Entry slip: What along what structure in
what organ does most of the absorption of
nutrients take place in the alimentary
Lesson 1.7- Describe the homeostatic role
of the liver with respect to
regulation of nutrient levels in the blood
and nutrient storage
(pp365-368) of Biology-McGraw-Hill
I. Homeostasis (p772):
a.The body’s maintenance of a relatively
constant internal environment (i.e.
water content, O2 level, temperature,
b. Ex: the thermostat in your home
functions to keep the temperature
“just right”. When the furnace heats
the home above a certain
temperature, it shuts off. When the
temperature falls again, the
thermostat senses this and starts up
the furnace to keep the home at a
II. The liver has several homeostatic
a. Fat: The human body needs fat. Bile
salts produced from the liver help fat
get emulsified (remember the
detergent with an oily jar) so the fat
can be easily used by the body. Its
i. “burned” in cells for energy
ii. Used and construction material for
hormones and cells
iii. Stored for later use in fat cells
b. CHO’s: Excess blood-sugar is stored
in the liver as “glycogen”. This
substance is like heavy syrup and is
composed of molecules with many
glucose rings attached to each other.
When blood-sugar levels go down
because the sugar in the blood is used
up and the person does not have a
meal for a long time, the liver converts
glycogen back to simple glucose and
deposits it into the bloodstream.
c. Protein: excess amino acids are de-
aminized (the Nitrogen is removed
and excreted) and the rest of the C’s,
H’s and O’s are converted to fat.
d. Vitamins: excess vitamins A, D, E and
K are stored in the liver and released
into the blood stream when needed.
e. Alcohol: excessive alcohol levels are
dangerous to the body. The liver
quickly converts the alcohol to an
Mr. Gustave’s body is short of a few
organs and is interviewing for a
position as an organ. You are a liver
and are applying for a job to work in
Mr. Gustave’s body; your competition
is a stomach and a small intestine.
Write a half-page (at least 100 words)
cover letter explaining:
1. Past experiences and
accomplishments as a substitute
2. What you would do to help the
body with homeostasis.
3. Hand in for marks the next day.
4. Clear writing or printing or size