Ch 26

The most abundant cation in extracellular fluid is potassium

False The most abundant cation (or positively charged ion) in the extracellular fluid (ECF) is sodium (Na+). The most abundant anion (or negatively charged ion) in the ECF is chloride (Cl-). The most abundant cation in the intracellular fluid (ICF) is potassium (K+). The most abundant anion in the ICF is hydrogen phosphate (HPO4-).

Parathyroid hormone (PTH) increases Ca2+ deposition in the bones.

False Parathyroid hormone (PTH) is released in response to low Ca2+ levels. PTH causes the release of Ca2+ from the bones, increases absorption of Ca2+ by the small intestine, and increases calcium reabsorption in the proximal convoluted tubule of the kidneys.

The largest percentage of body water is located in what compartment?

intracellular fluid

Pica, the desire to consume substances that are not normally considered food, such as chalk or clay, may be triggered by a deficiency of __________.

iron

Antidiuretic hormone (ADH) acts on the __________ to __________ water excretion.

kidneys; decrease

Diuresis peaks __________ after drinking water.

one hour

Any arterial pH between __________ is considered physiological acidosis.

7.0 and 7.35

Most fluid in the body is in the extracellular fluid (ECF) compartment.

False Water in the body occupies two main fluid compartments. Most fluid (about two-thirds) is in the intracellular fluid (ICF) compartment. ICF is fluid found inside of cells. The rest of our body water (about one-third) is in the extracellular fluid (ECF) compartment. The ECF consists of plasma and interstitial fluid (IF), the fluid in the spaces between tissue cells.

Which condition would cause a drop in pH?

Hypoventilation causes a drop in pH. Breathing slowly increases PCO2.

The only cation exerting significant osmotic pressure in the ECF is _________

Na+

Renal acid-base control mechanisms are coupled to __________.

Na+ transport

What is the most abundant cation in intracellular fluid?

Potassium is the most abundant cation in the intracellular fluid and is required for essential metabolic activities, influencing the resting membrane potential and normal neuromuscular functioning.

Which statement about acids is true?

Weak acids only dissociate partially in solution. Strong acids dissociate fully, and weak acids dissociate incompletely.

A major stimulus for the release of antidiuretic hormone is __________.

a rise in plasma osmolality

Which of the following tissues is the least hydrated?

adipose

Estrogens are chemically similar to __________ and are therefore associated with water retention.

aldosterone

When the concentration of Na+ in the ECF decreases, __________.

aldosterone levels increase which causes facultative Na+ reabsorption.

Which of the following individuals would have the most body water?

an infant An infant's body is 73% or more water.

The most important buffer system of extracellular fluid, such as plasma, is the __________ buffer system.

bicarbonate

When atrial natriuretic peptide is released by the heart because of increased blood pressure, it causes __________.

decreased sodium and water reabsorption ANP reduces blood pressure and blood volume by inhibiting nearly all events that promote vasoconstriction, sodium retention, and water retention.

Parathyroid hormone __________.

enhances release of calcium from bone PTH activates osteoclasts, which break down the bone matrix, releasing calcium.

All of the following factors would stimulate the hypothalamic thirst center EXCEPT __________.

hypotonic extracellular fluid Angiotensin II would stimulate the hypothalamic thirst center.

Which of the following is associated with a swelling of cells?

hypotonic hydration Hypotonic hydration causes hyponatremia (low concentration of Na+ in the extracellular fluid), leading to cell swelling. Edema (tissue swelling) is an atypical accumulation of fluid in the interstitial space, leading to tissue (not cell) swelling. Edema can be caused by any event that increases fluid loss from the blood to the tissues, or that prevents effective return of fluid from the interstitial space to the bloodstream.

The only organ(s) of the body that can remove excess nonvolatile fixed acids is/are the __________.

kidney

All of the following would occur if there were an increase in plasma osmolality EXCEPT __________.

production of large amounts of urine If the plasma osmolality were to increase, the urine would be concentrated.

Which of the following would increase sodium excretion?

progesterone Reabsorption of sodium does not exhibit a transport maximum. In healthy individuals, nearly all sodium in the renal filtrate is reabsorbed in the proximal convoluted tubules of the kidneys. Atrial natriuretic peptide (ANP) and progesterone increase Na+ excretion. Progesterone appears to decrease NaCl reabsorption by blocking the effect aldosterone has on the renal tubules. Aldosterone is the key regulator of sodium reabsorption in the kidney. It encourages Na+ reabsorption. Estrogens, like aldosterone, encourage Na+ reabsorption. Glucocorticoids enhance tubular reabsorption of sodium.

The most important buffer system in the intracellular fluid compartment (ICF) is the __________ buffer system.

protein Most of the buffering power of body fluids resides in cells, and most of this reflects the buffering activity of intracellular proteins

Someone who is suffocating would develop __________.

respiratory acidosis

Hyperventilation can lead to __________.

respiratory alkalosis

The most prevalent electrolyte in the extracellular fluid is __________.

sodium

The most important factor that influences K+ secretion is __________.

the concentration of K+ in the ECF

Infants are more likely to experience problems regulating acid-base balance because of several factors, including __________.

the inefficiency of infant kidneys The kidneys are immature at birth; they are approximately half as proficient at concentrating urine as mature kidneys. Infant kidneys are also inefficient in ridding the body of acids.