Intro to kidneys and body fluid Flashcards
Define osmoregulation.
Regulation of body water
Define Volume regulation.
Regulation of body salt through control of circulating plasma volume in the ECFV
What percentage of body weight is water?
60% (42L)
What percentage of body weight water is intracellular?
40% (28L)
What percentage of body weight water is extracellular?
20% (14L)
- 3L plasma
- 11L interstitial fluid
What must there be between ICF compartment and ECF compartment?
An osmotic equilibrium to prevent massive shifts of water between intracellular and extracellular volumes
What maintains the osmotic equilibrium between ECFV and ICFV?
Osmoregulation
Define osmolarity.
Total concentration of osmotically active solutes
What is the major determinant of ECF osmolarity? Why?
Sodium, because it is the principle electrolyte of the ECF
Why is controlling body fluids important?
Cell structure and function
-large shifts between ECFV and ICFV will disrupt tissue structure and function
Tissue Perfusion
-depends on the balance between circulating plasma volume and interstitial volume
What is the Composition of plasma and interstitial fluid?
Not very different as electrolytes and small molecules would equilibrate between them
What is the Plasma osmolarity calculation?
2(Na) + 2(K) + (glucose) + (urea)
What are the 2 ways to change osmolarity of a solution?
1) Add/Remove water
2) Add/Remove sodium
Describe the Rise in plasma osmolarity.
More water is needed
kidneys respond by producing small volume of concentrated urine (water retention)
Describe the Fall in plasma osmolarity.
Too much water
kidneys respond by producing large volume of dilute urine (water excretion)
What maintains adequate ECFV to support plasma volume?
Volume regulation
How are changes in blood plasma volume detected?
Indirectly by stretch and pressure receptors in the cardiovascular system, which in turn indicates changes in blood pressure
What happens when blood volume increases?
Increased blood pressure
Kidneys excrete Na
Water osmotically follows
Blood volume restored
What happens when blood volume decreases?
Decreased blood pressure
Kidneys retain Na
Water osmotically follows
Blood volume restored
What is the role of the kidney?
homeostasis
*urine production is a by-product of kidney function (homeostasis)
What is the function of the kidney?
- osmoregulation
- volume regulation
- acid-base balance
- regulation of electrolytes
- removal of metabolic waste products from the blood
- removal of foreign chemicals in the blood (e.g. drugs)
- regulation of red blood cell production (EPO)
- acts as an endocrine organ (EPO, Renin, Vitamin D)
What is the nephron?
Function unit of the kidney, consisting of an interaction between blood vessels (including glomerulus capillary network) and the renal tubule (including Bowman’s Capsule)
How many nephrons are there per kidney?
1.25 million
What are the 4 basic processes of renal function?
1) Glomerular Filtration
2) Tubular Reabsorption
3) Tubular Secretion
4) Excretion of water and solutes
