Sports Nutrition_Chapter 2_Nutrients

1. Nutrients:
Ingestion to
Energy
Metabolism
Chapter 2

2. What happens to nutrients after they are
ingested?
• Two types of digestion
– Mechanical: includes chewing, peristalsis
– Chemical: includes digestion enzymes
• Absorption
• Transport
• Assimilation and/or energy production

3. Digestion: Anatomy and Functions of the
Digestive System
Mouth to anus is 25 ft!
• Mouth (oral cavity)
• Esophagus
• Stomach
• Small intestine
• Large intestine
• Rectum

4. Digestion: Salivary Glands
• Salivary glands
– See figure to right
• Secrete saliva
– Moistens food
– Contains enzymes

5. Digestion: Stomach
• Muscular organ
• Primary function:
digestion
• Major secretions
– Hydrochloric acid
to unravel proteins
– Mucus to protect
stomach tissue from
acid.
– Digestive enzymes

6. Digestion and Absorption:
Small Intestine
• Duodenum
– Majority of digestion
occurs here
• Jejunum
– Little digestion
– Absorption
• Ileum
– Absorption

7. Absorption: Surface of Small Intestine
• Convoluted interior
• Villi
• Microvilli
• Result: Increased
surface area for
absorption

8. Absorption: Large Intestine
• Colon
– Ascending
– Transverse
– Descending
• Rectum
• Anus
• Some absorption
– Water
– Sodium
– Chloride
– Potassium
– Vitamin K

9. Absorption: Mechanisms
• Passive diffusion – move from high to low
concenration
• Facilitated diffusion- move from high to low
concentration carried by protein carrier.
• Active transport – Concentration gradient not a
factor.
• Endocytosis

10. Absorption: Mechanisms
• Passive diffusion
• Facilitated diffusion
• Active transport
• Endocytosis

11. Absorption of Nutrients
Review this figure
to see where along
the GI tract
individual
nutrients are
absorbed.

12. Carbohydrates: Digestion
• Mouth
– Mastication
(chewing)
– Amylase
• Stomach
– Churning
– Acid
• Small intestine
– Sugar enzymes
• Large intestine
– Bacteria

13. Carbohydrates: Absorption
• Most absorption occurs
in small intestine
• Mechanisms
– Facilitated diffusion
• Fructose
– Active transport
• Glucose
• Galactose

14. Carbohydrates: After Absorption
• Transport via blood
• Cellular uptake
– Insulin
– Glucose transporters
• Fates
– Storage in liver or
muscles as glycogen.
– Conversion to
adipose tissue (fat).
– Energy

15. Fats: Digestion
• Mouth
– Mastication
– Lingual lipase [Insert Fig. 2.12 here]
• Stomach
– Gastric lipase
• Small intestines
– Bile
– Pancreatic lipase
– Micelle formation

16. Fats: Absorption
• Occurs in small intestine
• Mechanism
– Passive diffusion
• Very little fat makes it to
large intestine
– Steatorrhea
– Crohn’s disease
– Cystic fibrosis

17. Fats: After Absorption
• Transport
– Lymph
• Chylomicrons
– Blood
• Cellular uptake
– Lipoprotein lipase
• Fates
– Storage
– Energy

18. Proteins: Digestion
• Mouth
• Mastication
• Stomach
• Churning
• Acid Denaturation: acid unravels proteins so
peptide bonds can be cleaved by enzymes. Very
important function of the stomach.
• Small intestine
• Proteases
• Peptidases

19. Proteins: Absorption
• Occurs in small intestine
• Mechanism
– Facilitated diffusion
– Active transport
• Very little makes it to large intestine

20. Proteins: Absorption
AMINO ACID SUPPLEMENTATION
CAUTION
• Carrier proteins are responsible for facilitating absorption of amino
acids.
• Similar amino acids share the same active transport systems and
protein carriers.
• Taking amino acid supplements containing large amounts of single
amino acids can affect the absorption of other amino acids if they
share the same transport carrier.
• If an athlete takes a large amount of a single amino acid this may
result in overabsorption of that amino acid at the expense of another
amino acid.

21. Proteins: After Absorption
• Transport
– Blood
• Become part of amino acid pool
• Fates
– Body proteins such as
muscle, enzymes,
hormones.
– Conversion to body fat.
– Energy : Used for energy
only when carbohydrate is
not available fuel source.
Not preferred fuel source as
it has more important and
essential roles in body.

22. Cellular Protein Synthesis
• Transcription
– DNA
– mRNA
• Translation
– Transfer RNA
– Amino acids

23. Vitamins, Minerals, and Water
• Digestion causes release from foods
• Absorption occurs in small and large intestines

24. What is energy?
• It is the entity that
enables our bodies to
perform work.
• It has no shape.
• It has no physical mass.
• Our bodies rely on
chemical energy.
Photo © Photodisc

25. What is the body’s source of energy?
• Macronutrients
– Carbohydrates
– Fats
– Proteins
• Body’s direct energy
source
– Adenosine
triphosphate (ATP)

26. Adenosine Triphosphate (ATP)
• Body’s energy source
• Two high-energy
bonds
• Other phosphates
– ADP
– AMP

27. Cell Structure and Organelles Necessary
for ATP Production

28. What are the three energy systems?
• Phosphagen System
• Anaerobic Energy System
• Aerobic Energy System

29. Comparison of the Three Energy Systems

30. Metabolic Pathways

31. Energy Nutrients

32. Cellular ATP Production:
The Metabolic Factory

33. Phosphagen Energy System
• Stores of high-energy
phosphates
– ATP
– Creatine phosphate
(CP)
• Also known as:
– Immediate energy
system
– ATP-CP system

34. Anaerobic Energy System
• Involves only
carbohydrates
• Does not require oxygen
• Also known as:
– Anaerobic glycolysis

35. Aerobic Energy System
• Involves all
macronutrients
• Requires oxygen
• Also known as:
– Oxidative system

36. Energy System Contributions to
Activities of Varying Intensity
The small storage pool
of ATP is the source of
energy whenever
instantaneous energy is
needed.

37. Energy System Contributions to
Activities of Varying Intensity
During short bursts of
intense activity (i.e.,
100m run), the
phosphagen system is
the main energy system
that supplies the ATP
pool.

38. Energy System Contributions to
Activities of Varying Intensity
During longer lasting
sprint activities of lower
intensity (i.e., 800m
run), the main supplier
is the anaerobic system
with help from the
phosphagen and aerobic
systems.

39. Energy System Contributions to
Activities of Varying Intensity
During longer lasting
activities of even lower
intensity (i.e., mile run),
the main supplier
becomes the aerobic
system with help from
the anaerobic system.

40. Energy System Contributions to
Activities of Varying Intensity
During long lasting
activities of low
intensity (i.e., any
sustainable activity), the
main supplier becomes
the aerobic system with
minimal help from the
other systems.

41. Summary:
The Energy Systems Work
Together to Meet ATP Demand

42. How does carbohydrate intake impact
protein metabolism?
• Carbohydrates are an
important energy
source.
• Low CHO results in
muscle protein
breakdown.
• Gluconeogenesis.