RENAL OVERVIEW Flashcards
What is the basic unit of the kidney?
The nephron
How many nephron units are there per kidney?
400 000 – 800 000
What are the different parts of the tubule that starts in the glomerulus and ends with the papillary duct which opens out into the renal papilla?
Proximal convoluted tubule Descending limb of the loop of Henle Thin ascending limb of the loop of Henle Thick ascending limb of the loop of Henle Distal convoluted tubule Collecting duct
Where is the juxtaglomerular apparatus found in the nephron of a kidney?
Between the arterioles entering and leaving the Bowman’s capsule and the macula densa which is found on the distal convoluted tubule.
Where does secretion into the nephron tubule occur?
In the glomerulus and in the proximal convoluted tubule.
What are the three layers of the filtration in the glomerulus of the nephron?
Endothelial cells of the capillary
Glomerular basement membrane
Epithelial cells of the Bowman’s capsule
What size are the pores in the endothelial wall of the capillaries in the glomerulus of the nephron?
70 nm
What are the main functions of the kidney?
Control extracellular environment (eg sodium, potassium, calcium etc)
Secrete products of metabolism
Fluid volume regulation
Secrete EPO
What is actively reabsorbed in the proximal convoluted tubule of the nephron?
Sodium Potassium Calcium Phosphate Glucose Amino acids Proteins (via endocytic receptors)
Is the filtrate hypo-, hyper- or iso-osmotic by the time it reaches the end of the proximal convoluted tubule in the nephron?
Iso-osmotic
What are the five main hormones that work on the kidney?
Vasopressin (ADH) Aldosterone Natriuretic peptides Parathyroid hormone Angiotensin II
What is the role of ADH in the kidney?
Promotes water reabsorption in the collecting duct
Where is ADH produced?
Posterior pituitary gland
What is the role of aldosterone in the kidney?
Promotes sodium reabsorption in exchange for potassium in the collecting ducts.
Where is aldosterone produced?
Adrenal glands
What is the role of natriuretic peptide hormone in the kidney?
Promote sodium excretion in the collecting ducts by inhibiting ENaC channels
Where are natriuretic peptides produced?
Cardiac cells
What is the role of parathyroid hormone in the kidney?
Promotes renal phosphate excretion, calcium reabsorption and vitamin D activation.
What are the four main hormones produced by the kidney?
Renin
Activated Vitamin D
Erythropoietin
Prostaglandins
What is the role of renin, produced in the kidney?
Activates the angiotensin system.
What is the role of angiotensin II in the kidney?
Promotes sodium reabsorption in the proximal tubules. Activates aldosterone (hence further reabsorption of sodium)
What is the role of activated Vitamin D, produced in the kidney?
Promotes calcium and phosphate absorption from the gut
What is the role of erythropoietin, produced by the kidney?
Promotes red cell production in the bone marrow
What is the role of prostaglandins, produced by the kidney?
Renal vessel tone
What diseases might cause someone to experience flank pain synonymous with kidney pain?
Renal stones
Infection
Renal cysts
What would suspect was in the urine if it was described as frothy?
Protein
What might dark urine indicate?
Myoglobinuria
Rhabdomyolisis
Haemolysis
What might reccurent intermittent frank haematuria be indicative of in a young patient?
Immunoglobin A (IgA) glomerulonephritis
What might recurrent intermittent frank haematuria be indicative of in an elderly individual?
Renal cancer
Would haematuria as a result of glomerular bleeding be present only at the beginning of the stream, only at the end or all the way through the stream?
All the way through
What might haematuria only at the beginning of the stream indicate in terms of where the blood is coming from?
Urethral bleeding
What might haematuria only at the end of the stream indicate in terms of where the blood is coming from?
Bladder or prostate bleeding
What is the different between polyuria and increased urinary frequency?
Polyuria is an increase in total urine volume. Increased urinary frequency is an increase in the frequency of micturition and has nothing to do with volume (in fact it is often decreased as in benign prostate hyperplasia)
What might total anuria indicate?
Urethral or bilateral ureteric obstruction
A rapidly progressive glomerulonephritis
Aortic or bilateral renal arterial occlusion
What is the infection that most commonly precedes infective glomerulonephritis?
Strep throat (S. pyogenes)
What are the most common over the counter nephrotoxic drugs that predispose someone to chronic kidney failure?
NSAIDs
What substance do we normally use to estimate the glomerular filtration rate?
Creatinine
What does creatinine levels in the blood of someone with normal kidney function depend on?
Muscle bulk
What is the definition of the glomerular filtration rate?
Volume of filtrate formed in 1 minute
How do we measure creatinine clearance (eGFR)?
Clearance = UV/P
where U is the creatinine concentration in the urine
V is the volume of urine produced per minute
P is the creatinine concentration in the plasma
Why is creatinine clearance an over estimation of eGFR?
Because some creatinine is excreted into the PCT
What substance is used to accurately measure GFR for research purposes?
Inulin
What radioactive substance is used clinically to more accurately measure GFR?
51Cr-EDTA
