Turn on thread page Beta
    Offline

    0
    ReputationRep:
    (Original post by kimmey)
    what do you mean by respiratory centre, chemoreceptors ?
    chemoreceptors detect changes in the pH of the blood when there is more carbon dioxide (lowers pH - increases heart beat/breathing rate to remove more CO2) or when there is less carbon dioxide (does the oposite) and the main ones are in the carotid sinus which sends signals to the cardiovascular centre and respiratory centre in the medulla oblangata.

    The respiratory centre controls breathing rate in response to the changes in carbon dioxide concentration to prevent respiratory acidosis.
    Offline

    7
    ReputationRep:
    (Original post by sumsum123)
    Yeh, for instance if you excercise your carbon dioxide levels will increase you can increase your breathing rate and tidal volume. The way your breathing rate is increased is, the chemoreceptors in your carotid artery/aorta/brain detect the extra hydrogen ions and sends the info. to the respiratory centre. And the response will then be increased breathing rate and tidal volume. Tidal volume is synoptic as stuff , the volume of air you breathe in a single breath
    Correct me if I am wrong please
    thanks that seems to make sense
    Offline

    7
    ReputationRep:
    (Original post by l.a.s)
    chemoreceptors detect changes in the pH of the blood when there is more carbon dioxide (lowers pH - increases heart beat/breathing rate to remove more CO2) or when there is less carbon dioxide (does the oposite) and the main ones are in the carotid sinus which sends signals to the cardiovascular centre and respiratory centre in the medulla oblangata.

    The respiratory centre controls breathing rate in response to the changes in carbon dioxide concentration to prevent respiratory acidosis.
    thank you
    Offline

    2
    ReputationRep:
    (Original post by kimmey)
    thanks that seems to make sense
    No probs
    Offline

    0
    ReputationRep:
    (Original post by l.a.s)
    You'll need to know about what mineralocortocoids and glucocortocoids do, (control sodium/potassium ion concentrations in the blood and control metabolism of carbohydrates and fats, respectively) and that they're secreted by the adrenal cortex. Probably need to know that they act directly with their target cells as they're soluble in the plasma membrane so can pass straight into the cell to create a change. Rather than binding with receptors and forming a secondary messenger etc.. etc... You won't need to know the details behind how they create a change though!
    Thank you soo muchh !!
    Offline

    2
    ReputationRep:
    I thought I would mention two AS synoptic calculations,
    How to work out the image size:
    Image size= Actual size * Magnification and you must measure the actual size in micormetres I think. I remembered it as I AM
    And how to work out the cardiac output of the heart:
    Cardiac output = Stroke volume * Heart rate
    Offline

    1
    ReputationRep:
    Hi guys i'll share some notes with you which I hope you find useful..I'm also doing it so it can also help me to revise ..by typing lol ..I'll do one topic at a time...

    Neurones:

    The myelin sheath is an insulating layer of fatty material which Na and K ions cannot pass through. Between the Schwann cells are gaps - called Nodes of Ranvier, which contain voltage-gated sodium and potassium ion channels, allowing ionic exchange to occur. The action potential 'jumps' from one node to the next - (saltatory conduction).

    1) Membrane is at its resting state - polarised with the inside being -60mV compared to the outside.
    2) Sodium ion channels open and some sodium ions diffuse in.
    3) the membrane depolarises - it becomes less negative with respect to the outside and the threshold value of -50mV is reached.
    4) voltage gated sodium ion channels open, and sodium ions flood in. As more sodium ions enter, the membrane becomes positively charged on the inside compared to the outside.
    5) the potential difference across the membrane reaches +40mV, the inside is positive compared to the outside.
    6) the sodium ion channels close and the potassium ion channels open.
    7) potassium ions diffuse out of the cell, bringing the potential difference back to negative inside compared to outside - this is called REPOLARISATION.
    8) the potential difference overshoots slightly making cell hyperpolarised.
    9) the original potential difference is restored so the cell returns to its resting state.
    Offline

    7
    ReputationRep:
    i have a couple of questions...

    why is the RQ of carbohydrates 1 ?

    also during oxidative phosphorylation do the protons get pumped from the matrix into the intermembrane space and then back through ATP synthase. so if i were to take the pH of the matrix it would be high and if i were to take the pH of the intermembrane space it would be low to start and then get higher as protons flow through atp synthase by chemiosmosis ?
    Offline

    1
    ReputationRep:
    A stimulus at the higher intensity will cause the sensory neurones to produce more generator potentials.
    More frequent action potentials in the sensory neurone.
    More vesicles released at the synapse.
    A higher frequency of action potentials in the postsynaptic neurone
    A higher frequency of signals to the brain.
    A more intense stimulus.

    MYELINATED NEURONES:
    100-120ms -1
    up to 1m transmission distance
    Fast response time
    Used in movement
    1/3 of all neurones
    One neurone is surrounded by a Schwann cell, wrapped round several times

    NON-MYELINATED NEURONES:

    2-20ms -1
    Slow response time
    Used in breathing and digestion
    2/3 of all neurones
    Many neurones are surrounded by one Schwann cell

    Synaptic knob contains:
    - many mitochondria
    - a large amount of smooth endoplasmic reticulum
    - vesicles containing acetylcholine
    - there are also voltage gated sodium ion channels in the membrane

    Postsynaptic membrane contains:
    - specialised sodium ion channels that will only open when acetylcholine binds to them
    Offline

    2
    ReputationRep:
    (Original post by kimmey)
    i have a couple of questions...

    why is the RQ of carbohydrates 1 ?

    also during oxidative phosphorylation do the protons get pumped from the matrix into the intermembrane space and then back through ATP synthase. so if i were to take the pH of the matrix it would be high and if i were to take the pH of the intermembrane space it would be low to start and then get higher as protons flow through atp synthase by chemiosmosis ?
    I have no idea for your first q. sorry. Oxidative phosphorylation the protons get pumped from the matrix into the intermembrane space by co-enzymes related to the enzyme carriers. And the co-enzymes related to some enzyme carries use energy given off when the electrons are being passed around. ^& the ph of the intermembrane space would be low because of the protons and the the ph of the matrix would be abit higher I think. and as the protons flow thru atp synthase the ph of the intermembrane space would increase.
    Offline

    0
    ReputationRep:
    (Original post by kimmey)
    i have a couple of questions...

    why is the RQ of carbohydrates 1 ?

    also during oxidative phosphorylation do the protons get pumped from the matrix into the intermembrane space and then back through ATP synthase. so if i were to take the pH of the matrix it would be high and if i were to take the pH of the intermembrane space it would be low to start and then get higher as protons flow through atp synthase by chemiosmosis ?
    The RQ of carbohydrates is 1 because they have the general formula Cn(H2O)n, and when they're respired they use as much oxygen as they produce carbon dioxide, (carbon dioxide released/oxygen used) so C6H12O6 + 6O2 -> 6CO2 + 6H2O.. so it's 1! Although i imagine it actually varies slightly between different carbohydrates..

    And yes, i think, the pH of the intermembrane space will be much lower because of the higher concentrations of protons. I imagine it would assuming that no more protons were being pumped back in across the inner membrane.
    Offline

    2
    ReputationRep:
    (Original post by Raj K)
    Hi guys i'll share some notes with you which I hope you find useful..I'm also doing it so it can also help me to revise ..by typing lol ..I'll do one topic at a time...

    Neurones:

    The myelin sheath is an insulating layer of fatty material which Na and K ions cannot pass through. Between the Schwann cells are gaps - called Nodes of Ranvier, which contain voltage-gated sodium and potassium ion channels, allowing ionic exchange to occur. The action potential 'jumps' from one node to the next - (saltatory conduction).

    1) Membrane is at its resting state - polarised with the inside being -60mV compared to the outside.
    2) Sodium ion channels open and some sodium ions diffuse in.
    3) the membrane depolarises - it becomes less negative with respect to the outside and the threshold value of -50mV is reached.
    4) voltage gated sodium ion channels open, and sodium ions flood in. As more sodium ions enter, the membrane becomes positively charged on the inside compared to the outside.
    5) the potential difference across the membrane reaches +40mV, the inside is positive compared to the outside.
    6) the sodium ion channels close and the potassium ion channels open.
    7) potassium ions diffuse out of the cell, bringing the potential difference back to negative inside compared to outside - this is called REPOLARISATION.
    8) the potential difference overshoots slightly making cell hyperpolarised.
    9) the original potential difference is restored so the cell returns to its resting state.
    I thought I would add to your awesome notes . More on the cell becoming hyperpolarised. It is difficult to cause an action potential in a hyperpolarised membrane because the potential difference is alot greater now , at -80mv rather than -60mv. So threshold wont be eached because it is harder to fully depolarise the membrane. Also, there are more sidum inons inside the cell so that also reduces the concentration gradient when sodium ion channels open and the sodium ions diffuse in.
    Offline

    1
    ReputationRep:
    Organisms need to respond to external stimuli, internal environments change too- build up of carbon dioxide as a result of respiration changes the pH of tissue fluid, and therefore inhibits enzyme activity. Multicellular organisms need to coordinate different organs, so this requires a good communication system which will:

    - cover the whole body
    - enable cells to communicate with each other
    - enable specific communication
    - enable rapid communication
    - enable both short term and long term responses

    Cells need to communicate with each other by a process called cell signalling.
    Neuronal and hormonal systems are examples of cell signalling

    Negative feedback = process in which any change in a parameter brings about the reversal of that change so that the parameter is kept fairly constant.

    Positive feedback = process in which any change in a parameter brings about an increase in that change.

    Homeostasis = maintenance of a constant internal environment despite external changes.

    Any change is detected by receptors, the communication system transmits a message from receptor to effector, and through negative feedback, the effectors reverse the change.
    Offline

    1
    ReputationRep:
    (Original post by sumsum123)
    I thought I would add to your awesome notes . More on the cell becoming hyperpolarised. It is difficult to cause an action potential in a hyperpolarised membrane because the potential difference is alot greater now , at -80mv rather than -60mv. So threshold wont be eached because it is harder to fully depolarise the membrane. Also, there are more sidum inons inside the cell so that also reduces the concentration gradient when sodium ion channels open and the sodium ions diffuse in.
    thankuuu! i'll add some more..and hopefully the things we know will come up in the exam!!!!!
    Offline

    0
    ReputationRep:
    (Original post by kimmey)
    i have a couple of questions...

    why is the RQ of carbohydrates 1 ?

    also during oxidative phosphorylation do the protons get pumped from the matrix into the intermembrane space and then back through ATP synthase. so if i were to take the pH of the matrix it would be high and if i were to take the pH of the intermembrane space it would be low to start and then get higher as protons flow through atp synthase by chemiosmosis ?
    Just to add on to whats been said , the ph would be lower in the inner membrane space than the matrix as it has high no. of protons.
    The protons flow through the ATP synthase and join with oxygen, so the ph in the matrix will never be higher than the inner membrane space., unless there is no oxygen acceptor for the protons. ( which leads on to another story... )
    Offline

    0
    ReputationRep:
    (Original post by Lalaa)
    Just to add on to whats been said , the ph would be lower in the inner membrane space than the matrix as it has high no. of protons.
    The protons flow through the ATP synthase and join with oxygen, so the ph in the matrix will never be higher than the inner membrane space., unless there is no oxygen acceptor for the protons. ( which leads on to another story... )
    please do tell us this other story (anaerobic respiration) in animal cellz plz xox
    Offline

    0
    ReputationRep:
    (Original post by l.a.s)
    please do tell us this other story (anaerobic respiration) in animal cellz plz xox
    Mmmm.. well the story actually lead on to...

    Theres no oxygen to accept the hydrogen, therefore the electorn carriers cannot pass on their electorns, so they cannot accpet any more from NADH.
    So, NADH cannot be converted to NAD, which means that theres nothing to get the hydrogens in the 1st palces from link and krebs. so itll stop.

    This leads on to, anaerobic respiration.
    Glycolysis can still occur, so pyruvate can still be made
    Pyruvate and NADH gets converted to lactae and NAD
    its dehydrogenase enzyme/ Lactate dehydrogencase that CATALYSES it.
    NADH gets oxidised
    Pyruvate is the ALTERNATIVE hydrogen acceptor.
    this generate small amount of ATP

    =)

    Correct me if im wrong pleasee =)
    p.s sorry about the spellings!
    • PS Reviewer
    Offline

    16
    ReputationRep:
    PS Reviewer
    Sorry if this has already been asked but - does anyone have any ideas on what subjects will come up in the exam?
    Offline

    1
    ReputationRep:
    Has anyone got all the definitions which could be asked in the exam? Annnnnnnnd, could someone explain local currents to me please? (:
    Offline

    0
    ReputationRep:
    Guys what synoptic links from AS Biology do you think might come up?
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: November 26, 2012

University open days

  • Heriot-Watt University
    School of Textiles and Design Undergraduate
    Fri, 16 Nov '18
  • University of Roehampton
    All departments Undergraduate
    Sat, 17 Nov '18
  • Edge Hill University
    Faculty of Health and Social Care Undergraduate
    Sat, 17 Nov '18
Poll
Have you ever experienced bullying?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.