THE EXCRETORY
SYSTEM
10th GRADE
LEARNING OBJECTIVES
At the end of the Lesson, all students will be able to;
•Understand What excretion is and why it
occurs in the body of living organisms.
•Students will identify the Excretory organs
and parts of the human body
STARTER
SUGGEST WHAT WILL HAPPEN TO YOU IF ALL THE LIQUID YOU TAKE
INTO YOUR BODY STAY TRAPPED AND CANNOT LEAVE…
DO YOU KNOW;
• WHICH PART OF YOUR BODY TAKES THE EXTRA LIQUID OUT OF YOUR
BODY?
• THAT MOST OF THE FOOD WE EAT CONTAINS LIQUID?
• WHICH PARTS OF YOUR BODY THAT THROWS EXTRA LIQUID OUT?
VOCABULARY
• METABOLISM
• POISON/TOXIC
• EXCRETION
• EXCRETORY PRODUCTS
• EXCRETORY ORGANS
• All living cells have a great many metabolic reactions
going on inside them.
• Metabolic reactions often produce other substances as
well, which the cells do not need.
IF METABOLIC EXCRETORY
PRODUCTS REMAINS IN THE
BODY?!
If such substances are allowed to remain
in the cells,
these substances may become poisonous or toxic.
We need a passage to get them out
THE EXCRETORY SYSTEM
Humans have organs which are specialized for the
removal of certain excretory products
• They include the lungs, kidneys, skin and liver
KIDNEY
The kidneys are
excretory organs
that perform three
main functions to
produce urine,
filtration,
reabsorption and
secretion
LUNGS
During cellular
respiration, the
lungs give out
carbon dioxide as
their waste product.
BILE
SKIN
The skin plays a role in excretion
through the production of sweat
by sweat glands. Sweating
eliminates excess water and
salts, as well as a small amount
of urea
WHAT IS THE MAJOR MAKE UP OF
URINE ???
THE KIDNEYS
Part of urinary system
The 2 Kidneys are at the back of the
abdomen, behind the intestines.
WHAT IS INSIDE?
The kidney has three main parts
1. cortex,
2. medulla
3. pelvis.
Leading from the pelvis is a tube, called
the ureter.
The ureter carries urine that the kidney has
made to the bladder.
URINARY STRUCTURES INCLUDING KIDNYES
SOILD ?!
WHAT DO YOU THINK ?!
KIDNEY TUBULES
Although they seem solid, kidneys are actually made
up of thousands of tiny tubules, or nephrons.
Each nephrons begins in the cortex, loops down
Into the medulla, back into the cortex, and then goes
Down again through the medulla to the pelvis.
In the Pelvis, the tubules join up with the ureter.
ONE NEPHRON
MADE OF URINE
The final liquid produced by the kidneys is a
solution of urea and salts in water.
It is called urine, and it flows out of the
kidneys, along the ureters and into the
bladder.
It is stored in the bladder for a while, before
being released from the body through the
urethra.
MADE OF URINE
1. FILTRATION
Any molecules small enough to go through the holes within the capillary walls will
be squeezed through, into the space in the renal capsule
2.
REABSORPTION
The kidneys are extremely efficient at reabsorbing water. Over 99% of the
water entering the tubules is reabsorbed.
In humans, the two kidneys filter about 170dm3 of water per day, yet only
about 1.5 dm3 of urine are produced in the same period.
AMAZING KIDNEYS
The kidneys adjust the amount of urine that they produce,
according to the needs of the body.
1. If your body is short of water - perhaps because you have been doing
exercise in the heat and have lost a lot of water by sweating - then the
kidneys produce small volumes of concentrated urine.
2. If your body contains too much water - perhaps because you have
been drinking a lot - then the kidneys produce large volumes of dilute
urine, which helps to get rid of the excess water.
THE BLADDER
• The urine from all the tubules in the kidneys flows into the ureters. The
ureters take it to the bladder.
• The bladder stores urine. It has stretchy walls, so that it can hold quite
large quantities.
• Leading out of the bladder is a tube called the urethra. There is a
sphincter muscle at the top of the urethra, which is usually tightly closed.
When the bladder is full, the sphincter muscle opens, so that the urine
flows along the urethra and out of the body.
• Adult mammals can consciously control this sphincter muscle. In young
mammals, it opens automatically when the bladder gets full.
KIDNEY DIALYSIS
• Sometimes, a person's kidneys stop working properly. This might be
because of an infection. Complete failure of the kidneys allows urea
and other waste products to build up in the blood and will cause
death if not treated.
• The best treatment is a kidney transplant, but this is not easy to
arrange.
• The usual treatment for a person with kidney failure is to have several
sessions a week using a dialysis unit.
Dialysis unit
ALL IS, OK?
• Excretion, why?!
• The kidneys excrete urea and excess water and ions.
• Identify in diagrams and images the kidneys, ureters, bladder and urethra
• Identify in diagrams and images the structure of the kidney.
• Outline the structure and function of a nephron and its associated blood
vessels
• Kidney dialysis
• Excretion, why?!
• The kidneys excrete urea and excess water and ions.
• Identify in diagrams and images the kidneys, ureters, bladder
and urethra
• Identify in diagrams and images the structure of the kidney.
• Outline the structure and function of a nephron and its
associated blood vessels
• Kidney dialysis