renal Flashcards
name the 8 functions of the renal system
- maintenance of homeostasis formation of urine
- excretion of waste and toxins
- regulation of electrolyte balance
- regulation of fluid balance
- regulation of acid/base balance
- production of renin- control blood pressure
- produce erythropoietin
8.metabolise vitamin D (convert from inactive-active)
how many nephrons are present per kidney
1 million
what are the 6 structural components of the nephron
- glomerulus, 2. Bowmans (glomerula) capsule, 3. proximal convoluted tubule, 4. loop of henle, 5. distal convoluted tubule, 6. collecting duct
what are the 2 segments of the loop of henle
thin segment- descending and thick segment- ascending
what are the 3 stages of formation of urine
- filtration 2. reabsorption 3. secretion
where is the filtration membrane located
glomerulus capsule
name 2 stages of filtration
- fenestrations (pores) allow small molecules through 2.filtration membrane helps retain large molecules, membrane is -ve charged repelling -ve molecules and allowing +ve molecules through
what is the rate of kidney filtration called
glomerular filtration rate (GFR)
name 3 molecules found in filtrate
glucose, amino acid, wastes, vitamins, electrolytes, nutrients, water
what is the approximate GFR
125ml/min
what is the measurement of filtrate produced a day
180 liters but only 1.5 litres of urine a day, therefore majority is reabsorbed by body
what is the equation for net filtration
outgoing-ingoing=net filtration
what is the definition of reabsorption
return of useful substances and water from filtrate to blood
where does reabsorption begin
PCT- proximal convoluted tubule
what does Tm stand for
transport maximum- maximum amount of substance that can be reabsorbed
what condition occurs if glucose exceeds its Tm
it is lost in urine- glycosuria- identifying diabetes
how does ADH affect reabsorption
affects permeability of collecting duct for water, helping to increase reabsorption or loss
which ion is actively reabsorbed
Na+
after active reabsorption of Na+ which molecules follow passively
h2o, ions and nutrients
define secretion
active removal of unwanted substances/wastes from the blood into filtrate
where does secretion occur
all along tubule
what is a major importance of secretion
help maintain pH
name 3 substances to secrete
H+, K+, ammonium, creatine, drugs
what are the percentage compositions of urine
95% water, 5% solutes
name as many components of urine as possible
- water, 2.urea(breakdown of amino acids), 3.sodium, 4.pottasium, 5.phosphate, 6.creatine(from metabolism of muscle tissue), 7.uric acid(from metabolism of nucleic acid)
why is urine measured in clinical setting
to indicate level of renal function
what is 1 Osmol
1 mol of particle per Kg of H2O
what does mOsm stand for and why is it used
milliosmols- how body fluids are expressed due to much smaller volume
what is the urine mOsm measurement at top of descending limb, what is measurement at bottom of descending limb and what is measurement at top of ascending limb
top of descending= 300mOsm
bottom of descending = 1200mOsm
top of ascending = 325mOsm
what does ADH stand for
anti-diuretic hormone
how does increase in ADH and decrease in ADH affect volume of urine
increased ADH= greater reabsorption, less urine
decreased ADH= less reabsorption, more urine
how does the renal system maintain pH
if pH falls then increase in H+ ions into urine, in tubules the H+binds with buffer and excreted in urine as ammonia.
opposite if alkotic
where is erythropoietin produced
by kidneys
what does EPO stand for
erythropoietin
