OCR Additional Science Brain and Mind 11/06/2018 OCR Additional Science Brain and Mind

The Nervous System 11/06/2018 The 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: Light receptors in the eyes Sound receptors in the ears Taste receptors on the tongue Smell receptors in the nose Touch, pressure and temperature receptors in the skin Changes of position receptors in the ears (balance)

Stimulus Receptor Coordinator Effector Response Nervous Reactions 11/06/2018 When 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?

Examples of reactions Stimulus Receptor 11/06/2018 Stimulus 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

Types of nerve cell (“neuron”) 11/06/2018 Nucleus Axon Muscle strands (effector) Fatty sheath Nerve cells (neurons) are elongated with branched endings to connect to many muscles fibres. 1) Motor neurone 2) Sensory neurone 3) Relay neurone Impulse Impulse

Words – chemical, synapse, neurone, touch, reabsorbed Synapses 11/06/2018 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

Conscious actions 11/06/2018 A conscious action is one where the brain makes a considered response. Here’s what happens: 4) The brain decides to move away the hand 3) Here another sensory neurone carries the signal to the brain 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 1) Receptors in your skin detect a stimulus 6) Which then moves the hand away Stimulus Receptor Sensory Neurone Coordinator Motor Neurone Effector Response

Reflex actions 11/06/2018 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…

Reflex actions 3. Relay neurone in the spinal chord 2. Sensory neurone 11/06/2018 3. Relay neurone in the spinal chord 2. Sensory neurone 4. Motor neurone 5. Effector 1. Receptor

Simple reflexes in humans 11/06/2018 Babies can demonstrate simple reflexes: Stepping reflex Startle reflex Grasping reflex Rooting reflex Sucking reflex

The Iris Reflex 11/06/2018 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.

Conditioned reflexes - Pavlov’s Dog 11/06/2018 Ivan Pavlov, 1849-1936 I won the Nobel Prize in 1904 and am most famous for investigating “conditioned responses”: Steak + dog = saliva Steak + bell + dog = saliva Bell + dog = saliva

Complex Behaviour 11/06/2018 PET scan showing areas “activated” by doing algebra. 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.

Feral children 11/06/2018 Task: to find out what “feral children” are, what has caused their condition and what the consequences are.

The Cerebral Cortex 11/06/2018 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.

Other techniques of studying the brain 11/06/2018 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.

Memory Our memory is divided into two types: short term and long term. 11/06/2018 Our 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 memory e.g. exam revision

Words – memory, slows, increasing, faster, happy The Effect of Drugs 11/06/2018 Drugs 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