water & the major minerals chapter 12. water & the body fluids water – makes up 60% (3/5)...
TRANSCRIPT
Water & The Major Minerals
Chapter 12
Water & the Body Fluids
• Water – Makes up 60% (3/5) of adult’s body weight.• Higher for children
– Makes up 75% (3/4) of lean muscle.• 25% (1/4) of fat
– Males have more water (more lean muscle)• Females, the elderly, obese have less
Water & the Body Fluids
• Water in body fluids:– Carries nutrients & waste products through the body.– Maintains structure of large molecules.– Participates in metabolic reactions.– Serves as a solvent so substances can participate in
metabolic reactions.– Acts as a lubricant & cushion around joints, inside eyes,
in the spinal cord, & as amniotic sac during pregnancy.– Aids in regulation of body temperature.– Maintains blood volume.
Water Balance & Recommended Intakes
• Fluid inside cell – Intracellular fluid
• Fluid outside cell– Extracellular fluid
• Interstitial fluid– Fluid surrounding cells
• Composition between the two differs.
• Composition in each remains constant under normal conditions.
Water Balance & Recommended Intakes
• Water intake– Influenced by thirst & satiety
Sensed by hypothalamus & nerves.
Water Balance
– Dehydration : loss of water & loss not replaced.• Symptoms:
– Water intoxication (rare) : excessive water consumption, may result due to a kidney disorder which reduces the amount of urine produced.• Symptoms
• Hyponatremia
Water Balance
Water Balance
• Water Sources– Nearly all foods contain
water – Water is produced
during cellular respiration & during condensation reactions.
Water Balances
• Water losses– Body must excrete a
minimum of 500 mL (~ 2 cups) of urine a day.• Reason
– Water is also lost• As sweat• From lungs as vapor• In feces
– Average daily losses
Water Balance
• Water Recommendations– Water needs vary depending on diet, environmental
conditions, activity, & humidity.– Sometimes expressed in proportion to amount of
energy expended under average environmental conditions.• For a person that expends 2000 kcal a day, the amount is 2 –
3 L (8 – 12 cups).– Agrees with AI for total amount set by DRI.
• If physically active or a hot day, a person will probably need more.
Water Balance
• Water Recommendations (continued)– Any beverage can meet fluid needs.• Caffeinated beverages
– Caffeine acts as a diuretic.» Causes more water to be lost.
– People can consume it to meet daily fluid needs, however.
• Alcohol– Acts as a diuretic.– Should not be used to meet daily fluid needs.
Water Balance
• Health Effects of Water– Protection against
– Hard or Soft Water makes a difference
Water Balance
• Bottled water – people may think its better & safer.– Not necessarily true in US.
• Distilled water– Has all minerals removed.
• Natural water– Comes from spring or well– Mineral content may not be changed.
• Mineral water– Comes from spring or well– Contains more minerals.
• Minerals give it unique taste.
– Usually has higher sodium content.
Blood Volume & Blood Pressure
• Kidneys are major control for homeostasis of body fluids.– Kidneys regulate blood volume which influences
blood pressure.– Kidneys reabsorb needed substances.– Kidneys excrete metabolic wastes with some
water.
Nephron (p. 387)
Blood Volume & Blood Pressure
• ADH (antidiuretic hormone)– Released
– Action
Blood Volume Regulation (p. 388)
Blood Volume & Blood Pressure
• Renin
• Angiotensin
• Aldosterone
Fluid & Electrolyte Balance
• Dissociation of Salt in Water– Mineral salts dissociates (separates) into ions
when dissolved in water.• Ions -
– Positive ions called cations.– Negative ions called anions.
• Electrolytes – salts that dissolve in water & dissociate into ions.• conduct electrical currents.
Fluid & Electrolyte Balance
• Dissociation of Salt in Water (continued)– Electrolyte
• Balance
• Major extracellular ions
• Major intracellular ions
Fluid & Electrolyte Balance
• Electrolytes attract water– Water has net charge of
zero.– Water is polar molecule
• Hydrogen
• Oxygen
Fluid & Electrolyte Balance
• Water Follows Electrolytes– Water moves across cell membranes when
electrolytes move across.– Osmosis
– Osmotic pressure
Osmosis (p. 391)
Fluid & Electrolyte Balance
• Proteins Regulate Flow of Fluids & Ions– Sodium –Potassium Pump (protein)• Regulates
• Regulation of Fluid & Electrolyte Balance– GI tract & Kidneys regulate• GI tract
• Kidneys
Fluid & Electrolyte Imbalances
• Different Solutes Lost by Different Routes– Solutes lost due to vomiting, sweating, bleeding or
diarrhea• Sodium and chloride
– Adrenal gland tumor• Oversecretion of aldosterone• Kidneys may excrete too much potassim.
– Uncontrolled diabetes• Excretion of glucose
Fluid & Electrolyte Imbalances
• Replacing Lost Fluids & Electrolytes– Normal replacement of lost fluids• Drink water
– Severe cases• ORT (oral rehydration therapy)
Acid – Base Balance
• Ions also regulate acidity of fluids.• pH of body (7.35- 7.45) must be maintained
otherwise life threatening situations result.– Examples
• Acidity is determine by H+
• 3 system defend against pH fluctuations
Acid-Base Balance
• Systems to prevent pH fluctuations– 1. Regulations by Buffers
– 2. Regulation in the Lungs• Raising & slowing
respiration rate
– 3.Regulation in Kidneys• Reabsorb or excreting
bicarbonate.
The Minerals - Overview
• Inorganic– Retain chemical identity– Remain in body until excreted– Can’t be changed into anything else– Can’t be destroyed by heat, air, acid, or mixing.
• Body’s Handling of Minerals
The Minerals - Overview
• Variable Bioavailability– Binders• Found in some foods.
– Prevent mineral absorption» Phytates» Oxalates
Sodium
• Sodium Roles in body– Maintains normal fluid electrolyte balance– Assists in nerve impulse conduction– Assists in muscle contraction
• Sodium & Hypertension
Sodium
• Sodium & Bone Loss– Calcium excretion increased with high salt intake.
– See in summary: p. 397
Chloride
• Chloride Roles in Body– Maintains normal fluid & electrolyte balance.– Part of HCL – Necessary for proper digestion
Potassium
• Potassium Roles in Body– Maintains normal fluid & electrolyte balance.– Assists in may reactions.– Supports cell integrity– Assists in nerve impulse conduction.– Aids in muscle contraction.
• Potassium & Hypertension
Calcium
• Calcium Roles in Body– Mineralization of bones & teeth.– Involved in muscle contraction & relaxation.– Important in nerve functions, blood clotting, blood
pressure.
Calcium
• Calcium in bones– As bones form, calcium forms hydroxyapatite on
matrix of collagen.• As mineralization continues, bones become denser &
stronger.
– Bones constantly remodeled.• Bones gain & lose minerals • Children gain more than they lose.
– Teeth • Formed in similar pattern, but they are not bone.• Fluoride hardens & stabilizes the crystals of teeth
Calcium
• Calcium in body fluids– Extracellular fluids• Helps maintain blood pressure
– Reason
• Also participates in blood clotting.
– Intracellular fluids• Binds to proteins and activates them
– Proteins participate in
Calcium
• Calcium & Disease Prevention– May protect against hypertension.
• Calcium & Obesity– May help maintain a healthy body weight.
Calcium
• Calcium balance– Involves hormones &
vitamin D.– 3 organs respond
whenever blood calcium levels rise or fall.• Intestines, bones, kidneys • Note figure 12 -12, p. 401
– Calcium rigor– Calcium tetany
Calcium
• Calcium absorption– Factors to enhance absorption
• Acidity of stomach keeps Ca soluble.• Vitamin D helps to make the calcium binding protein needed for
absorption.
– Factors that inhibit absorption (many that enhance also inhibit)• Lack of stomach acid• Vitamin D deficiency• High phosphorus intake• Phytates• Oxalates
Calcium
• Calcium in Milk– Calcium most abundant in milk– Consequences of drinking too little milk.
• Calcium in other foods– Tofu– Almonds– Broccoli
Calcium
• Calcium Deficiency– Stunted growth in children– Osteoporosis in adults
• Toxicity Symptoms– Constipation– Risk of kidney stones– Interference with absorption of other minerals.
Phosphorus
• Phosphorus Roles in Body– Mineralization of bones & teeth– Part of every cell– Important in genetic material– Part of phospholipids– Used in energy transfer & in buffer systems
• Phosphorus Deficiency– Muscular weaaakness– Bone pain
Magnesium
• Roles in Body– Bone mineralizaiton– Building of proteins– Enyme action– Muscular contraction– Nerve impulse conduction
• Deficiency– Weakness– confusion
Sulfate
• Part of proteins• Stabilizes protein shape– Disulfide bridges