Page 347 - Biology_F5

Biology for Advanced Level Secondary Schools

The bean-shaped kidneys have an outer contains parts of the nephrons, glomeruli
convex side and an inner concave side and capsule, while the medulla contains
called the renal hilus. A transverse section tubular part of the nephrons and blood
(T.S) of the kidney reveals an outer part vessels, forming the renal pyramids
called cortex and an inner part called which project into the pelvis, leading to
medulla. A thin connective tissue called the ureter. Kidneys are well supplied by
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fibrous capsule surrounds each kidney. blood vessels, forming a network of blood
This capsule maintains the kidneys’ shape capillaries (Figure 7.6).
and protects the inner tissues. The cortex

Nephron

Renal cortex
Collecting duct

Capsule
Minor calyx
Renal medulla Major calyx
Renal pelvis
Renal pyramid
Renal artery
Renal papilla Renal vein

Venule
Blood capillaries Arteriole

Ureter

Figure 7.6: Transverse section through the mammalian kidney

General functions of the kidneys
Kidneys are multifunctional organs, some core functions of the kidneys include:

(a) Excretion
Kidneys filter out toxins, excess salts, and nitrogenous wastes created by cell
metabolisms. Urea is synthesised in the liver and transported through the blood to the
kidneys for removal in urine.

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