11.3a The Kidney

25/11/2013 § 1 Comment

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Page 244, blood supply to the kidney

1. Compare the rate of blood flow to the kidney with flow to the other organs. –> The kidney has the highest rate of blood flow than the other organs, by far. All other organs range below 100 ml min-1 100 g-1 but the kidney can support 420 ml per minute 100 g-1.

2. Calculate the volume of oxygen delivered to the organs per litre of blood. –> 576.7 total blood, 115.3 total oxygen. 115.3 ÷ 576.7 = 0.19 ml per litre of blood.

3. In the brain, 34% of the oxygen that is delivered is consumed. Calculate the same percentage for the other organs. –>

  • skin: 0.38 ÷ 2.6 = 14.6%
  • skeletal muscle (resting): 0.18 ÷ 0.5 = 36%
  • heart muscle: 11.0 ÷ 17.4 = 63.2%
  • kidney: 6.8 ÷ 84 = 8.1%

4. Discuss the reasons for the difference between the kidney and the other organs in the volume of blood flowing to the organ, and the percentage of oxygen in the blood that is consumed. –> Okay, I mean, we know that the purpose of the kidney is 1) excretion and 2) osmoregulation. For this to happen, a lot of the blood in the body needs to flow to the kidney. And, disregarding the kidney (which takes in a lot of oxygen that comes in the blood), the heart is the next organ to receive the most oxygen, understandably so because it frequently also pumps blood to the lungs in order to OXYGENISE that blood. The concentrations of oxygen and the amount of blood that flows into the organ differ depending on that organ’s function.

5. Some parts of the kidney have a higher percentage rate of oxygen consumption, for example the outer part of the medulla. This is because active processes requiring energy are being carried out. Suggest one process in the kidney that requires energy. –> Actiiiiiive traaaaanspooort!!!!

6. Predict, with a reason, one change in blood flow that would occur if the person were moved to a cold environment. –> If a person were moved to a cold environment, in order to maintain their core heat as a type of homeostatic response, the blood flow would slow down or stop flowing.

§ One Response to 11.3a The Kidney

  • Dave Ferguson says:

    Grade 7 A consistent and thorough understanding of the required knowledge and skills, and the ability to apply them almost faultlessly in a wide variety of situations. Consistent evidence of analysis, synthesis and evaluation is shown where appropriate. The student consistently demonstrates originality and insight and always produces work of high quality.

    Data-based questions: blood supply to the kidney
    page 244
    The kidney has the highest blood flow rate of the tissues shown –
    five times more than the heart muscle and nearly 200 times resting skeletal muscle.

    • The kidney receives 420 mL per minute. In 2.38 minute 1 litre is delivered to 100 mg of tissue;
    • in this time (84.0 × 2.38) 5 200 mL of oxygen is delivered.

    Skin 14.6%
    Skeletal muscle 36%
    Heart muscle
    Kidney 8%

    4 Answer should refer to:
    • Blood flows to different organs for different reasons.
    • All blood needs toxic waste products removed so must flow to kidney.
    • Some oxygen demand is variable depending on activity.
    • Such as by skeletal muscle during activity.
    • Some blood flow is variable such as thermoregulation and the skin.

    5 Selective re-absorption/active transport.

    6 Blood flow to the skin would change; to support thermoregulation.

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