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    Do we need to know about detoxification of alcohol or is it just urea and ornithine
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    (Original post by Nat900)
    Please explain this to me? Where is this? I've drawn myself at point blank :O
    To increase heart rate, an electrical impulse is sent down the ACCELERATOR nerve to the cardiovascular system in the medulla oblongata, which sends impulses to the SAN to increase waves of contraction of the ventricles. This is part of the sympathetic system, where noradrenaline secreted.

    To decrease heart rate, same as above buuuuut VAGUS nerve, and PARASYMAPATHETIC system, and ACETYLCHOLINE released.

    That's what I remember of it anyway, double check in the textbook because this is one of the topics I need to recap myself lol
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    (Original post by Beanhead456)
    Do we need to know about detoxification of alcohol or is it just urea and ornithine
    You need to know alcohol detoxification
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    (Original post by Nat900)
    Yeah sorry that's what I meant! :-D. I have officially lost it...
    haha, I did think it was a silly mistake, I just wanted to make sure just in case!! I managed to write "threshold gradient" instead of "threshold potential" in a paper earlier and stared at it for a good five minutes just thinking "but why did I think that was even remotely correct"
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    (Original post by maisie__x)
    Nervous an hormonal mechanisms;
    -adrenaline in the blood causes an increase in heart rate
    -the heart rate is controlled by two nerves, accelerator (releases noradrenaline), vagus nerves (releases acetyl choline which slows heart rate)
    -the heart rate is also controlled by medulla oblongata which controls frequency of contractions
    -worth mentioning the heart is myogenic, initiates it's own rhythm

    Do you have the textbook? It's on page 29. If not I'll explain the next bit too?
    Please do, I can't seem to find my textbook... I'm so sorry, I really have lost it. If you can explain, please do. If not, don't worry xx
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    guys can someone please hellp me!
    what are the roles of liver in detoxification?
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    (Original post by bballislife)
    could someone please outline the control of heart rate please?
    Unfortunately we haven't covered it in class and so I would be rather grateful if someone could just go through what happens, both chemically and electrically please?

    When we respire we produce carbon dioxide. This reacts with water to form carbonic acid. This dissociates to produce HCO3- ions and H+ ions. Ph decreases. Change detected by chemoreceptors. Electrical impulses sent to Cardiovascular centre in the medulla oblongata. This then sends impulses via the accelerator nerve to increase frequency of contractions as cells need more oxygen quickly.
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    if any one wants last minute notes these are quite good and have coloured diagrams
    Attached Images
  1. File Type: pdf unit-1-communication-and-homeostasis2.pdf (512.8 KB, 176 views)
  2. File Type: pdf unit-2-excretion.pdf (547.1 KB, 144 views)
  3. File Type: pdf unit-3-photosynthesis.pdf (479.3 KB, 97 views)
  4. File Type: pdf unit-4-respiration.pdf (460.1 KB, 141 views)
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    What do we need to know about thermoregulation?
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    (Original post by Asif_m96)
    My prediction on what will come up:
    Photosynthesis experiment (either leaf disks or photsynthometer)
    Adrenaline
    Diabetes
    Thermoregulation
    Heart
    Respiration ( 1 markers)
    Role of Synapse
    Possibly kidneys and regulation of blood glucose conc...
    I don't reckon the roles of synapes will come up 2 years in a row. But I guess you never know....
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    (Original post by Nat900)
    Please explain this to me? Where is this? I've drawn myself at point blank :O
    Hormonal mechanisms:
    Adrenaline is released into bloodstream from adrenal medulla (in response to stress) and increases heart rate.
    Neuronal mechanisms:
    Cardiovascular centre in the medulla oblongata controls heart rate.
    Eg if we excercise, we produce CO2 which we need to get rid of, so this is detected by medulla oblongata and it sends impulses down the ACCELERATOR nerve to the SAN which increases 'wave of excitation' over atria and therefore down the AVN and purkyne fibres to ventricles = heart rate increase.
    Heart rate is also increased when pH of blood is low (due to excess CO2 being present)
    Heart rate is also increased when more O2 is needed in muslces.
    Heart rate is decreased when blood pressure is too high which is monitored by receptors in the carotid sinus in carotid artery, which sends impulses to heart via VAGUS nerve = heart rate decrease.
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    (Original post by ShivanjaliNP)
    I don't reckon the roles of synapes will come up 2 years in a row. But I guess you never know....
    Yeah... Maybe pregnancy testing.
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    (Original post by Nat900)
    Please do, I can't seem to find my textbook... I'm so sorry, I really have lost it. If you can explain, please do. If not, don't worry xx
    Of course I can so this is factors affecting heart rate;
    -if a person is exercising this is detected by stretch receptors in the muscle walls which sends impulses down accelerator nerve to the cardiovascular system to increase heart rate (because more O2 may be needed in muscles to supply more ATP for muscle contraction)

    -exercise means more co2 produced by respiration, which combines with water in blood to produced carbonic acid. This lowers blood ph which is detected by chemo receptors in carotid arteries. Again impulses sent to cardiovascular system to increase heart rate, which increases respiration and so removes excess co2 from body

    Hope that helps
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    (Original post by abOO)
    Sodium-potassium pumps actively transport Na ions out of the PCT wall into the blood. Therefore lowering the conc of Na ions in PCT wall cells.
    So.... Na ions are bought into the PCT wall from the tubule, along with glucose and amino acids, by facilitated diffusion through co transporter proteins (uses ATP).
    Then because of the high conc of Na in the walls compared the the blood, Na are pumped into the blood.
    Water follows from the PCT into the PCT wall as Na are removed from the PCT (due to high water potential in tubule).
    And then Water diffuses again from PCT walls into blood, down a conc gradient by osmosis.
    Ahh I understand everything up until 'Water follows from the PCT into the PCT wall as Na are removed from the PCT' maybe bc I don't understand the structure:/ but thank you
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    (Original post by abbiecharlottee)
    What respiration experiments are there, do we need to know them?
    To evaluate the evidence of chemiosmosis


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    (Original post by kewla1)
    guys can someone please hellp me!
    what are the roles of liver in detoxification?
    They contain the necessary enzymes to break down alcohol, i.e. ethanol dehydrogenase and ethanol dehydrogenase. They also have their own ribosomes to synthesise these proteins (enzymes)
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    (Original post by bballislife)
    could someone please outline the control of heart rate please?
    Unfortunately we haven't covered it in class and so I would be rather grateful if someone could just go through what happens, both chemically and electrically please?
    The heart rate is controlled by the cardiovascular centre in the medulla oblongata. This is connected to the sino-atrial node of the heart via the vagus nerve and accelerator nerve. The vagus nerve decreases heart rate while the the accelerator nerve increases the heart rate. Adrenaline when released by the adrenal medulla also increases heart rate in times of being nervous. Low blood pH/high concentration of CO2 in the blood is detected by chemoreceptors in brain, aorta and carotid arteries. This causes impulses to be sent down the accelerator nerve to increase the heart rate. The movement of the limbs is detected by stretch receptors in the muscles which sends impulses to the brain to suggest if muscles are being used or not. Finally high blood pressure is detected by stretch receptors in the wall of the carotid arteries which leads to a decrease in heart rate.
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    (Original post by abOO)
    Hormonal mechanisms:
    Adrenaline is released into bloodstream from adrenal medulla (in response to stress) and increases heart rate.
    Neuronal mechanisms:
    Cardiovascular centre in the medulla oblongata controls heart rate.
    Eg if we excercise, we produce CO2 which we need to get rid of, so this is detected by medulla oblongata and it sends impulses down the ACCELERATOR nerve to the SAN which increases 'wave of excitation' over atria and therefore down the AVN and purkyne fibres to ventricles = heart rate increase.
    Heart rate is also increased when pH of blood is low (due to excess CO2 being present)
    Heart rate is also increased when more O2 is needed in muslces.
    Heart rate is decreased when blood pressure is too high which is monitored by receptors in the carotid sinus in carotid artery, which sends impulses to heart via VAGUS nerve = heart rate decrease.
    (Original post by maisie__x)
    Of course I can so this is factors affecting heart rate;
    -if a person is exercising this is detected by stretch receptors in the muscle walls which sends impulses down accelerator nerve to the cardiovascular system to increase heart rate (because more O2 may be needed in muscles to supply more ATP for muscle contraction)

    -exercise means more co2 produced by respiration, which combines with water in blood to produced carbonic acid. This lowers blood ph which is detected by chemo receptors in carotid arteries. Again impulses sent to cardiovascular system to increase heart rate, which increases respiration and so removes excess co2 from body

    Hope that helps
    Thank you all soooooo much. Honestly I really appreciate it!!!!! xxxx :-) :-) :-) :-)
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    Hey guys.

    Based on previous exams for F214, the following has not come up as much, and was not present in last year's paper:

    - Control of heart rate
    - Synaptic transmission
    - Aerobic Respiration
    - Respirometer experiment
    - Photosynthesis
    - ADH/osmoregulation.

    Please understand that this is not an exhaustive list. I strongly recommend everybody go through the specification which is available on the OCR website. If you are not comfortable with every point, then go through it. Good luck to you all, my friends!
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    (Original post by Beanhead456)
    Do we need to know about detoxification of alcohol or is it just urea and ornithine
    Yeah we do there's a bit about ethanol dehydrogenase
 
 
 
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