Body Water Composition and Functions
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Questions and Answers

What prompts the movement of water during osmosis?

  • Water flows equally in both directions.
  • Water moves toward areas with higher solute concentration. (correct)
  • Water moves toward areas with lower solute concentration.
  • Water moves randomly across a membrane.

How should fluid intake be managed during exercise lasting more than one hour?

  • Electrolytes alone should be consumed.
  • No additional fluids are necessary.
  • Water and a carbohydrate solution should be consumed. (correct)
  • Only water should be consumed.

What happens to vegetables that are sprinkled with salt?

  • They absorb more water from the soil.
  • They retain their moisture and do not change.
  • They become firmer as water moves into them.
  • They release water due to osmosis toward the higher salt concentration. (correct)

What is the purpose of consuming electrolytes during intense or prolonged exercise?

<p>To balance the water lost through sweat. (D)</p> Signup and view all the answers

What role does the hypothalamus play in regulating water intake?

<p>It monitors blood concentration of water and solutes. (D)</p> Signup and view all the answers

Which of the following groups should notably increase their water intake?

<p>Athletes exercising in high heat and humidity. (B)</p> Signup and view all the answers

What is the best indicator of dehydration?

<p>Darker urine color. (A)</p> Signup and view all the answers

What triggers the sensation of thirst?

<p>High concentration of solutes in the blood. (D)</p> Signup and view all the answers

Which physiological process is NOT directly involved in regulating fluid intake?

<p>Increased urine output. (D)</p> Signup and view all the answers

Why might infants require more water than adults?

<p>Their cells are increasing in size. (D)</p> Signup and view all the answers

Dehydration can lead to which of the following symptoms?

<p>Dizziness and muscle cramps. (B)</p> Signup and view all the answers

Which dietary factor significantly influences the need for increased water intake?

<p>High protein consumption. (B)</p> Signup and view all the answers

When is dehydration most likely to occur?

<p>Before one feels thirsty. (A)</p> Signup and view all the answers

What is the daily recommended intake of water for females?

<p>2.7 liters. (D)</p> Signup and view all the answers

What can excessive water consumption potentially lead to?

<p>Heart attack or organ failure (B)</p> Signup and view all the answers

Which of the following is primarily involved in maintaining electrolyte balance?

<p>Water intake (D)</p> Signup and view all the answers

Which statement about the pH scale is true?

<p>The pH scale ranges from 0 to 14. (A)</p> Signup and view all the answers

Which ion is considered the main intracellular cation?

<p>Potassium (K+) (D)</p> Signup and view all the answers

What is the result of mixing hydrochloric acid (HCl) and sodium hydroxide (NaOH)?

<p>Sodium chloride and water (C)</p> Signup and view all the answers

What defines an acid in terms of electrolyte behavior?

<p>Releases hydrogen ions (A)</p> Signup and view all the answers

Which statement accurately describes water's role as a solvent?

<p>It enhances the ionization of substances. (C)</p> Signup and view all the answers

What is NOT a significant contributor to electrolyte balance?

<p>Exposure to UV light (D)</p> Signup and view all the answers

What characterizes an electrolyte?

<p>It ionizes in water solution. (D)</p> Signup and view all the answers

Which of the following best describes the term 'solutes'?

<p>Substances that are dissolved in a solution. (D)</p> Signup and view all the answers

What percentage of water is made up of intracellular fluid in the body?

<p>55% (B)</p> Signup and view all the answers

Which group is likely to have a higher water content in their bodies?

<p>Children (D)</p> Signup and view all the answers

Which of the following is NOT a function of water in the body?

<p>Stores excess energy as fat (A)</p> Signup and view all the answers

During which digestive process is most water absorbed?

<p>In the small intestine (B)</p> Signup and view all the answers

Which type of food typically contains a high proportion of water and low kcal content?

<p>Fruits (D)</p> Signup and view all the answers

What is the main consequence of prolonged fecal retention in the large intestine?

<p>Increased water absorption back into the body (D)</p> Signup and view all the answers

Which type of fluid comprises the majority of extracellular fluid?

<p>Interstitial fluid (D)</p> Signup and view all the answers

What characteristic of fats relates to their water content?

<p>Low water content and high kcal (D)</p> Signup and view all the answers

What is the primary role of renin in the body?

<p>To initiate the activation of angiotensinogen (C)</p> Signup and view all the answers

What effect does angiotensin have on the adrenal gland?

<p>It stimulates aldosterone secretion (D)</p> Signup and view all the answers

Under normal conditions, which is the typical range of total water excretion per day?

<p>1450 – 3300 ml (D)</p> Signup and view all the answers

What condition can result from excessive water intake without adequate electrolyte balance?

<p>Water intoxication (C)</p> Signup and view all the answers

What symptom is commonly associated with water intoxication due to decreased electrolytes?

<p>Swelling of cells (edema) (D)</p> Signup and view all the answers

How can a person develop a craving for salt during water intoxication?

<p>Due to low sodium levels in the body (C)</p> Signup and view all the answers

What happened to the man who drank water excessively as reported in the newspaper article?

<p>He exhibited confusion and paranoia (B)</p> Signup and view all the answers

What is the role of aldosterone in the body?

<p>To promote sodium retention and water reabsorption (D)</p> Signup and view all the answers

Which of the following is NOT a common means of water excretion in the body?

<p>Salivary glands (B)</p> Signup and view all the answers

What could happen if pure water is administered to a dehydrated person without electrolytes?

<p>Development of water intoxication (A)</p> Signup and view all the answers

Flashcards

Water content in the body

The human body is made up of approximately 60% water, with variations based on age, gender, body composition, and bone density.

Intracellular fluid

Water found inside the cells, making up about 55% of the body's total water content.

Extracellular fluid

Water found outside the cells, constituting about 45% of the body's total water content.

Water in foods

Foods high in water content typically have a low calorie count, while foods high in fat have a lower water content and higher calorie count.

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Functions of water

Water plays many crucial roles in the body, including nutrient and waste transport, lubrication, temperature regulation, and chemical reactions.

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Water absorption

Over 80% of ingested water is absorbed in the small intestine, with smaller amounts absorbed in the stomach and large intestine.

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Relationship between water and constipation

The longer feces stays in the large intestine, the more water is absorbed back into the body, leading to constipation.

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Soluble fiber and water absorption

Soluble fiber, found in foods like oats and beans, can help absorb water and prevent constipation.

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Osmotic Pressure

The force that drives water to move across a semi-permeable membrane from an area of low solute concentration to an area of high solute concentration.

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Osmosis

The movement of water across a semi-permeable membrane from an area of high water concentration (low solute concentration) to an area of low water concentration (high solute concentration).

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Electrolyte Balance

The balance of electrolytes (like sodium, potassium, and chloride) in the body's fluids.

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Water Loss During Exercise

The body loses water through sweating during exercise, which can lead to dehydration if not replenished.

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Electrolytes and Exercise

During exercise, electrolytes are lost through sweat. Replenishing electrolytes is crucial for performance and health, especially in long or intense workouts.

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Psyllium's effect on stool

Psyllium, a soluble fiber, absorbs water in the large intestine (LI), which softens the stool and helps prevent constipation.

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Sources of water intake

We get water from three main sources: 1) Drinking, 2) Eating, and 3) Metabolism. The total daily intake can vary greatly depending on individual needs and lifestyle.

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Hypothalamus role in thirst

The hypothalamus, a part of the brain, monitors the concentration of water and solutes in the blood. When it detects a high concentration of solutes (dehydration), it triggers impulses that stimulate thirst.

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Thirst mechanism

The sensation of thirst helps motivate us to drink fluids, which is essential for restoring water balance in the body.

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Dehydration signs

Dehydration is a loss of body fluids. Symptoms include thirst, muscle cramps, fatigue, dizziness, and fainting. Darker urine color indicates greater dehydration.

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Who needs more water?

Athletes, people working in hot climates, the elderly, lactating women, infants, those on high-protein diets, people with fever, those taking diuretics, and individuals with diarrhea/vomiting or high salt intake should increase their water intake.

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Renin's role in water regulation

When blood flow to the kidneys reduces, they release renin, an enzyme that helps regulate blood volume.

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Pituitary gland's role in water balance

The pituitary gland, stimulated by the hypothalamus, releases hormones to regulate water balance in response to high salt concentrations in the blood.

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Water balance regulation: Summary

The body regulates water intake and excretion through a complex system involving the hypothalamus, kidneys, pituitary gland, and other organs. These mechanisms work together to maintain adequate water balance.

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Water balance: Key takeaway

Maintaining proper hydration is crucial for overall health. Understanding the mechanisms of water intake and excretion helps individuals make informed choices for staying healthy and hydrated.

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Electrolyte

A substance that breaks down into ions (charged particles) when dissolved in water. Examples include sodium chloride (NaCl).

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Acid

A substance that releases hydrogen ions (H+) when dissolved in water.

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Base

A substance that accepts hydrogen ions (H+) in a solution, often releasing hydroxide ions (OH-).

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pH Scale

A numerical scale measuring the concentration of hydrogen ions (H+) in a solution. Lower pH means higher H+ concentration and stronger acidity.

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Solute

A substance that is dissolved in a solution.

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Salt

A substance formed by the reaction between an acid and a base.

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Anion

A negatively charged ion.

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Cation

A positively charged ion.

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Sodium (Na)

The main extracellular cation in the body.

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Potassium (K)

The main intracellular cation in the body.

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Chloride

A major anion in body fluids.

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What initiates the renin-angiotensin-aldosterone system?

Renin, an enzyme produced by the kidneys, starts the cascade of events leading to the production of angiotensin II, which causes vasoconstriction and aldosterone release.

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What does angiotensin II do?

Angiotensin II is a potent vasoconstrictor, meaning it narrows blood vessels, increasing blood pressure. It also triggers the release of aldosterone from the adrenal glands.

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What is the role of aldosterone?

Aldosterone is a hormone produced by the adrenal glands. It acts on the kidneys to increase sodium reabsorption and potassium excretion, ultimately leading to an increase in blood volume.

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What does ADH do?

Antidiuretic hormone (ADH) is released by the pituitary gland. It increases water reabsorption in the kidneys, reducing urine output and maintaining blood volume.

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How does the body regulate water balance?

The body maintains water balance through a complex interplay of hormones like renin, angiotensin, aldosterone, and ADH. These hormones work together to regulate sodium and water levels in the blood, ensuring appropriate fluid balance for proper functioning.

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What are the main routes of water excretion?

The body excretes water through the kidneys (urine), feces, lungs (breathing), and skin (sweat).

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What is water intoxication?

Water intoxication occurs when the body takes in excess water, leading to a decrease in electrolytes, particularly sodium. This imbalance can cause a range of symptoms including edema, muscle cramps, and confusion.

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What are the symptoms of water intoxication?

Symptoms of water intoxication include edema (swelling), muscle cramps, confusion, and even convulsions. These symptoms arise due to a decrease in electrolytes, particularly sodium, disrupting cellular function.

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Why is it dangerous to administer pure water to a dehydrated person?

Administering only pure water to a dehydrated person can worsen the situation. Dehydration often involves electrolyte loss, and adding only water without electrolytes can lead to further imbalance and potentially water intoxication.

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What is a salt craving often a sign of?

A salt craving often indicates an electrolyte imbalance. This can happen when the body loses electrolytes through sweating or other mechanisms, leading to a deficiency that the body tries to correct by craving salty foods.

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Study Notes

Water Content in the Body

  • The human body is comprised of 60% water.
  • Water content varies by age, sex, and lean body mass.
  • Children and males have a higher proportion of water compared to adults and females.
  • Muscle tissue contains a higher water percentage (70%) than fat tissue (10%).
  • Bone density also affects water content, being higher in children and males.

Body Water Distribution

  • 55% of body water is intracellular fluid (inside cells).
  • 45% of body water is extracellular fluid (outside cells).
  • 5% of body water is present in other fluids like bone, gallbladder (bile), glands, and fluids in the spine and digestive system.
  • Interstitial fluid is a component of extracellular fluid, encompassing lymph and blood plasma.
  • Blood pressure is the force exerted by blood against blood vessels.

Water in Foods

  • Foods with high water content have low caloric content.
  • Foods rich in fat have little water and high caloric density.

Water Functions

  • Water transports nutrients and waste products throughout the body.
  • It carries vitamins and minerals.
  • Water acts as a lubricant and cushion for joints, eyes, and amniotic fluid.
  • It aids in chewing, tasting, and swallowing (saliva).
  • Sweating helps regulate body temperature.
  • Water maintains blood volume (blood is 90% water).
  • Water is essential for chemical reactions like hydrolysis, condensation, and metabolism.

Water Absorption

  • Over 80% of ingested water is absorbed in the small intestine.
  • A small amount is absorbed in the stomach.
  • Water absorption in the large intestine (LI) increases with longer transit time, causing constipation.
  • Soluble fiber (e.g., psyllium) absorbs water in the LI, softening stool and reducing constipation.

Water Intake Sources

  • Water intake from food ranges from 700 to 1000 ml.
  • Water intake from drinking ranges from 550 to 1900 ml.
  • Water from metabolism accounts for 200 to 300 ml.
  • Total daily water intake is approximately 1450 to 3300 ml.
  • Recommended daily intake (AI) for males is 3.7 liters, and for females is 2.7 liters.

Water Intake Regulation

  • The hypothalamus, part of the brain, regulates thirst.
  • The hypothalamus monitors water and solute concentration in the blood.
  • When blood concentration is high (dehydration), the hypothalamus triggers signals to drink.
  • The mouth, stomach lining and nerves act as stretch receptors to detect fluid volume, stopping ingestion when sufficient. Thirst lags behind the need for water.
  • Dehydration is the loss of fluids in the body.

Water Excretion

  • The kidneys excrete 500 to 1500 ml of water.
  • Feces remove 100 to 200 ml of water.
  • Lungs expel 250–400 ml of water.
  • Skin excretes 600–1200 ml of water.
  • Total water output approximates daily intake (1450–3300 ml).

Water Balance (non-exercisers)

  • Daily water intake for a non-exercising individual is approximately 2.625 liters (or 2250ml) with water input (food and beverages) contributing 1,875 ml and metabolism providing the remaining amount
  • This is balanced by excreting approximately water in the form of urination, perspiration and excretion (feces) with excretion roughly around 2.25 liters.

Water Intoxication

  • Water intoxication occurs when body water levels become excessively high.
  • This can happen from drinking large volumes in a short period or administering pure water to dehydrated individuals (without electrolytes).

Water Intoxication Symptoms

  • Symptoms include cellular swelling (edema), muscle cramps, convulsions, and confusion, due to electrolyte imbalance.

Electrolyte Balance

  • Electrolytes are substances that ionize in water solutions.
  • They include sodium, chloride and potassium.
  • Electrolyte balance occurs when the amounts entering the body match those leaving.
  • This balance is crucial for maintaining cellular function and body processes.

Types of Electrolytes

  • Acids release hydrogen ions, based accept them and OH predominates.

pH Scale

  • The pH scale measures the concentration of hydrogen ions (H+).
  • The lower the pH, the higher the H+ concentration, indicating acidity.
  • Blood pH is typically between 7.35 and 7.45

Solutes

  • Solutes are substances dissolved in a solution.

Important Electrolytes (cont'd)

  • Sodium (Na+) is the major extracellular cation.
  • Potassium (K+) is the major intracellular cation.
  • Chloride (Cl−) is another significant electrolyte.

Osmosis and Cell Hydration

  • Osmosis is the process where water moves across a membrane from an area of low to high solute concentraction.
  • Osmosis maintains electrolyte balance in body cells.

Water and Electrolytes for Exercise

  • For exercise lasting an hour or less, only water is needed.
  • For exercise greater than an hour, a carbohydrate and electrolyte solution (6-8% CHO) might be needed (important if hot/humid or exercise long duration).
  • Excessive water consumption can cause water intoxication and heart attack or organ failure.

Bottled Water

  • Bottled water is water intended for human consumption, put in a sealed container.
  • It can be taken from natural sources or municipal water supplies.

Additional Notes

  • Individual needs for water and electrolyte replacement vary based on several factors, such as exercise intensity, duration, environment, health status, medical conditions (e.g., diabetes, kidney disease).
  • Always consult a medical professional for specific guidance on hydration and electrolyte needs.
  • Electrolyte supplements are not necessary for average healthy individuals unless exercising heavily and/or intensely.

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Description

Explore the vital role of water in the human body through this quiz. Learn about the percentages of water in different tissues, how distribution varies with age and sex, and the functions of water in bodily processes. Test your understanding of body water distribution and its implications for health.

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