A&P CH 24

True or false: A newborn baby's weight is as much as 75% water, whereas obese and elderly people's weight is as little as 45% water.

True

Which represents the largest fluid compartment in the body?

Multiple choice question.

Intracellular fluid

A person is in a state of fluid ________ when daily gains and losses are equal.

balance

Which is produced as a by-product of dehydration synthesis reactions and aerobic respiration?

Metabolic Water

Which term refers to water that is taken into the body in food and drink?

Preformed water

The total body water content of a 70kg (150 lb) young male is about ______.

40 L

True or false: Most of the water (65%) is found in the extracellular compartment.

True false question.

False

We typically gain and lose about ______ mL of fluids a day.

Multiple choice question.

2500

Which are examples of preformed water? Select all that apply.

-Water in a glass of milk

-Water in an apple

-Water in a baked potato and steak dinner

Which term refers to water formed by dehydration synthesis and aerobic respiration?

Multiple choice question.

metabolic water

True or false: Respiratory loss decreases in cold weather.

True false question.

False

Which term refers to water that is produced as a by-product of dehydration synthesis reactions and aerobic respiration?

Metabolic Water

Fluid intake is governed by thirst and it is regulated by a group of hypothalamic neurons called ________ , which respond to angiotensin II and to rising osmolarity of the ECF.

osmoreceptors

Which represents the largest fluid compartment in the body?

Intracellular fluid

Water output is primarily controlled through variations in which of the following?

Urine Volume

Which best defines preformed water?

Water ingested in food (700 mL/d) and drink (1600 ml/d)

Hypovolemia and dehydration are both examples of fluid deficiency. How do they differ?

In dehydration water is lost, and in hypovolemia both water and electrolytes are lost.

Prolonged, heavy work increases which of the following? Select all that apply.

-Perspiration

-Respiratory loss

True or false: In cases of volume depletion, total body water declines but fluid osmolarity is normal.

True

Which best defines osmoreceptors?

Multiple choice question.

Hypothalamic neurons that respond to increased solute concentration in the extracellular fluid

Which factors can lead to volume depletion (hypovolemia), in which proportionate amounts of water and sodium are lost?

-Chronic vomiting

-Diarrhea

-Hemorrhage

True or false: The only way to control water output significantly is through variations in urine volume.

True

Which are types of fluid deficiency? Choose two of the options from the list below.

-Dehydration

-Volume depletion

True or false: Respiratory loss decreases in cold weather.

False

Which are effects of dehydration?

- Increased blood osmolarity

- Reduced blood pressure

- Reduced salivation

Which term is another name for volume depletion? This occurs when proportionate amounts of both water and sodium are lost without replacement.

Hypovolemia

Which may occur when proportionate amounts of water and sodium are lost without replacement, for example due to hemorrhage, chronic vomiting, or diarrhea?

Hypovolemia

The simplest cause of dehydration is a lack of drinking water. Which of the following can also cause dehydration? Select all that apply.

-Cold or hot weather

-Overuse of diuretics

-Diabetes mellitus

-Profuse sweating

True or false: Dehydration affects the extracellular fluid exclusively.

True false question.

False

What happens to ECF osmolarity during dehydration?

It Increases

In which form of fluid imbalance is total body water reduced while osmolarity remains normal?

Chronic vomiting

Hemorrhage

Diarrhea

Which best defines fluid sequestration?

A condition in which excess fluid accumulates in a particular location

Why are infants more vulnerable to dehydration than adults?

they have higher metabolic rates and produce toxic metabolites faster

Sodium, potassium, calcium and hydrogen ions are examples of which of the following?

Cations

Dehydration that occurs in cases such as in profuse sweating affects which of the following fluid compartments?

ICF, blood, & tissue fluid

Which statement about dehydration is true?

Dehydration raises blood osmolarity.

Match each form of fluid imbalance to its description.

Hypovolemia-

Dehydration-

Volume Excess-

Hypotonic Hydration-

Hypovolemia- Total body water is reduced; ECF remains isotonic.

Dehydration- Total body water is reduced; ECF becomes hypertonic.

Volume Excess- total body water is elevated; ECF remains isotonic.

Hypotonic Hydration-Total body water is elevated; ECF becomes hypotonic.

Which statement is correct regarding the relative abundance of electrolytes in the ECF and ICF?

Sodium is more abundant in the ECFpotassium is more abundant in the ICF.

Which statements are true regarding fluid sequestration? Select all that apply.

It is a condition in which excess fluid accumulates in a particular location.

Causes of fluid sequestration include edema and hemmorhage

Which is referred to as the "salt-retaining hormone" because it plays the primary role in adjusting sodium excretion?

aldosteron

Chloride (Cl-), bicarbonate (HCO3-), and phosphates (Pi) are examples of what?

Anions

Which ion is the most significant solute in determining total body water and the distribution of water among fluid compartments?

sodium

True or false: Dehydration affects the extracellular fluid exclusively.

False

Which regulate sodium homeostasis?

Antidiuretic hormone

Aldosterone

Natriuretic peptides

The most abundant solute particles are electrolytes, especially potassium in the intracellular fluid (ICF) and ______ in the extracellular fluid (ECF).

Sodium

Which ion is the greatest determinant of intracellular osmolarity and cell volume?

Potassium

What stimulates the secretion of aldosterone? Select all that apply.

hyperkalemia

hypotension

hyponatremia

Imbalances in which ion are the most dangerous of all electrolyte imbalances?

Potassium

Which are important functions of sodium?

It participates in muscle and nerve depolarization.

It is involved in generating body heat via the Na-K pump.

It participates in cotransport of glucose, K+ and Ca+.

Cells maintain a very low intracellular calcium concentration to avoid crystallization of calcium phosphate. Which mechanisms maintain intracellular calcium concentrations low?

Cells often have a protein called calsequestrin, which binds the stored Ca2+ and keeps it chemically unreactive.

Cells actively pump out Ca2+.

Cells sequester Ca2+ in the smooth ER and release it only when needed.

Calcium does which of the following?

Participates in muscle contraction.

Participates in bone and tooth development.

Acts as second messenger and activates exocytosis during neurotransmission.

Acts as a factor for blood clotting

Aldosterone, antidiuretic hormone, and the natriuretic peptides help maintain concentrations which of the following?

Sodium

Most magnesium is found in intracellular fluid complexed with ______.

ATP

Which ion is the most abundant cation of the ICF?

Potassium

Potassium imbalances are the most dangerous of all electrolyte imbalances. What is the most serious consequence of potassium imbalance?

cardiac abnormlalities

What is the most abundant anion in the extracellular fluid?

Chloride

Why do cells maintain a very low intracellular calcium concentration?

Calcium phosphate crystals would precipitate in the cytoplasm if levels were high.

Which ion acts as an important buffer that helps stabilize the pH of body fluids?

phosphate

Which is a cation that lends strength to the skeleton, activates muscle contraction, serves as a second messenger for some hormones and neurotransmitters, and is an essential factor in blood clotting?

Calcium

Slight deviations from the body's normal range can shut down metabolic pathways as well as alter the structure and function of other macromolecules. Buffer systems help to avoid this.

ph

About 54% of the body's magnesium is found in which type of tissue?

Bone

Which property of a solution is determined by the concentration of hydrogen ions?

pH

An acid such as hydrochloric acid (HCl) that ionizes freely, gives up most of its hydrogen ions, and can markedly lower the pH of a solution is known as what type of acid?

Strong

Which ions are the most abundant anions of the ECF and thus make a major contribution to its osmolarity?

Chloride

An acid such as carbonic acid (H2CO3-) that ionizes only slightly and keeps most hydrogen in a chemically bound form that does not affect pH, is classified as which type of acid?

Weak

Which are important functions of phosphate ions?

Regulating metabolic pathways by activating and deactivating enzymes

Helping to stabilize the pH of body fluids

Which is the best definition of a weak base?

A base that binds only some of the available H+ and has relatively small effect on pH

Why is it important to maintain the pH of blood and tissue fluids within normal limits?

The structure and function of macromolecules are pH dependent

Slight deviations from normal pH can shut down metabolic pathways.

The structure and function of macromolecules are pH dependent and Slight deviations from normal pH can shut down metabolic pathways.

Chemical buffer

The pH of a solution is determined solely by the concentration of which ion?

hydrogen

Which two organ systems form physiological buffers that help stabilize pH by controlling the body's output of acids, bases, or CO2? Select two options from the list below.

Respiratory system

Urinary system

HCl ionizes freely, gives up most of its hydrogen ions, and can markedly lower the pH of a solution. Because of this it is classified as which of the following?

Strong acid

Any substance that binds H+ and removes it from solution as its concentration begins to rise, or releases H+ into solution as its concentration falls is classified as a ______ buffer. Examples include proteins, bicarbonate, and phosphate.

Chemical

H2CO3 ionizes only slightly and keeps most of its hydrogen in a chemically bound form that does not affect pH. Because of this it is classified as which of the following?

Weak acid

As compared to hydroxide (OH-), bicarbonate (HCO3-) binds a relatively small amount of the available H+ and therefore has less of an effect on pH. Because of this, bicarbonate is classified as which of the following?

weak base

Name the three important chemical buffer systems in the body.

Bicarbonate, phosphate, and protein

A buffer can be generally defined as a mechanism that does which of the following?

Resists changes in pH.

What is the complete chemical equation for the bicarbonate buffer system?

CO2 + H2O

A ______ buffer is a system (for example the respiratory or urinary system) that stabilizes pH by controlling the body's output of acids, bases, or CO2.

physiological

Which type of buffer is defined as a substance that binds H+ and removes it from solution as its concentration begins to rise, or releases H+ into solution as its concentration falls?

Chemical

Which statements are true regarding the phosphate buffer system? Select all that apply.

It plays an important role in the ICF where there is constant production of metabolic acids.

Its optimal pH is 6.8.

It plays an important role in the renal tubules.

Which statements are true concerning the protein buffer system?

Carboxyl groups (-COOH) release H+ and buffer increases in pH.

Amino groups (-NH2) bind H+ and buffer decreases in pH.

The protein buffer system is especially important in the ICF.

What are the major chemical buffer systems of the body? Select three options from the list below.

The bicarbonate buffer system

The phosphate buffer system

The protein buffer system

How can the respiratory system compensate for a drop in blood H+ concentrations?

Reduced pulmonary ventilation allows CO2 to accumulate, lowering the pH back to normal.

The most important buffer system in the blood is the bicarbonate buffer, which is a solution of ______ acid and bicarbonate ions.

weak

Of the two major physiological buffer systems, the respiratory system can restore the pH quickly, whereas the system can take several hours to days to restore the pH.

urinary

The ______ buffer system is a solution of H(PO4)2 and H2(PO4).

phosphate

Which organ can neutralize more acid or base than either the respiratory system or the chemical buffers?

Kidney

The buffering ability of proteins is primarily due to which of the following?

Amino side groups bind when pH falls.

Carboxyl side groups release h+ when pH begins to rise.

A tissue fluid pH below 7.35 is defined as a state of ______.

acidosis

The addition of CO2 to the body fluids raises H+ concentration and lowers pH, while the removal of CO2 has the opposite effect. This is the basis for the strong buffering capacity of which system?

Respiratory

In the bicarbonate buffer system, H2CO3- acts as a ______ by releasing H+ and lowering pH, while HCO3- acts as a ______ by binding H+, removing the ions from solution, and raising pH.

weak acid, weak base

Which blood pH values are considered lethal?

7.8

6.9

Which physiological buffer system exerts an effect within a few minutes but cannot alter the pH as much as the urinary system?

Respiratory system

______ acidosis occurs in hypoventilation, when carbon dioxide accumulates in the ECF and lowers its pH.

Respiratory

Why can the kidneys neutralize more acid or base than any other buffer in the human body?

Only the kidneys actually expel H+ from the body.

Which results when CO2 is eliminated faster than it is produced (for example, during hyperventilation)?

Respiratory alkalosis

Which term refers to a tissue fluid pH above 7.45?

Alkalosis

Which are true regarding respiratory compensation?

It corrects the pH of the body fluids by expelling or retaining CO2.

It is effective in correcting for Pco2 imbalances.

A pH below 6.8 or above 8.0 is which of the following?

Quickly fatal