chapter 9

PBF

Although the percentages vary for men and women, the main constituent of the body is water. The percentage of water varies tremendously among tissues. For example, muscle is 73% water, adipose tissue is 10% to 20% water, and bone contains approximately 20% water. As the fat content of the body increases, the percentage of lean muscle decreases, and subsequently the percentage of body water decreases. When body composition measurements are performed on extremely lean athletes, the percentage of body water can be around 70%.

______ bone is the compact tissue on the outer surfaces of bones that provides strength and stability.

Cortical

PBF

Despite those mechanisms that work to conserve water, fluid continues to be lost via the feces, skin, and lungs. ​ Those losses must be replaced. In addition, there is a limit to how concentrated urine can become. ​ Eventually, if fluid is not consumed, the body becomes dehydrated and suffers ill effects.​ By the time a person loses 1% to 2% of body weight in fluids, he or she will be thirsty and experience loss of appetite and hemoconcentration. ​ Even this small water deficit can cause one to feel tired and dizzy and to experience headaches. ​ At a 4% loss of body weight from fluids, muscles lose significant strength and endurance, and central nervous system function is negatively affected. Things like memory and reaction time are compromised and one becomes impatient. ​ By the time body weight is reduced by 10% from fluid loss, heat tolerance is decreased and weakness results.​ Ultimately dehydration will lead to kidney failure, coma, and death. Dehydration is a contributing factor to heat exhaustion and heatstroke, a serious condition.. Heart rate is increased and the skin becomes dry. Unassisted, the individual will become unconscious and die. ​ Another potential consequence of inadequate fluid intake is kidney stones. When urine production is lower than about 500 milliliters (approximately 2 cups) per day, the urine is concentrated, increasing the risk of kidney stone formation in susceptible people (generally men). Kidney stones form from minerals and other substances that have precipitated out of the urine and accumulate in the kidney

Fact: When you have a fever, you do need more energy but it is not a reason to overeat. For every increase of 1°F (0.5°C) in internal temperature above normal, your BMR increases by 7%. Physical activity will likely be lower than normal, however, which lowers overall energy needs.

FAKE NEWS: You should feed a fever. Fever is an increase in body temperature caused by an immune response. When you have a fever, you do need more energy. For every increase of 1°F (0.5°C) in internal temperature above normal, your basal metabolic rate (BMR) increases by 7%. Although BMR is elevated for a person with a fever, physical activity will likely be lower than normal, which lowers over-all energy needs. Thus, having a fever is not a reason to overeat.

FIGURE 9-6 gives examples of sources for water. On MyPlate, the fill of the background color (none, 1/3, 2/3, or completely covered) within each group on the plate indicates the average nutrient density for water in that group. Overall, the vegetables, fruits, dairy, and protein groups contain many foods that are nutrient-dense sources of water. Fats and oils, on the other hand, have almost no water Water comes from food, beverages, and metabolic water. Looking at MyPlate, and a lot of foods are 50, 60, or 70 percent water. Our biggest contributors are fruits and veggies; they are mostly water. Even though grains seem pretty dry, they do have some water. Protein foods do, as well. Meat, which is animal muscle tissue, is kind of like your muscle tissue. It's probably about fifty or sixty percent water. All dairy foods are good sources of water. Although not depicted on MyPlate, all beverages are nearly 100% water. Alcohol and caffeine are diuretics that would cause you to excrete a little extra fluid. A diuretic is an agent that would cause you to lose water. It's going to stimulate urination. This doesn't mean that alcoholic beverages and caffeinated beverages don't contribute to your fluid status, because they do, it's just that not a hundred percent of that fluid is retained, some of it is lost in the urine. If you're trying to rehydrate after a race, you don't want to drink beer; a lot of people do.

Fluid Conservation Hormones Antidiuretic hormone (ADH) •Secreted by pituitary gland when blood concentration of solutes is high •Tells kidneys to reduce water excretion which increases in blood volume

Which of the following minerals are involved in antioxidant reactions in the body? Multiple select question. Manganese Selenium Zinc Calcium

Manganese, selenium, and zinc.

Water Percentages in Body Components

Muscle: 73% water Adipose tissue: 10 to 20% water Bone: approximately 20% water Human body: 50 to 70% water As body fat content increases. •% of lean tissue decreases and total body water decreases. Extremely lean athletes: 70% body water

PBF

One of the hormones is called antidiuretic hormone, and there's another one called aldosterone. ​ Those are the hormones that help regulate fluid balance. ​ Antidiuretic hormone comes from the pituitary gland in your brain. ​ Aldosterone comes from the adrenal glands on your kidneys.

Spinach contains plenty of calcium, but only about 5% of it can be absorbed because of the vegetable's high concentration of what calcium binder?

Oxalic acid

Water Is the Universal Solvent Universal solvent •Dissolves substances in the body. Water transports nutrients and wastes. Most nutrients are water-soluble. Primary component of blood and lymph. Primary medium for chemical reactions. •Result in metabolic water.

PBF :One of the biggest functions of water is as the universal solvent. It helps get rid of waste by transporting it to the kidneys to be excreted in the urine; the main component of urine is water. It takes oxygen and nutrients all around your body. It is the main part of our blood, so it maintains blood volume. It is a medium for most chemical reactions in your body. Sometimes it even participates in those reactions. When we break down carbohydrates for energy, one of the byproducts is water.

Which of the following minerals are involved in muscle contraction and nerve impulse transmission?

Potassium Calcium Sodium

Ion Concentration and Electrolytes​ Ions dissolve in water​ positively (+) or negatively (-) charged​ Ion concentration controls how much water is inside vs. outside of cells​ Electrolytes: ​ Charged ions that transfer electrical current.​

Primary extracellular ions:​ Sodium (Na+)​ Chloride (Cl-)​ Primary intracellular ions:​ Potassium (K+)​ Phosphate (PO4-)

Water is also a lubricant that helps things move smoothly. It is the main part of your gastrointestinal secretions. All those enzymes and bile are in an environment of water. The starts with the saliva and includes the protective mucus in the GI tract. It is an important part of the cerebral spinal fluid in and around the spinal cord and brain.

The Water Balancing Act: Water Intake Adequate Intake for total water (fluid and food): •Women: 2.7 liters per day (11 cups) •Men: 3.7 liters per day (15 cups) •Fluid alone •Women: 2.1 liters (9 cups) •Men: 3 liters (13 cups) Many fruits and vegetables: more than 80% water Many meats: at least 50% water

PBF

The claim to drink eight 8-ounce (1 cup) glasses of water per day has probably been accepted for a long time because it is easy to remember. Eight glasses is a half gallon of water or about 2 liters. The claim, otherwise known as the 8 x 8 rule, is not supported by scientific evidence. The National Academy of Medicine recommendation (Adequate Intake) is somewhat greater at 9 cups (2.7 liters) per day for women and 13 cups (3.7 liters) per day for men, but it is a guideline for total beverage consumption, not just water. Water is not the only beverage that contributes to fluid balance, and most foods are full of water. The truth is that water intake need varies by individual and can be partially guided by thirst. Body size, body composition, activity level, and climate are all factors that impact fluid needs. Drink when you are thirsty and drink more during hot weather and exercise.

PBF

The majority of the nutrients we consume—carbohydrates, proteins, minerals, and many vitamins—are water soluble. Recall that lipids, although they are not soluble in water, can be surrounded by a layer of water-soluble protein so that they can be dispersed throughout the water-based environment within and around cells and tissues. As the primary component of blood and lymph, water acts to transport nutrients to all the cells of the body. The metabolism of nutrients generates some waste products, most of which can dissolve in water and exit the body as part of urine. For example, when proteins are broken down as fuel, the nitrogen portion of amino acids cannot be used for energy production. Remember that the liver converts these nitrogenous waste products into urea. In addition, when we consume more than we need of some nutrients, such as sodium, the excess can be dissolved in water and excreted in urine. Typical urine output ranges from 1 to 2 liters per day, depending mostly on our intakes of fluid, protein, and sodium.

Urine Production​ Typical urine production: 1 liter​ Less than 500 ml (2 cups) = concentrated urine and increase work by kidneys​ A way to determine adequacy of fluid intake is to observe urine color:​ Clear or light yellow is good hydration​ Dark yellow and pungent is poor hydration

The simplest way to determine if water intake is adequate is to observe urine color.​ ​ If hydration is adequate, urine should be clear or pale yellow (like lemonade); concentrated urine is dark yellow (like apple juice). r .​

Thirst: Good Indicator of Hydration Status?​ In certain situations thirst can lag.​ Can lag behind in some situations, exercise, illness​ Infants and children​ Need close monitoring, especially if vomiting, diarrhea​ Athletes​ Should consume 2 to 3 cups fluid or water for each pound lost during exercise​

Thirst is usually good enough to keep us hydrated. In most situations, healthy people can rely on their sense of thirst to maintain adequate fluid volume. ​ Part of the hormones that are released to regulate blood volume signal thirst in the body. ​ When your blood becomes too concentrated, that signals thirst, then that stimulates you to drink more water. ​ If you just drink when you're thirsty, you should maintain a good fluid balance. ​ Thirst is not going to be completely reliable for certain populations. ​ The sensation of thirst tends to dull when you get older. ​ Older adults are at risk for dehydration. ​ ​ Athletes lose a lot of fluid when they sweat in a short amount of time, and the thirst sensation might not keep up with their fluid needs. Athletes need to make an effort to stay hydrated. They need to drink before they feel thirsty to make sure they maintain good hydration. Actually, dehydration can significantly affect sports performance. ​ ​ People who are vomiting, have diarrhea, and losing a lot of fluid can't rely on thirst to keep them hydrated; they're going to need to push fluids. ​ Infants are on there because they can't tell us when they're thirsty. ​ That's another group to think about being at risk for dehydration. ​ But, for most people, drink when you're thirsty, and you'll stay hydrated.

Dehydration​ Inadequate intake of water to replace losses​ Body water loss:​ 1 to 2% loss: feeling of thirst​ 4% loss: tired, dizzy, headache​ 10% loss: decreased heat tolerance and weakness

Ultimately leads to ​ Kidney failure​ Coma​ Death​ Contributing factor to:​ Heat exhaustion​ Heat stroke​ Kidney stones​

Water Transports Nutrients and Wastes Protein breakdown: •Nitrogen: part of protein that cannot be used for energy—has to be excreted as urea. •Excess protein intake requires increase in water intake.

Water Transports Nutrients and Wastes Sodium: Excess sodium consumption leads to increased sodium excretion in urine. Urine output •(1 to 2 liters per day). Depends on intake of fluid, protein and sodium.

PBF

Water helps to regulate your body temperature. It does this in two ways; one way is perspiration. When water evaporates from your skin, it releases heat energy; this helps to keep you cool. Water also regulates our temperature because water is a pretty good heatsink. It would take a lot of energy to change the temperature of a lot of water. Since the body is about 60 percent water, it takes a lot of energy to change your temperature. It helps you maintain your constant temperature. The steps that take place when your body becomes overheated are listed on the right side of the slide.

Overhydration:​ water intake far exceeds kidneys' processing ability, sodium becomes diluted in blood

Water intoxication and Hyponatremia​ potentially fatal condition​ occurs with high intake of water​ results in severe dilution of blood and other fluid compartments​ dangerously low blood sodium level​ swelling of brain, nerves, fluid in lungs​

PBF

Water is not a micronutrient, it's a macronutrient, but it goes along with fluid balance. We're going to discuss the functions of water in your body and where you find it. You will learn some new things about the functions of water, and then we will talk about electrolyte minerals like sodium, potassium, and chloride.

PBF

Water makes up about 60 percent of your body. This picture shows that about 62 percent of the whole body is water for a healthy man who weighs 170 lbs. For a woman, it's about 57 percent. This is going to vary based on several factors. Why do women have lower body water content than men? When it comes to body composition, men tend to have more lean mass. Whereas women have, on average, a greater proportion of fat mass. That's normal and because of reproductive function. Water distributes in muscle and your blood, so it will distribute in lean tissue. If you have a lot of adipose tissue or fat tissue, you're not going to have as much body water. That's the biggest difference there.

You can drink too much water. Too much water would over-dilute the solutes in your blood. Then the proteins and the electrolytes in your blood would get diluted. ​ The functions of electrolytes, like nerve impulse conduction, are involved in muscle contraction. These functions won't work as well if you have too much fluid in your system. ​ The technical term for water toxicity is hyponatremia; this means low blood sodium. If you see the term hyponatremia, that's the same as water toxicity. ​ The most susceptible population to get water toxicity would be inexperienced athletes. For example, people that don't typically run that decide to run a marathon. They start training and running with their friends, and every mile or so, there's a water stop. They're chugging along and drinking water as they go. ​ If they're not an experienced athlete, they could drink too much. If they're running at a pretty slow pace, they're probably not sweating that much. If you're only replacing the fluid and you're not sweating that much, you could end up over-hydrating. ​ So, the most susceptible population to this would be inexperienced athletes. ​ There are other examples of this. Feeding extra water to an infant could result in hyponatremia. A very young infant's kidneys are not as mature as an adult's kidneys; breast milk or formula is all they need to stay hydrated. ​ A way to combat hyponatremia is to not just replace fluids when working out but also replace those electrolytes. ​ That's where sports drinks like Gatorade come in. ​

What Is the Difference Between Hard and Soft Water?​ Hard water​ Contains high levels of calcium and magnesium.​ 89% of homes have hard water.​ Soap does not lather.​ Soft water​ Can contain a high level of sodium.​ Cleaner clothes.​ Hard water can be converted to soft water ​ Calcium and magnesium exchange with sodium.​

PBF

When your blood pressure gets too low, that's going to tell your kidneys to retain water. It helps our bodies to maintain a balance of fluid. ​ Hormones regulate fluid balance by controlling the movement of sodium across the cell membrane, which makes water follow it. ​ Kidneys activate an enzyme cascade involving angiotensin and aldosterone. ​ These hormones increase reabsorption of Na+ and Cl- by the kidneys, which results in increased water retention by the kidneys. ​

For which of the following population groups does typical calcium intake fall short of recommendations in the United States? Multiple select question. young adult men adolescent girls older adult men young adult women

adolescent girls older adult men young adult women

The fluid that surrounds and protects the fetus during development is called ______ fluid. Multiple choice question. cerebrospinal intracellular synovial amniotic

amniotic

If a person's diet is low in sodium and then they develop persistent vomiting or diarrhea, what may happen to this individual?

become depleted in sodium

Choose foods that are good sources of phosphorus. Multiple select question. spinach bran fish eggs nuts

bran fish eggs nuts

Growth and Development

calcium, phosphorus, zinc

Exceeding the UL for ______ can lead to hip fractures, still joints, and stomach inflammation among adults.

fluoride

he Adequate Intake (AI) for total water is 2.7 liters (11 cups) for adult women and 3.7 liters (15 cups) for adult men. This amount is based primarily on average water intake from fluids and foods. For fluid alone, this corresponds to about 2.2 liters (9 cups) for women and about 3 liters (13 cups) for men. Fluid intake—including water, fruit juice, coffee, tea, soft drinks, milk, and even alcoholic beverages— makes the biggest contribution to our total water needs.

illustrates estimates of water balance—intake versus output—in a woman. We primarily maintain body fluids at an optimum amount by adjusting water output to intake. As you can see with this woman, most water comes from the liquids we consume. Some comes from the moisture in foods, and the remainder is manufactured during metabolism. Water output includes that lost via urine, skin, lungs, and feces. How much water do you need? For men and women, this is an average. It's going to vary a lot based on body temperature, environment, how much you exercise, and genetic variations. There's an adequate intake (AI) for total water, which includes the fluid you drink and the fluid from the food you eat. For men, on average, they need 13 cups of water per day. For women, on average, it is 9 cups per day. Those are some good numbers to remember. Balancing fluid losses with fluid intake is what we're trying to do. If we look at water intake and water output, we want the volume coming in to equal the volume going out. One of the things that make up water intake is beverage intake. That's the biggest contribution. Water from food is the second largest. Then the third one is metabolic water. That's the water that gets produced as a byproduct of metabolism. Those are your three parts of water intake: drinks, foods, and metabolic water. Urine is the biggest component of water output. Perspiration is usually the second biggest component. You also lose some water when you breathe out; that is respiration. You also lose a little bit in the feces; usually it's less than half a cup a day. When you're sick, this could be a lot more. This is called insensible water loss because you don't realize you're losing that water. Urine is the largest component of fluid loss. Ideally, these are going to balance out.

The body controls the amount of water in the intracellular and extracellular compartments mainly by controlling the movement and concentration of

ions

Vitamin C improves absorption of which mineral?

iron

A high-fiber diet, in excess of current recommendations, can decrease the absorption of ______.

iron and zinc

Blood Health

iron, copper, calcium, zinc

Large amounts of phytic acid found in fiber from grains, excess phosphorous, polyphenols in tea, and vitamin D deficiency all contribute to ______. limiting calcium absorption enhancing calcium absorption enhanced absorption of iron

limiting calcium absorption

The passage of water through a selectively permeable membrane from a region of low solute concentration to a region of high solute concentration is called osmosis. dissolution. electrolysis. pinocytosis.

osmosis

The presence of ______ in food can decrease the bioavailability of calcium from that food, but not the absorption of calcium from other foods.

oxalates

What are factors that affect the bioavailability of calcium? Multiple select question. oxalates phytic acid tannins fluid intake

oxalates phytic acid tannins

Milk, cheese, meat, and bread are all rich sources of

phosphorus

Whereas average calcium intakes of Americans fall below recommendations, average intakes of ______ exceed the RDA for this nutrient.

phosphorus

Calcium absorption is increased by

pregnancy. high blood levels of parathyroid hormone. the presence of lactose in the diet.

Excess dietary intake of ____ may increase blood pressure.

sodium

Muscle Contraction and Relaxation

sodium, chloride, potassium, calcium, magnesium

Nerve Impulses

sodium, potassium, chloride, calcium

Fluid and Electrolyte Balance

sodium, potassium, chloride, phosphorus, water

is a liquid in which other materials dissolve forming a solution.

solvent

Because of differences in the rates of bone remodeling, ______ bone is most susceptible to biological and lifestyle factors that affect bone health.

trabecular

Which fluid compartment contains the most fluid? Multiple choice question. water found outside the cell membrane or extracellular fluid water found in the blood plasma water found inside the cell membrane or intracellular fluid

water found inside the cell membrane or intracellular fluid

PBF Functions of Water:

•Component of body fluids and maintains blood volume. •Removes waste products from cells. •Maintains body temperature. •Distributes nutrients to cells. •Lubricant for joints and moistens organs, G I tract, eyes, skin. •Participates in and in a medium for chemical reactions. •Participates in acid-base balance

Water: Essential to Human Life

•H2O: 2 molecules of Hydrogen, 1 Oxygen •Most abundant molecule in your body. •Comprises 50% to 70% of human body. •Your body can lose water through lungs, skin, urine, and feces. •Your body cannot store water.

Select the Upper Level for iodine. Multiple choice question. 1.1 mg/day 1.5 mg/day 0.8 mg/day 1.8 mg/day

1.1

Evaporation of 1 quart of perspiration releases about ______ kilocalories of heat energy from the body.

600

PBF

Body temperature is reduced when heat is transported from the body through the bloodstream to the surface of the skin. As perspiration evaporates from the surface of the skin, heat is dissipated. This cools the blood, which circulates back to the body, reducing body temperature.

Which of the following minerals are involved in bone health?

Calcium Copper Phosphorus

Cell Metabolism

Calcium Phosphorus Magnesium Zinc Chromium Iodide Water

What is the most nutrient-dense source of calcium? Fat-free milk, because of its high bioavailability and low calorie content. Whole milk cheese, because of its high bioavailability and lactose content. Sardines, because of the bones and the availability of protein. Cottage cheese, because of its high bioavailability and increased density related to processing

Fat-free milk, because of its high bioavailability and low calorie content.

PBF

Life as we know it could not exist without water. Every cell, tissue, and organ contains some water. Overall, water comprises 50% to 70% of the human body. Indeed, water is essential for life. Whereas humans can live for several weeks without food, we cannot survive for more than a few days without water.

Water Moistens, Lubricates, and Cushions Saliva •helps food pass from esophagus to stomach Mucus •protective coating through GI tract & lungs Cerebral spinal fluid •spinal cord and brain Amniotic fluid •shock absorber in mother's womb

Lubricating fluids •in knees and other joints •tears in eyes

Aldosterone •Produced by adrenal glands when blood volume is low. Tells kidneys to conserve sodium and water which increases blood volume

One of the hormones is called antidiuretic hormone, and there's another one called aldosterone. Those are the hormones that help regulate fluid balance. Antidiuretic hormone comes from the pituitary gland in your brain. Aldosterone comes from the adrenal glands on your kidneys.

_______ in foods affect the bioavailability of calcium from the food source and other foods in the meal, as well.

Phytates

What is the major positive ion outside cells in extracellular fluid, and a key factor for retaining body water?

Sodium

_______in foods affect the bioavailability of calcium from the food source and other foods in the meals, as well.

Tannins

_______ increases the absorption of calcium from the small intestine.

Vitamin D

Water Contributes to Body Temperature Regulation Body holds heat efficiently 50% to 70% water Requires a lot of energy to change body temperature Macronutrients: Energy released 60% becomes heat 40% used by cells

Water Contributes to Body Temperature Regulation When overheated: •Body secretes fluid: perspiration •Evaporates through skin pores •Heat energy is released •Body is cooled •1 liter of evaporated perspiration equals 600 kcal of heat lost

Middle Eastern populations consume relatively high amounts of unleavened breads and this is associated with the decreased bioavailability of what mineral?

Zinc

Secretions of the digestive tract, respiratory tract, and urogenital tract best exemplify the role of water as

a lubricant.

Bone health

calcium, phosphorus, iron, zinc, copper, fluoride, manganese

Sodium, potassium, and ______ help to regulate fluid balance.

chloride

Sodium, potassium, and ______ help to regulate fluid balance. phosphorus selenium fluoride chloride

chloride

Fluid present outside the cells such as plasma, lymph, and interstitial fluid is termed _____.

extracellular fluid

Which of the following are rich sources of iodine?

fat-free milk yogurt eggs

Like trace minerals, ultratrace minerals are present in the diet and in the human body in small amounts. However, unlike the 9 trace minerals, ultratrace minerals

have not been shown to be essential for human health.

Which of the following are used to assess iron status in the clinical setting?

hemoglobin hematocrit

A high intake of chloride, usually in the form of sodium chloride, is linked to arthritis. type 2 diabetes. celiac disease. hypertension.

hypertension

Most of the body's potassium is found

inside the cells.

The thyroid gland uses ______ to synthesize thyroid hormones.

iodine

Which of the following food items provides the most iodine? Multiple choice question. iodized salt, 1/2 tsp egg, hard-boiled, 1 large tuna, 3 oz milk, 8 fl oz

iodized salt, 1/2 tsp

Body Defenses

magnesium, iron, selenium, zinc, copper, manganese

Which type of cell requires estrogen for maximal activity?

osteoblast cells

What are the two main sources of sodium in typical American diets?

processed foods foods prepared in restaurants

Hematocrit is the portion of blood comprised of Multiple choice question. red blood cells. water. plasma. white blood cells.

red blood cells.

A daily intake of 1500 milligrams is the Adequate Intake for ______.

sodium

The bioavailability of calcium is limited by the presence of vitamin D. Reason: Vitamin D increases calcium absorption. tannins. oxalates. phytic acid.

tannins. oxalates. phytic acid.

Fluoride content of foods is limited, so in areas where fluoridation of the water supply is not feasible, this mineral can be supplied by

topical fluoride treatments. toothpaste. fluoride tablets.

The primary route of chloride excretion is via _____.

urine