Page 93 - Biology_Form_3

Biology for Secondary Schools

2. Use a hand lens to observe the as well as the blood vessels of nephrones
internal structure of the kidney which together form the renal pyramid. The
3. Draw a large diagram of what you renal pyramid project into the pelvis leading
to the ureter. Kidneys are well supplied
have observed. with blood vessels forming a network of
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Safety precaution blood capillaries. The blood in human
All sharp objects should be handled with body is filtered several times a day by the
care. All safety gears should be properly kidneys. This is why about 8% of all oxygen
used. absorbed through the lung is used by the
Questions kidneys. Oxygen is used by the kidneys to
provide energy needed to filter the blood
1. Describe the structure of the and produce urine.
mammalian kidney.
2. How does the structure of the kidney Cortex
facilitate removal of metabolic
wastes? Renal artery
The kidneys are two bean-shaped organs
in the renal system. It has an outer convex Pelvis Renal vein
side and an inner concave side called the
renal hilum. The renal artery supplies blood
to the kidney and the renal vein removes
blood from the kidney through the renal Medulla Ureter
hilus. The kidney is surrounded by fibrous Figure 4.2: Internal structure of mammalian
connective tissue. kidney

The transverse section of the kidney has Activity 4.2:
three distinct regions, the outer darker
layer called the cortex, the inner region Examining the urinary system of the
called the medulla, and the pelvis. Pelvis mammals
is an expanded portion of the ureter. See Materials
Figure 4.2. The renal pelvis is the region Dissected animal or model of rat, mouse
into which urine temporarily accumulates or rabbit, and hand lens
before it is drained into the urinary bladder. Procedure
A thin connective tissue called fibrous 1. Use hand lens to observe the
capsule surrounds each kidney. This capsule displayed urinary system of the
maintains the kidneys shape and protects provided mammal.
the inner tissues. Safety precaution
The cortex contains parts of nephrones, All safety gears should be properly used.
numerous glomeruli (singular: glomerulus) 2. Identify the kidneys, ureters, urinary
and capsules. The medulla mainly consists bladder, and urethra.
of the loop of Henle and collecting ducts

86 Student’s Book - Form Three

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