A&p Ii: Chapter 24

Front 1

NUTRITION

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A. NUTRIENT: portion of food used to promote growth, maintenance and repair of body (general term)

1. MAJOR NUTRIENTS: make up the bulk of our food
a. CARBOHYDRATES all major nutrients are shuffled around by body to
b. LIPIDS form what it needs: interconvertable energy sources
c. PROTEINS
d. WATER

2. MINOR NUTRIENTS: make up the lesser portion of our food
a. VITAMINS
b. MINERALS

3. ESSENTIAL NUTRIENTS: cannot be made by the body - must be taken in through the
diet (some: amino acids, fatty acids,vitamins)

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NUTRITION 2

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B. CARBOHYDRATES: sugars and starches (energy source of choice)
1. glucose (sugar) taken into the cells, broken down to make ATP
2. DEOXYRIBOSE, RIBOSE (sugars) found in nucleic acids DNA, RNA

C. LIPIDS: fats, triglycerides, cholesterol (second main energy source, used by all tissues except brain)
1. cushion, insulate, store energy
2. help absorb fat-soluble vitamins
3. triglycerides: major energy source for skeletal m. and liver
4. phospholipids: main component of cell membr. and myelin sheath
5. cholesterol forms part of cell membranes, bile salt precursor, steroid hormone precursor,
vitamin D precursor, etc..

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NUTRITION 3

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D. PROTEINS: made of amino acids - not a big energy source
1. structural proteins: collagen, elastin, muscle (actin, myosin…), hair & nails (keratin)
2. functional proteins: enzymes, hemoglobin, hormones, antibodies

E. VITAMINS: organic compounds needed in minute amounts for growth and good health
1. not broken down for energy, not building blocks
2. COENZYMES: act w/enzyme to accomplish a particular reaction
3. most are taken in by diet, few are made by body including:
a. VIT D: skin b. VIT K, VIT B: intestinal bacteria
c. VIT A: from breakdown of carotene
4. FAT SOLUBLE: A,D,E,K bind with lipids for absorption into GI tract. All except K are
stored, toxic if taken in excess
5. WATER SOLUBLE: B-complex (except B12), C. Absorbed with water into GI tract. Not
stored, if in excess, excreted in urine

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NUTRITION 4

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F. MINERALS: Ca, P, K, S, Na, Cl, Mg in moderate concentrations & minute amts of other elements
1. not used for fuel
2. strengthen tissues: bones, teeth
3. help to form organic compounds
4. Na, Cl ions help maintain water balance and responsiveness of neurons and muscle cells
5. may be toxic if ingested in mass quantities

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ANABOLISM

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synthesis reactions, making new, larger products
1. store energy in bonds
2. energy comes from the breakdown of ATP, this energy is used to form new bonds to build
new molecules. ATP is the energy currency all cells of the body understand

ATP ---> ADP + P + energy (used to make new bonds, do cellular work, heat)


3. examples:
a. GLUCONEOGENESIS: formation of glucose from non-carbohydrate sources (fats and
proteins)
b. GLYCOGENESIS: formation of glycogen from glucose
glucose + ATP --> glycogen + water + ADP + P
c. PROTEIN SYNTHESIS:
amino acids + ATP --> proteins + water + ADP + P
d. LIPOGENESIS: formation of lipids
glycerol + fatty acids + ATP -> triglyceride + water + ADP + P

Front 6

CATABOLISM

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decomposition reactions, making new, smaller products
1. release energy as break bonds: energy used to make ATP, or released as heat or stored
in temporary energy storage molecules: NADH and FADH2 to be stored in ATP later

2. TWO MAIN CATABOLIC PROCESSES
a. HYDROLYSIS: use of water to help break bonds (digestion)
1) GLYCOGENOLYSIS: breakdown of glycogen into monosaccharides
glycogen + water -> glucose + ATP

2) LIPOLYSIS: breakdown of lipids into fatty acids and monoglycerides
3) PROTEOLYSIS: breakdown of proteins into amino acids

b. CELLULAR RESPIRATION: use of oxygen to break bonds

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CELLULAR RESPIRATION

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uses O2 to get energy out of carbs, prot., fats

A. GETTING ENERGY FROM CARBOHYDRATES: IE MONOSACCHARIDES: involves a
series of complicated reactions grouped into 3 main processes

1. GLYCOLYSIS: occurs in cytoplasm, no O2 is required (anaerobic)

glucose -> 2 pyruvic acid + energy (to make ATP)

a. if no O2 present, ANAEROBIC RESPIRATION continues

pyruvic a. -> lactic a. -> to liver converted to waste or carbohydrate

b. if O2 present AEROBIC RESPIRATION continues

pyruvic a. -> to mitochondrion, converted to acetyl Coenzyme A (ACoA)

Front 8

CELLULAR RESPIRATION 2

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2. KREBS CYCLE: occurs in the mitochondrion in presence of O2

ACoA -> CO2 + H+ energy (used to make ATP, NADH, FADH2)

3. ELECTRON TRANSPORT CHAIN occurs in the mitochondrion

H+ + O2 + FADH2 + NADH --> energy (to form ATP) + water

4. NET AEROBIC REACTION yields 36-38 ATP per glucose

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GETTING ENERGY FROM PROTEINS

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: proteolysis
1. not a prime energy source, used only if in excess or if have low carbs and fats. Usually,
proteins are broken down and reorganized into new proteins.

2. DEAMINATION: removal of NH2 from amino acids
a. occurs in liver, NH2 excreted as urea
b. remainder = KETOACID

3. KETOACID -> pyruvic acid -> ACoA -> Krebs cycle, ETC -> CO2, H20, ATP

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GETTING ENERGY FROM LIPIDS

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lipolysis
1. fatty acids & triglycerides: important source of energy used in all parts of body except brain

2. TRIGLYCERIDE -> glycerol + 3 fatty acids

glycerol -> glycolysis -> Krebs -> ETC -> ATP, H2O, CO2

FATTY ACIDS -> beta oxidation -> ACoA -> Krebs, ETC -> ATP, H2O, CO2

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BODY ENERGY BALANCE

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A. CALORIE: C = MEASUREMENT OF ENERGY LIBERATED FROM CATABOLISM OF FOOD
1C = energy needed to raise temperature of 1 Kg of water 1 degree C

B. energy liberated is used in three ways:
1. physical activity: energy used to do work
2. thermogenesis: 60% released as heat
3. energy storage: as fat or glycogen (only during growth and fat storage)

C. BASAL METABOLIC RATE (BMR): energy the body needs to perform essential activities
(breathing, maintaining resting levels of: neural, cardiac, liver, and kidney function). varies with:
^age decrease BMR
sex (and muscle mass) males, more muscle mass higher BMR
^surface area of body/volume, ^BMR (ie tall,thin vs short,fat)
ingestion of food ^BMR
fever, stress ^BMR
hormones: especially THYROXINE from thyroid gland (^BMR)

D. TOTAL METABOLIC RATE (TMR): rate of kilocalorie consumption to fuel all ongoing activities

TMR = BMR + voluntary activities (skeletal muscle contraction, food ingestion)

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REGULATION OF BODY TEMPERATURE

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A. AT REST: 70% heat production from liver, heart, brain and endocrine organs, 30% from inactive
skeletal muscles (muscle tone)

B. ACTIVITY: skeletal muscles make up the bulk of heat production



C. HOMEOSTASIS: keep body between 35.6 C to 37.8 C (96-100 F)
1. temp too low: depressed rate of reactions
2. temp too high: enzymes stop working, proteins denature
3. blood is the major heat transfer agent: brings heat from body core to the surface to be released

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REGULATION OF BODY TEMPERATURE 2

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4. HYPOTHALAMUS: thermoregulatory center in the brain
a. for heat production/conservation, hypothalamus stimulates:
i. vasoconstriction of surface vessels
ii. increase metabolic rate (chem. reactions)
iii. shivering
iv. release of thyroxine (thyroid hormone)

b. for heat loss, hypothalamus stimulates:
i. vasodilation of surface vessels
ii. sweating
iii. increased respiratory rate