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    (Original post by Remarqable M)
    ok lets get started:

    1) why are sensory neurones called transducers and why is this important?

    2) Brief explain how neurones generate an nerve impulses.

    3) state 3 things that make a nearone specialised to carry nerve impulses.

    4) what is meant by the resting potential of a membrane and explain how this is maintained.

    5) the state value of the resting potential of a typical membrane.

    6) Describe and explain how an action potential is generated.

    7) briefly explain the important of myelin sheat( mention only 3 points)

    8) Is the diffusion of ions associated with action potential diffusion or active?

    9) List the main structure of a cholinergic synapse.

    10) Describe how an action potential is transmitted across a synapse( typical 7 mark question give only 7 points - picture yourself the synapse)

    11) what is the role of the enzyme acetylcholinesterase?

    12) what is meant by all-or nothing.

    13) what is meant by summation.

    answer all these question by 9:45

    1) they convert any change in energy detected, into electrical energy. this is important so they can be sent along the nervous system.

    2) Sodium ions enter neurone membrane down diffusion gradient. Threshold potential is reached - 50mV then voltage gated sodium ions open and sodium ions enter. pd reaches +40mV. They close, potassium ion channels open, they leave - depolarisation. overshoots, hyperpolarisation. Restored by pumps during refractory period.

    3) Many mitochondria for ATP of pumps and vesicles.
    Cell body has ribosomes to make proteins.
    Long axon to send impulses across the body.

    4) REsting pot is when Na+/k+ pumps actively transport 3 sodium ions out of the neurone membrane for every 2 that enter. some potassium ions leave so overall neg. compared to outside. it is -60mV at rest.

    5) -60mV

    6) Accidently answered it on prev question.

    7) Mylein sheath protects and insulates axon from other electrical activity. It speeds up rate of conduction as it allows saltatory conduction, gaps where schwann cells meet are nodes of ranvier, the sodium ions enter here via channels allowing node to node movement of action potentials.

    8) Diffusion..i think.

    9) Presynaptic nuerone: calcium ions - voltage gated, vesicles with Ach, mitochondria for exocytosis. postsynaptic complementary receptors on sodium ion channels for AcH. sodium enter, action pot generated.

    10) action arrives at pre, calcium ion channels open, vesicles fuse with membrane, release AcH by exo, diffuses across cleft, binds to complemetary receptor sites on sodium ion channels, sodium enter, threshold reached, action potential generated.

    11( break down AcH so does not continue to generate action potential. Recylcles it.

    12) same magnitude, either generated or not. travels all the way along a neurone.

    13) amplification of low level signals, constantly send vesicles to release ach, eventually action potential is reached.

    sorry for spelling errors and rushyness lol
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    1) why are sensory neurones called transducers and why is this important?

    They can change energy to electrical energy. Any stimulus provides energy, which sensory neurones can convert to electrical energy to start an action potential, and send a signal to the CNS.

    2) Brief explain how neurones generate an nerve impulses.

    NA-K pumps 3 na ion out of cell and 2k ions in, against their conc.gradient. It is polarized what the inside is -60mv compared to the outside. Local currents cause generator potentials, which might be enough for an action potential at -50mv. It it i, an action potential or impulse is generate and sent along the neurone.


    Depolarisation - VG NA channels open and flood in. When it reaches +40 mv, they shut and potassium ion channels open - repolarisation. Hyper polarisation is when it over shoots and then NA-K pumps work again to achieve resting potential

    (Not sure if its right)

    3) state 3 things that make a nearone specialised to carry nerve impulses.

    It has long dendron/axon to carry the nerve impulse over a long distance. Have synaptic knobs which mean it can only go in one direction. Myelinated sheath means that nerve impulse dont interfere with each other and transmission faster.

    4) what is meant by the resting potential of a membrane and explain how this is maintained.

    NA-K pumps again conc gradient. When -60mv is reached, it is maintained by leaky K ion and Na channels? Also Na-K continually pump.

    5) the state value of the resting potential of a typical membrane.

    -60mv

    6) Describe and explain how an action potential is generated.

    See 2?

    7) briefly explain the important of myelin sheat( mention only 3 points)

    Saltatory conduction makes it faster
    Stops interference with other neurones
    -something else?

    8) Is the diffusion of ions associated with action potential diffusion or active?

    Diffusion

    9) List the main structure of a cholinergic synapse.

    Vesicles with Ach, VG Ca2+ ions, Mitochondira...

    10) Describe how an action potential is transmitted across a synapse( typical 7 mark question give only 7 points - picture yourself the synapse)

    AP arrive, which opens CA2+
    Calcium floods in
    makes vesicles fuse to presynaptic membrane
    ACH is released. Diffusion across cleft.
    ACH combines with receptors to open sodium gate.
    sodium flows into post synaptic membrane.
    AP generate is large enough


    11) what is the role of the enzyme acetylcholinesterase?

    Break down Ach so an action potential doesnt ocur. Can recyle the Ach (broken in ethanoic acid and choline) into presynaptic know vesicles.

    12) what is meant by all-or nothing.

    Either an action potential is generated or not. It is doesnt meet the threshold level, an action potential wont occur. If it does, its magnitude doesnt change and it travels all the way across the neurone.

    13) what is meant by summation.

    Amplification of low level signals to generate AP

    Temporal is many to 1 while spacial is 1 to 1, but the frequency is enough to generate one

    answer all these question by 9:45

    I need help!?!?!?
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    1) they tranform one form of energy to electrical impulse. The brain can only intepret information in the form of nerve impulses.

    2) Sodium channels open and sodium ions rushes into the cytoplasm of axon(depolarisation)
    Sodium ion channels open only when the generator potential is greater than the threshold potential of the cell which is usually -60mV
    at -60mV sodium channels close and potessium channels open(repolarisation)
    Once an nerve impulse is created another cannot be created due to refractory period.
    hyperpolarisation and the resting potential value of the cell is restored by sodium/K pumps.

    3) Sodium/K pump/ sodium ion channels and potassium channels

    4) Resting potential is the potential difference of a cell membrane when there is no action potential stimulated. It is usually -60mV and created and maintained by sodium/K pumps
    for every 2 potassium pumped out 3 sodium ions are actively pumped in.
    5) -60mV

    6)Action potential is generated when the potential difference of a cell suface membrane of a neurone depolarises to -60mV. During depolarisation sodium ion channels open - sodium ion diffuses into the neurone and influx of sodium ions upsets
    the balance of the potential difference of the neurone inside the cell. This results in a chain reaction in which one opening of one sodium channels causes further opening of the many sodium channels on the membrane.
    It's all or nothing. At -60mV the sodium ion channels and potassium channels open - K ions diffuse out of the cells. This is called repolarisation. When the repolarisation is finish a slight overshoot causes hyperpolarisation and the
    balance of ionic concentrations is quickly restored by sodium/potassium pumps.

    7) 1) faster transmission of nerve impulses 2) node of ranvier 3)

    8) Diffusion

    9)a synaptic knob which contains vesicles containing acetylcholine molecules and numerous mitochondria, synaptic cleft, calcium ion channels and pre-synaptic membrane.

    10) An action potential arrives at the synaptic knob and stimulates calcium ion channels to open - calcium ions diffuse into the synaptic knob.
    Calcium ions causes vesicles containing acetycholine molecules to fuse with the pre-synaptic membrane and the vesicles leace the pre-synaptic membrane by exocytosis


    aaah time is up lol
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    Guys well done! now i will give you some time to look over your answerr and correct it
    go revise what you didn't answer properly.

    Once you understand everything we'll proceed to the next module and because we have no time
    we need to vote:

    anyone who wants to carry on to do endocrine system say aye
    and those who don't want to carry on to endocrine but to
    the next module(excetion) say nye!
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    (Original post by Remarqable M)
    Guys well done! now i will give you some time to look over your answerr and correct it
    go revise what you didn't answer properly.

    Once you understand everything we'll proceed to the next module and because we have no time
    we need to vote:

    anyone who wants to carry on to do endocrine system say aye
    and those who don't want to carry on to endocrine but to
    the next module(excetion) say nye!
    Nyee.

    I think Im alright at endocrine. :p:
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    ok i will start on module 2 excretion at 10am.

    ok revise and recap excretion for 10min!
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    Ooo I'm joining in on this
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    Ive done liver, but not kidneys yet.
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    (Original post by Tinkerbelle ♥)
    Ooo I'm joining in on this
    Morning! :yep:
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    (Original post by Chunkeymonkey62)
    Morning! :yep:
    I overslept
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    (Original post by Chunkeymonkey62)
    1) why are sensory neurones called transducers and why is this important?

    They can change energy to electrical energy. Any stimulus provides energy, which sensory neurones can convert to electrical energy to start an action potential, and send a signal to the CNS.

    2) Brief explain how neurones generate an nerve impulses.

    NA-K pumps 3 na ion out of cell and 2k ions in, against their conc.gradient. It is polarized what the inside is -60mv compared to the outside. Local currents cause generator potentials, which might be enough for an action potential at -50mv. It it i, an action potential or impulse is generate and sent along the neurone.


    Depolarisation - VG NA channels open and flood in. When it reaches +40 mv, they shut and potassium ion channels open - repolarisation. Hyper polarisation is when it over shoots and then NA-K pumps work again to achieve resting potential

    (Not sure if its right)

    3) state 3 things that make a nearone specialised to carry nerve impulses.

    It has long dendron/axon to carry the nerve impulse over a long distance. Have synaptic knobs which mean it can only go in one direction. Myelinated sheath means that nerve impulse dont interfere with each other and transmission faster.

    4) what is meant by the resting potential of a membrane and explain how this is maintained.

    NA-K pumps again conc gradient. When -60mv is reached, it is maintained by leaky K ion and Na channels? Also Na-K continually pump.

    5) the state value of the resting potential of a typical membrane.

    -60mv

    6) Describe and explain how an action potential is generated.

    See 2?

    7) briefly explain the important of myelin sheat( mention only 3 points)

    Saltatory conduction makes it faster
    Stops interference with other neurones
    -something else?

    8) Is the diffusion of ions associated with action potential diffusion or active?

    Diffusion

    9) List the main structure of a cholinergic synapse.

    Vesicles with Ach, VG Ca2+ ions, Mitochondira...

    10) Describe how an action potential is transmitted across a synapse( typical 7 mark question give only 7 points - picture yourself the synapse)

    AP arrive, which opens CA2+
    Calcium floods in
    makes vesicles fuse to presynaptic membrane
    ACH is released. Diffusion across cleft.
    ACH combines with receptors to open sodium gate.
    sodium flows into post synaptic membrane.
    AP generate is large enough


    11) what is the role of the enzyme acetylcholinesterase?

    Break down Ach so an action potential doesnt ocur. Can recyle the Ach (broken in ethanoic acid and choline) into presynaptic know vesicles.

    12) what is meant by all-or nothing.

    Either an action potential is generated or not. It is doesnt meet the threshold level, an action potential wont occur. If it does, its magnitude doesnt change and it travels all the way across the neurone.

    13) what is meant by summation.

    Amplification of low level signals to generate AP

    Temporal is many to 1 while spacial is 1 to 1, but the frequency is enough to generate one

    answer all these question by 9:45

    I need help!?!?!?
    You made a mistake, summation does consist of spatial/temporal summation but its the other way round. temp-1 to 1, while spatial is when many Presynaptic neurones come to one post synaptic neurone
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    (Original post by Tinkerbelle ♥)
    I overslept


    Oh Well. You up now and have plenty of time to revise with us! :p:
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    (Original post by mohamed aden)
    You made a mistake, summation does consist of spatial/temporal summation but its the other way round. temp-1 to 1, while spatial is when many Presynaptic neurones come to one post synaptic neurone
    Ha! Thanks

    Need to go over the myelin/summation page later.
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    I'm off guys, good luck for your exam.
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    (Original post by Chunkeymonkey62)


    Oh Well. You up now and have plenty of time to revise with us! :p:
    I know. Always looking on the bright side lol
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    I do hope this exam is easy
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    1) Outline the blood flow to and from the liver. (5mark)

    2) Briefly describe the arrangement of the hepatocytes in the liver.

    3) Along which special chamber does the branches of hepatic artery and hepatic portal vein mix?

    4) what is function of kupffer cells?

    5) List the functions of the liver.

    6) What is the purpose of deamination of Amino acids in the liver and why is it important.

    7)What is the name of the organic compound that enters the krebs cycle?

    8) summarise the ornithine cycle.

    9) Summarise the structure of the kidneys.

    10) What does the nephron consist of?

    11) How does the composition of the fluid in nephron change?

    12) why is the afferent arteriole larger in diameter than efferent arteriole?

    13) Describe and Explain unltrafiltration

    14) Describe and explain selective reabsorption

    15) What is the overall effect of the countercurrent multiplier?

    16) In the ascending limb what causes high water potential in the limb?

    17) what is role of the kidney in osmoregulation?

    18) Briefly outline the advantages and the disadvantages of kidney transplant.

    you have until 10:45 to answer all these questions!
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    (Original post by Tinkerbelle ♥)
    I know. Always looking on the bright side lol
    :yep:

    Like Wednesday evening. All exams are over.
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    1) Outline the blood flow to and from the liver.

    Hepatic Vein takes deoxygenated blood to the vena cava and to the heart.

    Hepatic portal vein comes from the intestine and mies with oxgenated blood from the haptic artety. The HPV blood contains many digested products which may need to be metabolised.

    2) Briefly describe the arrangement of the hepatocytes in the liver.

    They are in a sinusoid, so have maxumum exposure to the blood supply. There are many liver cells in the lining of each sinusoid, as well as the bile canaliculus.

    3) Along which special chamber does the branches of hepatic artery and hepatic portal vein mix?

    Sinusoid

    4) what is function of kupffer cells?

    To break down old red blood cells. A by product of the break down of Haemoglobin is bilirubin - the brown poo pigment.

    5) List the functions of the liver.

    Detoxification of alcohol and drugs
    synthesis of glucose, bile salts and cholestrol
    storage of vitamins and glycogen
    Destriction of RBC's


    6) What is the purpose of deamination of Amino acids in the liver and why is it important.

    Deamination removes the amine group to form ammonia and keto acid. the acid can be used in respiration, the the ammonia must be excreted. Ammonia is very slube and more toxic than urea, also it must not accumulate or it can destroy cells. It can be converted to urea for excretion.

    7)What is the name of the organic compound that enters the krebs cycle?

    Keto acid?

    8) summarise the ornithine cycle.

    Ornithine plus CO2 plus NH3 minus a water becomes arginine

    Citruline minus water plus NH3 to form Arginine

    Arginine plus water becomes Ornithine and urea is taken out


    ---------- Revising -------------



    9) Summarise the structure of the kidneys.

    Branches of renal artery and vein into pelvis.

    Capsule - Cortex - Medulla - pelvis - ureter

    10) What does the nephron consist of?

    Bowmans capsule, golerulus, afferent and efferent arterioles, Proximal and distal convoluted tubules and a collecting duct and the loop of henle.

    11) How does the composition of the fluid in nephron change?

    12) why is the afferent arteriole larger in diameter than efferent arteriole?

    The efferent is smaller, so that the blood and be put under high pressure. This forces the blood plasma out inclucing its substance, glucose, inorganic ions, amino acids, water etc

    13) Describe and Explain ultrafiltration

    Blood is forced out its capilaries by high BP.

    Endothelium of capillary lets everything through, but molecules with mass greater than 69000 mean they are stopped by the basement membrane, a mine mesh of collagen and glycolipids.

    Glucose, small ions, water, urea and amino acids are filtered. Proteins not cause they are too big.

    Podocytes line the bowmans capsules and have foot processes, which ensures thare are gaps in the cell.

    14) Describe and explain selective reabsorption

    Okay Here we go:

    In the PCT, there are amino acids, glucose, water and ions such as NA+

    Co factors and channel proteins allow glucose into the cells of the PCT by facillitated diffusion, with also allows amino acids and Na+ in with it. It floods to the other side of the cell, close to the blood supply, and the glucose and amino acids are able to ddiffuse out into the tissue fluid and then into the blood. The Na is pumped via Na-K pump but requires energy from ATP, which is made by the mitochondria in the cell.

    The low water potential in the tissue fluid means water diffuses out via osmosis into the blood.

    15) What is the overall effect of the countercurrent multiplier?

    16) How is the overall effect in the loop of henle?

    17) what is role of the kidney in osmoregulation?

    18) Briefly outline the advantages and the disadvantages of kidney transplant.

    Adv -
    No need for dialysis - trip to hospital
    Independence

    Dis -
    Someone needs to die
    Medication for rest of life
    invovles dangerous surgery - inc anaesthic
    Revoery time.
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    a question im finding quite tricky: Q: For the proper functioning of neurone circuits, neurotransmitters have to be removed from the receptors in the postsynaptic membrane and from the synaptic cleft. Explain why this is so. Help?
 
 
 
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