Renal Flashcards
What are the functions of the kidneys?
Water and electrolyte balance
Filter and secrete excess/ waste substances
Reabsorb glucose, amino acids and bicarbonates
Activates 25-hydroxy vitamin D
Synthesise erythropoietin
What is GFR?
Glomerular filtration rate–> How much blood is filtered through the glomeruli into Bowman’s space per minute
What is a normal GFR?
120ml/min (7.2L/h, 170L/day)
What is the eGFR and how is it calculated?
The estimated glomerular filtration rate–> Best estimation of kidney function. Calculated from blood creatinine tests, age, body size and gender
What is creatinine and what happens to it?
A chemical compound left over from energy producing processes in the muscles that is filtered out of the blood by the kidneys and excreted in urine.
What does elevated creatinine levels indicate?
impaired kidney function or kidney disease
What are the different parts of the nephron?
Glomerulus, Bowman’s capsule, proximal convoluted tubule, Loop of Henle, Distal convoluted tubule, collecting duct.
What is the afferent arteriole?
Blood vessel that supplies the nephron (ARRIVES)
What is the efferent arteriole?
Blood vessels that carry blood away from the glomerulus (EXITS)
What is the glomerulus and what happens here?
Loop of capillaries, where ultrafiltration occurs
What makes up the filtration barrier at Bowman’s capsule?
Endothelial cells
Glomerular basement membrane
Podocytes
How is a pressure gradient created in the glomerulus to allow filtration?
The afferent arteriole dilates at the proximal glomerulus and the efferent arteriole constricts at the distal glomerulus.
What is the PCT lined with?
Simple cuboidal epithelial cels with brush borders and filled with large amount of mitochondria.
What is reabsorbed at the PCT?
65% of sodium, potassium and chloride, followed by water
100% of glucose
100% of amino acids
90% of bicarbonate.
What is the action of the loop of Henle?
Reabsorbs 25% of sodium and water
Which limb of the loop of Henle is impermeable to water?
The thick ascending limb.
Where do loop diuretics usually target?
The loop of Henle as this is where the most sodium filtration takes place.
What is the macula densa?
Area of specialised cells lining the proximal distal tubule. Play key sensory and regulatory functions in the maintenance of body fluid, electrolyte homeostasis and blood pressure. (sense salt levels and generate chemical signals to control kidney functions)
What happens at the distal convoluted tubule?
Fine tunes salt and water reabsorption and plays a major role in acid-base balance
What diuretics tend to target the distal convoluted tubule?
Thiazide diuretics
What is the main role of the collecting duct and how?
Reabsorption of water under the influence of ADH and aquaporins.
What is the juxtaglomerular apparaturs?
The location of renin-secreting cells and macula densa between the loop of Henle and distal nephorn which regulates blood pressure and GFR.
Where is water concentration detected?
Through osmoreception in the hypothalamus
When is erythropoietin produced by the kidney and why?
Produced in response to tissue hypoxia as it produced haemoglobin.