NVCC Bio 212

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Holes Human Anatomy and Physiology Tenth
Edition Shier w Butler w Lewis
Chapter 18Nutrition and Metabolism Lecture 10
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Lecture Overview

• Nutrition, nutrients, and metabolism
• Macronutrients
• Energy and energy requirements
• Vitamins
• Minerals
• Nutritional abnormalities
• Life-span changes

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Nutrients
Nutrients chemical substances supplied by the
environment required for survival (used for
growth, repair, or maintenance of the body)

• Macronutrients
• carbohydrates
• proteins
• fats

• Micronutrients
• vitamins
• minerals

• Essential Nutrients
• human cells cannot synthesize
• include certain fatty acids, amino acids,
  vitamins

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Review of General Metabolic Pathways
Overall goal of catabolism is to generate a pool
of 2- or 3-carbon molecules the intermediates
of metabolism as well as energy (ATP)
(6C)
(3C)
(2C)
Figure from Martini, Anatomy Physiology,
Prentice Hall, 2001
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Carbohydrates

• Sources
• sugars (simple)
• starches (complex) - usually from plant sources
• glycogen (complex) in meats
• cellulose (complex) is indigestible fiber

• Excesses lead to
• obesity
• dental caries
• nutritional deficits

• Deficiencies lead to
• metabolic acidosis
• weight loss

Recommended (Dietary) Daily Allowance (RDA) is
125-175g

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Utilization of Carbohydrates
Disaccharides Sucrose, lactose, and
maltose Monosaccharides Glucose, fructose,
galactose
Glucose is the bodys CHO energy source

• oxidized for energy
• production of certain molecules (ribose,
  deoxyribose)
• stored in liver and muscles as glycogen
• converted to fats and stored in adipose tissue

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Utilization of Carbohydrates
Glucose is the bodys CHO energy source
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Lipids

• Sources
• meats
• eggs
• milk
• lard
• plant oils

• Excesses lead to
• obesity
• increased serum cholesterol
• increased risk of heart disease

• Deficiencies lead to
• weight loss
• skin lesions
• hormonal imbalances

RDA is 80-100g (? 30 of calories) (? 10
saturated fat)
Fats generally take the longest to digest. Why?
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Utilization of Lipids
Figure from Saladin, Anatomy Physiology,
McGraw Hill, 2007
How is fat absorbed from the digestive tract?
Know these terms (see table of these terms later
in this lecture)

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Beta-Oxidation of Fatty Acids
Mitochondrion
Long chain fatty acids (FA) require carnitine for
transport into mitochondria FA are broken down
in a step-wise manner, 2 carbons at a time in
beta-oxidation Oxidation of FA yields about
1.5-2.0 times the energy from a comparable amount
of glucose
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Energy Values of Food
Calorie (kilocalorie, big calorie) amount of
heat needed to raise the temperature of 1 kg of
water by 10 C
Carbohydrates 4.1 Calories per gram
Diet is 2000 Calories. What is the maximum
number of grams of fat that should be taken in
daily?
Proteins 4.1 Calories per gram
How many grams of fat are there in a Whopper with
cheese and a small order of french fries?
Lipids 9.5 Calories per gram
Know this - you can round these off to the 4, 4,
and 9)
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Lipoprotein Traffic
Figure From Martini, Anatomy Physiology,
Prentice Hall, 2001
TG-rich
Cholesterol-rich
Cholesterol can be manufactured from Acetyl-CoA
Note the role of HDLs as scavengers of
tissue/blood cholesterol.
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Summary of Lipoproteins
Designation Origin Action
Chylomicron GI tract Transports dietary fats (mainly triglycerides) to liver for processing
Very Low Density Lipoprotein (VLDL) Liver Transports triglycerides from liver to adipose cells
Low Density Lipoprotein (LDL) Liver Transports cholesterol from liver to cells in body
High Density Lipoprotein (HDL) Liver Removes excess cholesterol from cells and transports to liver
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Utilization of Lipids
The liver uses fatty acids to synthesize a
variety of lipids
Linoleic, linolenic (plant oils)
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Proteins

• Sources
• meats
• cheeses
• nuts
• legumes

Excesses can lead to obesity

• Deficiencies lead to
• extreme weight loss
• muscle wasting
• anemia
• growth retardation

Incomplete proteins unable to maintain human
tissues or support normal growth and development
by themselves
RDA is 0.8g/kg body weight or 10 of diet (1 kg
2.2 lbs)
Essential amino acids (10 8 in adult) cannot be
synthesized by the body (isoleucine, leucine,
lysine, threonine, tryptophan, phenylalanine,
valine, and methionine arginine, histidine)
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Utilization of Proteins

• regulation of water balance
• control of pH
• formation of antibodies

• build cell structures
• enzymes
• hormones
• transport of oxygen

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Utilization of Proteins for Energy
Ammonia, NH3, or ammonium, NH4 Highly toxic,
even in small amounts Liver converts these to
urea, a harmless water-soluble compound that can
be excreted in the urine

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Transamination
Clinically important transaminases - Alanine
Transaminase (ALT) (also Alanine
Aminotransferase, Glutamic-Pyruvic Transaminase
(SGPT)) primarily for detecting liver disease
- Aspartate Transaminase (AST) (also Asparatate
Aminotransferase, Glutamic-Oxaloacetic
Transaminase (SGOT) detect cell death in
tissues with high metabolic activity
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Nitrogen Balance
Variety of compounds in the body contain nitrogen
(N) amino acids, purines, pyrimidines, creatine,
porphyrins. The body neither stores nor maintains
reserves of N. Theres only about 1 kg of N in
body at any one time. During starvation,
N-containing compounds, like skeletal muscle, are
conserved CHO and fats are metabolized first
(protein-sparing effect). Order of usage CHO,
fat, protein.

• nitrogen balance - amount of nitrogen taken in
  is equal to amount excreted
• negative nitrogen balance develops from
  starvation
• positive nitrogen balance develops in growing
  children, pregnant women, or an athlete in
  training

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The Fed (Absorptive) State
Know this
Figure from Martini, Anatomy Physiology,
Prentice Hall, 2001
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The Fasted (Postabsorptive) State
Know this
Figure from Martini, Anatomy Physiology,
Prentice Hall, 2001
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Metabolism
Hormones Fed Insulin Fasted Glucagon,
Corticosteroids, Epi/NE
-olysis ? breakdown of -neo ? new-genesis ?
creation of

• Glycolysis metabolism of glucose to pyruvate
  (Fed)
• Gluconeogenesis metabolism of pyruvate to
  glucose (CHO from non-CHO source) (Fasted)
• Glycogenesis metabolism of glucose to glycogen
  (Fed)
• Glycogenolysis metabolism of glycogen to
  glucose (Fasted)
• Lipolysis breakdown of triglyceride into
  glycerol and fatty acids (Fasted)
• Lipogenesis creation of new triglyceride (fat)
  (Fed)

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Energy Requirements

• Basal metabolic rate (BMR)
• rate at which body expends energy at rest
  (kcal/hr)
• primarily reflects energy needed to support
  activities of organs
• varies with gender, body size, body temperature,
  and endocrine function

BMR is proportional to body weight Bodys basal
metabolic rate (BMR) falls 10 during sleep and
about 40 during prolonged starvation

• Energy needed
• to maintain BMR
• to support resting muscular activity
• to maintain body temperature
• for growth in children and pregnant women

BMR is profoundly affected by circulating thyroid
hormone levels
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Energy Balance

• occurs when caloric intake in the form of food
  equals caloric output from BMR and muscular
  activities
• positive energy balance leads to weight gain
• negative energy balance leads to weight loss

Body Mass Index (BMI) Wt (kg) / Height2 (m)
Thin lt 18.5
Healthy or Normal 18.5 24.9
Overweight 25.0 29.9
Obese 30.0 39.9
Morbidly Obese ? 40.0
Source World Health Organization
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Overview of Vitamins

• Organic substances required in small amounts that
  are not synthesized in adequate amounts to meet
  the bodys needs
• Divided into two groups by solubility
• Water-soluble vitamins B (group) and C
• Not generally stored
• Excesses are excreted, e.g., in urine
• Fat-soluble vitamins A, D, E, and K
• Stored in liver, adipose, other tissues
• Excesses accumulate in tissues

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The Fat-soluble Vitamins

• Absorbed with fats in digestive tract
• Function/Other sources
• Vitamin A structural component of retinal
• Vitamin D
• increases absorption of calcium and phosphorus
  from intestine
• skin and UV light
• Vitamin E
• stabilizes internal cellular membranes
• antioxidant
• Vitamin K
• Clotting (Klotting)
• bacteria in intestine and green, leafy vegetables

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Deficiency/Excess of Fat-soluble Vitamins

• Deficiency (avitaminosis)
• Rarely occurs in developed countries
• Stored in adipose tissues
• Deficiencies from other causes more common
• Insufficient absorption
• Inadequate storage
• Excess (hypervitaminosis)
• Excessive intake
• Inability to excrete
• Vitamin toxicity

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Water-soluble Vitamins

• Rapidly exchanged between fluid compartments of
  digestive tract and circulating blood
• Excesses excreted in urine
• Vitamins B12 and C are stored in larger
  quantities than other water-soluble vitamins
• B vitamins know these functions
• as a group, are coenzymes used to harvest energy
• Vitamin B12 is important in hematopoiesis and
  maintenance of myelin sheath and epithelial cells
• Vitamin C (ascorbic acid) know these functions
• collagen production
• Antioxidant / immune system booster
• ? absorption of iron

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History of USDAs Food Guidance
Slide from http//www.mypyramid.gov/downloads/MyP
yramid20Peer20to20Peer.ppt
Food for Young Children
1992
1916
1940s
1970s
2005
1950s-1960s
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New Food Pyramid (2005)
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Food Pyramid
From http//www.mypyramid.gov/downloads/MyPyramid
20Peer20to20Peer.ppt
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Malnutrition

• poor nutrition
• undernutrition deficiency of essential
  nutrients
• overnutrition excess of nutrient intake
• primary malnutrition malnutrition from diet
  alone
• secondary malnutrition diet is sufficient but
  nutrients cannot be absorbed, e.g., insufficient
  bile

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Starvation

• person can survive 50-70 days without food (but
  vitamin deficiencies and their effects begin to
  appear after a week or two)
• symptoms include metabolic acidosis, low blood
  pressure, slow pulse, chills, dry skin, hair
  loss, and poor immunity
• Marasmus lack of all nutrients
• Kwashiorkor protein starvation
• Anorexia nervosa eating disorder
  self-starvation
• Bulimia eating disorder bingeing and purging

Body will adapt to starvation by using CHO first,
then fats, and finally protein

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Regulation of Appetite
Figure from Saladin, Anatomy Physiology,
McGraw Hill, 2007
Also see Table 18.2 in Hole
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I didnt want to say anything, Dear, but
A mutation in the leptin gene in the ob/ob mouse
(Right) leads to morbid obesity and provides an
excellent experimental model.
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Life-Span Changes

• BMR rises in early childhood and peaks in
  adolescence
• BMR declines in adulthood
• change in nutrition often reflects effects of
  medical conditions and social and economic
  circumstances

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Review
Mineral Symbol Major/Trace Primary Distribution Major Function(s) Major Sources Conditions
Calcium Ca Major Bones Teeth Structure of bone/teeth nerve impulse conduction muscle contraction milk kidney stones - stunted growth
Phosphorus P Major Bones Teeth Structure of bone/teeth ATP Nucleic acid proteins meats cheese milk none - stunted growth
Potassium K Major Intracellular Fluid maintenance of resting membrane potential (RMP) avocados bananas potatoes none - muscular cardiac problems
Sulfur S Major skin, hair, nails essential part of amino acids, thiamine, insulin, biotin, and MPS meats milk eggs none - none
Sodium Na Major Extracellular Fluid maintenance of RMP, electrolyte, water, pH balance table salt cured ham hyperten-sion, edema - cramps, convulsions
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Review
Mineral Symbol Major/Trace Primary Distribution Major Function(s) Major Sources Conditions
Chlorine Cl Major Extracellular Fluid maintenance of RMP, electrolyte, water, pH balance table salt cured ham vomiting - muscle cramps
Magnesium Mg Major Bones needed in mitochondria for cellular respiration ATP/ADP conversion milk dairy legumes diarrhea - neuro-muscular problems
Iron Fe Trace Blood part of hemoglobin liver liver damage - anemia
Manganese Mn Trace liver, kidneys occurs in many enzymes nuts none - none
Copper Cu Trace liver, heart, brain essential in synthesis of hemoglobin, bone, melanin, myelin liver oysters crabmeat rare - rare
Iodine I Trace thyroid essential in the synthesis of thyroid hormones iodized table salt thyroid hormone imbalance - goiter
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Review
Mineral Symbol Major/Trace Primary Distribution Major Function(s) Major Sources Conditions
Cobalt Co Trace widely distributed component of cyanocobalamin (B12) liver lean meats heart disease - pernicious anemia
Zinc Zn Trace liver, kidneys, brain wound healing part of several enzymes meats cereals slurred speech - decreased immunity
Fluorine F Trace bones teeth tooth structure fluorida-ted water mottled teeth - none
Selenium Se Trace liver kidney occurs in enzymes lean meats cereals vomiting, fatigue - none
Chromium Cr Trace widely distributed essential for use in carbohydrates liver lean meats none - none
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Review

• Metabolism and fate of macronutrients
• Carbohydrate
• Broken down into monosaccharides
• Metabolism, glycogen, fat, pentose sugars
• Lipids
• Saturated vs. unsaturated fats
• Broken down into glycerol and fatty acids
• Used for energy (or storage of energy)
• Proteins
• Complete vs. incomplete proteins
• Broken down into amino acids
• Structural components or energy

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Review

• Fat-soluble vitamins
• Excesses are stored in tissues (liver, adipose)
  and not excreted may become toxic
• Includes vitamins A, D, E, and K
• For exam see Table 18.8 on p. 708 and know the
  functions of the fat-soluble vitamins
• Water-soluble vitamins
• Excesses are excreted, e.g., urine
• Vitamins B and C
• For exam see Table 18.9 on p. 713
• B vitamins know name/designation and know that
  the B vitamins are coenzymes that function in
  energy metabolism
• Vitamin C know its name and functions