Nutrition and Metabolism
Chapter 17
Copyright © 2016 by Elsevier Inc. All rights reserved.
1
Learning Objectives
Lesson 17.1: Nutrition and Metabolism
1.
2.
3.
4.
Explain metabolism, and define and contrast
catabolism and anabolism.
Describe the metabolic roles of
carbohydrates, fats, proteins, vitamins, and
minerals.
Define basal metabolic rate and list some
factors that affect it.
Discuss the physiological mechanisms that
regulate body temperature.
Copyright © 2016 by Elsevier Inc. All rights reserved.
2
Definitions

Nutrition


Metabolism


Process of using food molecules as energy sources
and as building blocks for our own molecules
Catabolism


Food, vitamins, and minerals that are ingested and
assimilated into the body (Figure 17-1)
Breaks food molecules down, releasing their stored
energy; oxygen used in catabolism
Anabolism

Builds food molecules into complex substances
Copyright © 2016 by Elsevier Inc. All rights reserved.
3
Food Guide
www.ChooseMyPlate.gov is hosted by the United States Department of Agriculture (USDA).
Copyright © 2016 by Elsevier Inc. All rights reserved.
4
Metabolic Function of the Liver





Secretes bile, which breaks down large fat
globules
Helps maintain normal blood glucose level
Helps metabolize carbohydrates, fats, and
proteins
Synthesizes several kinds of protein
compounds
Removes toxins from the blood
Copyright © 2016 by Elsevier Inc. All rights reserved.
5
Macronutrients

Dietary sources of nutrients



Macronutrients: Carbohydrates, fats, and proteins
Micronutrients: Vitamins and minerals
Carbohydrate metabolism


Carbohydrates are preferred energy food of the
body
Three series of chemical reactions in glucose
metabolism (Figure 17-2)
1.
Glycolysis



Changes glucose to pyruvic acid
Anaerobic (uses no oxygen)
Occurs in cytoplasm
Copyright © 2016 by Elsevier Inc. All rights reserved.
6
Macronutrients (Cont.)

Carbohydrate metabolism

Three series of chemical reactions in glucose
metabolism
2.
Citric acid (Krebs) cycle



3.
Changes pyruvic acid to carbon dioxide
Aerobic (requires oxygen)
Occurs in mitochondria
Electron transfer system (ETS)


Transfers energy from high-energy electrons (from citric
acid cycle) to ATP molecules
Located in mitochondria
Copyright © 2016 by Elsevier Inc. All rights reserved.
7
Metabolism of Glucose
Copyright © 2016 by Elsevier Inc. All rights reserved.
8
Macronutrients (Cont.)

Carbohydrate metabolism



The mitochondrial part of the pathway (citric acid
cycle and electron transport system) is aerobic
(requires oxygen) and generates up to 36 ATP
molecules per original glucose molecule
Carbohydrates are primarily catabolized for energy
Adenosine triphosphate (ATP)
•
•
Molecule in which energy obtained from breakdown of
foods is stored
Serves as a direct source of energy for cellular work
(Figure 17-3)
Copyright © 2016 by Elsevier Inc. All rights reserved.
9
Macronutrients (Cont.)

Carbohydrate metabolism

Storage of glucose
•
•
Glucose that is not needed immediately for making ATP is
stored as glycogen (a long chain of glucose subunits) in the
liver and muscle cells
Glycogenesis

•
Anabolic process of joining glucose molecules together in a
chain to form glycogen (to store glucose for later use)
Glycogenolysis

Catabolic process of breaking apart glycogen chains,
releasing individual glucose molecules for use in making ATP
Copyright © 2016 by Elsevier Inc. All rights reserved.
10
Adenosine Triphosphate (ATP)
Copyright © 2016 by Elsevier Inc. All rights reserved.
11
Macronutrients (Cont.)

Carbohydrate metabolism

Blood glucose (imprecisely, blood sugar)
•
•

Fat metabolism


Normally stays between about 80 and 110 mg per 100
mL of blood during fasting
Insulin accelerates the movement of glucose out of the
blood into cells, therefore decreases blood glucose and
increases glucose catabolism
Catabolized to yield energy and anabolized to
form adipose tissue (Figure 17-4)
Protein metabolism

Primarily anabolized and secondarily catabolized
Copyright © 2016 by Elsevier Inc. All rights reserved.
12
Catabolism of Nutrients
Copyright © 2016 by Elsevier Inc. All rights reserved.
13
Micronutrients

Vitamins


Organic molecules that are needed in small amounts
for normal metabolism (Table 17-3)
Minerals

Inorganic molecules found naturally in the earth,
required by the body for normal function (Table 17-4)
Copyright © 2016 by Elsevier Inc. All rights reserved.
14
Major Vitamins
Copyright © 2016 by Elsevier Inc. All rights reserved.
15
Major Minerals
Copyright © 2016 by Elsevier Inc. All rights reserved.
16
Regulating Food Intake

Hypothalamic centers



Appetite center: Promotes feeling of hunger
Satiety center: Promotes feeling that we are
satisfied or “full”
Our body’s regulation of food intake is
complex with many factors including:






Hormones
Neurotransmitters
Emotions
Environmental cues
Food sensations
Habits
Copyright © 2016 by Elsevier Inc. All rights reserved.
17
Metabolic Rates

Basal metabolic rate (BMR)


Rate of metabolism when a person is resting but
awake, is not digesting food, and is comfortably
warm
Total metabolic rate (TMR)

Total amount of energy (expressed in calories)
used by the body per day (Figure 17-5)
Copyright © 2016 by Elsevier Inc. All rights reserved.
18
Basal and Total Metabolic Rates
Copyright © 2016 by Elsevier Inc. All rights reserved.
19
Body Temperature

Hypothalamus


Regulates the homeostasis of body temperature
(thermoregulation) through a variety of processes
Skin

Can cool the body by losing heat from the blood
through four processes: radiation, conduction,
convection, and evaporation (Figure 17-6)
Copyright © 2016 by Elsevier Inc. All rights reserved.
20
Mechanisms of Heat Loss
Copyright © 2016 by Elsevier Inc. All rights reserved.
21
Questions?
Copyright © 2016 by Elsevier Inc. All rights reserved.
22