Chapter 25: Fluid and Electrolytes Anatomy & Physiology

Flashcards covering fluid compartments, electrolyte balance (Na+, K+, Ca2+), hormonal regulation (ADH, Aldosterone, ANP), and acid-base disturbances based on the Integrative Approach lecture notes.

What is the typical range for the percentage of fluid by weight in the human body?

Between $45\%$ and $75\%$.

How do adipose and skeletal muscle tissue differ in their water content?

Adipose tissue is approximately $20\%$ water, while skeletal muscle is approximately $75\%$ water.

What portion of the total body fluid is contained within the intracellular fluid (ICF)?

Two-thirds of total body fluid.

What are the two major components of extracellular fluid (ECF) and their relative proportions?

Interstitial fluid (compiles two-thirds of ECF) and blood plasma (compiles one-third of ECF).

What is the primary chemical distinction between blood plasma and interstitial fluid?

Protein is present in blood plasma, but there is very little protein in interstitial fluid.

Which ions are more prevalent in the intracellular fluid (ICF)?

$K^{+}$, $Mg^{2+}$, and $PO_4^{3-}$.

Which ions are found in higher concentrations in the extracellular fluid (ECF)?

$Na^{+}$, $Ca^{2+}$, $Cl^{-}$, and $HCO_3^{-}$. balance.

By what process does water move between fluid compartments when osmolarity varies?

Osmosis, moving from a hypotonic solution to a hypertonic one until concentrations are equal.

How much fluid is typically added to the body daily through ingested water and metabolic water?

Total fluid intake is approximately $2500\,mEq/L$ ($2300\,mL$ from ingested water and $200\,mL$ from metabolic water produced by aerobic cellular respiration).

What is the difference between sensible and insensible water loss?

Sensible water loss is measurable (urine and feces), while insensible water loss is not measurable (expired air, sweat, and cutaneous transpiration).

Which type of fluid output is hormonally regulated in the kidney nephrons and dependent on hydration state?

Facultative water loss.

What characterizes hypotonic hydration (water intoxication)?

Water gain or retention is greater than solute gain, making plasma hypotonic and causing water to move into cells, potentially leading to cerebral edema.

What are four examples of fluid sequestration mentioned in the text?

Edema, ascites, pericardial effusion, and pleural effusion.

What stimuli activate the thirst center in the hypothalamus?

Decreased blood volume/blood pressure, increased blood osmolarity, and decreased salivary secretions.

Name the four hormones that play a major role in regulating fluid and electrolyte balance.

Angiotensin II, Antidiuretic hormone (ADH), Aldosterone, and Atrial natriuretic peptide (ANP).

What is the effect of Atrial natriuretic peptide (ANP) on the kidneys?

It increases GFR (glomerular filtration rate) and urine output, while inhibiting $Na^{+}$ and water reabsorption to decrease blood volume and pressure.

What is the normal range for sodium ion ($Na^{+}$) concentration in blood plasma?

$135\text{ to } 145\,mEq/L$.

Why is potassium balance considered the most lethal of electrolyte imbalances?

Imbalances can lead to cardiac or respiratory arrest.

How do changes in blood plasma $H^{+}$ concentration affect potassium ($K^{+}$) distribution?

Increased $H^{+}$ in the ECF causes $H^{+}$ to move into the ICF, forcing $K^{+}$ to move out of the cell to maintain the electrochemical gradient.

Which hormone is a steroid released from the adrenal cortex that increases $Na^{+}$ reabsorption and $K^{+}$ secretion?

Aldosterone.

What is the normal range for arterial blood pH?

$7.35\text{ to } 7.45$.

Differentiate between a fixed acid and a volatile acid.

Fixed acids (e.g., lactic acid, ketoacids) are metabolic wastes regulated by the kidney; volatile acids (carbonic acid) are produced from gaseous $CO_2$ and regulated by the respiratory system.

What are the three most important chemical buffering systems in the body?

The protein buffering system, the phosphate buffering system, and the bicarbonate buffer system.

What determines respiratory acidosis and what is a common cause?

It is defined by arterial $PCO_2$ above $45\,mm\,Hg$; causes include hypoventilation due to airway obstruction, emphysema, or injury to the respiratory center.

How does the kidney compensate for metabolic acidosis?

Type A intercalated cells secrete $H^{+}$ into the urine and reabsorb $HCO_3^{-}$ into the blood.

What is the primary cause of metabolic alkalosis?

The most common cause is vomiting (loss of $H^{+}$) or the overuse of diuretics and antacids.