Renal 1: Renal System Overview Flashcards
What are the 8 rental functions?
- Excretion of metabolic waste and foreign substances
- REgulation of water and electrolyte balance
- Regulation of ECFV
- Regulation of Plasma Osmolality
- Regulation of RBC production (EPO)
- Regulation of Vascular Resistance (RAA system)
- Regulation of Acid-Base balance
- Regulation of Vitamn D production (calcitriol)
What are the components of the urinary system
Kidney, ureter, bladder, urethra
What is the outer region just beneath the capsule in the kidney called?
Cortex
What is the inner region of the kidney called?
Medulla
Describe the structural units of the medulla
Made of renal pyramids (Apex: papilla and base originates at the corticomedullary border)
Papilla lies within the minor calyx that feeds into the major calyx
Describe the renal pelvis
Major calyces feed into the renal pelvis and continues on to the ureter which takes urine to bladder
What does the nephron consist of
renal corpuscle, proximal tubule, loop of Henle, distal tubule, collecting duct system
What does the renal corpuscle consist of
glomerular capillaries and Bowman’s capsule
Describe the structure of the proximal tubule
Forms several coils and then straight piece descending into the medulla
Describe the structure of the loop of Henle
Straight part of proximal tubule -> descending thin limb -> hairpin turn -> ascending thin limb -> ascending thick limb
What is the macula densa
short segment of thick ascending limb that passes between the afferent and efferent arterioles of the same nephron
Describe the structure of the distal tubule
After macula densa. Extends into the cortex where it joins 2 or more nephrons to form a cortical collecting duct
Describe the cortical collecting duct
Enters the medulla -> outer medullary collecting duct -> inner medullary collecting duct
What makes up the filtration barrier of the glomerular capillary?
endothelim
basement membrane
foot processes of podocytes
What is the structural function of glomerulus
ultrafiltration
What is the structural function of the proximal tubule
High volume, low gradient reabsorption
What is the structural function of the loop of Henle
Form high interstitial osmolality
What is the structural function of the distal tubule
low volume, high gradient reabsorption
What is the structural function of the Macula Densa
Juxtaglomerular Apparatus (JGA) Senses tubular flow
What is the structural function of the collecting duct (post nephron structure)
Concentrate/Dilute final urine
What are the 2 cell types found in the collecting duct?
Principal Cells: moderate invagination of basolateral membrane and few mitochondria; Reabsorbs NaCl and secrete K+
Intercalated Cells: regulate acid-base balance; high concentration of mitochondria
2 types of intercalated cells
1. secrete H+/reabsorb HCO3-
2. Secrete HCO3-
What are the functions of the primary cilia found in the cells of the nephron?
Mechanosensors: detect changes in rate of flow of tubule fluid
Chemosensors
What is a typical value for renal blood flow and what percent of cardiac output is it?
1200 mL/min and 25%
What is a typical value for renal plasma flow
660 mL/min
Name the progression of the renal arteries
Renal Arteries -> interlobar artery -> arcuate artery -> interlobular artery -> afferent arteriole -> glomerular capillaries
What is a typical value for glomerular filtration rate?
125 mL/min
How do we calculate filtration fraction?
FF = GFR/RPF. typical value is about 20%
What do the glomerular capillaries turn into?
Form the efferent arterioles which lead to the peritubular capillaries to supply blood to the nephron
What percent of RBF passes the peritubular capillaries?
90% RBF (Cortical)
What is another function of the peritubular capillaries besides providing blood flow
Reabsorption of water and solutes from renal cortex
What percent of RBF passes vasa recta capillaries?
10% RBF (Medullary: 8% outer 2% inner)
What is another function of the vasa recta capillaries besides providing blood flow
reabsorption of water and solutes from the renal medulla
What are the 2 main routes of renal blood flow?
Renal arterial blood can pass through glomerular capillaries to either peritubular or vasa recta capillaries. there is little mixing between the two paths.
How much urine is excreted on a typical day?
600-2500 mL/day
What is the amber color of urine due to?
pigment urochrome, a compound of urobilin or urobilinogen
Why does urine turn dark amber on standing?
oxidation of urobilinogen
What does dark amber urine on collection indicate?
state of anti-diuresis with ventilation less than 1 mL/min
What does pale amber con collection indicate?
state of water diuresis with ventilation > 1 mL/min
What is clearance?
volume of plasma completely cleared of substance in one minute
Substance present in urine -> being cleared by body -> clearance >0.0mL/min
Substance not present in urine -> being preserved by body -> clearance = 0.0mL/min
What substances should not be found in urine (reabsorbed completely)
HCO3-, glucose, amino acids, protein, blood, ketones, bilirubin, leukocytes
What hormones are released by the kidney? (4) What do they do?
Erythropoietin- stimulate RBC production from bone marrow
calcitriol/vitamin D3- bone resorption
Renin- enzyme that increases circulation levels of angiotensin
Prostaglandins- renal vasodilation and regulate RPF and GFR
What hormones act on the kidney?
ADH from posterior pituitary- water balance
Aldosterone from adrenal cortex - positive sodium and water balance
Atrial Natriuretic Peptide from heart -> negative sodium and water balance
Parathyroid hormone- calcium reabsorption by renal tubules
How does congestive heart failure affect the following?
effective circulating volume, perfusion of kidney, and
salt and water reabsorption
decrease, decrease, increase
