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[Bio] (自創)全港首題(cardiovascular system cross over homeostasis in kidney)

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(自創)全港首題(cardiovascular system cross over homeostasis in kidney)



Reading materials:

1. Cardiac Output (measured in L/ min) is the measure of how much blood is pumped out of the heart per unit time
    It usually has a direct influence on the blood pressure of the vascular system
    Cardiac output is measured by the following formula:
    Cardiac output = Stroke volume (the volume of blood pumped from one ventricle of the heart with each beat) * Heart rate
    i.e. CO = SV * HR

2. Atrium of the heart is known to have the ability to produce a hormone called ANH when the blood pressure is high. ANH can        induce vasodilation in the afferent glomerular arteriole, and vasoconstriction in the efferent glomerular arteriole. It can also
    inhibit sodium reabsorption in the nephron.



Try to answer the following questions:

1.  Calculate the cardiac output of a man having an average stroke volume of 70ml and a heart rate of 70 beats per minutes
(1 mark)

2.  Describe the physiological process of water reabsorption in the nephron (3 marks)

*3. Explain how ANH can decrease blood pressure (5 marks)

4. Suggest an advantage to the heart of having ANH as a regulating hormone (1 mark)
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Please try and see whether you can get an A in Biology

Answer will be posted later
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勁TAS...
PHY CHEM PURE 2011 AL!!!

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sorry...係TST-.- AL上腦...唔好意思
PHY CHEM PURE 2011 AL!!!

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各位係時候開始溫BIO
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回覆 #6 ch252525 的帖子

"Added to the inhibition of sodium ion, which is the cause of high blood pressure"
sorry,我bio屎 唔明

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1. 4.9L/min
2. water potential of glomerula filtrate is higher than that of blood, water moves through the wall of kidney tubule and wall of capillary by osmosis,
   so water is reabsorbed back into blood
3. ANH cause vasodilation, total cross sectional area of blood vessels increase, it also inhibit reabsorption of sodium ions, water potential of blood
   remains high, the rate of water reaborption decrease, the volume of blood increase at lower rate. these lead to a lower blood pressure
4, lower risk of heart risk

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anymore attempts?
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push push push
encourage more attempts
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1.  Calculate the cardiac output of a man having an average stroke volume of 70ml and a heart rate of 70 beats per minutes
4.9L/min

2.  Describe the physiological process of water reabsorption in the nephron (3 marks)
As plasma protein is present in blood plasma but not in glomerular filtrate, the water potential of glomerular filtrate is higher than that of plasma.  Water is absorbed in the kidney tubule through osmosis through the conc. gradience.

*3. Explain how ANH can decrease blood pressure (5 marks)
ANH cause vasodilation of afferent glomerular arteriole, and vasoconstriction in the efferent glomerular arteriole.
The difference of cross section area of the two vessel increase and the amount of glomerular filtrate formed increase.  Since sodium reabsorption in the nephron in inhabited, the amount of salt in glomerular filtrate remains high while the that in blood decrease. The water potential gradience between glomerular filtrate and blood decrease, thus less water is reabsorbed into blood.
The total volume of blood decrease and reduce pressure on blood vessels.

4. Suggest an advantage to the heart of having ANH as a regulating hormone (1 mark)
lowering the risk of stroke

sorry for attempting this question so late....
2 days till the exam, looking forward for the answers.=]]

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