Metabolism
Chapter 14
The Main Function of Metabolism
 Metabolism
= living cells use nutrients in
many chemical reactions that provide
energy for vital processes and activity.
 Homeostasis = a healthy and relatively
constant internal environment.

To maintain homeostasis, the body regulates
its systems to avoid dangerous lacks or
excesses.


Ex. You breathe to take in oxygen and expel carbon
dioxide
Normal metabolism helps make homeostasis possible
(allow body to maintain or regain an “even keel”
The Metabolic Process
Chemical balance – just like a car who needs
hydrogen and carbon to run our body needs the
right balance of nutrients and other substances
in our body
 Oxygen – (like “burning of gasoline that make a
engine run) many metabolic processes require
oxygen to take place (breathing)
 Temperature – (a car wont start it it’s temp. is too
low) an organism’s body temperature must be
within a certain range
 Removal of waste products – (exhaust system to
rid water vapor and carbon monoxide) the waste
products of metabolism are water and carbon
dioxide, these are carried in the blood to the
lungs where you exhale them

Energy for Metabolism

During metabolism, energy is both used and
produced
 Energy originates from the sun, plants trap
energy, humans eat plant they gain nutrients
which provide energy for metabolism
 Of the 6 essential nutrients, protein,
carbohydrates and fats supply energy for
metabolism

Glycogen = the form of carbohydrates stored in the
muscles


Remaining carbohydrates are converted to fat
Protein is use for body mass, excess amounts are
converted to fat
Catabolism & Anabolism

Metabolism is 2 separate process

Catabolism = breaking down complex molecules into
simpler ones during chemical reactions


Anabolism = the combining of molecules during
chemical processes in order to build the materials of
living tissue


Nutrients are broken down into simple material which can enter
the cell, which then releases energy
Molecules broken down by catabolism are reconstructed into
body cells ex. Protein in peanut butter becomes protein in your
muscles through anabolic reactions
Cytoplasm = colloidal substance consisting of
organic and inorganic substances, including
proteins and water found in a living cell. This is
the main component of both animal and plant
cells.
• Catabolism breaks down food to make cytoplasm which the
body uses for maintenance during anabolic process
Catabolism and Anabolism
Catabolic Reaction (glycogen breaks down, which releases energy)
Glycogen
Glucose
Anabolic Reaction (glycogen is created, which takes energy)
Glucose
Glucose
Glycogen
The ATP Cycle
 Adenosine
Triphosphate = Certain
molecules serve as energy warehouse
• ATP molecules combine the compound adenosine
with 3 phosphate groups, forming a chain A-P-P-P

Energy is carried in the bonds between phosphate
groups
• When a cell needs energy the bond between the two
phosphate groups is broken and the third group
transfers to another molecule.
• With only 2 phosphate groups remaining ATP
becomes ADP which will latter turn back to ATP
trough using energy to link with another phosphate
group reforming ATP
Storing Energy – Energy is stored when a third phosphate group
bonds to ADP, forming ATP
ENERGY
P
A
P
P
A
P
P
P
Using Energy – When a cell needs energy, a phosphate bond in ATP
breaks, release energy and produces ADP and separate phosphate group
ENERGY
A
P
P
P
A
P
P
P
Chemical Balance during
Metabolism

The cells in the body are mostly cytoplasm
walled in by:


Membranes = thin layers of tissue (these are
semipermeable)
Semipermeable = they allow varying amounts of
specific substances to pass through them
• The open door policy can lead to a chemical imbalance


Osmosis = the movement of fluid through a semipermeable
cell membrane to create an equal concentration of solution on
both sides
Metabolic rate = how fast the chemical
processes for metabolism takes place
Body Temperature
 We
have mechanisms to keep our body
temperature fairly stable
• Ex. In a cold room, you shiver to increase body
heat

In cold-blooded creatures, (lizards) – body
temperature is more dependent on
environmental temperature.

Lizard metabolic rate rises as it lies in the sun – thus the
metabolic rate varies more in a given day than a healthy
human’s rate
Body Size
 Small
animals like a rabbit have more
surface area so they lose body heat more
quickly, thus their metabolic rate is much
higher.
• In one minute a mouse breathes 150 times,
elephant 6 times and a human 16 times.
• In 2005 61% of the US population is considered
overweight (I am sure it’s higher now)
Physical Development & Age, Body
Composition & Energy Supply

Scientists believe that cell function rapidly in
young individuals for development. Thus,
metabolic rate is high, as an adult their
metabolism drops to a lower, “maintenance”
level
 Lean tissue (muscle) takes more calories to
maintain than other types. Ex. Males who tend to
have a greater portion of lean mass generate a
higher metabolic rate.
 When your body sense less food availability, the
body stretches the food supply by burning at a
slower rate (survival mechanism)
Basal Metabolism
 Basal
Metabolism = energy used by a
body at rest to maintain automatic, lifesupporting processes.
• Regulating heartbeat, breathing and body
temperature and a few examples.
 Basal
Metabolic Rate = (BMR) measure
of heat given off per time unit
Voluntary Activities

Voluntary Activities = Conscious and
deliberate actions
• Sedentary Activity – (reading) burns 80-100 calories per hour
• Light Activity - (walking) burns 100-170 calories per hour
• Moderate Activity - (brisk walk) burn 170-250 calories per
hour
• Vigorous Activity – (waxing your car) burns 250-350 calories
per hour
• Strenuous Activity - (swimming or bicycling) burns 350 +
calories per hour
TURN TO PAGE 212 – ANSWER QUESTIONS 1 & 2
Weight-Loss Diets
 To
lose weight you shouldn’t starve your
body – that can back fire!!!
 Crash Diet (BAD)
• After exhausting its blood sugar and glycogen
supplies for energy, the body breaks down its fat
and protein deposits. (reduces muscle mass,
which is eliminated in our urine and waste)
• Ketones start accumulating, upsetting blood
chemistry and vital cell functions – condition is
acidosis
• Hair loss, weakened immune system, to sudden
death
• Best way to eat is 5-6 small meals a day, which will
help your metabolic rate and energy levels.
Questions
1.
2.
3.
4.
5.
6.
How is metabolism related to homeostasis?
Describe an environment in which metabolism
can occur.
How do humans get energy?
How are carbohydrates metabolized?
How are anabolism and catabolism related?
How is energy transferred from nutrients to the
body’s cells?
Questions Continued
7.
8.
9.
10.
11.
12.
13.
How does a body maintain its supply of ATP?
Why is osmosis necessary for metabolism?
Why is your metabolic rate different from an
alligator’s?
How does your metabolic rate compare to
small animals?
Do you use energy while sleeping? – Explain.
How will your body respond if you start
skipping meals?
How can you prevent lactic acid buildup? Why
do these techniques work?