Fluid Balance and Electrolyte Regulation in the Body

Body Fluid Percentage

Human body fluid ranges from 45% to 75%.

Fluid Variation Factors

Fluid percentage varies by age and tissue type.

Infant Fluid Percentage

Infants have the highest body fluid percentage.

Elderly Fluid Percentage

Elderly have the lowest body fluid percentage.

Adipose Tissue Water Content

Adipose tissue contains about 20% water.

Skeletal Muscle Water Content

Skeletal muscle contains about 75% water.

Fluid Imbalance Risk

Lower body fluid percentage increases fluid imbalance risk.

Intracellular Fluid (ICF)

Fluid within cells, comprising two-thirds of body fluid.

Extracellular Fluid (ECF)

Fluid outside cells, includes interstitial fluid and plasma.

Interstitial Fluid (IF)

Fluid surrounding cells, two-thirds of extracellular fluid.

Blood Plasma

Extracellular fluid within blood vessels, contains proteins.

Capillary Permeability

Capillaries allow ions to pass, but not proteins.

Cerebrospinal Fluid

Fluid surrounding the brain and spinal cord.

Synovial Joint Fluid

Fluid in joints, lubricates and cushions movement.

Osmolarity Changes

Fluid movement responds to osmolarity concentration changes.

Hypotonic Solution

Lower concentration solution causing water influx.

Hypertonic Solution

Higher concentration solution causing water efflux.

Fluid Movement Mechanism

Water moves by osmosis to equalize concentrations.

Water Intake Effects

Drinking water decreases plasma osmolarity.

Fluid Compartments Distinction

ICF and ECF have distinct chemical compositions.

Electrolyte Composition

ICF has more K+, ECF has more Na+.

Protein Presence

Blood plasma contains proteins, interstitial fluid has little.

Fluid Loss Response

Water moves from cells if body loses fluid.

Fluid balance

Fluid intake equals fluid output in the body.

Fluid intake

Addition of 2500 mL water daily to body.

Ingested water

Water absorbed from food and drink sources.

Metabolic water

Water produced from cellular respiration processes.

Fluid output

Loss of 2500 mL water daily from body.

Sensible water loss

Measurable fluid loss through feces and urine.

Insensible water loss

Unmeasurable fluid loss via expired air and skin.

Obligatory water loss

Water loss that always occurs in the body.

Facultative water loss

Controlled water loss regulated by body hydration.

Volume depletion

Isotonic fluid loss exceeds isotonic fluid gain.

Volume excess

Isotonic fluid gain exceeds isotonic fluid loss.

Dehydration

Fluid imbalance due to deficiency of body fluid.

Hypotonic hydration

Fluid imbalance from excess body fluid.

Fluid sequestration

Fluid imbalance where fluid accumulates in compartments.

Osmolarity change

Fluid imbalance affecting body fluid concentration.

Breathing water loss

Water lost through respiration during normal breathing.

Skin water loss

Fluid lost through sweat and cutaneous transpiration.

Urination percentage

60% of fluid output occurs via urination.

Environmental factors

Physical activities and conditions affect fluid loss.

Fluid loss mechanisms

Includes breathing, sweating, and defecation.

Aldosterone role

Hormone influencing fluid retention in kidneys.

Daily water intake

Normal intake includes 2300 mL from food.

Fluid imbalance

Disruption in normal fluid distribution in the body.

Dehydration

Water loss exceeds solute loss, causing hypertonicity.

Hypertonic

Higher solute concentration than surrounding fluid.

Hypotonic hydration

Excess water retention compared to solute retention.

Water intoxication

Excessive water intake leading to cellular swelling.

ADH hypersecretion

Excess antidiuretic hormone causing water retention.

Cerebral edema

Swelling of brain cells due to excess fluid.

Fluid sequestration

Normal total body fluid but abnormal distribution.

Edema

Fluid accumulation in interstitial spaces causing puffiness.

Ascites

Fluid accumulation in the peritoneal cavity.

Pericardial effusion

Fluid accumulation in the pericardial cavity.

Pleural effusion

Fluid accumulation in the pleural cavity.

Blood volume

Total amount of blood in the circulatory system.

Blood pressure

Force exerted by circulating blood on vessel walls.

Blood plasma osmolarity

Concentration of solutes in blood plasma.

Fluid intake

Amount of fluid consumed by the body.

Fluid output

Amount of fluid excreted from the body.

Thirst center

Brain region regulating fluid intake signals.

Renin

Hormone released by kidneys to regulate blood pressure.

Angiotensin II

Hormone stimulating thirst and blood pressure increase.

Decreased salivary secretions

Reduced saliva production affecting thirst sensation.

Stomach distension

Stretching of stomach signaling fullness to the brain.

ADH release

Hormone release promoting water reabsorption in kidneys.

Thirst center

Brain region regulating fluid intake and balance.

Fluid intake

Volume of fluid consumed by the body.

Fluid output

Volume of fluid excreted from the body.

Increased blood volume

Higher volume of blood circulating in vessels.

Increased blood pressure

Elevated force exerted by circulating blood.

Renin release

Hormone released by kidneys affecting blood pressure.

Angiotensin II

Hormone that stimulates thirst and blood pressure.

Blood osmolarity

Concentration of solutes in blood plasma.

ADH release

Hormone regulating water retention by kidneys.

Salivary secretions

Fluid produced by salivary glands.

Stomach distension

Stretching of stomach due to fluid intake.

Nonelectrolytes

Molecules that do not dissociate in solution.

Electrolytes

Substances that dissociate into ions in solution.

Milliequivalents per liter

Concentration unit for electrolytes in solution.

Sodium ion (Na+)

Principal cation in extracellular fluid (ECF).

Na+/K+ pumps

Transport proteins maintaining sodium and potassium gradients.

Sodium balance

Regulation of sodium levels in the body.

Hypertonic ECF

ECF with increased sodium concentration.

Hypotonic ECF

ECF with decreased sodium concentration.

Hypernatremia

Excess sodium levels in the blood.

Hyponatremia

Deficient sodium levels in the blood.

Aldosterone

Hormone regulating sodium and water retention.

Intracellular Fluid (ICF)

Contains 98% of body potassium.

Extracellular Fluid (ECF)

Contains 2% of body potassium.

Na+/K+ Pump

Maintains potassium balance across cell membranes.

Potassium Ion (K+)

Key cation for intracellular osmotic pressure.

Normal Potassium Range

3.5 to 5.0 mEq/L in blood.

Hyperkalemia

Elevated potassium levels in blood.

Hypokalemia

Low potassium levels in blood.

Potassium Redistribution

Changes due to plasma K+ and H+ levels.

H+ Concentration Effect

Increased H+ moves K+ into ICF.

Insulin's Role

Stimulates Na+/K+ pump, lowers blood K+.