FOCUS ON THE KIDNEY
20 AUGUST 2014
Lesson Description
In this lesson we:
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Dissect a lamb’s kidney
Look at kidney diseases:
o Kidney failure
o Bilharzia
o Kidney stones
o Kidney infections
Summary
Kidney Dissection
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Examine the external structure of the kidney. Remove any fat if it is present.
Note the position of the blood vessels and ureter if they are present.
Measure the length and width of the kidney (through the mid-point) and record this
information.
Using a scalpel, cut the kidney in half longitudinally. Make sure that you don’t cut away the
blood vessels or ureter if they are present.
Arrange one of the cut halves on a dish.
Identify the capsule, cortex, medulla, renal pyramids, pelvis, ureter, blood vessels and hilum.
Describe what each of these looks like in your specimen, mentioning colour and texture
(where relevant).
Draw a diagram of the dissected kidney and label all the parts that you have identified (up to
six labels). Make your drawing life size.
Place the dissected kidney and diagram next to each other.
Kidney Diseases and Problems
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If one kidney stops working, it does not matter too much. We can live a relatively normal life
with just one kidney.
Sometimes both kidneys stop working because of an infection that causes damage to the
cells of the kidneys.
If both kidneys stop working, excretion and water balance are affected. The following things
happen:
o
Wastes are not removed from the blood.
o
The amount of urea in the blood increases day by day
Excess water and salts are not removed from the blood. They accumulate in the tissues. This
puts a strain on the heart.
Methods to counteract these effects:
o
Dialysis
o
kidney transplant.
(Solutions for all Life Sciences, Macmillan, p260)
(Solutions for all Life Sciences, Macmillan, p265)
Kidney Failure
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The kidney is easily damaged by a hard punch or blow to the side of the body or to the small
of the back.
People who are likely to experience this kind of injury are sportsmen and women and can
protect their kidneys by wearing kidney belts.
Over-use of painkillers such as aspirin and paracetamol may also lead to kidney failure. Not
everyone is at risk.
Diabetes and high blood pressure can cause kidney damage.
So can various diseases.
Bilharzia
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A disease caused by parasitic worms.
The worms live in the blood vessels around the bladder and they lay their eggs in the blood.
The eggs pass into the bladder and then into the water in lakes or dams when urine comes
into contact with this water.
You can become infected with bilharzia when swimming in, washing in or touching
contaminated water.
Symptoms of bilharzia may include a fever, fatigue and blood in the urine.
Bilharzia can be treated with oral pharmaceutical drugs.
Long-term infection with bilharzia can lead to kidney damage.
Test Yourself
Question 1
The urinary system is also known as
A.
the endocrine system
B.
the renal system
C.
the reproductive system
D.
the gastric system
Question 2
Internally both kidneys have three distinct regions:
A.
the cortex, the medulla and the peritoneum
B.
the cortex, medulla and pelvis
C.
the carina, medulla and pelvis
D.
the cortex, mediastinum and pelvis
Question 3
Each kidney contains approximately:
A.
1 billion nephrons
B.
1 thousand nephrons
C.
1 million nephrons
D.
1 hundred nephrons
Question 4
Glomerular capsule and convoluted tubules always lie within the …
A.
renal pelvis
B.
renal medulla
C.
renal cortex
D.
none of these
Question 5
Glomerular filtrate passes from glomerular capsule into the
A.
Loop of the nephron
B.
Proximal convoluted tubule
C.
Glomerular capsule
D.
Convoluted tubule
Question 6
The hollow space at the centre of kidney where urine is collected after its formation is called
A.
renal pelvis
B.
glomerulus
C.
distal convoluted tubule
D.
urethra
Question 7
The main nitrogen-containing waste excreted in urine is
A.
ammonia
B.
creatine phosphate
C.
nucleotides
D.
urea
Question 8
The muscular tubes which take the urine from the kidneys to the bladder are
A.
Urinary bladders
B.
Ureters
C.
Urethras
D.
Nephrons
Improve your Skills
Question 1
(Adapted from Solutions for all Life Sciences, Macmillan, p268 – 269)
The diagram below shows a longitudinal section though a human kidney.
1.1
Provide labels for A, B, C and D.
(4)
1.2
In which part of the kidney does the filtration of blood occur (A, B, C or D)?
(1)
1.3
About 180 l of glomerular filtrate is formed every day in the nephrons of the kidneys, but only
1,5 l of urine are formed. What happens to the rest of the liquid?
(2)
1.4
Explain the difference between tubular reabsorption and tubular excretion.
1.5
Answer the following questions:
1.5.1
1.7
How is the inner wall of the Bowman’s capsule specialised for the process of
ultrafiltration?
(2)
(3)
1.5.2
What features of the cells forming the walls of the proximal convoluted tubule do you
think help the process of tubular reabsorption?
(3)
1.5.3
What does the presence of many mitochondria in the cells tell you about the process
of tubular reabsorption?
(2)
1.6.1
What volume of water is reabsorbed into the blood?
(1)
1.6.2
What percentage of each substance is reabsorbed into the blood? Show your
calculations.
(8)
1.6.3
Use the information in the table to explain why urea is more concentrated in the urine
than it is in the filtrate.
(2)
1.6.4
Draw a flow diagram to show the path of a molecule of urea from the time that it
enters the kidney to the time that it leaves the body (only list organs or large visible
structures).
(5)
Explain why:
1.7.1
there is no glucose in the urine of a healthy person
(2)
1.7.2
dialysis solution must have the same concentration of glucose as blood plasma. (2)
1.7.3
it is difficult for people in southern Africa who suffer from kidney failure to get a kidney
transplant.
(2)
Links
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http://www.s-cool.co.uk/a-level/biology/gas-exchange/revise-it/gas-exchange-in-humans
http://www.enotes.com/homework-help/what-process-gas-exchange-human-body-467185
http://www.mrothery.co.uk/exchange/exchange.htm
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FOCUS ON THE KIDNEY 20 AUGUST 2014 Lesson Description

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