Question 1

Water loss from the body that we do not notice is known as:

Accepted Answer

Insensible water loss refers to the water lost from the body through breathing and perspiration that we are not consciously aware of. This is in contrast to sensible water loss, which refers to the water lost through urine output and sweating that we can see and feel. Obligatory water loss and nonsense water loss are not commonly recognized terms in the field of human physiology.

Question 2

Classify sodium balance in the human body.

Accepted Answer

Sodium is an electrolyte and its balance in the human body is necessary to maintain electrolyte balance.

Question 3

Which of the following accounts for about 60% of our total body water?

Accepted Answer

Cytosol, the liquid found inside cells, accounts for about 60% of the body's total water content.

Question 4

What part of the brain controls the thirst mechanism?

Accepted Answer

The hypothalamus is the part of the brain responsible for regulating the thirst mechanism. It receives signals from certain receptors in the body that indicate a decrease in fluid levels and subsequently triggers the sensation of thirst.

Question 5

Predict the effect of hypertonic fluid on a cell.

Accepted Answer

Hypertonic fluids have a higher solute concentration than the cytosol of the cell. This causes water to move out of the cell to achieve equilibrium, leading to the cell shrinking or crenating. Therefore, hypertonic fluid causes water to move out of the cytosol and the cell shrinks.

Question 6

How much water does the average person lose per day?

Accepted Answer

The average person loses about 2.5 liters of water per day through processes such as sweating, breathing, and urination.

Question 7

Which system is responsible for the most common route of water loss from the body?

Accepted Answer

The urinary system is responsible for the most common route of water loss from the body, as it eliminates water along with waste products through urine.

Question 8

The average young adult human male body contains about liters of total body water.

Accepted Answer

The average young adult human male body contains about 42 liters of total body water, which is approximately 60% of its total body weight.

Question 9

Which type of extracellular fluid (ECF)solution will cause a cell to gain water?

Accepted Answer

A hypotonic ECF solution has a lower concentration of solutes than the intracellular fluid (ICF) of the cell, so water will diffuse from the hypotonic ECF into the cell, causing the cell to swell and gain water.

Question 10

How much urine is lost through obligatory water loss each day?

Accepted Answer

Obligatory water loss refers to the minimum amount of water that must be excreted by the body in order to eliminate waste products. This is typically around 500 ml per day, which includes urine as well as water lost through sweating and breathing. Option B is the closest to this value. The other options are too high or too low.

Question 11

Determine the pH value that represents a basic,or alkaline,solution.

Accepted Answer

A pH value of 7 is considered neutral, anything less than 7 is considered acidic and anything greater than 7 is considered basic or alkaline. Therefore, a pH value of 10 represents a basic solution.

Question 12

What is the most potent stimulus of the thirst mechanism?

Accepted Answer

The osmolarity of the extracellular fluid (ECF) is the most potent stimulus of the thirst mechanism. When there is an increase in osmolarity, the hypothalamus detects this change and triggers the release of antidiuretic hormone (ADH) to conserve water and stimulate thirst. This is why we feel thirsty when we eat something salty or when we are dehydrated. Atrial natriuretic peptide (ANP), increased blood pressure, and increased plasma volume can all have the opposite effect of inhibiting the thirst mechanism.

Question 13

What best describes hydrostatic pressure?

Accepted Answer

Hydrostatic pressure is the force exerted by fluids against the capillary wall. It is mainly determined by the volume of fluid in the vessel and the force of gravity. This pressure is balanced by the oncotic pressure, which is the force exerted by proteins in the blood vessels. Together, they help regulate the movement of fluids and solutes across the capillary wall.

Question 14

Which of the following fluids has the greatest concentration of potassium ions?

Accepted Answer

Potassium ions have a high concentration inside the cell, so the cytosol, or intracellular fluid, has the greatest concentration of potassium ions compared to extracellular fluids like ECF, plasma, and interstitial fluid.

Question 15

Select the statement that best describes an acid.

Accepted Answer

An acid is defined as a chemical that releases hydrogen ions (H+) when dissolved in water. This is known as dissociation. Choice D accurately describes this process. Choices A and C are incorrect as they do not describe the defining characteristic of an acid. Choice B is incorrect as it describes a neutral solution where the amount of hydrogen ions and hydroxide ions is equal, rather than an acid specifically.

Question 16

What type of neuron detects changes in plasma osmolarity?

Accepted Answer

Osmoreceptors are specialized neurons that detect changes in plasma osmolarity, which reflects the concentration of solutes in the blood. When osmoreceptors detect high levels of solutes in the blood, they trigger the release of anti-diuretic hormone (ADH) from the posterior pituitary gland, which increases water reabsorption in the kidneys and helps to dilute the blood. This mechanism helps to maintain homeostasis of body fluid balance. Baroreceptors, nociceptors, and chemoreceptors detect changes in blood pressure, tissue damage, and chemical composition, respectively.

Question 17

Which of the following dissociates into ions when placed in water?

Accepted Answer

An electrolyte is a substance that dissociates into ions when placed in water. Therefore, the correct answer is A, electrolyte. Starch and glucose are both carbohydrates that do not dissociate into ions when placed in water, making them nonelectrolytes.

Question 18

In what direction will water move when hypotonic fluids are present in the plasma?

Accepted Answer

Hypotonic fluids have a lower concentration of solutes than the plasma, which creates a concentration gradient. Water will move from an area of higher concentration (the hypotonic fluid) to an area of lower concentration (the plasma) through osmosis, which pulls water from the interstitial fluid and plasma into the cell. This can cause cells to swell and potentially burst if the influx of water is too great.

Question 19

The following represents the main locations fluids are found in the human body.Rank these body fluids in order from the fluid that accounts for most in the human body to the fluid that accounts for the least.

Accepted Answer

Cytosol (intracellular fluid) accounts for the most fluid in the human body, followed by interstitial fluid and plasma. This is because the cytosol makes up the majority of the volume of cells in the body and there are more cells than there are plasma and interstitial fluid. Interstitial fluid comes next as it surrounds the cells and is found in the spaces between cells. Plasma, which is the liquid part of blood, accounts for the least amount of fluid in the body.

Question 20

Fluid balance in the human body is roughly equivalent to:

Accepted Answer

Fluid balance in the human body refers to the amount of water entering and leaving the body to maintain a stable level of hydration. This includes both water intake from liquids and foods and water loss through sweat, urine, and breathing. Therefore, the best choice is A, water balance. The other options may also contribute to overall fluid balance, but they are more specific and do not encompass the entire concept of fluid balance.

Quiz 25: Fluid, Electrolyte, and Acid-Base Homeostasis