chapt 09 lecture 2

Chapte r 9
Water and
Minerals


Water
 50%-70%
 Muscle

of body weight

contains 73% water

– Fat contains ~20%
 Intracellular

fluid

– Fluid within the cells
 Extracellular

fluid

– Fluid outside the cells



Fluid Balance



Water shifts freely in and out of cells
Controlled by electrolyte concentration
– Have electrical charges . . .Na, K, Cl, P, Mg, Ca




Osmosis (where an Ion goes, H2O flows)
Intracellular water volume
– Depends on intracellular potassium and phosphate
concentrations



Extracellular water volume
– Depends on extracellular sodium and potassium
concentrations


where an Ion goes, H2O flows: fig 9:2

Na

Na

Na

Na

Na

H2O

Na

Na

Na


Functions of Water


Body temperature regulation
– Water absorbs excess heat
– Body secretes fluid via perspiration
– Skin is cooled as perspiration evaporates
– Humidity (bad) & fans (good) ~ evaporation



Removal of body waste via urine
– Urea excretion (Nitrogen from Protein breakdown
– Sodium excretion
– Avoid concentrated urine (brownish)



Amniotic fluid, joint lubricants, saliva, bile



Are You Drinking Enough?

Fluid recommendation: 9 cups for women and
13 cups for men as a starting point

Min. 2-4 water bottles/day


Thirst Mechanism
Not reliable
 Concerns for infants, older adults, athletes
 Athletes


– Weigh before and after training session
– Consume 3 cups for every pound lost


Illness (vomiting, diarrhea, fever)
– Get additional water


Ignoring the Thirst Signal
Shortage of water increases fluid
conservation
 Antidiuretic hormone (vassopressin)


– Released by the pituitary gland
– Forces kidneys to conserve water (reduce
urine flow)


Aldosterone
– Responds to drop in blood pressure
– Signals the kidney to retain sodium (water)


Hydration


Loss of 1%-2% of body weight in fluid
– Thirst signal



Loss of 2% or more of body weight causes
muscle weakness (stay hydrated –training)
– Lose significant strength and endurance



Loss of 10%-12%
– Heat intolerance



Loss of 20%

– Coma and death



Too Much Water
 Overburden
 Low

the kidneys

blood electrolyte concentrations

 Blurred

vision


-Confirming your knowledge Q

What is the Minimal amt. of H2O from fluids
that Humans require/day to replace daily loss?



What is the recommended amt. of water from
fluids that women and men require/day?


Minerals
 Various

functions in the body
 Major Minerals
– Require >100 mg /day
– Calcium, phosphorus etc.

 Trace

Minerals

– Require < 100 mg/day
– Iron, zinc, selenium etc.


For 5 pts & Make it a Half day???
What do you say?
Go see “Food Inc.” the movie
 Nickelodean theatre (downtown SC)
 3, 5, 7 & 9PM showtimes. . .


– Answer 3 short questions (class website)
– Turn in with TICKET STUB Next Wednesday
– See Trailer
/>

-Confirming your knowledgeWhat are the 7 Major minerals
required in the body?
1
2

3
4
5
6
7


-Confirming your knowledgeWhat are the 7 Trace minerals
required in the body?
1
2
3
4
5
6
7


Most mineral requirements
are obtained without defic. in
N. American diets


Bioavailability of Minerals



Fe

Mg

Cu

Zn
~Degree of absorption
Affected by binders in plants (oxalic acid, phytic acid)

– Fibrous foods






Animal products are better absorbed
Plants depend on mineral content of soil
Refinement lowers mineral content (i.e. milling Grains)
Mineral-mineral competition (e.g. >>Zinc vs – Avoid mega-supplements (2X RDA): unless prescribed



Vitamins-mineral interactions:

– Iron w/ (Vit C), Calcium w/ (Vit. D) most efficient


Mineral Toxicity
 Trace

minerals are more toxic

– e.g. Fe, stomach irritation
 Result

of supplementation

– Presence of contaminants (esp. Lead (Pb))
– Look for the United States Pharmacopeia
(USP)-approved brands (most reliable)


Minerals of Concern in the Diet


Sodium (Na) ~ consume too much >2400mg/day 
Hypertension (HTN) and CVD



Calcium (Ca) ~ not enough, esp. Women  osteoporosis



Iron (Fe) ~ not enough, esp. Women
– Men require
8 mg/day
– Women require 18 mg/ day
 Menstral flow
 Supplements hard to digest ?



All other Major and Trace minerals (ok) ~ balanced diet
– Avoid supplementing to try and balance or optimize
 Leads to mineral competition  deficiencies


Sodium









Table salt (NaCl): 40% sodium, 60% chloride
95% of ingested sodium is absorbed
Positive ion in extracellular fluid
Aldosterone regulates sodium balance
Key for retaining body water
Excretion regulated by the kidneys
Muscle contraction
Conduction of nerve impulses


Food Sources of Sodium
Most sodium is added by food

manufacturers and restaurants
 Milk and dairy products
 Processed foods
 Sodium content listed on the labels




Sodium Needs
Adequate Intake is 1500 mg for adults
 Body only needs 200 mg to function
 Daily Value is 2400 mg/day
 Upper Level is 2300 mg


 Typical


intake is 4700 mg/day (US)

Sodium-sensitive individuals should restrict
intake (African American)