Renal Flashcards
Functions of the Kidneys
- Regulation of water, inorganic ion balance, and acid-base balance
- Removal of metabolic waste products from the blood and their excretion in the urine
- Removal of foreign chemicals from the blood and their excretion in the urine
- Production of hormones/enzymes:
a. Erythropoietin: hormone that controls erythrocyte production
b. Renin: enzyme that controls the formation of angiotensin and influences blood pressure and sodium balance
c. 1,25-dihdyroxyvitamn D: active vitamin that influences calcium balance.
Main physiological function of the kidney
Regulation of water, inorganic ion balance, and acid-base balance. e.x. removal of antibiotics. Urine will be smelly or change color.
Location of the kidneys
behind the peritoneum on either side of the cerebral column against the posterior abdominal wall
Whole renal system
Kidney –> Ureter –> Bladder –> Urethra.
Components of the Kidney
Renal Cortex, Renal Medulla, Renal Pelvis, Ureter (going out)
What the renal medulla structure is called
renal Pyramids
Role of renal Pelvis
where initial urine is followed through into the ureter.
Renal Artery
brings blood into the kidney
Renal Vein
Brings/drains blood out of the kidney
Interlobar artery
runs between the pyramid lobes
Arcuate artery
branches out towards the surface of the kidney into the cortex
Interlobular artery
supplies blood to the function unit of the kidney/specific part called the nephron.
How many nephrons in a single kidney
-each kidney contains ~1 mill subunits called Nephrons
Nephron consists of
Consists of
- Tubule
- Renal corpuslce: inside has a glomerulus (capillary loops) and bowmans capsule
Components in the Cortex
-glomerulus (glomerular capillaries)
-Bowmans Space in Bowmans capsule.
Above is all in the renal Corpuscle
Why long tube is called the tubule
it is a hollow tube surrounded by a mono layer of epithelial cells.
Renal corpuscle
combination of the glomerulus and bowman’s capsule
Bowmans Capsule(visceral layer)
epithelial cells that directly touch the glomerulus = visceral layer: podocytes)
Bowmans Capsule (parietal layer)
cells on the outside
Bowmans space
where first filtered urine is collected.
Glomerular Capillary Wall
- A lot of foot like processes that tightly interdigitate. Cells that do this are called podocytes.
Glomerular Capillary Wall (filtration barrier)
Filtration barrier consists of three parts: visceral glomerular epithelial cells (podocytes), glomerular basement membrane (GBM), and Endothelial Cells.
Fenestra
holes in the Lumen side of the layer of endothelial cells.
Path of blood filter in the capillary wall
Blood or plasma is filtered through the endothelial cells “windows” and through the light of the GBM. Then through the filtration slits to the bowmans space.
Function of glomerulus
to filter blood to make urine
Efferent arteriole
Carries blood away from the glomerulus
Afferent arteriole
Carries blood to the glomerulus
Three processes of urine formation
- Glomerular filtration
- Tubular secretion
- Tubular reabsorption
Glomerular Filtration
Filtration of plasma from the glomerular capillaries into Bowman’s space. Beginning of urine formation
Glomerular Filtrate
“Fluid in Bowmans space”, that is cell-free and except for proteins, contains all the substances in plasma in virtually the same concentrations as in plasma. There should be an absence of blood and big proteins.
Tubular secretion/absorption
As glomerular filtrate passes through the tubules, its composition is altered by movements of substance.
Tubules –> peritubular capillaries = Reabsorption
Peritubular capillaries –> tubules = Secretion
Amount Excreted =
Amount Filtered + Amount Secreted - Amount Reabsorbed
Excretion
fluid will leave the body
Secretion
fluid moving from the peritubular capillary to the tubule.
What is filtered by glomerular filtration
water and low-molecular weight substance
What is not filtered by glomerular filtration
cells, proteins(albumin, globulins), protein-bound substances(1/2 of calcium ion, fatty acids)
Forces involved in filtration
Favoring Filtration
-Glomerular capillary blood pressure (Pgc) 60 mmHg
Opposing Filtration
- Fluid pressure in Bowman’s space (Pbs) 15 mmHg
- Osmotic Force due to protein in plasma “Oncotic pressure” (piegc) 29mmHg
Net Glomerular filtration pressure
Pgc - Pbs - piegc(oncotic pressure) = 16 mmHg.
Higher force going into bowmans space. Net movement in that direction as well. Most important force that pushes filtration is Glomerular Capillary pressure
Glomerular Filtration Rate (GFR)
the volume of fluid filtered from the glomeruli into Bowman’s space per unit time.
What GFR is regulated by
- net filtration pressure
- membrane permeability
- surface area available for filtration
Normal GFR in 70 kg person
180L/Day (125ml/min)
Normal Blood Plamsa volume of this person is 3.5 L
180L/3.5 = 51.
Plasma is filtered 51x a day at glomeruli.
Decreased GFR
- Constrict Afferent Arteriole = lower pgc, decreased pressure favoring filtration
- Dilate Efferent Arteriole = blood flow goes up, less time for glomeruli to filter, less pressure for Pgc.
Increased GFR
- Constrict Efferent arteriole = more time for the glomeruli to filter, increase in pGC, favoring pressure for filtration
- Dilate Afferent Arteriole = increase in Pgc, favoring pressure for filtration
Filtered Load
-total amount of any freely filtered substance
FR = GFR x plasma concentration of the substance
e.g.
filtered load of glucose = 180 L/Day x 1 g/L = 180 g/day
net reabsorption
filtered load > amount excreted in the urine
Net secretion
filtered load