do

the reaction)

Response (i.e. action

taken)

Bright light

Sour taste

Losing balance

Sit on a drawing pin

19/04/23Types of nerve cell Types of nerve cell (“neuron”)(“neuron”)

Nucleus Muscle strands (effector)

Axon

1) Motor neurone 2) Sensory neurone 3) Relay neurone

Impulse Impulse

Nerve cells (neurons) are elongated with branched endings to connect to many muscles

fibres.

Fatty sheath

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SynapsesSynapses

Neurones never ____ each other – there is a small gap between them called a _____. A signal is sent from one _______ to the next by a _______ transmitter across the synapse (called a “neurotransmitter”). These transmitters are then ________ back into the sensory neurone to be used again. Children have around 1000 trillion synapses whereas adults only have between 100 and 500 trillion.Words – chemical, synapse, neurone, touch,

reabsorbed

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Conscious actionsConscious actionsA conscious action is one where the brain makes a considered response. Here’s what happens:

Stimulus Receptor Sensory Neurone Coordinator

Motor Neurone Effector Response

1) Receptors in your skin detect a stimulus

3) Here another sensory neurone carries the signal to the brain

4) The brain decides to move away the hand

5) This impulse is sent by MOTOR NEURONES to the hand muscles (the effectors) via the spinal chord…

2) The impulse is carried by SENSORY NEURONES to the spinal chord

6) Which then moves the hand away

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Reflex actionsReflex actions

Sometimes conscious action is too slow to prevent harm, e.g…

In situations like this the body bypasses the brain to produce a quicker response. Here’s how it works…

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Reflex actionsReflex actions

1. Receptor

2. Sensory neurone

3. Relay neurone in the spinal chord

4. Motor neurone

5. Effector

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Simple reflexes in humansSimple reflexes in humansBabies can demonstrate simple reflexes:

1) Stepping reflex

2) Startle (or moro) reflex

3) Grasping reflex

4) Rooting reflex

5) Sucking reflex

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The Iris ReflexThe Iris Reflex

When the light is bright the radial muscles relax, the circular muscles contract and the pupil increases in size.

When the light is bright the radial muscles _____, the circular muscles _______ and the pupil ________ in size.

19/04/23Conditioned reflexes - Pavlov’s Conditioned reflexes - Pavlov’s DogDog

Ivan Pavlov, 1849-1936

I won the Nobel Prize in 1904 and am most famous for investigating

“conditioned responses”:

1) Steak + dog = saliva

2) Steak + bell + dog = saliva

3) Bell + dog = saliva

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Complex BehaviourComplex Behaviour

When the brain is asked to do certain tasks different areas are “activated”. New experiences cause new neuron pathways to develop, while pathways that are not used are eventually destroyed. This is why we become better at certain tasks when we practice them more often.

PET scan showing areas “activated” by doing algebra.

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Feral childrenFeral children

Task: to find out what “feral children” are, what has caused their condition and what the consequences are.

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The Cerebral CortexThe Cerebral Cortex

By studying the effects (e.g. memory/sight loss) when different parts of the brain are damaged scientists have been able to identify which parts of the brain control which functions.

19/04/23Other techniques of studying the Other techniques of studying the brainbrain

1) An electroencephalogram (EEG) is a visual record of the electrical activity generated by neurons in the brain. It works by amplifying and detecting the electrical signals from the brain.

2) Magnetic resonance imaging (MRI) scanning is a new technique that produces images of different cross sections of the brain and uses colours to represent activity.

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MemoryMemoryOur memory is divided into two types: short term and long term.

Short term memory is capable of storing a limited amount of information for a limited amount of time. Long term memory is when more information is stored over a much longer time.

Ways of improving short term memory, e.g. a phone number

Ways of improving long term memorye.g. exam revision

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The Effect of DrugsThe Effect of DrugsDrugs can have different effects on the nervous system. For example, alcohol _____ reactions down by affecting chemical transmitters in the brain whereas caffeine causes nerve impulses to be sent ______, thereby _______ reaction time.Serotonin is a neurotransmitter in the central nervous system that is associated with feeling ____. The drug ecstasy blocks the synapses where the serotonin is removed, making the feeling last longer. However, the neurons are harmed in this process and taking ecstasy can lead to long term _____ loss.

Words – memory, slows, increasing, faster, happy

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