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Biology 30 – Ch. 12 Excretion Notes
What is Excretion?
 _____________ is the process by which ___________________________
are removed from the organism. Excretion is not ________________.
 __________________ is the process of ____________________________.
In contrast to excretion, the substance ________________________, rather
than being a ___________________________.
 Humans excrete wastes using the following organs:
______________________________________________________
Excretion in other organisms
 Small organisms that diffuse gases directly do _______________________
for ____________________________________________.
 Organs are unnecessary as wastes may be __________________________.
 Waste removal must occur ____________________________________.
 Protists and Hydra have no specialized organs. Excretion is by __________
through ____________________________________.
Excretion in Earthworms
 Earthworms are considered large organisms and utilize specialized
structures to rid their bodies of ___________________ called __________
-- urine consists of _____________________________________.
Excretion in Insects
 Grasshoppers and other insects use structures called __________________
to remove wastes from the blood.
 Nitrogenous wastes are produced as __________________. Body fluids are
drawn into the ______________________________________ due to large
concentrations of potassium inside the tubule.
 _______________ pass back into the body, nitrogenous wastes empty into
the insect's gut. ______________ is reabsorbed and waste is expelled from
the insect.
Human Excretion
 The majority of waste excreted by the human excretory system is filtered
by the ____________________. However the lungs, skin and liver also
serve an excretory role.
 The lungs excrete _____________________________________.
 The skin secretes _____________________________________________.
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Biology 30 – Ch. 12 Excretion Notes
 The liver produces a digestive substance called ___________ that breaks
fats into smaller pieces so it can be digested. ________________________
so it serves two roles in the body.
The Urinary System
 The urinary system is made-up of the ______________________________
____________________________________________________________.
 Waste is filtered from the blood and collected as ________ in each kidney.
 Urine leaves the kidneys by _____________, and collects in the ________.
The ____________________ to store urine that eventually leaves through
the _____________________.
 Blood flows into the kidney through the _______________. The blood that
enters the kidney is under _________________________. Blood leaves the
kidney via the ________________. The kidney acts as a ___________ that
captures excessive substances in the blood channeling it into the ureter.
The kidney can be described as having three regions:
 ______________________ - ________________________________
 _________________ - reabsorption of ____________________ into blood
 __________ - collection of ____________ to pass on to _______________
The Formation of Urine in the Kidney
1. Filtration
 Takes place in the ________. The ________, an evolutionary modification
of the __________________, is the kidney's functional unit.
 The nephron consists of 6 main parts; ______________________________
____________________________________________________________
____________________________________________________________
 The ___________________ is a ____________________________.
 ___________________ – cuplike structure that surrounds the __________.
 _________________ in the glomerulus forces water, urea, glucose, amino
acids and salts into the lumen of the Bowman’s Capsule.
 ____________________________ are too large and remain in the blood.
 The glomerulus forms about 180 L of filtrate a day.
2. Reabsorption
 The filtrate in the lumen is concentrated and passes through the first part of
the nephron called the __________________________.
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Biology 30 – Ch. 12 Excretion Notes
 ______________ is reabsorbed back into the bloodstream in the ________
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______________________.
The waste becomes even more concentrated as ________ is reabsorbed.
____________is very precious to our body and the nephron absorbs as
much as possible. Approximately 99% of the water is reabsorbed by the
kidney.
The filtrate continues on to the section of the nephron called the ________
___________. Continued reabsorption of water and other nutrients occurs.
The concentrated filtrate moves on to the _________________ collecting
in the ________________________.
The filtrate is now _________. Urine is composed largely of ________, a
nitrogenous waste. Recall that during protein digestion the _____________
___________ group is stripped from the molecule. Nitrogen is a toxic
substance in our tissues and must be removed in a non-harmful way. _____
is that way.
All of the amino acids, glucose and some salts are reabsorbed by the blood
in the nephron by diffusion.
All other substances reabsorbed via active transport (requires ATP).
Most substances have what is called a ____________________________.
If the concentration of a substance in the blood is ____________________
_____________, the excess substance is __________________________.
For example, the blood sugar level of a person with diabetes is so high that
not all of the glucose in the filtrate can be returned to the blood. As a result
glucose appears in the urine. Under normal conditions all of the glucose is
reabsorbed.
What substances that remain makes up the urine which travels the _______
____________________________________________________________
Summary:
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