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Chapter 22Nutrition and Metabolism
Lecture 10
Martini’s VisualAnatomy and Physiology
First Edition
Martini Ober
2
Lecture Overview
• Nutrition, nutrients, and metabolism
• Macronutrients
• Energy and energy requirements
• Vitamins
• Minerals
• Nutritional abnormalities
• Life-span changes
3
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
4
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)
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
(3C)
(2C)
(6C)
5
Carbohydrates
Sources• sugars (simple)• starches (complex) - usually from plant sources• glycogen (complex) in meats• cellulose (complex) is indigestible fiber
Recommended (Dietary) Daily Allowance (RDA) is 125-175g
Excesses lead to • obesity• dental caries• nutritional deficits
Deficiencies lead to • metabolic acidosis• weight loss
*
7
Utilization of Carbohydrates
Glucose is the body’s CHO energy sourceFigure from: Hole’s Human A&P, 12th edition, 2010
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LipidsSources
• meats• eggs• milk• lard• plant oils
RDA is 80-100g ( 30% of calories)( 10% saturated fat)
Excesses lead to • obesity• increased serum cholesterol• increased risk of heart disease
Deficiencies lead to • weight loss• skin lesions• hormonal imbalances
Fats generally take the longest to digest. Why?
9
Utilization of Lipids
How is fat absorbed from the digestive tract?
Know these terms (see table of these terms later in this lecture)
Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007
*
Oxaloacetic acid
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Energy Values of Food
Carbohydrates4.1 Calories per gram
Lipids9.5 Calories per gram
Proteins4.1 Calories per gram
Calorie (kilocalorie, big calorie) – amount of heat needed to raise the temperature of 1 kg of water by 10 C
Diet is 2000 Calories. What is the maximum number of grams of fat that should be taken in daily?
How many grams of fat are there in a Whopper with cheese and a small order of french fries?
Know this - you can round these off to the 4, 4, and 9)
12
Lipoprotein Traffic
Figure From: Martini, Anatomy & Physiology, Prentice Hall, 2001
Note the role of HDLs as scavengers of tissue/blood cholesterol.
TG-richCholesterol-rich
*Cholesterol can be manufactured from Acetyl-CoA
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Summary of LipoproteinsDesignation 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
Know this chart
14
Utilization of Lipids
The liver uses fatty acids to synthesize a variety of lipids
Triglyceride
Linoleic, linolenic (plant oils)
Figure from: Hole’s Human A&P, 12th edition, 2010
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Proteins
Sources• meats• cheeses• nuts• legumes
*RDA is 0.8g/kg body weight or 10% of diet(1 kg = 2.2 lbs)
Excesses can lead to obesity
Deficiencies lead to • extreme weight loss• muscle wasting• anemia• growth retardation
Essential amino acids (10; 8 in adult)– cannot be synthesized by the body (isoleucine, leucine, lysine, threonine, tryptophan, phenylalanine, valine, and methionine; arginine, histidine)
Incomplete proteins – unable to maintain human tissues or support normal growth and development by themselves
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Utilization of Proteins
• build cell structures• enzymes• hormones• transport of oxygen
• regulation of water balance• control of pH• formation of antibodies
Figure from: Hole’s Human A&P, 12th edition, 2010
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Utilization of Proteins for EnergyAmmonia, 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
*Figure from: Hole’s Human A&P, 12th edition, 2010
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Nitrogen Balance
• 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
Variety of compounds in the body contain nitrogen (N): amino acids, purines, pyrimidines, creatine, porphyrins.
The body neither stores nor maintains reserves of N. There’s 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.
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The “Fed” (Absorptive) State
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Know this
21
The “Fasted” (Postabsorptive) State
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001Know this
22
Metabolism
• 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)
-olysis breakdown of -neo new-genesis creation of
Hormones: Fed – Insulin Fasted – Glucagon, Corticosteroids, Epi/NE
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Energy RequirementsBasal 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
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
BMR is proportional to body weight
Body’s basal metabolic rate (BMR) falls 10% during sleep and about 40% during prolonged starvation
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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 < 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 body’s 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 (‘K’lotting)• bacteria in intestine and green, leafy vegetables
*
28
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
29
History of USDA’s Food Guidance
1940s
1950s-1960s
1970s
1992
2005
Food for Young
Children
1916
Slide from: http://www.mypyramid.gov/downloads/MyPyramid%20Peer%20to%20Peer.ppt
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USDA Food Pyramid(2005) and Food Plate (2011)
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Food Pyramid
From: http://www.mypyramid.gov/downloads/MyPyramid%20Peer%20to%20Peer.ppt
Harvard School of Public Health
32Source: http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/pyramid/
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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
*
36
I didn’t 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.
38
Review
*Mineral *Symbol *Major/Trace Primary Distribution
*Major Function(s)
MajorSources
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
39
Review
*Mineral *Symbol *Major/Trace Primary Distribution
*Major Function(s)
MajorSources
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;oysterscrabmeat
+ rare- rare
*Iodine I Trace thyroid essential in the synthesis of thyroid hormones
iodized table salt
+ thyroid hormone imbalance- goiter
40
Review
*Mineral *Symbol *Major/Trace Primary Distribution
*Major Function(s)
MajorSources
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- decreasedimmunity
Fluorine F Trace bones & teeth tooth structure fluorida-ted water
+ mottled teeth- none
Selenium Se Trace liver & kidney occurs in enzymes lean meatscereals
+ vomiting, fatigue- none
Chromium Cr Trace widely distributed essential for use in carbohydrates
liver;lean meats
+ none- none
41
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
42
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