chapter 10 notes

water intoxication: over hydration

- A condition that occurs when a person drinks enough water to lower the concentration of sodium in the blood - hyponatremia.- results in abnormal fluid accumulation in body tissues. - Water leaves the blood and enters the tissues. - Swelling in the brain can cause disorientation, convulsion, coma, and death.

summary: hypertension

- A healthy blood pressure is less than 120/80 mm Hg. Blood pressure that is consistently 140/90 mm Hg or greater indicates hypertension. Hypertension affects about a third of adults in the U.S. Essential hypertension has no obvious external cause. - The risk of developing high blood pressure is increased by a family history of hypertension, aging, obesity, diabetes, and lifestyle factors such as a lack of physical activity, heavy alcohol consumption, smoking, stress, and a poor diet. A diet high in sodium increases blood pressure in most individuals. High intakes of the minerals potassium, magnesium, and calcium helps lower blood pressure. - Diets high in sodium and low in potassium are associated with an increased risk of hypertension. The DASH diet - a dietary pattern moderate in sodium; high in potassium, magnesium, calcium, and fiber; and low in fat, saturated fat, and cholesterol - lowers blood pressure. Blood pressure management also requires maintenance of a healthy weight, an active lifestyle, and a limit on alcohol consumption.

resources for water in the diet

- AI: 3.7 liters/day for men and 2.7 liters/day for women - This can vary depending on factors: activity, heat, humidity, and diet - Bottled water expensive, uses oil to make plastic bottles, sometimes is just tap water.

how sodium, potassium and chloride function in the body

- Almost all of the three minerals consumed in the diet are absorbed. - Concentrations of these electrolytes in body are regulated because they play a role in regulation of fluid balance, nerve conduction and muscle contraction. - Distribution of fluid among body compartments depends on concentration of electrolytes as all body fluids are in osmotic balance. - Sodium is high outside of the cell and potassium is high inside the cell. - This is maintained by cell membranes and the sodium-potassium ATPase, a pump in cell membranes that pumps sodium out and potassium into the cell. - Sodium potassium pump: each pump cycle uses the energy in ATP to pump 2K + IN the cell and expel 3 Na+ ions OUT. - The maintenance of concentration is important for nerve conduction and muscle contractions, and consumes a lot of energy estimated to be 20-40% of resting energy expenditure of an adult. - There are also separate pumps that pump glucose or amino acids into cells and sodium out. - Role of Na+ and K+ in Nerve conduction • You feel a pinprick because it stimulates nerves beneath the surface of the skin. This stimulation increases the permeability of the nerve cell membrane to sodium, which rushes into the cell, initiating the nerve impulse. • Nerves have an electrical charge or membrane potential because a greater number of negative charges are found just inside the cell membrane. For a energy signal to occur, sodium ions rush into the cell changing the electrical charge. The signal is like a wave and behind the wave the membrane potential returns to its normal charge. A similar mechanism occurs to initiate muscle contractions. - The textbook mentions three populations with vastly different intakes of sodium chloride, but despite these differences, homeostatic mechanism ensures that blood levels of sodium are not significantly different among the three groups. - Salt and water go hand in hand, if salt intake is high, thirst increases and so does water consumption, when salt intake is low in diet, the salt appetite drives us to consume more salt.

bottled water vs tap water

- Americans = 28 gallons bottled water/person annually - Why • Think it tastes better, no chlorine or aftertaste • Think its safer than tap water • Convenient... Easy to grab and go. - 25% of bottled water sold in the U.S. = tap water - some = tap water that's been filtered, disinfected, treated • distilled and purified water = treated tap water • artesian water, spring water, well water, mineral water = come from underground sources - by definition: bottled water can be ANY water as longa s no added ingredients (except antimicrobial agents or fluoride). - Tap water = regulated by EPA - Certified outside lab tests annually - Tap water must be filtered and disinfected - Bottled water = FDA (uses most EPA standards) - Bottled water companies do their own testing - No federal filtration or disinfection requirements for bottled water - Contamination = safety concern for both • 38 chemical pollutants in 10 popular brands of bottled water... caffeine, bacteria, Tylenol, radioactive isotopes, fertilizer residue • since 2004, 315 pollutants found in tap water and more than half = chemicals that can be present in ANY amount because they are not subject to regulations. - Cost = one of the strongest arguments against bottled water... even if you can afford it.... Can the Planet? • Consumer cost (1900 x cost of tap water) • Environmental cost (1.5 million tons of plastic waste/year globally from bottled water) + oil + gas. - So which is better? In the U.S., bottled water and tap water = both generally safe. If you recycle your bottle, does it matter which you choose?

forces distributing body water

- Amount of water in blood and tissues = determined by blood pressure and the force generated by osmosis. - Osmosis causes water to move into and out of cells in response to the concentration of dissolved substances inside and outside the cell. - Higher blood pressure at the arterial end of the capillaries forces water from the blood into the tissues. - Lower blood pressure and differences in solute concentration at the venous end draw water back into capillaries by osmosis.

osmosis

- Concentration of sugar starts out greater outside of the strawberries than inside the strawberries and then is equalized by osmosis as water leaves the strawberries - Water consumed in the diet is absorbed form the GI tract by osmosis. Absorption of nutrients "pulls" water with it. - Forces distributing body water - Osmosis causes fluid to move into and out of cells in response to the concentration of dissolved substances inside and outside of the cells. • Higher blood pressure at the arterial side of the capillaries forces water form the blood into the tissues. • Lower blood pressure and differences in solute concentration at the venous side draw fluid back into the capillaries by osmosis.

10.4 healthy electrolyte intake: choosing dietary pattern to lower blood pressure

- Eat plenty of fruits and vegetable - Choose and prepare foods with less salt. - Aim for a healthy weight - blood pressure increases with increases in body weight and decreases when excess weight is reduced. - Increase physical activity - it helps lower blood pressure, reduce the risk of other chronic disease, an d manage weight - If you drink alcoholic beverages, do so in moderation. Excessive alcohol consumption has been associated with high blood pressure. - Quit smoking - Reduce stress - over time, stress can raise blood pressure and contribute to the development of hypertension. - When eating :limit use of salt at the table, limit cured, salted, or smoked meats, cut down of cheeses, limit soy sauce, BBQ sauce, ketchup, and mustard. - When eating out: choose foods without sauces, limit fast food intake, reduce salt in your diet gradually. - Generally a food with: <5% DV Na = low in sodium, >20% DV = high in sodium • Light in sodium = contains at least 50% less sodium per serving. - The American Heart Association has designated six commonly eaten foods that are loaded with sodium as the "salty six." These include bread, cold cuts, pizza, poultry, soup, and sandwiches.

10.2 electrolytes: salt of the internal sea

- Electrolytes are the salts of the internal sea. - Properties of electrolytes, including electrical charge, affect nerve and muscle function in the body. - Mineral salts dissociate in water to form ions. - There are many electrolytes in the body, in nutrition; the term is typically used to refer to sodium, potassium, and chloride. - Electrolytes are positively and negatively charged ions that conduct an electrical current in solution. - The correct combination and amounts of electrolytes are essential for life - Distribution of electrolytes affects the distribution of water throughout the body. - Na+, K+, Cl- = the principle electrolytes in body fluids.

electrolyte deficiency

- Fluid loss and medications may cause K+ loss. - Lasix = used to treat HTN

factors that affect the risk of hypertension

- Genetics, age, diet, obesity, ethnicity, diabetes, smoking, stress, alcohol, and limited physical activity. - Hypertension has no outward symptoms - Blood pressure should be monitored regularly - "the silent killer"

10.3 hypertension - what causes hypertension?

- Hypertension = high blood pressure. Increase in pressure of blood against arterial wall - Optimal blood pressure is 120/80 mm Hg • First number = systolic (maximum pressure) when the heart beats/contracts • And the latter is diastolic (minimum pressure in artery) in between heartbeats, when heart is resting. - Prehypertension: above 120/80 up to 139/89 - Hypertension = consistently elevated blood pressure of and above 140/90. • Can result in damage to artery walls, increases workload of heart (hypertrophy), blood vessels can weaken and rupture. • Increased risk for atherosclerosis, heart attack, stroke, kidney disease. - Essential hypertension = diagnosis when no other disease is causing the hypertension; otherwise would be secondary hypertension such as occurs if have atherosclerosis in arteries feeding blood to the kidneys. - Essential hypertension = disorder of regulation of body fluids and electrolytes; often treat with ACE (angiotensin converting enzyme) inhibitors.

how diet affects blood pressure

- In general, higher sodium gives higher blood pressure, but diets high in fiber, potassium, calcium, and magnesium result in lower blood pressure. - Some individuals are more sensitive to higher salt intake- so-called salt sensitive individuals - Changing just one individual nutrient may not show a beneficial effect, but changing dietary pattern is effective... DASH • DASH diet lowers systolic blood pressure and diastolic blood pressure. • A diet high in fruits and veggies (good sources of K+, Mg, Fiber) reduces blood pressure compared to a similar diet with fewer fruits and vegetables. • The DASH (Dietary Approaches to Stop Hypertension) has been effective in lowering blood pressure, reducing cancer risk, preventing osteoporosis and protecting against heart disease.

distribution of body water (2)

- In young adults, total body water comprises ~72% of fat-free mass (everything in the body but fat: muscle, bone, blood, tendons, and interstitial spaces). - At birth, total body water accounts for 80% of the fat-free mass (less "Dry" bone and more "wet" cartilage). - During growth, the amount of total body water increases but the percentage of water in the fat-free mass decreases until it reaches 72% at maturity. - Older individuals experience a decrease in total body water as they age which may be due to a decrease in fat-free mass. - Throughout life, total body water is always lower in females.

how electrolyte balance is regulated

- Kidney = primary regulator of Na+, Cl-, and K+ - Excretion via urine decreased when intake is low and increased when intake is high. Water follows by osmosis and the ability of kidney to conserve NA+ = a way to conserve body water. • NA+ plays key role in regulating extracellular fluid volume • Na+ concentration high, by osmosis = water and increased blood volume = blood pressure changes.

sodium

- Major positively charged ion in extracellular fluids - Functions • Regulating fluid balance • Regulating blood pressure • Transmitting nerve impulses • Contracting muscles • Helping nutrient transport - Consumption • AI = 1500 mg/day • Food sources: table salt and processed foods • UL for adults = 2300 mg/day • Overconsumption can cause hypertension • When purchasing process foods, select "reduced sodium" or "low sodium" varieties and watch the serving size. - Decrease sodium intake • Use food labels, choose unprocessed foods, fresh or frozen vegetables, fresh or frozen fish, poultry and meat • When cooking: prepare meals from scratch, don't add salt to the water when cooking rice, pasta, and cereals. Flavor foods with ingredients such as lemon juice, onion, or garlic powder, pepper, curry, dill, basil, oregano, or thyme over salt.

water balance: acid-base balance

- Normal range of blood pH is very narrow. - No chemical reactions below 7.35 or above 7.45.

electrolyte toxicity

- Not possible to consume excess K+ in foods • Excess supplements, decreased kidney fxn (renal disease), can cause toxicity, may = death - Difficult to consume excess Na because we drink more water.. fluid is increase to compensate. - Sodium and potassium are highly regulated

water deficiency: dehydration

- Occurs when water loss exceeds intake - 1-2% body water loss = impair cognitive and physical performance • early symptoms: headache, fatigue, loss of appetite, dry eyes and moth, dark-colored urine - 5% loss of body weight as water = nausea and difficulty concentrating - 7% loss = confusion, disorientation - 10-20% loss can be fatal - Are you at risk for dehydration? • Urine color = indicates if you are drinking enough (Pale yellow = well hydrated, The darker the urine = greater level of dehydration) - Consequences of dehydration • Can live about 8 weeks without food, but a lack of water results in death in a few days. • Low blood volume reduces delivery of oxygen and nutrients • Loss of 1-2% can impair physical and cognitive performance - ORAL Rehydration Therapy • Replace lost fluids and electrolytes • Restore the body's water balance by promoting the absorption of water + Na • Drink dissolved mixture of: 1 Liter of clean water, ½ tsp. salt, 2 Teaspoons sugar. • Oral rehydration solutions maximize the rate of water absorption, but when water losses are too severe intravenous fluids may be necessary. This bypasses the GI tract and puts fluid directly into the blood.

potassium

- The Daily Value K+ is at least 3500 mg/day - No UL because there has never been toxicity reported with food consumption in people with normal kidney function - However, potassium supplements or impaired kidney function can result in too much potassium in blood and tissues resulting in death from irregular heart rhythms or cardiac arrest.

summary

- The U.S. diet is abundant in sodium and chloride from processed foods and table salt but generally low in potassium, which is high in unprocessed foods such as fresh fruits and vegetables. - The minerals sodium, chloride, and potassium are electrolytes that are important in the maintenance of fluid balance and the formation of membrane potentials essential for nerve transmission and muscle contraction. - Electrolyte and fluid homeostasis is regulated by the kidneys. A decrease in blood pressure or blood volume signals the release of the enzyme renin, which helps form angiotensin II. Angiotensin II causes blood vessels to constrict and the hormone aldosterone to be released. Aldosterone causes the kidneys to reabsorb sodium and hence water, thereby preventing any further loss in blood volume. Failure of these regulatory mechanisms may be a cause of hypertension. - Low levels of sodium, chloride, and potassium can occur when water and electrolyte losses are increased due to excessive sweating, chronic diarrhea or vomiting, or kidney disorders. High blood sodium most commonly results from dehydration.

water loss

- Typical adult (not sweating) = loses 2.7 to 3.7 L of water/day via urine, feces, evaporation (skin/lungs) - Typical urine output = 1-2 liters/day (depending on amount of water intake).. Proportional increase - Fecal loss = unusually small • 95% reabsorption • 9 liters (38 c) enters GI daily, but only 200 mL (<1C) - lost daily

how water is distributed throughout the body: distribution of body water

- Water is distributed intra- and extra-cellularly and its total volume is well regulated in healthy individuals. - About 2/3s of body water is found inside the cells. Water inside cells is called intracellular fluid - Extracellular fluid is found outside the cells (remaining 1/3). Consists of blood plasma, lymph, and interstitial fluid - The fluid pressure of blood against the blood vessels is called blood pressure. - Interstitial fluid consists of the fluid between cells. - In a young adult, blood is about 90% water, 75% muscle, 25% bone, and 105 adipocytes. (note that fat cells contain very little water.

recommended water intake

- We need more water each day than any other nutrient - Needs carry greatly based on: activity level, environmental temperature, humidity, high protein diet (increased urea), low kcal diet (ketones and urea as fat/protein = broken down), etc.

antidiuretic hormone

- assists in fluid intake • Increased ketones increase dietary protein (increase urea production), increased sodium increase water losses in urine. • Recall that alcohol is a diuretic and promotes increased water loss in urine. • Infants have a higher requirement per unit of body weight because infant's kidneys cannot concentrate urine as well as older children. Also their insensible loss is proportionally greater. • Blood volume decreases, solute increases → pituitary gland → antidiuretic hormone → kidney → body water conserved

how water functions in the body

- blood = 90% water - water functions as a lubricant and cleanser - blood transports oxygen and nutrients to cells and remove carbon dioxide and waste products - tears wash away dirt, synovial fluid lubricates joints, saliva assists in chewing, tasting, and swallowing, and spinal fluid protects against shock. - assists in regulating body temperature by holding onto heat and changing temperature slowly.

water functions: water helps cool the body

- blood carries heat from the body's core to the capillaries near the surface of the skin - heat is released from the skin to the environment - water in sweat evaporates from the skin causing heat to be lost. - evaporation cools the skin and the blood at this skin's surface. - cooled blood returns to the body's core.

how water functions in the body: water participates in metabolic reactions

- hydrolysis reaction adds water. breaks large molecules - condensation reaction removes water. disaccharide formation - beside participation in these types of reactions, water is the medium in which most reactions occur

water in the body - intracellular fluid - extracellular fluid - interstitial fluid

- intracellular water associated with body cell mass which is: potassium rich, metabolically active, and protein rich. - extracellular fluid: high in sodium, low in potassium and phosphate, protein-rich. - interstitial fluid: lowest in protein (than extracellular and intracellular fluids)

thirst mechanism

- motivates water intake to restore water balance - Thirst can be quenched before water balance is restored and often the sensation of this can lag behind a decrease in water balance (need for water). - Decrease water in blood. • Blood volume decreases, solute concentration increase, saliva secretion decreases • Thirst: in hypothalamus, thirst center in stimulated • Blood volume increases, and solute concentration decreases.

water balance: water and pH balance

- pH is the log of the hydrogen ion concentration - High hydrogen ion concentration: acidosis (too much acid): stomach acid, lemon juice, vinegar, tomato juice, black coffee - Normal blood pH (7.35-7.45) intracellular fluid - Low hydrogen ion concentration: alkylosis (too much base): detergents, household ammonia, bleach - Water is also needed as a transport medium to allow the respiratory tract and kidneys to regulate acid-base balance. - Most reactions in body occur in slightly basic solution around pH 7.4.

water is a polar solvent in the body

- the polarity of water comes from hydrogen [+] and oxygen [-]. - opposite charges attract. - Polar nature causes sodium chloride [NaCl] to dissolve when placed in water. the Na and Cl dissociate because the negative side of water molecules attract the positive Na and the positive side of water attract to the negative Cl. - water is a solvent. -- A solvent is a fluid in which one or more substances are dissolved. these dissolved substances are called solutes. The solvent plus solutes is called a solution. -- Na+ and Cl- are ions. An ion is an atom or group of atoms that carry an electrical charge. -- dissociate is separation of charged ions usually in a solution -- electrons (negatively charged particles) spend more time around oxygen and thats why there is a dipole and polarity with water.

water intake

- water intake must equal water lost (urine, evaporation, etc.) - 75-80% of total water intake comes from fluids - 20-25% comes from foods. - fruits and vegetables have a high water content compared to other foods.

10.1 Water: The internal sea

- water is an essential nutrient that must be consumed for survival. - without water, death occurs within a few days. - water is a polar solvent in the body.

blood pressure regulation

1. A decrease in blood pressure triggers the kidneys to release the enzyme renin 2. Renin converts angiotensinogen into angiotensin I, which is activated to angiotensin II by angiotensin -converting enzyme (ACE). 3. Angiotensin II increases blood pressure by constricting the walls of blood vessels. 4. Angiotensin II stimulates release of aldosterone from the adrenal gland. 5. Aldosterone increases sodium reabsorption by the kidneys 6. Water follows sodium, decreasing urine output.

summary: water deficiency

dehydration can occur if water intake is too low or output is excessive. Mild dehydration can cause headache, fatigue, loss of appetite, dry eyes and mouth, and dark-colored urine. Severe dehydration can be fatal.

review

o Functions of water: Regulates body temperature, Transports nutrients and oxygen, Lubricates joints, Present in mucus and saliva, Cushions tissues, Acts as a solvent, Removes waste - Water balance in the body • 2/3 of water is intracellular • 1/3 water is extracellular water moves by osmosis ( Based on concentration of solutes) • Since water can pass across the membrane, but the solutes cannot, water will be drawn into the cell toward the higher concentration of solute particles in an attempt to equalize the concentration of solutes on both sides of the membrane. • Increases in activity level, altitude, and ambient temperature or humidity will greatly increase water losses via the skin and the lungs. (Input: beverages, food, byproduct of metabolism, Output: lungs, skin (sweat), feces, urine), The lighter your urine, the more hydrated you are.) - Antidiuretic hormone and water balance • The hypothalamus in the brain detects increased concentration of solutes in blood. It also receives signals when blood volume (pressure) drops. • In response, the hypothalamus stimulates the pituitary to release antidiuretic hormone (ADH) into the blood. • In response, ADH decreases • ADH stimulates the kidney to retain more water, increasing blood volume and decreasing solute concentration, which suppresses ADH release. - Water in take recommendations • Total water intake: men (3.7 liters) and women (2.7 liters). • Fluid intake: men (3.0 liters) and women (2.2 liters) - Deficiency: dehydration, nausea, dizziness, elevated temperature - Excess water consumption without electrolytes: hyponatremia, confusion, nausea, vomiting, bloating, swelling around the brain.

summary: how water is distributed throughout the body

the adult human body is about 60% water by weight. Body water is distributed between intracellular and extracellular compartments. The amount in each compartment depends largely on the concentration of solutes. Since water will diffuse by osmosis from a compartment with a lower concentration of solutes to one with a higher concentration, changes in the concentration of electrolytes and other solutes in each compartment cause changes in the distribution of water.

summary: water balance and intake

water cannot be stored, so intake must balance losses to maintain homeostasis. Fluid intake is stimulated by the sensation of thirst , which occurs in response to a decrease in blood volume and an increase in the concentration of solutes. Water is lost from the body in urine and fecees, though evaporation from the skin and lungs, and in sweat. The kidney is the primary regulator of water output. If water intake is low, antidiuretic hormone will cause the kidney to conserve water. If water intake is high, more water will be excreted in urine.

summary: water functions in the body

water is an essential nutrient that provides many functions in the body. The polar structure of water allows it to act as a solvent for the molecules and chemical reactions involved in metabolism. Water helps to transport other nutrients and waste products within the body and to excrete wastes from the body. It also helps to protect the body, regulate body temperature, and lubricate areas such as the eyes and the joints.

sodium, potassium, and chloride in our food

• The modern diet is high in salt (sodium chloride) and low in potassium because of high fast food consumption and processed foods with salt added, and low consumption of whole grains, fruits and vegetables that are low in sodium and high in potassium. • Processing affects sodium and potassium: more processed food has higher salt and lower potassium. - Other sodium salts are added to foods, but sodium chloride is considered a health problem when consume too much; although it is not without some controversy over the years. - Softened water is produced by exchanging sodium for other "harder" minerals and can contribute a significant amount of salt. - Prehistoric diets were low in salt and high in potassium (nuts, berries, roots and greens); fresh animal foods like meat and milk are also low in salt; these all are high in potassium. - Salt is a food preservative and enhances flavor so was highly valued in ancient times. - Roman soldiers paid in sal, Latin word for salt, and now we have the word salary. - Today salt is abundant and not prized, but rather associated with hypertension (high blood pressure - 140/90 mm Hg or greater) - Sodium's role in hypertension has been debated over the years. - Deficiencies of the electrolytes are rare because they are plentiful in the diet and if kidneys are healthy the electrolytes are well-regulated. - Deficiency can occur with heavy and persistent sweating, diarrhea, or vomiting or kidney disorders that lead to excessive urinary losses. - Medications can affect the status of electrolytes; thiazide diuretics used to treat hypertension by increasing fluid and sedum loss in urine cause increased excretion of potassium. - Medications known to cause loss of potassium are accompanied by potassium supplements. - Sudden death can occur in fasting or anorexia nervosa, or starvation this may be due to potassium deficiency and heart failure.