Chapter 43 Flashcards
Where must water/electrolytes be balanced?
- inside the cells
- interstitial spaces (between cells)
- in blood vessels
What is an electrolyte?
- a molecule whose bonds permit breakup into ions
- when put into a solution, it will break into ions
- ex. NaCl
What are anions?
- negatively charged ions
- proteins
What are cations?
-positively charged ions
What percent of our body weight is water?
- 45-75%
- depending on size and fat content
What are the body fluid compartments?
- intracellular fluid
- extracellular fluid
Where is the intracellular compartment?
- inside the cells
- cytosol
- makes up 2/3 of body fluids
What makes up the extracellular compartment?
- plasma found in blood vessels (20%)
- interstitial fluid (80%)
- makes up 1/3 of body fluids
How does plasma fluid differ from interstitial fluids?
- plasma has more anions due to more proteins
- they are chemically similar
How does intracellular fluid differ from extracellular fluid?
- sodium
- chloride
- potassium
- calcium
- phosphate
- bicarbonate
- magnesium
- sodium: most abundant cation in ECF
- chloride: most abundant anion in ECF
- potassium: most abundant cation in ICF
- calcium: most abundant mineral, mainly ECF cation
- phosphate: important ICF anion
- bicarbonate: second most abundant anion in ECF
- magnesium: important cation in ICF
Why is sodium important?
- necessary for action potentials
- is responsible for 50% of osmolarity of ECF
- 90% of the ECF cations
Why is potassium important?
- establishes resting membrane potential
- maintenance of normal ICF volume
- regulates pH
- followed by Chloride
Why is calcium important?
- blood clotting
- neurotransmitter release
- muscle tone
- regulated by parathyroid hormone
Why is phosphate important?
- important buffer to Hydrogen (pH)
- bound to ATP and DNA/RNA
Why is magnesium important?
- cofactor for enzymes
- neural synapse
- neuromuscular activity
- heart muscle function
How does the body gain water?
- ingestion
- metabolic processes
What is the metabolic process that creates water?
- cellular respiration
- electron transport train
How does the body lose water?
- kidneys (urine)
- lungs (humidified CO2)
- skin (sweating)
- intestines (secreted with digestive juices)
How is urine volume regulated?
- depends on water intake that is regulated by the thirst center in the hypothalamus
- glomerular filtration rate (do not want to change)
- rate of water reabsorption by the renal tubules
What hormones regulate water reabsorption?
- ADH
- Aldosterone
- Atrial natriuretic hormone
What abnormal conditions cause fluid loss? Why?
- hyperventilation
- vomiting
- diarrhea
- something is wrong pathologically
What influences how much water and electrolytes pass between the interstitial fluid and plasma?
- blood hydrostatic pressure
- blood colloid osmotic pressure
- interstitial hydrostatic pressure
- interstitial colloid osmotic pressure
What is blood hydrostatic pressure?
-the pressure of the fluid to get out of the blood vessel on the arteriole side
What is blood colloid osmotic pressure?
- moving the water back into the capillary on the venous side
- depends on the electrolyte concentration gradient (Na and K)
