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Biology for Secondary Schools

Table:4.2: Summary of parts of the kidney and their functions

S/N Parts of the kidney Description

1 Renal hilum An indentation near the centre of the concave side of the kidney
where the renal vein and ureter leave the kidney and the renal artery
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enters the kidney

2 Capsule A tough, fibrous membrane, surrounding the kidney. It consists of
dense, irregular connective tissues which protect and help to maintain
the kidney’s shape. It is also surrounded by fatty tissue which helps
to protect the kidney from damage
3 Cortex The outer reddish part of the kidney that has a smooth texture. It
is where the Bowman’s capsule, glomeruli, proximal and distal
convoluted tubules and blood vessels are found

4 Medulla The inner striated red-brown part of the kidney. It have tubular parts
that contains loop of Henle’s and blood vessels

5 Renal pyramids The stripped and triangular shaped structures within the medulla,
which are made of straight tubules and corresponding blood vessels.
6 Renal pelvis The funnel-shaped cavity that receives urine drained from the
nephrones through the collecting duct.
7 Renal artery The blood vessel that delivers oxygen- rich blood to the kidney; it
enters the kidney through the hilus and divides into smaller arteries
which further divide into afferent arterioles that serve each of the
nephrones.
8 Renal vein The blood vessel that receives deoxygenated blood from the kidney
and returns it to the systemic circulation.
9 Afferent arteriole The blood vessel that delivers oxygen-rich blood to the glomerulus
under high pressure.

10 Efferent arteriole The blood vessel that receives oxygenated blood from the glomerulus.

11 Kidney nephrones The functional units where the kidney’s main functions are performed.
There are about a million nephrones in each kidney.

12 Collecting duct The part of the kidney nephrone through which several other tubules
empty their contents to the pelvis of the kidney.
13 Ureter The tubular structure which conveys urine from the pelvis of the
kidney to the urinary bladder.

88 Student’s Book - Form Three

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