Download Chap 23 –Nutrition, Part III

Chap 23 –Nutrition,
Part III (Energy
Metabolism)
Learning Objectives
The student will be able to:
1. Discuss the use of glucose as energy for our cells including
the storage of excess glucose as either glycogen or fat.
2. Explain metabolism.
3. Discuss the two types of metabolic processes (anabolism
and catabolism).
4. Describe the importance of cellular respiration (and its
components such as Kreb’s cycle).
5. Define ATP and explain its importance as the cell’s “energy
currency”.
6. Explain the 3 major stages involved in the processing of
energy-containing nutrients in the body.
Focus: Carb-Loading in Athletes
This runner has a marathon to
run in 3 days.
He is eating a diet heavy in
carbs (70% or more) and
reducing his activity prior to
the big race.
How will this make a difference
or will it?
Carb-Loading continued
When we eat carbs they are basically converted into
__________ (blood sugar) for our cells to use.
Sometimes, when we eat too much carbohydrate (more
than our bodies need at the present time), the reserve is
stored as either:
- ___ (*fats account for 80-85% stored energy)
- _________ (*accounts for the remaining15 – 20% and is
temporarily placed in the muscles).
So, the athlete’s goal is to eat so much carb that there is
excess stored as ________ in the muscle.
When exercising, ______ reserves from the muscles are
burned off first. In other words, glycogen is the most readily
available fuel. On average, you have to continue aerobic
exercise for more than 30 minutes to touch fat reserves.
Quick Check
• What is glycogen?
What is glucose?
Opening Question
• When we say “metabolism”, what are we
really talking about?
Discussion
Once food is digested, how do our cells
‘use’ the energy we consume from food?
Now, for the rest of the story…
The 2 Basic Metabolic Processes
Metabolic processes are either:
1. Anabolic - ________________
Example: The bonding together of amino
acids to make ________
2. Catabolic - _______________
Example: Digestion of food in the GI tract
3 Stages of Metabolism of EnergyContaining Nutrients
Stage 1
In a very simplified way we can say that…
- ________ are broken into amino acids
- _____ into glucose and other sugars
- ____ into glycerol and fatty acids
… which are taken up by the small intestine and
reach tissues via the bloodstream.
Stage 2 Glycolysis
• Occurs in the cell’s _________
• Newly delivered nutrients are either built into lipids,
carbs, and proteins through ___________ processes
OR
torn apart (broken down) by ___________ processes
into pyruvic acid and acetyl CoA
Stage 3 – Kreb’s
Cycle
• Occurs in the
__________ of the
cell
• Almost completely
____________
• Requires ___
• Completes the
breakdown of foods
• Produces ____,
________, and large
amounts of ______
What is ATP?
• An organic molecule known as
• _______________ that releases and
stores chemical energy for use in body
cells
• You will die without its production
Check out “Metabolic Poisons” page 849 in the section
called, “Homeostatic Imbalance”.
A Closer Look at Stage 3 (Kreb’s Cycle)
Named after the man who discovered it – Hans Kreb (Nobel Prize in Medicine, 1953)
Summary
• The average person at rest uses about
100 kcal/hour or roughly 116 watts which
is slightly more than a ______ _______.
• This corresponds to an energy capture
rate of about _____ making cells far more
efficient than any human-made machines
(which typically only use _______ of
energy available to them.
Chap 23 Wrap-Up & Review
• See handout
• Estimated time = 10 minutes
• If not able to finish in class, becomes
homework (use it to study for your next
exam as well)