Nutrition

1
Mariebs Human Anatomy and Physiology Ninth
Edition Marieb w Hoehn

• Chapter 24
• Nutrition Metabolism
• Lecture 12
• Part 2 Proteins, Metabolic States, Vitamins
  Minerals

2
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)
3
Utilization of Proteins
Figure from Holes Human AP, 12th edition, 2010

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

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

4
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

Figure from Holes Human AP, 12th edition, 2010
5
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

6
The Fed (Absorptive) State
Know this
Figure from Martini, Anatomy Physiology,
Prentice Hall, 2001
7
The Fasted (Postabsorptive) State
Know this
Figure from Martini, Anatomy Physiology,
Prentice Hall, 2001
8
Pyruvate is a Key Junction in Metabolism
Pyruvate is used to synthesize amino acids and
Acetyl CoA Pyruvate can also be used to
synthesize glucose via gluconeogenesis.
?Glycogenesis
Glycogenolysis ?
?Lipo-genesis
Lipolysis ?
Figure from Martini, Anatomy Physiology,
Prentice Hall, 2001
9
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)

10
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
11
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
12
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

13
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

14
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

15
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
16
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
17
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
18
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