A-LEVEL BIOLOGY, TOPIC EIGHT,8, GREY MATTER. 8.2.

Question 1

THE CENTRAL NERVOUS SYSTEM.

Answer 1

THE BRAIN, ALONGSIDE THE SPINAL CORD, IS PART OF THE CENTRAL NERVOUS SYSTEM, THE CNS.

Question 2

BRAIN, MADE OF.
BASIC STRUCTURE.

Answer 2

THE BRAIN, IS MADE OF BILLIONS OF INTERCONNECTED NEURONES.

WITHIN THE BRAIN, ARE DIFFEREENT REGIONS THAT CARRY OUT DIFFERENT FUNCTIONS.

Question 3

THE CEREBRUM, BASIC.

Answer 3

THE CEREBRUM, IS THE LARGEST PART OF THE BRAIN IN HUMANS, ACCOUNTING FOR 80%, OF THE TOTAL MASS OF THE BRAIN.

Question 4

THE CEREBRUM, FUNCTIONS.

Answer 4

IT CARRIES OUT A LARGE VARIETY OF FUNCTIONS, INVOLVED WITH THE CONSCIOUS ACTIVITIES, INCLUDING:

VISION,
HEARING,
SPEECH,
THINKING,
AND MEMORY.

Question 5

THE CEREBRUM, STRUCTURE.

Answer 5

THE CEREBRUM, IS DIVIDED INTO TWO,2, HALVES KNOWN AS CEREBRAL HEMISPHERES.

THE HEMISPHERES, ARE JOINED TOGETHER BY A BAND OF NERVE FIBRES, KNOWN AS THE CORPUS CALLOSUM.

THE RIGHT HEMISPHERE, CONTROLLS THE LEFT SIDE OF THE BODY, AND THE LEFT HEMISPHERE, CONTROLS THE RIGHT SIDE OF THE BODY.

THE CEREBRUM, HAS A THIN OUTER LAYER KNOWN AS THE CEREBRAL CORTEX, OR GREY MATTER.

THE CEREBRAL CORTEX, CONSISTS OF THE CELL BODIES OF NEURONES.

IT IS TIGHTLY FOLDED, WHICH INCREASES ITS SURFACE AREA AND ALLOWS IT TO CONTAIN A GREATER NUMER OF NEURONES.

WITH MORE NEURONES IN THE BRAIN, MORE NEURONE CONNECTIONS CAN BE MADE.

THIS IS IMPORTANT, AS THE MORE CONNECTIONS BETWEEN NEURONES IN THE BRAIN, THE GREATER THE ABILITY OF THE BRAIN TO CARRY OUT MORE COMPLEX BEHAVIOURS.

BENEATH THE CEREBRAL CORTEX, OR GREY MATTER LAYER, IS THE WHITE MATYER.

THE WHITE MATTER, CONSISTS OF MYELINATED AXONS OF NEURONES.

Question 6

THE HYPOTHALAMUS.

Answer 6

THE HYPOTHALAMUS MONITORS, THE BLOOD AS IT FLOWS THROUGH THE BRAIN, AND, IN RESPONSE, RELSEASES HORMONES OR STIMULATES THE NEIGHBOURING PITUITARY GLAND TO RELEASE HORMONES.

THE HYPOTHALAMUS, PLAYS AN IMPORTANT ROLE IN SOME HOMESTATIS MECHANISMS.

Question 7

THE HYPOTHALAMUS, REGULATING BODY TEMPERATURE.

Answer 7

THE HYOTHALAMUS, MONITORS BLOOD TEMPERARTURE, AND INITIATES A HOMEOSTATIC RESPONSE IF THIS TEMPERATURE GETS TOO HIGH, OR TOO LOW.

Question 8

THE HYPOTHALAMUS, OSMOREGULATION.

Answer 8

CELLS IN THE HYPOTHALAMUS, MONITOR THE WATER, H2O, BALANCE OF THE BLOOD AND RELEASE THE HORMONE, ADH, IF THE BLOOD BECOME TOO CONCENTRATED.

ADH, INCREASES ABSORPTION OF WATER, H2O, IN THE KIDNEYS.

Question 9

THE HYPOTHALAMUS, REGULATING DIGESTIVE ACTIVITY.

Answer 9

THE HYPOTHALAMUS, REGULATES THE HORMONES THAT CONTROL APPETITE, AS WELL AS THE SECRETION OF DIGESTIVE ENZYMES.

Question 10

THE HYPOTHALAMUS, CONTROLLING ENDOCRINE FUNCTIONS.

Answer 10

THE HYPOTHALAMUS, CAUSES THE PITUITARY GLAND TO RELEASE HORMONES THAT CONTROL A VARIETY OF PROCESSES, SUCH AS METABOLISM, GROWTH AND DEVELOPMENT, PUBERTY, SEXUAL FUNCTIONS, SLEEP AND MOOD.

Question 11

THE CEREBELLUM.

Answer 11

THE CEREBELLUM, COORDINATES MOVEMENT.
THIS INCLUDES BALANCE, A HIGHLY COMPLEX FUNCTION, THAT REQUIRES COORDINATION BETWEEN MULTIPLE PARTS, INCLUDING EYES, SEMICIRCULAR CANALS IN THE EARS, AND MANY MUSCLES.

Question 12

THE MEDULLA OBLONGATA.

Answer 12

ALSO KNOWN AS THE MEDULLA.

THE MEDULLA, CONTAINS CO-ORDINATION CENTRES, THAT CONTROL DIFFERENT FUNCTIONS.

SUCH AS,
THE CARDIAC CENTRE CONTROLS THE HEART RATE.

THE RESPIRATORY CENTRE, CONTROLS BREATHING RATE.

Question 13

UNDERSTANDING BRAIN STRUCTURE AND FUNCTION.

Answer 13

OUR UNDERSTANDING, OF BRAIN STRUCTURE AND FUNCTIONS IS LIMITED.

THE BRAIN IS INCREDIBLY COMPLEX, AND VERY DELICATE.

DIFFERENT REGIONS, WORKS TOGETHER TO BRING ABOUT BRAIN FUNCTION, SO CAN NOT BE STUDIED IN ISOLATION.

Question 14

STUDYING THE BRAIN, WITHOUT SURGICAL INTERVENTION.

Answer 14

SPECIALISED SCANNERS AND TECHNIQUES, CAN BE USED TO STUDY THE BRAIN, WITHOUT HAVING TO RESORT TO SURGICAL INTERVENTION.

Question 15

COMPUTERISED TOMOGRAPHY, WHAT IS IT AND HOW DOES IT WORK?

Answer 15

COMPUTERISED TOMOGRAPHY, OR CT, SCANS, PRODUCE CROSS-SECTION IMAGES OF THE BRAIN USING X-RAY RADIATION.

A BEAM OF X-RAYS ARE AIMED AT A PATIENT FROM ALL ANGLES AROUND THE BODY.

DIGITAL, X-RAY DETECTORS, ARE USED TO PICK UP THE X-RAYS, AS THEY EXIST IN THE PATIENTS BODY.

DENSER TISSUE ABSORBS MORE OF THE X-RAY RADIATION, SO SHOWS UP AS A LIGHTER REGION ON A SCAN.

Question 16

COMPUTERISED TOMOGRAPHY, WHAT DO THEY PRODUCE?

Answer 16

A SCAN PRODUCED THIS WAY, SHOWS PHYSICAL STRUCTURES OF THE BRAIN AND ALLOWS VISUALISATION OF ANY TISSUE DAMAGE.

FOR EXAMPLE, BLOOD IS LESS DENSE THAN BRAIN TISSUE, SO A CT SCAN CAN BE USED TO LOCATE DAMAGED BLOOD VESSELS AND AREAS OF BLEEDING, AFTER A PATIENT HAS HAD A STROKE.

Question 17

COMPUTERISED TECHNOLOGY, WHAT DO THEY NOT SHOW US?

Answer 17

THE SCANS, DO NOT DIRECTLY SHOW THE FUNCTIONS OF THE REGIONS OF THE BRAIN, BUT IT IS POSSIBLE TO LINK VISIBLE SYMPTOMS, WITH THE LOCATION OF THE TISSUE DAMAGE.

THIS CAN ALLOW NEUROLOGISTS, TO WORK OUT WHICH REGIONS OF THE BRAIN, ARE RESPONSIBLE, FOR WHICH FUNCTIONS.

Question 18

COMPUTERISED TECHNOLOGY, NOT RECOMMENDED.

Answer 18

CT SCANS, ARE NOT RECOMMENDED FOR PREGNANT PATIENTS, OR CHILDREN, DUE TO THE RISKS OF EXPOSURE TO THE X-RAY RADIATION, WHICH IS GIVEN AT A HIGHER LEVEL THAN IN A NORMAL X-RAY.

THE RISK OF DAMAGE, FROM SUCH SCANS IS STILL VERY LOW.

Question 19

MAGNETIC RESONANCE IMAGING.

Answer 19

MAGNETIC RESONANCE IMAGING, OR MRI, USES A COMBINATION OF A MAGNETIC FIELD AND RADIO WAVES, TO GENERATE IMAGES THROUGH THE BODY.

THE PATIENT BEING SCANNED, MUST REMAIN VERY STILL, WHILE INSIDE A LARGE MAGNET.

Question 20

MRI, SOFT TISSUE.

Answer 20

SOFT TISSUE, CAN BE SEEN CLEARLY USING MRI, AND IMAGES PRODUCED ARE AT A HIGHER RESOLUTION, THAN THOSE PRODUCED FROM CT SCANNING.

Question 21

MRI, USED FOR.

Answer 21

AS WITH CT SCANNING, MRI IS USEFUL, FOR IDENTIFYING AREAS OF ABNORMAL OR DAMAGED TISSUE, BUT ONLY ENABLES BRAIN FUNCTION TO BE ANALYSED BY LINKING DAMAGE ON A SCAN WITH VISIBLE SYMPTOMS IN A PATIENT.

MRI, IS ESPECIALLY USEFUL FOR TUMOR DIAGNOSIS, AS TUMORS SHOW UP CLEARLY IN IMAGES GENERATED THIS WAY.

MRI SCANS, CAN THEREFORE BE USED TO IDENTIFY AND LOCATE TUMORS IN THE BRAIN.

Question 22

MRI, COST.

Answer 22

MRI, SCANS ARE CONSIDERABLY MORE EXPENSIVE TO CARRY OUT THAN CT SCANS, BUT DO NOT CARRY THE RISK ASSOCIATED WITH THE USE OF POTENTIALLY HARMFUL X-RAYS.

Question 23

MRI, PRECAUTIONS.

Answer 23

THE MAGNETIC FIELD OF AN MRI SCANNER CAN INTEFERE WITH MEDICAL DEVICES, SUCH AS PEACEMAKERS AND INSULIN PUMPS, SO PATIENTS WITH SUCH DEVICES CANNOT HAVE MRI SCANS.

Question 24

FUNCTIONAL MRI.

Answer 24

FUNCTIONAL MRI, fMRI, FUNCTIONS IN A SIMILAR WAY TO MRI, MAKING USE OF A MAGNETIC FIELD AND RADIO WAVES TO GENERATE, IMAGES OF BRAIN STRUCTURE.

Question 25

MRI, AND fMRI DIFFERENCES.

Answer 25

THE DIFFERENCE BETWEEN MRI, AND fMRI, IS THAT fMRI SCANS, ALLOW BRAIN FUNCTION TO BE STUDIED IN REAL TIME.

fMRI SCANS, SHOW THE LOCATION OF OXYGENATED BLOOD IN THE BRAIN, THEREFORE INDICATING WHICH BRAIN REGIONS, ARE ACTIVE AT ONE TIME.

THE SCANNER MEASURES, THE RATIO OF OXYGENATED TO DEOXYGENATED HAEMOGLOBIN.

Question 26

fMRI, CHANGES IN BLOOD FLOW.

Answer 26

PATIENTS CAN BE ASKED TO CARRY OUT PARTICULAR ACTIONS, ANSWER QUESTIONS, OR THINK ABOUT A SPECIFIC TOPIC WHILE INSIDE A SCANNER AND THE CHANGE IN BLOOD FLOW TO REGIONS OF THE BRAIN CAN BE ASSESSED.

Question 27

POSITRON EMISSIONS TOMOGRAPHY.

Answer 27

PET SCANS, USE RADIOACTIVE TRACERS, WHICH COLLECT IN AREAS WHERE THERE IS INCREASED BLOOD FLOW, METABOLISM, OR NEUROTRANSMITTER ACTIVITY.

THE TRACER, IS INTRODUCED TO THE BLOOD IN ADVANCE OF THE SCAN SO THAT IT CAN BE DETECTED BY THE SCANNER.

THE SCANNER, CAN DETECT AREAS OF HIGH RADIOACTIVITY, AND SO THE MOVEMENT OF THE TRACER THROUGH THE BODY AND ANY ACCUMULATION OF TRACER IN THE BRAIN CAN BE SEEN.

THE AMOUNT OF RADIOACTIVE TRACER PRESENT IN THE BRAIN REGION, CAN INDICATE WHETHER THAT REGION IS ACTIVE OR INACTIVE.

THIS HAS BEEN USEFUL IN BUILIDING AN UNDERSTANDING OF SPECIFIC DISEASES SUCH AS ALZHIEMER’S, WHERE BRAIN ACTIVITY IN CERTAIN REGIONS DECREASES.

NEUROLOGISTS, CAN USE THE IMAGES TO STUDY THE STRUCUTURE AND FUNCTION OF THE BRAIN IN REAL TIME.

Question 28

THE VISUAL CORTEX, LOCATION.

Answer 28

THE VISUAL CORTEX, IS THE REGION OF THE CEREBRAL CORTEX, IN WHICH VISUAL INFORMATION IS PROCESSED.

THE CEREBRAL CORTEX, IS THE OUTER LAYER OF THE CEREBRUM.

Question 29

WHAT IS THE CEREBRAL CORTEX?

Answer 29

THE CEREBRAL CORTEX, IS THE OUTER LAYER OF THE CEREBRUM.

Question 30

THE VISUAL CORTEX, AFTER BIRTH.

Answer 30

SOON AFTER BITH, NEURONES IN THE VISUAL CORTEX OF BABY MAMMALS BEGIN TO FORM CONNECTIONS, OR SYNAPSES, ALLOWING VISUAL INFORMATION, TO BE TRANSFERRED THROUGH AND PROCESSED BY THE VISUAL CORTEX.

Question 31

THE ORGANISTION OF NEURONES, IN THE VISUAL CORTEX.

Answer 31

BOTH EYES NEED TO BE VISUALLY STIMULATED, IN ORDER FOR THE NEURONES IN THE VISUAL CORTEX, TO BE ORGANISED CORRECTLY DURING THIS PERIODS OF EARLY DEVELOPMENT, KNOWN THE CRITICAL PERIOD.

EVIDENCE FOR THIS CRITICAL PERIOD OF DEVELOPMENT, COMES FROM A STUDY USING ANIMAL MODELS, CARRIED OUT BY HUBEL AND WIESEL.

Question 32

THE STRENGTHENING OF THE SYNAPSES.

Answer 32

SYNAPSES, THAT PASS ON NERVE IMPULSES DURING THIS CRITICAL PERIOD ARE STRENGTHENED, AND BECOME PERMANENT PARTS OF THE STRUCTURE OF THE VISUAL CORTEX.

Question 33

SYANPSES, IMPULSES DURING THIS CRITICAL PERIOD.

Answer 33

SYNAPSES, THAT DO NOT RECEIVE NERVE IMPULSES DURING THIS CRITICAL PERIOD, ARE LOST, AND CANNOT BE RE-FORMED.

THIS CAN RESULT IN BLINDESS IN OR BOTH EYE, IF VISUAL STIMULATION IS NOT PROVIDED, DURING THE CRITICAL PERIOD.

Question 34

ANIMALS SURVIVAL, DEPENDANT ON.

Answer 34

ANIMALS MUST RESPOND TO CHANGES, IN THEIR EXTERNAL AND INTERNAL ENVIRONMENT, IN ORDER TO SURVIVE.

CHANGES IN THE ENVIRONMENT, OR STIMULI, SINGULAR STIMULUS, ARE DETECTED BY SPECIALISED RECEPTOR CELLS.

RECEPTORS, SEND SIGNALS, VIA THE NERVOUS SYSTEM OR THE HORMONAL SYSTEM, TO THE BODY’S CO-ORDINATION CENTRES, IN THE BRAIN OR THE SPINAL CORD.

SIGNALS, ARE THEN SENT ON TO THE PARTS OF THE BODY WHICH REDSPOND, KNOWN AS THE EFFECTORS.

Question 35

DETECTING AND RESPONDING TO STIMULI, ENERGY.

Answer 35

THE PROCESS OF DETECTING AND RESPONDING TO STIMULI, REQUIRES ENERGY, SO IT IS IMPORTANT THAT ANIMALS, DO NOT WASTE ENERGY RESPONDING TO NON-THREATENING STIMULI.

ANIMALS NEED TO CONSERVE ENERYG FOR ESSENTIAL PROCESSES, THAT INCREASE THEIR SURVIVAL CHANCES.

Question 36

HABITUATION.

Answer 36

IF A STIMULUS, IS REPEATED MANY TIMES WITH NO NEGATIVE OUTCOME, THEN AN ANIMAL WILL LEARN NOT TO RESPOND TO IT.

THIS PROCESS IS KNOWN AS HABITUATION.

AN ANIMAL THAT DOES NOT RESPOND, TO A STIMULUS, IS SAID TO BE HABITUATED, TO THAT STIMULUS.

Question 37

CHANGES TO A HABITUATED STIMULUS.

Answer 37

IF A STIMULUS TO WHICH AN ANIMAL HAS BECOME HABITUATED CHANGES, THEN THE NERVOUS SYSTEM WILL RESPOND TO IT AGAIN.

FOR EXAMPLE, A CONSTANT LOW-LEVEL SOUND THAT SUDDENLY BECOMES LOUDER.

Question 38

THE PROCESS OF HABITUATION.

Answer 38

ANIMALS BECOME HABITUATED, DUE TO CHANGES IN THE TRANSMISSION OF NERVE IMPULSES FROM ONE NEURONE TO THE NEXT.

NERVE IMPULSES, ARE TRANSMITTED ACROSS SYNAPSES BY THE DIFFUSION OF CHEMICAL NEUROTRANSMITTERS.

NEUROTRANSMITTERS, ARE RELEASED AT THE PRESYNAPTIC MEMBRANE, IN RESPONSE TO AN INFLUX OF CALCIUM IONS.

WHEN HABITUATION TAKES PLACE, FEWER CALCIUM IONS MOVE INTO THE PRESYNAPTIC NEURONE ON ARIVAL OF A NERVE IMPULSE.

AS A RESULT:

LESS NEUROTRANSITTER IS RELEASED AND AN ACTION POTENTIAL IS LESS LIKELY TO BE GENERATED IN THE POSTSYNAPTIC NEURONES.

FEWER MOLECULES OF NEUROTRASNSMITTER, BIND TO RECEPTORS ON THE POSTSYNAPTIC MEMBRANE.

FEWER SODIOUM ION CHANNELS OPEN.

FEWER SODIUM IONS MOVE INTO THE AXON, AND THE CHARGE INSIDE THE AXON REMAINS NEGATIVE.

THRESHOLD POTENTIAL IS NOT REACHED.

THE NERVE IMPULSE, THEREFORE DOES NOT REACH THE EFFECTOR ORGAN, AND THE ANIMAL DOES NOT RESPOND TO THE STIMULUS.

Question 39

NEUROTRANSMITTERS.

Answer 39

NEUROTRANSMITTERS, ARE CHEMICALS THAT TRANSMIT NERVE IMPULSES ACROSS SYNAPSES.

Question 40

NEUROTRANSMITTER IMBALANCE.

Answer 40

SOME DISORDERS AND DISEASES, ARE LINKED TO AN IMBALANCE OF NEUROTRANSMITTERS IN THE BRAIN.

TWO,2, EXAMPLES ARE:
PARKINSON’S DISEASE
AND DEPRESSION.

Question 41

PARKINSONS’S DISEASE.

Answer 41

PARKINSON’S DISEASE, IS A BRAIN DISORDER THAT AFFECTS THE CO-ORDINATION OF MOVEMENT, CAUSED BY THE LOSS OF NEURONES IN SOME PARTS OF THE BRAIN.

Question 42

PARKINSON’S DISEASE, SYMPTOMS.

Answer 42

SYMPTOMS INCLUDE:

A TREMOR TO THE SPECIFIC PARTS OF THE BODY,

SLOW MOVEMENT,

STIFF AND INFLEXIBLE MUSCLES,

DIFFICULTIES WITH BALANCE,

AND CHANGES TO SPEECH.

Question 43

PARKINSON’S DISEASE, CAUSES.

Answer 43

INDIVIDUALS THAT SUFFER FROM PARKINSON’S DISEASE, PRODUCE INSIGNIFICANT AMOUNTS OF DOPAMINE, DUE TO THE LOSS OF DOPAMINE PRODUCING NEURONES.

LESS DOPAMINE IS RELEASED INTO THE SYNAPTIC CLEFT, MEANING LESS IS ABLE TO BIND WITH RECEPTORS ON THE POSTSYNAPTIC MEMBRANE.

FEWER, SODIUM CHANNELS ON THE MEMEBRANE ARE OPENED, SO DEPOLARISATION OF THE POSTSYNAPTIC NEUROEN DOES NOT OCCUR.

THIS LEADS TO FEWER ACTION POTENTIALS, WHICH CREATES THE SYMPTOM, SUCH AS TREMORS AND SLOW MOVEMENT.

Question 44

DOPAMINE.

Answer 44

THE LOST NEURONES, NORMALLY PRODUCE THE NEUROTRANSMITTER DOPAMINE.

DOPAMINE, IS INVOLVED IN MUSCLE CONTROL.

Question 45

DOPAMINE AGONISTS.

Answer 45

PRODUCE THE SAME EFFECT AS DOPAMINE, BY BINDING TO AND ACTIVATING THE DOPAMINE RECEPTORS ON THE POSTSYNAPTIC MEMBRANE.

Question 46

DOPAMINE PRECURSORS.

Answer 46

THESE ARE CHEMICALS THAT CAN BE CONVERTED INTO DOPAMINE THE NEURONES.

SUCH AS, L-dopa.

Question 47

ENZYME INHIBITORS.

Answer 47

MONOAMINE OXIDASE B, MAOB, INHIBITORS INHIBIT, THE ACTIVITY OF ENZYMES THAT WOULD NORMALLY BREAK DOWN DOPAMINE THE SYNAPTIC CLEFT, RAISING LEVELS OF DOPAMINE PRESENT IN THE BRAIN.

Question 48

GENE THERAPY.

Answer 48

THIS WOULD INVOLVE THE ADDITION OF GENES TO THE AFFECTED CELLS IN THE BRAIN, TO EITHER INCREASE DOPAMINE PRODUCTION OR PREVENT THE DESTRUCTION OF DOPAMINE-PRODUCING CELLS.

Question 49

STEM CELL THERAPY.

Answer 49

STEM CELLS COULD BE USED TO REPLACE THE LOST DOPAMONE-PRODUCING CELLS IN THE BRAIN.

Question 50

DEPRESSION.

Answer 50

LOW LEVELS OF THE NEUROTRANSMITTER SERETONIN.

SERETONIN, TRANSMITS NERVE IMPULSES, THROUGH AREAS OF THE BRAIN THAT CONTROL MOOD.

LOW LEVELS OF SERETONIN, INCREASE EPISODES OF DEPRESSION.

Question 51

WHAT CAN THE CHEMICALS IN DRUGS IMPACT?

Answer 51

THE CHEMICALS IN DRUGS, CAN HAVE A MAJOR IMPACT ON THE FUNCTIONING OF THE BRAIN, AND THE NERVOUS SYSTEM.

Question 52

PESCRIPTION DRUGS, V.S RECREATIONAL DRUGS, EFFECT.

Answer 52

SOME PESCRIPTION DRUGS, CAN HAVE A BENEFICIAL EFFFECT, ON THOSE SUFFERING FROM NEUROLOGICAL DISORDERS.

WHILE RCREATIONAL DRUGS CAN HAVE A DAMAGING, OR EVEN FATAL EFFECT.

Question 53

WHAT DO MANY DRUGS IMPACT, AND HOW?

Answer 53

MANY DRUGS IMPACT THE NERVOUS SYSTEM, BY ALTERING THE EVENTS THAT OCCUR AT A SYNAPSE.

Question 54

DRUGS, INCREASE TRANSMISSION.

Answer 54

DRUGS CAN INCREASE TRANSMISSION OF IMPULSES AT A SYNAPSE BY:

CAUSING MORE NEUROTRANSMITTER TO BE PRODUCED IN THE SYNAPTIC KNOB,

CAUSING MORE NEUROTRANSMITTER, TO BE RELEASED AT THE PRESYNAPTIC MEMBRANE,

IMITATING THE EFFECT OF A NEUROTRANSMITTER, BY BINDING TO AND ACTIVIATING RECEPTOR, ON THE POSTSYNAPTIC MEMBRANE,

PREVENTING BREAKDOWN OF NEUROTRANSMITTERS BY ENZYMES,

PREVENTING THE REUPTAKE OF NEUROTRANSMITTERS, BY THE PRESYNAPTIC CELL.

Question 55

DRUGS, DECREASE TRANSMISSION.

Answer 55

PREVENTING PRODUCTION OF NEUROTRANSMITTER IN THE PRESYNAPTIC KNOB,

PREVENTING THE RELEASE, OF NEUROTRANSMITTER, AT THE PRESYNAPTIC MEMBRANE,

ENABLING NEUROTRANSMITTER, TO GRADUALLY LEAK OUT OF THE PRESYNAPTIC KNOB, SO THERE IS LITTLE LEFT WHEN AN ACTION POTENTIAL ARRIVES.
THE NEUROTRANSMITTER THAT LEAKS OUT OF THE CELL, IS DESTROYED BY ENZYMES.

BINDING TO RECEPTORS ON THE POSTYSYNAPTIC MEMBRANE, AND SO PREVENTING NEUROTRANSMITTERS FROM BINDING.

Question 56

WHAT IS MDMA?

Answer 56

MDMA, IS A RECREATIONAL DRUG THAT IS ALSO KNOWN AS ECSTASY.

Question 57

MDMA, USE AND SALE.

Answer 57

ITS USE AND SALE ARE CRIMINAL OFFENCES IN MOST PARTS OF THE WORLD.

Question 58

MDMA EFFECT, NEUROTRANSMITTERS.

Answer 58

MDMA EFFECTS MULTIPLE NEUROTRANSMITTERS, MOST NOTABLY SERETONIN,

MDMA INHIBITS THE REUPTAKE OF SERETONIN INTO THE PRESYNAPTIC NEURONE, BY BINDING TO THE SPECIFIC PROTIENS THAT ENABLE SERETONIN REUPTAKE, LOCATED ON THE PRESYNAPTIC MEMBRANE, THIS INCREASES THE AMOUNT OF SERETONIN PRESENT IN THE BRAIN.

SERETONIN IS USUALLY REABSORBED INTO THE PRESYNAPTIC NEURONE, TO BE RECYCLED FOR FUTURE ACTION POTENTIALS.

MDMA, ALSO TRIGGERS THE RELEASE OF FURTHER SERETONIN FROM THE PRESYNAPTIC NEURONES, FURTHER ADDING TO THE INCREASE.

Question 59

WHAT CAN SERETONIN AFFECT?

Answer 59

SERETONIN, CAN AFFECT PEOPLE IN MANY WAYS INCLUDING THEIR MOOD, ANXIETY AND SLEEP.

Question 60

MDMA, SYMPTOMS.

Answer 60

WHEN AN INDIVIDUAL TAKES MDA, THEY MAY FEELE XTREME EUPHORIA, AND ENHANCED TOUCH AND BODILY SENSATIONS.

Question 61

L-DOPA, USED FOR.

Answer 61

L-DOPA, IS A DRUG USED TO TREAT THE SYMPTOMS OF PARKINSON’S DISEASE.

Question 62

L-DOPA STRUCTURE.

Answer 62

IT HAS A VERY SIMILAR STRUCTURE TO DOPAMINE, A NEUROTRANSMITTER PRESENT AT LOWER LEVELS THAN USUAL IN THE BRAINS OF THOSE WHO SUFFER FROM PARKINSON’S DISEASE.

Question 63

L-DOPA, FUNCTION.

Answer 63

L-DOPA, IS TRANSPORTED FROM THE BLOOD, INTO THE BRAIN, WHERE IT IS CONVERTED INTO DOPAMINE, IN A REACTION CATALYSED BY THE ENZYME, DOPA-DECARBOXYLASE.

THE EFFECT IS TO INCREASE LEVELS OF DOPAMINE IN THE BRAIN.

INCREASED LEVELS OF DOPAMIE, MEAN THAT MORE NERVE IMPULSES ARE TRANSMITTED INPARTS OF THE BRAIN THAT CONTROL MOVEMENT, GIVING SUFFERES BETTER CONTROL OVER THEIR MOVEMENT AND LESSENING THE SYMPTOMS OF PARKINSON’S DISEASE.

Question 64

WHY CAN DOPAMINE NOT BE GIVEN DIRECTLY TO THOSE, WHO HAVE PARKINSON’S DISEASE?

Answer 64

IT CANNOT CROSS THE BARRIER BETWEEN THE BLOOD AND THE BRAIN.

Question 65

WHAT IS PERSONALISED MEDICINE?

Answer 65

PERSONALISED MEDICINE INVOLES THE DEVELOPMENT OF TARGETED DRUGS, TO TREAT A VARIETY OF HUMAN DISEASES IN INDIVIDUALS WITH DIFFERENT GENOTYPES.

Question 66

PERSONALISED MEDICINE, TESTING.

Answer 66

SUCH DRUGS, CAN BE TESTED ON SYNTHETIC TISSUES; GROUPS OF CELLS CULTURES IN A LAB THAT ARE GENETICALLY IDENTICAL TO CERTAIN GROUPS OF PATIENTS.

Question 67

GENOMIC MEDICINE.

Answer 67

INFORMATION GATHERED FROM GENOME PROJECTS, LIKE THE HUMAN GENOME PROJECT, HGP, CAN BE USED TO DEVELOP GENOMIC MEDICINE, WHICH USES INFORMATION ABOUT THE GENES TO DESIGN MEDICAL TREATMENTS.

Question 68

THE HUMAN GENOME PROJECT, HGP.

Answer 68

THE HUMAN GENOME PROJECT, HGP, INVOLVED SEQUENCING THE ENTIRE HUMAN GENOME.

THE INFOMRATION GAINED FROM THE HGP, IS STORED IN DATABASES, WITHIN WHICH GENES THAT CODE FOR CERTAIN PROTIENS CAN BE FOUND AND ANALYSED.

KNOWING THE SEQUENCE AND STRCUTURE OF PROTIENS INVOLVED IN DISEASES, ALLOWS THE DEVELOPMENT OF DRUGS THAT TARGET SPECIFIC PROTIENS.

FOR EXMAPLE, IF AN ENZYME IS INVOLVED WITH DISEASE, A DRUG THAT ACTS AS AN ENZYME INHIBITOR CAN BE DEVELOPED.

Question 69

GENOME.

Answer 69

THE COMPLETE SET OF GENETIC MATERIALS, PRESENT IN A CELL OR AN ORGANISM.

Question 70

GENETIC SCREENING.

Answer 70

GENETIC SCREENING ALLOWS INDIVIDUALS WITH A HIGH CHANCE OF DEVELOPING SPECIFIC DISEASES, TO BE IDNETIFIED, AND MEANS THAT PREVENTATIVE MEASURES CAN BE TAKEN.

Question 71

WHAT IS A GMO?

Answer 71

A GMO, IS A GENETICALLY MODIFIED ORGANISM.

Question 72

GENETIC ENGINEERING.

Answer 72

GENETIC ENGINEERING, IS A TECHNIQUE USED TO DELIBERATELY MODIFY A SPECIFIC CHARACTERISTIC OF AN ORGANISM.

THE TECHNIQUE INVOLVES, REMOVING A GENE THAT CODES FOR A DESIRED CHARACTERISTIC FROM ONE ORGANISM, AND TRANSFERRING THE GENE INTO ANOTHER ORGANISM, WHERE THE DESIRED GENE IS THEN EXPRESSED.

Question 73

THE DNA, IN A GENETICALLY ENGINEERED ORGANISM.

Answer 73

THE GENETICALLY ENGINEERED ORGANISM, IS SAID TO CONTAIN RECOMBINANT DNA, AND WILL BE A GENETICALLY MODIFIED ORGANISM, GMO.

Question 74

GENTICALL ENGINEERING, MEDICINE.

Answer 74

MICRO-ORGANISMS, PLANTS AND ANIMALS HAVE BEEN GENETICALLY ENGINEERED TO PRODUCE PROTIENS, USED IN MEDICINE.

Question 75

RESTRICTION ENZYMES.

Answer 75

RESTRICTION ENZYMES, ARE USED TO REMOVE THE GENE CODING FOR A DESIRED PROTIEN FROM AN ORGANISM’S GENOME.

THE PROTIEN CODED FOR HERE, WILL BE RESPONSIBLE FOR THE CHARACTERISTIC DESIRED IN THE GENEITCALLY MODIFIED ORGANISM, GMO.

SUCH AS THE ABILITY TO PRODUCE INSULIN.

MANY COPIES OF THE GENE ARE MADE USING THE POLYMERASE CHAIN REACTION, PCR.

THE ENZYME DNA POLYMERASE, IS USED TO JOIN FREE NUCLEOTIDES INTO NEW STRANDS OF DNA, THAT ARE COMPLIMENTARY TO THE ORIGINAL STRAND.

THESE COPIES ARE INSERTED INTO SMALL LOOPS OF DNA, CALLED PLASMIDS, WHICH THEN TRANSFER THE COPIES INTO MICRO-ORGANISMS.

THE PLASMIDS ARE SAID TO BE DNA VECTORS.
THE ENZYME DNA LIGASE, CATALYSES THE JOINING OF THE DESIRED GENE TO THE PLASMID VECTORS.

Question 76

GENETICALLY MODIFIED-ORGANISMS, WHERE ARE THEY GROWN?

Answer 76

THE GENETICALLY MODIFIED ORGANISMS, ARE GROWN IN LARGE FERMENTORS CONTAINING NUTRIENTS, ENABLING THEM TO MULTIPLY AND PRODUCE LARGE QUANTITIES OF THE NEW PROTIEN.

THE PROTIEN CAN BE ISOLATED, AND PURIFIED, BEFORE BEING PACKAGED AND DISTRIBUTED.
HUMAN INSULIN AND HUMAN BLOOD CLOTTING FACTORS, ARE EXAMPLES OF MEDICINAL PROTIENS PRODUCED BY GENETICALLY MODIFIED BACTERIA.

Question 77

GENETICALLY MODIFIED PLANTS.

Answer 77

A PROCESS USED TO INSERT, DESIRED GENES FROM OTHER ORGANISMS, INTO PLANT CELLS.

Question 78

GENETICALLY MODIFIED PLANTS, THE PROCESS.

Answer 78

AFTER THE GENE IS INSERTED INTO A PLASMID, AND THEN TRANSFERRED TO A BACTERIAL CELL, THE BACTERIA CAN BE USED TO INFECT PLANTS; THAT BACTERIUM ACTS AS A VECTOR FOR INTRODUCING THE GENE INTO THE PLANT DNA.

THE GENE IS TRANSFERRED, FROM THE BACTERIA CELL, INTO THE PLANT NUCLEUS, AFTER WHICH THE PLANT CELL IS STIMULATED TO MULTIPLY AND GROW INTO AN ADULT PLANT.

EACH CELL OF THE PLANT CONTAINS A COPY, OF THE GENE CODING FOR THE DESIRED PROTIEN.

THE PROTIEN CAN NOW BE PURIFIED FROM THE PLANT TISSUE, OR THE PLANT CAN BE EATEN TO DELIVER THE DRUG.

HUMAN INSULIN, AND A CHOLERA VACCIEN ARE EXAMPLES OF DRUGS PRODUCED BY MODIFIED PLANTS.

Question 79

GENE GUN.

Answer 79

TINY PELLETS, ARE COATED WITH THE DESIRED DNA, AND THEN FIRED INTO THE PLANT CELLS.

Question 80

GENETICALLY MODIFIED ANIMALS.

Answer 80

THE GENE THAT CODES FOR THE DESIRED PROTIEN, IS INJECTED INTO THE NUCLEUS OF A ZYGOTE.

THE ZYGOTE, IS IMPLANTED INTO THE UTERUS OF A SURROGATE ANIMAL, WHERE IT DEVELOPS INTO AN ADULT ANIMAL.

EVERY CELL, OF THIS GENTICALLY MODIFIED ANIMAL, WILL CONTAIN A COPY OF THE GENE CODING FOR THE DESIRED PROTIEN.

THE PROTIEN CAN BE PURIFIED, FOR EXAMPLE THE MILK OF THE ANIMAL.
HUMAN CLOTTING PROTIENS, CAN BE PRODUCED FROM THE MILK OF GENETICALLY MODIFIED ANIMALS.

Question 81

BRAIN DEVLOPMENT.

Answer 81

BRAIN DEVELOPMENT, REFERS TO THE GROWTH OF THE BRAIN, AND THE FORMATION OF CONNECTIONS, BETWEEN NEURONES, OR NEURAL PATHWAYS.

Question 82

FACTORS, THAT CAN BE MEASURED TO DETERMINE BRAIN DEVELOPMENT.

Answer 82

THERE ARE A NUMBER OF FACTORS, THAT CAN BE MEASURED TO DETERMINE BRAIN DEVELOPMENT;

BRAIN DEVELOPMENT,
NUMBER OF NEURONES,
AND THE LEVEL AT WHICH THE BRAIN IS FUNCTIONING.

Question 83

WHAT IS BRAIN DEVELOPMENT, INFLUENCED BY?

Answer 83

BRAIN DEVELOPMENT, IS INFLUENCED BY BOTH GENETIC, AND ENVIRONMENTAL FACTORS.

Question 84

THE IMPACT OF GENETIC FACTORS AND ENVIRONMENTAL FACTORS.

Answer 84

THE IMPACT OF GENETIC FACTORS, CAN BE REFFERED TO AS THE IMPACT OF ‘NATURE”, ON DEVELOPMENT.

WHILE THE IMPACT OF ENVIRONMENTAL FACTORS, CAN BE REFFERED TO THAT OF ‘NURTURE”.

Question 85

DETERMING, IF NATURE OR NURTURE, HAS THE GREATEST INFLUENCE ON BRAIN DEVELOPMENT.

Answer 85

IT IS VERY DIFFICULT TO DETERMINE, WHICH OF NATURE OR NURTURE HAS THE GREATEST IMPACT ON BRAIN DEVELOPMENT.

THIS IS BECAUSE THE GENES AND THE ENVIRONMENT, OF AN ORGANISM INTERACT WITH EACH OTHER, AND IT IS DIFFICULT TO SEPARATE OUT THE IMPACTS OF EACH.

A SCIENTIST, WOULD HAVE TO COMPLETLY REMOVE THE INFLUENCE OF ONE OF THE FACTORS, IN ORDER TO INVESTIGATE THE OTHER; AN ALMOST IMPOSSIBLE TASK.

THERE ARE MANY DIFFERENT GENES, AND ENVIRONMENTAL FACTORS TO INVESTIGATE.