Download Urinary System and Kidneys

Urinary System
Learning Objectives
 Recall the origin of CO2 and O2 as waste products
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of metabolism.
Recall that the lungs, kidneys and skin are organs
of excretion.
Understand how the kidney carries out its roles
of excretion.
Describe the structure of the urinary system.
Describe the structure of a nephron.
Excretion
 Some products of chemical reactions that occur
within cells are poisonous and so must be removed.
 Excretion is the removal from the body of:
 The ______
waste products of its chemical reactions.
 The excess ______
water and _____
salts taken in with the
diet.
hormones
 Spent __________.
rugs
 D____.
 Any other foreign substances taken into the
alimentary canal and absorbed by the blood.
Excretory Organs – Kidneys
 Excess amino acids are broken down in the liver,
urea The ____
urea is removed
to form glycogen and ____.
from tissues by the _____,
blood and expelled by the
kidneys.
 Urea and uric acid from the breakdown of protein
contain nitrogen – nitrogenous waste products.
 When hormones have done their job, they are
modified in the liver and excreted.
Urine is the watery solution excreted by the
 _____
kidneys which contains the nitrogenous waste
water drugs, toxins
products, excess salts and ______,
and spent hormones.
Structure of the Kidneys
 Two kidneys.
 Fairly solid, oval-shaped structures.
 Red-brown in colour.
 Enclosed in a transparent membrane.
 Attached to the back of the abdominal cavity.
 Renal artery branches off from the aorta and
supplies the kidneys with oxygenated blood.
 The renal vein takes deoxygenated blood back
to the vena cava.
 Ureter – a tube that connects each kidney to the
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bladder.
Renal tubules – many capillaries and tiny tubes in
the kidney tissue, held together with connective
tissue.
Cortex – dark outer region of kidney.
Medulla – lighter, inner zone.
Pelvis – space where the ureter joins the kidney.
Glomerulus – a divided and coiled capillary leading
from each arteriole. The renal artery divides up
into many arterioles and capillaries in the cortex.
 Renal capsule (Bowman’s capsule) – a cup-shaped
organ almost entirely surrounding the glomerulus.
It is a smooth semi-transparent membrane. The
renal capsule leads to the renal tubule.
 Collecting duct – the coiled and looped renal
tubule leads to the collecting duct. The collecting
duct passes through the medulla and opens into
the pelvis.
 Nephron – a single glomerulus with its renal
capsule, renal tubule and capillaries.
 There are thousands of glomeruli in the cortex,
and the surface area of their capillaries is very
large.
Glomerulus
(capillaries)
Renal capsule (Bowman’s)
A NEPHRON
Renal artery
(blood with
waste)
Renal tubule
Renal vein
(blood
without
waste)
Loop of Henle
Collecting duct