# 11.3a The Kidney

DBQ: Blood Supply to the Kidney (p.244)

1)The rate of the blood flow to the kidney is the highest compared to the other organs such as heart muscles, skeletal muscle, skin, and brain. With the fastest rate of 420.0ml min-1 100g-1 to the kidney, it is approximately 5 times the rate of blood flow to the heart muscle.

2) The blood flow rate of a kidney is  420.0 ml min-1 100g-1 &  1 liter is 2.38 min-1 100g-1.Thus, 84.0 × 2.38 = 200 ml volume oxygen.

3) Skin = 0.38/2.6 = 15%

Skeletal muscle (resting) = 0.18/0.5 = 36%

Heart muscle =11.0/17.4 =  13%

Kidney = 6.80/84.0 =  8%

4) The difference between the kidney and the other organs is in the volume of blood flowing to the organ, and the percentage of oxygen in the blood that is consumed is because all organs function differently and consume different amounts of energy, thus oxygen. For example, the kidney functions to remove all wastes from the blood thus the greatest volume of blood flows to the organ since all the blood flows into the kidney. Yet again, the skeletal muscle needs oxygen when a body is active and requires a different rate of blood flow and oxygen delivery as the kidney.

5) Active transport of substances (e.g. Na+), requires energy.
6) If the person were moved to a cold environment, vasoconstriction would occur causing a reduction in the blood flow to preserve the core temperature. Thus, the blood flow will slow down as a result.

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## One thought on “11.3a The Kidney”

1. 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
1
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.

2
• 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.

3
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.