Week 11 AS Biological Psychology


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Week 11 AS Biological Psychology

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  • Draw and complete by going to and from computer at the front.
  • In the brain, messages are passed between two nerve cells via a chemical synapse, a small gap between the cells. The (presynaptic) cell that sends the information releases neurotransmitters (including serotonin) into that gap. The neurotransmitters are then recognized by receptors on the surface of the recipient (postsynaptic) cell, which upon this stimulation, in turn, relays the signal. About 10% of the neurotransmitters are lost in this process; the other 90% are released from the receptors and taken up again by monoamine transporters into the sending (presynaptic) cell (a process called reuptake).To stimulate the recipient cell, SSRIs inhibit the reuptake of serotonin. As a result, the serotonin stays in the synaptic gap longer than it normally would, and may repeatedly stimulate the receptors of the recipient cell. The current model of SSRIs (the Monoamine Hypothesis) assumes that a lower homeostatic level of serotonin is primarily responsible for depression. While this holds in cases of major depression, minor to moderate cases are not as clear cut, and may in fact be caused by excess serotonin in specific areas of the brain.
  • Week 11 AS Biological Psychology

    1. 1. Pinky and The Brain … 1. 2. 3. 4. 5. 6. How many brain cells does an average brain contain? What percentage of the bodies energy does the brain use? How much does a brain weigh? What percentage of our brain do we use? How many times do our brain cells fire a second? How many times do synapses send information every second?
    2. 2. www.jamiesflipped.co.uk @jamiesflipped
    3. 3. Lesson Objectives By the end of the lesson you … • Must be able to define (AO1) the biological approach. • Must be able to define (AO1) the central nervous system, synapse, neurones and neurotransmitters.
    4. 4. “The human brain is not like other organs of the body in that looking at its structure does not reveal anything about how it functions. We can see that the wall of the small intestine acts as an absorptive surface; the heart as a pump. The brain, however, is a large mass of cells and fibres which, no matter how clearly we look at it, gives no indication of how we think, speak and remember.” Parkin, 2000
    5. 5. Approach Theories Studies Methods Biological Approach Biological Theory of Gender Development Money (1975) Raine (1997) Twin / adoption studies MRI / PET scanning Lab Experiments on Animals
    6. 6. How chemical activity mediates out behaviour. Genetic Influences over our behaviour Biological Approach Hormonal Influences over our behaviour
    7. 7. How chemical activity mediates out behaviour. Neurotransmitters • One way messages are passed within the brain is by neurotransmitters. • These are chemicals that pass from neuron to neuron. • Between neurones there are gaps called synapses. • If the receptors of one neuron are set to receive the neurotransmitters of another, then the message continues.
    8. 8. Genetic Influences over our behaviour Genetic Influences • Genes are passed on from parents to children and they govern behaviour as well as physical characteristics. Children receive (approx.) half their genes from their fathers and half from their mothers. • The human genome has recently been decoded, which means that all genes have been identified. • Does not mean the function of each gene is known because it is often the combination or the position of genes that leads to certain characteristics, rather than one particular gene.
    9. 9. Hormonal Influences over our behaviour Hormonal Transmission • Hormones are another way messages are passed around the body. • These send messages more slowly than neurotransmitters and are used for different purposes. • Hormones have a large part to play in our development as either male or female – for example, ANDROGENS are ‘male’ and OESTROGEN is ‘female’.
    10. 10. Consolidation Question Describe what is meant by the biological approach, giving at least 2 features of the approach in your answer. (6 marks) 10 minutes
    11. 11. The biological approach looks at chemical activity in the brain, including how neurotransmitters act at synapses to enable messages to be transmitted. Eg … Another way messages are transmitted is through hormones which act slower than neurotransmitters. Eg … The biological approach includes an evolutionary perspective, which examines how characteristics are inherited via genes. Eg …
    12. 12. Central Nervous System Hormones Neuron Brain Laterlisation Synapse Neurotransmitters
    13. 13. The Central Nervous System The central nervous system is made up of the brain and spinal cord. The brain functions to receive nerve impulses from the spinal cord and cranial nerves. The spinal cord contains the nerves that carry messages between the brain and the body.
    14. 14. A neuron (or neurone or nerve cell) is an electrically excitable cell that processes and transmits information by electrochemical signaling, via connections with other cells called synapses.
    15. 15. Neurones Neuronal cell bodies Axons Synapses occur at the junctions
    16. 16. Synapses • Neurones transmit signals electrically along their axons. • The synapses (junctions between neurones) transmit signals chemically.
    17. 17. Synapse Vesicles filled with neurotransmitter Synaptic cleft Location of receptors (postsynaptic density)
    18. 18. Neurotransmitters Information is carried by biochemical substances called neurotransmitters. The terminal buttons and the dendrites of other neurons do not touch, but instead pass the information containing neurotransmitters through a synapse.
    19. 19. Brain Lateralisation • The brain has many parts and is in two halves or hemispheres joined by the CORPUS CALLOSUM. • It is thought females use both halves of their brain more than males, and males are more right-brain dominant. • BRAIN LATERALISATION is the term used when considering the two halves of the brain separately.
    20. 20. Central Nervous System Hormones Neuron Brain Laterlisation Synapse Neurotransmitters Page 2 & 3
    21. 21. • Must be able to define (AO1) the biological approach. • Must be able to define (AO1) the central nervous system, synapse, neurones and neurotransmitters.
    22. 22. Define (without notes) • • • • • neurone neurotransmitter gene synapse CNS
    23. 23. Define (without notes) • neurone – a nerve cell that sends electrical impulses • neurotransmitter – a chemical released at the end of the neurone to pass a message on to another neurone. • gene – units of information that are inherited. • synapse – the space between two neurones which is crossed by neurotransmitters. • CNS – central nervous system – the brain and spinal cord which organise communication around the body.
    24. 24. Lesson Objectives By the end of the lesson you … • Must be able to describe (AO1) how the synapse, receptors, neurons and neurotransmitters pass ‘messages’ • Must be able to describe (AO1) the components of a neuron.
    25. 25. The Neurone
    26. 26. The Synapse
    27. 27. 1 Vesicles release neurotransmitter into synaptic cleft
    28. 28. 2 Neurotransmitter binds to receptors & activates them
    29. 29. 3 Excess neurotransmitter is taken up by the pre-synaptic neurone
    30. 30. 4 Enzymes are released to break down the remaining neurotransmitter
    31. 31. 5 Vesicles are replenished with new & reused neurotransmitter
    32. 32. Prozac Selective Serotonin Reuptake Inhibitor
    33. 33. Illustration 1 shows how this works in a healthy nerve transmission process
    34. 34. Illustration 2 shows the process when Major Depression is present. Note that fewer Serotonin molecules are present in the synaptic cleft and hence fewer make it to the next neuron to make it "fire."
    35. 35. Illustration 3 shows how an SSRI drug blocks the reuptake of Serotonin thus causing the concentration in the synaptic cleft to be increased. Consequently more serotonin makes it to the receptor sites on the next nerve cell and the functioning returns to normal.
    36. 36. Describe how neurotransmitters work. Include an explanation of synaptic transmission in your answer and give one example to illustrate. (8 marks)
    37. 37. • Must be able to describe (AO1) how the synapse, receptors, neurons and neurotransmitters pass ‘messages’ • Must be able to describe (AO1) the components of a neuron.
    38. 38. www.jamiesflipped.co.uk @jamiesflipped