A&P II Chapter 26

What are the main fluid compartments in the body

Intracellular and extracellular fluid

Where is Intracellular Fluid (ICF)

Fluid located inside cells

Where is interstitial fluid found

In between cells at lymph, CSF, humors of the eye, synovial fluid, serous fluid, and gastrointestinal secretions 

What proportion of body fluid is ICF

comprising 2/3 of body fluids.

What other body fluid is found in the ECF

Plasma and interstitial fluids

What proportion of the body fluid is ECF

comprising 1/3 of body fluids.

Where is Extracellular Fluid (ECF)

Fluid outside cells

Major Cation in ICF

Potassium (K+) is the primary cation.

Major Cation in ECF

Sodium (Na+) is the primary cation.

What effects does Potassium have on the body when cation out of normal range

Hyperkalemia and Hypokalemia.

Hyperkalemia

Elevated ECF potassium causes decreased resting membrane potential and causes depolarization, followed by decreased excitability.

Hypokalemia

Low ECF potassium causing hyperpolarization and nonresponsiveness.

What effects does sodium have on the body when cation out of normal range

Hypernatremia and Hyponatremia

What does Hyponatremia cause

Solute loss, water retention, or both (e.g., excessive Na* loss through vomiting, diarrhea, burned skin, gastric suction, or excessive use of diuretics) deficiencyof sodium in the blood, leading to symptoms such as headache, confusion, and in severe cases, seizures or coma.

What does Hypernatremia cause

Dehydration; uncommon in healthy individuals; may occur in infants, the elderly, or any individual unable to indicate thirst; or may result from excessive intravenous NaCl administration 

Regulation of Potassium

Aldosterone stimulates K+ secretion in kidneys.

Regulation of Sodium

Regulated by aldosterone, angiotensin II, ANP, Female sex hormones, and cardiovascular baroreceptors 

What factors regulate fluid movement between compartments

• Osmotic and hydrostatic pressures 

• Water moves freely along osmotic gradients. 

• Change in solute concentration of any compartment leads to net  water flow changes (compartmental exchanges)

What are disorders/abnormalities of water balance

Dehydration, hypotonic hydration, and Edema

Edema affect

Atypical accumulation of IF, resulting in tissue swelling (not cell swelling)  

Dehydration Effects

loss of water in the cell (cell shrinks) causes hemorrhage, severe burns, prolonged vomiting or diarrhea, profuse sweating, water deprivation, diuretic abuse, and endocrine disturbances.

Hypotonic Hydration Effects

Too much water causes water intoxication and causes cells to burst and lyse.  Leading to hyponatremia

Hypotonic hydration impacts on ECF osmolality and electrolytes

ECF osmolality decreases as well as electrolytes.

Dehydration impacts on ECF osmolality and electrolytes

Increases ECF osmolality, affecting electrolyte balance and potentially leading to complications like muscle cramps or confusion.

Nonelectrolytes

Organic molecules that do not dissociate in water and create no charged particles

Electrolytes

Ions that dissociate in water and conduct electricity.

What is the purpose of chemical buffer system in the body

system of one or more compounds that acts to resist pH changes when strong acid or bases are added 

What are the major buffering systems in the body

• Bicarbonate buffer system 

• Phosphate buffer system 

• Protein buffer system 

What molecules act as buffers in Bicarbonate Buffer System

Mixture of H₂CO₃ (weak acid) (carbonate ) and salts of HCO₃– (weak base)( Bicarbonate) 

What molecules act as buffers in Phosphate Buffer System

Sodium salts of dihydrogen phosphate (H₂PO₄⁻) (weak acid) and monohydrogen phosphate (HPO₄²⁻–) (weak base)

What molecules act as buffers in Protein Buffer System

Intracellular and plasma proteins (amphoteric molecules) 

How do the buffers work, what do they neutralize, what is the end-result after a molecule is neutralized

• Buffers neutralize strong acids by binding H+ and forming a weak acid. 

• Buffers neutralize strong bases by releasing/donating H+, and the H+ ties up the base. 

• End result: pH changes are resisted 

What organ system acts as a physiological buffering system?

Respiratory and Renal System 

Respiratory System Role in maintaining acid-base balance

• Increased respiratory rate and depth eliminate more CO2, reducing H+ concentration. 

• Decreased respiratory rate and depth cause CO₂ to accumulate, increasing H⁺ concentration 

What does decreased respiratory rate and depth causes

CO₂ to accumulate, increasing H⁺ concentration 

What does increased respiratory rate and depth causes

eliminate more CO2, reducing H+ concentration.

Renal System Role in maintaining Acid-base balance

• Kidneys eliminate nonvolatile (fixed) acids and regulate blood levels of alkaline substances. 

• Regulate acid-base balance by adjusting the amount of bicarbonate in the blood by conserving/generating or excreting HCO₃⁻ and by secreting or retaining H⁺. 

Thirst Mechanism Stimuli

Increased plasma osmolality , Dry mouth , Decreased blood volume and pressure , Angiotensin II or Baroreceptor input 

What inhibits the thirst mechanism

Drinking water , Relief of dry mouth, and activation of stomach and intestinal stretch receptors 

What receptors are involves in the thirst mechanism

Osmoreceptors in the hypothalamus and Baroreceptors 

What are the abnormalities of acid-base imbalances

• Respiratory acidosis    

• Respiratory alkalosis    

• Metabolic acidosis    

• Metabolic alkalosis 

Respiratory Acidosis Causes

Decreased ventilation or gas exchange, e.g., pneumonia.

Impaired lung function, impaired ventilatory movement, and narcotic or barbiturate overdose or injury to brain stem

Respiratory Alkalosis Causes

Hyperventilation often due to stress or pain.

Strong emotions, hypoxemia, and brain tumor or injury  

Metabolic Acidosis Causes

• Ingestion of too much alcohol    

• Excessive loss of HCO₃⁻ (e.g., diarrhea)    

• Accumulation of lactic acid (e.g., exercise or shock), ketosis, starvation, kidney failure

• Severe diarrhea  

Metabolic Alkalosis Causes

Vomiting acid contents or excessive base intake (over ingestion of antacid) ( sodium bicarbonate)  

Excess aldosterone 

Respiratory Acidosis Indicator

PCO2 above 45 mm Hg

Respiratory Alkalosis Indicator

PCO2 below 35 mm Hg

Metabolic Acidosis Indicator

Low blood pH and HCO₃⁻

Metabolic Alkalosis Indicator

Rising blood pH and HCO₃⁻