Ch. 25 Fluid, Electrolyte, and Acid-Base Balance

Who is made up of 73% or more water?

Infants

Who is made up of 60% water?

Adult Males

Who is made up of 50% water and why?

Adult Females; higher fat content

On average, how much total body water is there?

40 L

What is the universal solvent?

Water

What kind of solutes are organic?

Nonelectrolytes

What is the most abundant solute?

Electrolytes

Minerals that carry electrical charges that help maintain the body's fluid balance

Electrolytes

In ECF, what is the major cation?

Sodium

In ECF, what is the major anion?

Chlorine

In ICF there is low what?

Sodium and Chlorine

In ICF, what is the major cation?

Potassium

In ICF, what is the major anion?

Hydrogen Phosphate

_____ is equal to _____ and is equal to about 2500 ml/day.

Water intake; Water output

What are ways water is lost?

Urine, Perspiration, Feces, and Insensible water loss

What is the driving force of water intake?

Thirst Mechanism

What are the hypothalamic thirst center osmoreceptors stimulated by?

Plasma osmolality of 2-3%, angiotensin II, dry mouth, and substantial decrease in blood volume or pressure

What creates inhibition of the thirst center?

Drinking Water

What is the MINIMUM daily sensible water loss in urine?

500 mL

What is water reabsorption in collecting ducts proportional to?

ADH release

What is the main trigger of ADH release?

Hypothalamic Osmoreceptors

What are some other factors of ADH release?

Changes in blood volume or pressure

What causes negative fluid balance?

ECF water loss due to hemorrhage, severe burns, prolonged vomiting or diarrhea, profuse sweating, water deprivation, or diuretic abuse

What are the signs and symptoms of negative fluid balance?

Thirst, dry flushed skin, and oliguria

What are the side effects of negative fluid balance?

Weight loss, fever, mental confusion, hypovolemic shock, and loss of electrolytes

What is Hypotonic Hydration?

Cellular overhydration

What causes Hypotonic Hydration?

Renal insufficiency or rapid excess water ingestion

What are the side effects of Hypotonic Hydration?

Severe metabolic disturbances, nausea, vomiting, muscular cramping, cerebral edema, possible death

Atypical accumulation of IF fluid (tissue swelling)

Edema

This is due to anything that increases flow of fluid out of the blood or hinders its return

Edema

Abnormally low level of sodium in the blood

Hyponatremia

Abnormally low level of protein in the blood

Hypoproteinemia

What are salts, acids, and bases?

Electrolytes

What does electrolyte balance usually refer to?

Salt balance

What are the importances of salts?

Controlling fluid movements, excitability, secretory activity, and membrane permeability

What do changes in plasma sodium levels affect?

Plasma volume, blood pressure, and ICF and IF volumes

These are coupled to sodium ion transport

Renal acid-base control mechanisms

There are no known receptors in the body that monitor what levels?

Sodium

65% of sodium is reabsorbed where?

In the proximal tubules

25% of sodium is reclaimed where?

In the loops of Henle

Water follows sodium if what is present?

ADH

What is the main trigger for aldosterone release?

Renin-angiotensin mechanism

Granular cells of JGA secrete renin in response to what three things?

Sympathetic nervous system stimulation, filtrate osmolality, and stretch due to blood pressure

Renin catalyzes the production of what, which prompts what?

Angiontensin II; Aldosterone

_____ release is also triggered by elevated K+ levels in the ECF

Aldosterone

_____ brings about its effects slowly. (hours to days)

Aldosterone

Released by atrial cells in response to stretch (blood pressure)

ANP

ANP decreases what?

Blood pressure and blood volume

This promotes vasodilation directly and also by decreasing production of angiotensin II

ANP

What regulates the remaining 10% of sodium that is not reabsorbed?

Hormones

Abnormally low level of calcium in the blood

Hypocalcemia

Excessive calcium in the blood

Hypercalcemia

This imbalance inhibits neurons and muscle cells, and may cause heart arrhythmias

Hypercalcemia

__ affects all functional proteins and biochemical reactions.

pH

What is the pH of arterial blood?

7.4

What is the pH of venous blood and IF fluid?

7.35

What is the pH of ICF?

7.0

What is calcium balance controlled by?

Parathyroid Hormone and Calcitonin

What is alkalosis (alkalemia)?

pH greater than 7.45, which means a decrease in CO2 and H+

What is acidosis?

pH less than 7.35, which means an increase in CO2 and H+

Most H+ is produced by what?

Metabolism

The amount of H+ you produce is tied to what?

CO2

Bones are the largest reservoir for what?

Calcium and Phosphates

__ is regulated by chemical buffer systems, brain stem respiratory centers, and renal mechanisms

H+

System of one or more compounds that act to resist pH changes when strong acid or base is added

Chemical Buffer

Name some chemical buffer systems.

Bicarbonate buffer system, phosphate buffer system, and protein buffer system

Respiratory acidosis is also known as what?

Hypoventilation

Respiratory alkalosis is also known as what?

Hyperventilation

_____eliminate volatile carbonic acid by eliminating CO2.

Lungs

_____ eliminate fixed metabolic acids such as phosphoric, uric, and lactic acids, and ketones

Kidneys

What are the most important renal mechanisms?

Conserving and excreting HCO3