Pathology Exam 2: Chapters 7, 8, and 13

Extracellular Fluid (ECF)

• Divided into three main compartments: interstitial spaces, intravascular (blood vessels), and blood plasma
• Main function is to regulate body temperature, maintain pH, and transport nutrients and waste products

Hypertonic and Hypotonic Solutions

• Hypertonic solutions: NaCl, Lactated Ringer's, and 10.45% NaCl
• Hypertonic solutions have a higher concentration of solutes (particles) and a lower concentration of solvent (water)
• Hypotonic solutions: have a lower concentration of solutes and a higher concentration of solvent
• Isotonic solutions: have an equal concentration of solutes and solvent

Polydipsia

• Excessive thirst, which is normal when it accompanies conditions of water deficit
• Characterized by compulsive water drinking

Renin-Angiotensin-Aldosterone System (RAAS)

• Renin is secreted and stored by the kidneys and promotes the production of angiotensin
• Angiotensin II stimulates the secretion of aldosterone from the adrenal cortex
• Aldosterone causes the renal tubules to increase in the reabsorption of sodium
• Angiotensin II is a potent vasoconstrictive peptide that increases blood pressure

Osmolality and Osmolarity

• Osmolality (or osmolarity) refers to the concentration of dissolved particles of chemicals and minerals in blood serum
• Normal serum osmolarity is 275-295 mOsm/L
• Hypertonic solution has a value >295 mOsm/L

Body Water

• In the average adult male, body water is about 60% of body weight (about 42 L of H2O)
• In the average adult female, body water is about 50% of body weight (about 42 L of H2O) due to adipose tissue

Albumin and Oncotic Pressure

• Albumin is a protein made by the liver
• Albumin helps keep fluid in the bloodstream by exerting oncotic pressure
• Oncotic pressure creates a water molecule deficit, with water molecules moving back into the circulatory system within the lower venous pressure end of capillaries

SIADH and Hyponatremia

• SIADH (Syndrome of Inappropriate Antidiuretic Hormone) is a condition where the body retains water instead of excreting it normally in urine
• Signs and symptoms include nausea, vomiting, headache, confusion, weakness, and fatigue, with high urine osmolality (concentrated dark urine) and low serum osmolality

Diabetes Insipidus (DI)

• Absence of ADH in the body, leading to excessive urination, production of large amounts of pale urine, frequent urination, and bed wetting

Cell Membrane and Tonicity

• Cell membrane is semi-permeable, allowing solvent to pass through but not solute
• Tonicity is a measure of the osmotic pressure between two solutions
• Hypertonic cell size change: shrinks
• Isotonic cell size change: neither shrinks nor swells
• Hypotonic cell size change: swells