Homeostasis Flashcards
What are the three types of homeostatic balance?
-Fluid Balance
-Acid Base Balance
-Electrolyte Balance
What are the two types of fluid?
-Intracellular fluid
-Extracellular fluid
How many liters and what percentage of your body’s weight does intracellular fluid make up?
-25 L
-40%
What two types of fluid comprise Extracellular fluid?
-Interstitial fluid
-Plasma
How many liters do interstitial fluid and plasma individually comprise and what percentage of your body’s weight do they sum to?
20% of your bodies weight
Interstitial Fluid
-12 L
-80% of ECF
Plasma
-3L
-20% of ECF
What is the relationship between fluid in and fluid out?
In take matches losses
-2,500 mL/day In = 2,500 mL/day out
What is the breakdown of how fluid enters the body?
-Metabolic water = 200mL
-Food = 700 mL
-Drink = 1,600 mL
What is the breakdown of how fluid leaves the body?
-Feces = 200 mL
-Expired Air = 300 mL
-Cutaneous transpiration = 400 mL
-Sweat = 100 mL
-Urine = 1,500 mL
What would occur if you were so overhydrated you had no ADH?
-Dec. in osmolality of ECF
Leads to
-Dec. of ADH released from posterior pituitary
Leads to
-Dec. in # of aquaporins in collecting duct
Leads to
-Dec. in H2O reabsorption from collecting duct
Leads to
-Large volume of dilute in urine
What would occur if you were so dehydrated we had maximal ADH?
-Inc. in the osmolality of ECF
Leads to
-Inc. in ADH released from posterior pituitary
Leads to
-Inc. in # of aquaporins in collecting duct
Leads to
-Inc. H2O reabsorption from collecting duct
Leads to
-Small volume of concentrated urine.
What does alcohol inhibit?
ADH
What does caffeine inhibit?
Aldosterone
What hormone would be secreted if someone had hypertonic dehydration and why?
Since hypertonic dehydration is caused by a loss of just H2O, just ADH is released.
What hormone would be secreted is someone had isotonic dehydration and why?
Since isotonic dehydration is caused by the loss of H2O and solutes, both ADH and aldosterone will be released.
What is a potential cause for hypertonic dehydration?
profuse sweating
What is a potential cause of isotonic dehydration?
hemorrhage
What is dehydration caused by?
Negative water balance
Define hypovolemia
volume depletion
Is hypotonic hydration common or uncommon and why?
It is uncommon because of the filtration done by the kidneys.
What is a potential consequence of hypotonic hydration?
edema
What is hypotonic hydration?
Excess water and normal sodium
What is the osmolarity for hypovolemia and volume excess?
Both isotonic, so normal
What is the osmolarity of hypertonic dehydration?
Hypertonic, so elevated
What is the osmolarity of hypotonic dehydration?
hypotonic, so reduced
What is the primary regulator of sodium?
Aldosterone
What hormones affect Na+ concentrations?
ADH, ANP, Aldosterone, and other hormones
Are Na+ imbalances common or not common?
No common because increases or decreases in Na+ are accompanied by proportional changes in H2O
What does hypernatremia cause?
-Water retention
-Hypertension
-Edema
How much sodium should be in the perfect diet and how much is in the typical diet?
Perfect diet = .5 g/day
Usual = 3-7 g/day
What is the relationship between the electrolyte balance of Na+ and K+?
-More Na+ in ECF
-More K+ in ICF
-Basis for membrane potentiality
What is the principal extracellular cation?
Na+
What is the principal intracellular cation?
Potassium
What is the most important electrolyte for water balance?
Na+
What does aldosterone do?
Na+ reabsorption and K+ secretion
What does hyperkalemia cause?
Increase in RMP
What does hypokalemia cause?
hyperpolarizes cells?
What are the functions of Na+?
-RMP
-AP
-Na+/K+ pump
What are the functions of K+?
-RMP
-AP
-Na+/K+ pump
-Most important electrolyte in cell volume
-Protein synthesis
What is the normal amount of K+ to secrete?
about 10% but DCT and CD can alter secretion based on levels
What is the most dangerous electrolyte imbalance?
K+
What are the functions of Ca2+?
-Bones
-Muscle Contraction
Second Messenger Systems
-Blood Clotting
What keeps calcium in homeostasis?
Parathyroid hormone and calcitonin
What does hypercalcemia cause?
It inhibits depolarization so it causes muscle weakness, depressed reflexes, and cardiac arrhythmia.
What does hypocalcemia cause?
Overly excitable nervous and muscle tissue; can lead to tetany - laryngospasm.
What are the functions of phosphates?
-Concentrated in the ICF
-ATP
-Nucleic Acids
-Phospholipids
What happens when you have low levels of phosphates?
Low levels cause kidneys to reabsorb all of the phosphates
What happens when you have to many phosphates?
Parathyroid hormone indirectly cause excretion of excess phosphates.
What are the functions of Cl-?
-HCl
-Abundant ECF anion
-Chloride Shift
What causes hyperchloremia?
Excess dietary intake or IV saline
What is Cl- homeostasis linked to?
Cation homeostasis (Na+, K+, Ca2+
What causes hypochloremia?
usually linked to hyponatremia
What is the Ph of a solution determined by?
Determined solely by its hydrogen ions (H+)
What is an acid (for the purposes of this class)?
Any chemical that releases H+ in solution
What is a base (for the purposes of this class)?
Any chemical that accepts H+
What is one of the most important aspects of homeostasis?
Enzymes are sensitive to pH so any slight deviation from the normal pH can shut down entire metabolic pathways and alter the structure & therefore function of macromolecules.
What are the three chemical buffer systems to resist pH change?
-Bicarbonate
-Phosphate
-Protein
What are the two physiological buffer systems to resist pH change?
-Renal
-Respiratory
How is the bicarbonate buffer system used to lower pH?
Lungs conserve CO2 and kidneys secrete HCO3
How is the bicarbonate buffer system used to raise pH?
Kidneys excrete H+ and lungs secrete CO2
What is the equation for the bicarbonate buffer system?
CO2 + H2O <> H2CO3 <> HCO3- + H+
What does hyporventilating cause in the respiratory control of pH?
Lowers pH by releasing H+
What does hyperventilating cause in the respiratory control of pH?
Raises pH by binding H+
Does respiratory control of pH or do the chemical buffers neutralize more acid?
The respiratory control of pH neutralizes two or three times as much acid as chemical buffers.
What is the chemical formula for the phosphate buffer system?
HPO4 <>HPO4 + H+
What is an important buffer for the ICF and renal tubules?
The phosphate buffer system because phosphates are more concentrates and function closer to their optimum pH of 6.8.
What is the main buffer in the ICF?
The protein buffer system is responsible for 75% of all chemical buffering.
What are the two protein groups that give proteins there robust buffering abilities and why?
Carboxyl
-COOH
-Side groups release H+ when pH rises
Amino
-NH2
-Bind H+ when pH gets too low
What is the relationship between bi carb and the kidneys?
The kidneys secrete, reabsorb, and generate new HCO3.
What system can neutralize more acid or base than either the respiratory system or chemical buffers?
The Renal control of pH because the renal tubules secrete H+ in the tubular fluid and bound and free H+ are excreted in the urine giving the renal control of pH the only way for H+ ions to be expelled form the body.
What causes respiratory acidosis?
-Hypoventilation, apnea, or respiratory arrest
-Asthma
-Emphysema
-Cystic Fibrosis
-Chronic Bronchitis
-Narcotic overdose
What causes metabolic acidosis?
-Excess production of organic acids as in diabetes mellitus and starvation
-Long-term anaerobic fermentation
-Hyperkalemia
-Chronic Diarrhea
-Excessive alcohol consumption
-drugs such as aspirin and laxatives
What causes respiratory alkalosis?
-Hyperventilation due to pain or emotions such as anxiety
-Oxygen deficiency (as at high elevation)
What causes metabolic alkalosis?
-Rare but can result from chronic vomiting
-Overuse of bicarbonate (antacids)
-Aldosterone hypersecretion?
What happens if your blood pH falls below 6.8?
Your CNS is depressed which leads to coma and death
What happens if your blood pH rises above 7.8?
CNS is overexcited which leads to tetany and death
Why do we need more bicarb that carbonic acid?
Since most metabolic functions produce acid as a by-product, in order to maintain homeostatic conditions we require a surplus of bases and a very small amount of acids.
