1. Intro Flashcards
At which vertebral level is each kidney located?
Left - T11 to L2.
Right - T12 to L3.
What are the 4 functions of the kidneys?
Regulation - controls the concentrations of key substances in extracellular fluid (influencing intracellular fluid).
Excretion - excretes waste products.
Endocrine - synthesis of renin, erythropoietin, prostaglandins.
Metabolism - activate vitamin D, catabolism of insulin, calcitonin.
What is the normal osmolality of plasma/interstitial fluid/intracellular fluid?
280-310 mmol/L.
What ions is osmolality in extracellular fluid determined mainly by?
Na+ and Cl-.
What ions is osmolality in intracellular fluid determined mainly by?
K+.
What are the consequences of the kidneys failing to control ECF volume and osmolarity?
Volume - changes in BP, tissue fluid, cell function.
Osmolarity - cells shrink or swell.
How do the kidneys contribute to acid base balance?
Regulate the concentration of bicarbonate in plasma.
What is ultrafiltrate?
Water, ions and all small molecules that the kidneys filter.
What volume of ECF is filtered per day by the kidneys?
180L/day.
On average, what volume of urine if produced by the kidneys per day?
1.5L.
How many nephrons are in each kidney?
1.5 million.
Through what areas of the nephron does filtrate pass?
Glomerulus, proximal convoluted tubule, loop of Henle, distal convoluted tubule, connecting tubule, collecting duct.
What proportion of cardiac output goes to the kidneys?
22%.
What part of the nephron is the major site of reabsorption?
Proximal convoluted tubule.
What property of the epithelial cells lining the tubules of the nephrons allow transport across the epithelium?
Epithelial cells are polarised.
Movement of what ion across the basolateral membrane of the tubular epithelium provides energy for the reabsorption of other substances eg glucose?
Na+.
What is the main function of the loop of Henle?
Create a gradient of increasing osmolarity in the medulla by counter-current multiplication.
Where in the tubule does the most variable reabsorption of electrolytes and water take place?
Distal convoluted tubule.
What is diuresis?
Production of large volumes of dilute urine.
What is the main function of the collecting duct?
Water reabsorption down the osmotic gradient as it passes through the high osmolarity environment of the medulla.
What hormone is variable sodium recovery in the nephron controlled by?
Renin angiotensin system.
What hormone is variable water recovery in the nephron controlled by?
Anti diuretic hormone.
