營養學. 營養學 Nutrition ~ Water (H 2 O) ~

Transcription

1 營養學 營養學 Nutrition ~ Water (H 2 O) ~ 謝明哲 M.J.Shieh 臺北醫學大學公共衛生暨營養學院 保健營養學系 研究所 clark@tmu.edu.tw 1

2 Outline Function Homeostasis Requirement Deficiency syndrome Water Toxicity 2

3 Water (H 2 O) ~ An essential and major component of all living matter 3

4 Carbohydrate Lipid Source of energy Minerals Vitamins Water Growth and maintenance of tissue Regulation of body processes protein 4

5 Source of energy Carbohydrates Lipids Proteins Growth and maintenance of tissue Minerals Water & Protein Regulation of body processes Minerals Vitamins Water Protein 5

6 Body Nutrients Water 50-70% Crude Protein 14.4% Lipids 12.5% Minerals 4.8% Carbohydrate 0.4% 6

7 *Body elemental composition Elements O 65% C 18 % H 10 % N 3 % Minerals 4 % Ca, P % K, S, Na, Cl, Mg 0.95% Fe 0.004% Zn 0.002% Se % Mn % Cu % I % Mo, Co, Cr, F, Si, V, Mr 7

8 Changes in body composition with age (by percent) Premature 1yr 30-60yrs Fat Fat-free solids Intracellular Water Extracellular Water

9 9

10 Male>female Infant>older children>adults Lean>obese 10

11 Water The most important nutrient One can live for 1 weeks without food, but death is likely to follow a deprivation of 2 water for more than a few days. 11

12 A person can lose all reserve 3 carbohydrate and 4 fat and about half of the body 5 protein without real danger, but a loss of 6 10 percent of body water is a serious hazard, and death usually follows a percent loss. 12

13 Body Water Content and Regulation 1. Body water ~ is a function of 8 and 9 age composition 13

14 2. Distribution Water is a constituent of every cell of the body. 14

15 Water % blood muscle Lean body mass total body wt. adipose tissue bone teeth 15

16 1.ICF 60% : Intracellular fluid 2.ECF 40% : 1)Interstitial fluid 2)Plasma a. Lung: expired air b. Kidney:urine 16

17 ECF : Na + Cl - Blood or Intravascular fluid Na: K 28:1 Interstitial (Intercellular or extravascular fluid) Na: K 28:1 ICF: K +,protein Na: K 1:10 17

18 3. Regulation The distribution of water inside and outside the cells depends on adequate 10 protein and balanced 11 minerals intakes. 12 Sodium and 13 potassium are the principal minerals responsible for water balance. 18

19 Osmosis The interchange of water amount their cells, circulatory system, and extracellular species depends on their concentration of 14 protein and 15 electrolytes. 19

20 *Functions 1. Major structural component and a cushion of all cells. 20

21 *Functions The medium of all body fluids, including digestive juice, lymph, blood, urine, and perspiration. (Hydrolysis, end products) 21

22 *Functions A solvent for the products of digestion, for absorption, transportation and excretion of waste products. 22

23 *Functions As a body lubricant- Saliva: mucous secretion of the GI, respiratory, genitourinary tracts joint 23

24 *Functions Regulates body temperature- in perspiration: 600 kcal /1L 24

25 *Functions Cushion for body tissue 25

26 *Functions Necessary for proper muscle structure and function. 26

27 *Functions Actively participates in many chemical reactions. 27

28 *Water balance Homeostasis These fluids are constantly losing and replacing their constituent parts, yet the composition in each compartment remains remarkably constant at all times. The entair system of cells and fluids remains in a delicate but firmly maintained state of homeostasis. 28

29 Water intake (ml)= Water output (ml) Water and fluid Lung and skin evaporation Solid foods Urine *Metabolic water Feces (water of oxidation)

30 *Metabolic Water The oxidation of 16 protein 17 carbohydrate 18 lipidyields water. Water (ml) 100 g lipid 100g carbohydrate 100g protein

31 *Regulation of water balance Many variables influence water balance in the body 1) The amount of fluid consumed 2) 21 Protein and 22 minerals content of the diet 3) Physical activity 4) Metabolic and 23 respiratory rates 5) Body temperature 31

32 #Regulation by thirst and antidiuretic hormone * The regulation of water balance by thirst and antidiuretic hormone mechanism 32

33 Dehydration Thirst drinking water Increased osmotic pressure of plasma (high plasma Na) Stimulate osmorecptors in hypothalamus Posterior pituitary Shuts off Increases blood volume Lowers osmotic pressure dilute extracellular fluid Stimulates the kidney to reabsorb water Antiduretic hormone (ADH) * Increases permeability of distal water * ADH Causes water retention 33

34 *Factors that affect antidiuretic hormone ADH secretion Increase ADH secretion (and subsequent renal conservation of water) 1.Increased osmolarity of ECF 2.Decreased vascular or ECF volume (body water deficiency) 3.Certain drugs (e.g. nicotine) 4.Pain, anxiety 34

35 Decreased ADH secretion (and subsequent increased urinary water loss) 1.Decreased osmolarity of ECF 2.Increased volume of ECF (body water excess) 3.Certain drugs (e.g. alcohol) 35

36 *Water requirement The 24-hour water requirement is that replaces the losses by the 24 kidney, lungs, skin and bowel 1) Based on body weight (1) about 25 4 percent of body weight for adult (2) in infant about percent of body weight 36

37 *Water requirement 2) Based on body surface area, about ml/m2 37

38 *Water requirement 3) Based on energy expenditure, about 28 1 ml per kcal for adult and ml per kcal for infants 38

39 The requirements are increased in following: - Fever - In hot environments - With strenuous activity - With high intake of 30 protein and 31 salt - Pregnancy - Lactation - Air travel - Diarrhea - Polyuria 39

40 Water deficiency symptoms Causes: heavy sweat losses Burns Bleeding Vomiting Diarrhea Polyuria (water not conserved as a result of hormonal dysfunction) 40

41 *Spectrum of dehydration Normal 0 Weight Thirst 2 Stronger thirst, Dehydration Weight loss % Initial weight vague discomfort and sense of oppression, loss of appetite 41

42 4 Economy of movement lagging pace, flushed skin, impatience; in some: weariness and sleepiness, apathy, nausea, emotional instability 42

43 6 Tingling in arms, hands, and feet; heat oppression, stumbling, headache, fit man suffer heat exhaustion, increases in body temperature, pulse rate and respiratory rate 43

44 8 Labored breathing, dizziness, cyanosis, Indistinct speech, Increased weakness, mental confusion 44

45 10 Spastic muscles-positive Romberg sign (Inability to balance with eye closed ); general incapacity Delirium and wakefulness, swollen tongue Circulatory insufficiency; marked hemoconcentration and decreased blood volume; failing renal function 45

46 15 Shriveled skin; inability to swallow Dim Vision Sunken eyes; painful urination Deafness; numb skin; shriveled tongue Stiffened eyelids Cracked skin; cessation of urine formation 46

47 20Bare survival limit Death 47

48 #Water Toxicity Water excess Water intoxication Overhydration Water intake > > Water output 48

49 Causes: 1. Deliberately 2. Psychogenic 3. Administration of excess intravenous fluid 4. Diminished capacity of the kidney to excrete water 5. Inappropriate or excessive secretion of the ADH 6. Giving excessive amount of water between feeding or giving as excessively diluted formula, either deliberately or inadvertently. 49

50 Symptoms: Headache Vomiting Abdominal cramps Edema Convulsions Circulatory failure Death 50

51 Summary Water is an essential and major component of all living matter 51

52 52