Introduction Flashcards
What are the functions of the kidneys?
Regulation: control the concentration of key substances in extracellular fluid
Excretion: excretes waste product
Endocrine: synthesis of renin, erythropoietin, prostaglandins
Metabolism: active form of vitamin D, catabolism of insulin, PTH, calcitonin
Where are the kidneys?
Retroperitoneal
Left is higher because liver shoves right kidney down a bit
T12-L2/3
Where do the ureters run?
Along the tips of transverse processes and along transverse sacroiliac joint
Enter bladder around level if ischial spine
What artery and what vein supply the kidneys?
Renal artery and real vein
What is the calyx?
A cup that catches urine that filters down into pelvis and then ureter.
We have minor and a major calyx’s.
What is the parenchyma made from?
The cortex and the medulla
Where are the renal pyramids?
In the medulla
What is the function unit of the kidney?
A nephron - this is a filter unit connected to a long tube for reabsorption. There are 1.5million in each kidney.
List the parts of the nephron
Glomerulus -filter
Proximal convoluted tubule - in cortex
Loop of Henle - dips in and out of medulla
Distal convoluted tubule - in cortex
Collecting duct - passes through medulla to pelvis
What is the rough electrolyte composition of intracellular fluids?
High K+
Low Na+
Many large organic anions
What is the rough electrolyte composition of extracellular fluids?
Low K+
High Na+
Main anion Cl- and HCO3-
What happens if the kidneys fail to control ECF?
Changes in BP, tissue fluid and cell function
Failure to control ECF osmolarity - cells shrink or swell
What is the difference between osmolality and osmolarity?
Osmolality = solute per Kg of solvent Osmolarity = number of osmoles of solute per L
Usually similar as at 1Lsquared = 1Kg
Measured in mO
What must the kidney do?
Control volume
Control osmolarity
Control pH
Excrete some waste products
What happens in the glomerulus?
Filtration
Water, electrolytes and small molecules forced through it by constant filtration press in capillaries
Specialised circulation maintains filtration pressure which determines the glomerular filtration rate.
What happens in the PCT?
Main site for resorption
60-70% of na and water
80-90% of potassium
90% of bicarb
100& of glucose and amino acids.
Water follows osmotic gradients so filtrate remains isotonic with plasma
Reabsorbed materials leave by peritubular capillaries.
What happens in the loop of Henle?
Reabsorption and creates a gradient of increasing osmolarity in the medulla by counter current. This allows the formation of concentrated urine if water has to be conserved.
What happens in the DCT?
Variable reabsorption of electrolytes and water as fluid leaving loop of henle is hypotonic.
DCT removed more Na and Cl and actively secretes H+
Water may / may not follow - if not, large volumes of dilute urine formed (Diuresis)
What happens in the collecting duct?
Removes water to create low volume of conc urine. Occurs as:
CD passes though high osmolarity in medulla created by loop of henle
Water crosses epithelium and leaves urine creating low volume of conc.
What controls Na recovery?
Renin-angiotensin system.
This controls the ECF volume
What controls water recovery?
ADH
This controls the permeability of DCT and collecting duct to water which, in turn, controls ECF osmolarity.
