Chapter 25: Metabolism and Nutrition
1. Generalize the way in which nutrients are processed through the three major
metabolic fates in order to perform various energetic and structural functions in the
2. Review carbohydrate metabolism in the GI tract, liver and body cells.
3. Describe the controlled, facilitated entry of glucose into different cell types, and the
means to capture and/or release it from specific cells.
4. Describe the processes of glycolysis (review in text), glycogenesis, glycogenolysis,
and gluconeogenesis. Describe starting materials and end products and which
hormones control each process.
5. Explain the formation and removal of chylomicrons from blood.
6. Discuss how lipids are transported in blood.
7. Discuss the sources of cholesterol and indicate the concentrations that are considered
as potential problems for coronary artery disease.
8. Describe how lipolysis breaks down the triglycerides into glycerol and fatty acids.
Explain where glycerol enters carbohydrate metabolism. Describe how fatty acids
undergo beta oxidation and where those products enter the carbohydrate metabolism
9. Describe ketogenesis and lipogenesis.
10. Trace the general path of amino acid absorption and use by the liver and the body as a
whole. List the hormones that have a role in controlling protein metabolism.
11. Describe the difference between essential and non-essential amino acids.
12. Distinguish between the major characters of the absorptive and postabsorptive state in
term of the conditions that establish the states and hormones that control the
13. Discuss the metabolic reactions that occur for glucose, amino acids, and lipids that
predominate during the absorptive state.
14. Describe how metabolism during the absorptive state is regulated.
15. Describe the reactions of the postabsorptive state.
16. Describe how metabolism during the postabsorptive state is regulated.
17. Discuss the seven guidelines for healthy eating.
18. Discuss the importance of minerals in the body.
19. Discuss the importance of vitamins in the body. Distinguish between water soluble
and lipid soluble vitamins.
20. Discuss when vitamin and mineral supplements should be taken.
Chapter Lecture Notes
Introduction to Metabolism
The food we eat is our only source of energy for performing biological work (Fig 25.1)
Three major metabolic destinations for the principle nutrients from food
used for energy for active processes
synthesized into structural or functional molecules
stored as fat or glycogen for later use
Don't have time to go over the central pathway of metabolism; the processes of glycolysis, Krebs
(TCA) cycle, and the electron transport chain/oxidative phosphorylation
Please review on your own to recall the pathways
Will not be tested on those pathways
Most metabolism based on the central pathway which involves glucose
Digestive system brings carbohydrate nutrients into body
polysaccharides broken down into simple sugars
absorption of simple sugars (glucose, fructose & galactose)
Liver gets first chance at processing the incoming nutrients
fructose & galactose transformed into glucose
excess glucose can be stored as glycogen (also in muscle)
can oxidize glucose to produce energy
can store glucose as glycogen (liver & muscle)
can convert glucose into fats or amino acids
can store energy as triglycerides in adipose tissue (limited amount in muscle)
Glucose Movement into Cells
In GI tract and kidney tubules
Most other cells
GluT facilitated diffusion transporters
insulin increases the insertion of GluT transporters in the membrane of most cells
in liver & brain, always lots of GluT transporters
Glucose 6-phosphate forms immediately inside cell (requires ATP) thus, glucose is "hidden"
when it is in the cell
concentration gradient remains favorable for more glucose to enter
Other Carbohydrate Pathways
Glycogenesis (Fig 25.11)
production of glycogen, a polysaccharide, for glucose storage
4 steps to glycogen formation in liver or
stimulated by insulin
Glycogenolysis (Fig 25.11)
breakdown of glycogen for glucose release to the bloodstream
not a simple reversal of steps
one of the enzymes of glycogenolysis, phosphorylase, is activated by glucagon (pancreas) or
epinephrine (adrenal gland)
the final enzyme of the glycogenolysis pathway, glucose-6-phosphatase, is only in
liver has the ability to release glucose to the bloodstream
muscle cannot release glucose but uses the glucose released from glycogen as an energy
source for ATP production
Gluconeogenesis - the conversion of protein or fat molecules into glucose (Fig 25.12)
glycerol (from fats) may be converted to glyceraldehyde-3-phosphate
some amino acids may be converted to pyruvic acid
stimulated by cortisol, thyroid hormone, epinephrine, glucagon, and human growth hormone
Lipid transport - most lipids are transported in the blood in combination with proteins as
Chylomicrons (2 % protein)
form in intestinal mucosal cells
transport exogenous (dietary) fat
VLDLs (10% protein) (Fig 25.13)
transport endogenous triglycerides (from liver) to fat cells
converted to LDLs
LDLs (25% protein) - "bad cholesterol"
carry 75% of blood cholesterol to body cells
HDLs (40% protein) - "good cholesterol"
carry cholesterol from cells to liver for elimination
Two sources of cholesterol
food we eat
For adults, desirable levels of blood cholesterol
TC (total cholesterol) under 200 mg/dl
LDL under 130 mg/dl
HDL over 40 mg/dl
Normally, triglycerides are in the range of 10-190 mg/dl
lipids are stored in the body as triglycerides in adipose tissue
Lipid catabolism lipolysis (Fig 25.14)
triglycerides are split into fatty acids and glycerol
stimulated by epinephrine, norepinephrine, or glucocorticoids
glycerol can be converted into glucose by conversion into glyceraldehyde-3-phosphate
beta oxidation fatty acids are broken down as carbon atom pairs
the resulting pairs are converted to acetyl-coA and enter the Krebs cycle
Lipid catabolism ketogenesis (Fig 25.14)
two acetyl-CoA (from beta oxidation) bond to form acetoacetic acid which can then be
converted to beta-hydroxybutyric acid and acetone (ketone bodies)
occurs in liver
diffuses to other tissues through bloodstream
heart muscle & kidney cortex prefer to use acetoacetic acid for ATP production
Lipid anabolism lipogenesis (Fig 25.14)
lipogenesis - conversion of glucose or amino acids into lipids
stimulated by insulin
occurs in liver and adipose cells
Digestion, absorption and transport
proteins are hydrolyzed into amino acids in small intestine
amino acids are absorbed by the capillaries of villi and enter the liver via the hepatic portal
English Language Arts and Mathematics Tests Preliminary Results Spring 2015 Administration Highlights The new Ohio State Tests in English language arts and mathematics were administered for the first time during the 2014-2015 school year. These tests were produced by the Partnership for Assessment of Readiness …
Employment Application Cummins Location: Today's Date: Reviewed By: Date available to start work: Print name in full: LAST FIRST MIDDLE Social Security No.: Salary expected: Present address: City: State & Zip Code: Previous addresses over the past 10 years: Email address: Phone No. & Area …
Live your life, enjoy your life A guide to using your health plan In a hurry? Pages 45 shows where to find your medical plan information online quickly at myuhc.com. Welcome We're glad you're here. While no one can predict t the future, , you …
Fetal Pig Dissection Labs Dr. J. Lim Objective: In this exercise you will examine the organization of the many body systems studied this semester in the context of a single specimen, the fetal pig. Be sure to identify the major organs as you explore the …