16. The urinary system (Greg Michael) Flashcards
What is the overall function of the kidneys?
Regulation of the blood composition
Control of the blood pressure and volume
Describe the general structure of the kidney
Concave medially - this is the hilum where there is the renal pelvis and the major vessels
There are set lobes of the kidney and these are composed of lobules
The outer region of the kidney is the cortex and the inner region is the medulla
The medulla consists of medullary pyramids which are cone shaped tissues, ending in papillae (points)
What is the renal pelvis?
The broadened top part of the ureter into which the kidney tubules drain - first part of the kidney after the hilum
The calyces all come together to form the renal pelvis
What is a renal calyx?
This is a chamber of the kidney through which urine passes before going to the renal pelvis and the ureter
Give the intricate vasculature of the kidney
Renal artery - main branch of the renal artery - interlobar artery - arcuate artery - interlobular artery
(LOOK AT IMAGE)
What is the nephron of the kidney?
Basic structural and functional unit of the kidney
Funnel shaped epithelial structure - where a blood filtrate is processed to ultimately leave urine
Composed of Bowman’s capsule and the renal tubule
What is the renal corpuscle?
Renal corpuscle being the renal body
This is Bowman’s capsule with the glomerulus supported by cells and the ECM
What is the purpose of the ‘vascular pole’ of the renal corpuscle?
There is a vascular pole causing the glomerulus to have a negative charge
This means that the albumin remains in the blood rather than being filtered out into the urine
What is the function of the renal corpuscle?
Ultrafiltration of the blood
What is the ultrafiltration of the blood at the glomerulus dependant on and why?
Dependant on the size and charge of the components of the blood
Size: anything below molecular weight of 55,000 will automatically be filtered out
Charge: due to the vascular pole which carries a negative charge
What are the components of the glomerular filtration barrier?
Fenestrated capillary
Specialised thick basement membrane
Podocytes of the Bowman’s capsule with their finger-like processes
SO what gets filtered out of the blood in the glomerulus?
Anything that has a molecular weight of less than 55,000 - regardless of whether or not they are required in the blood
What is the function of the proximal convoluted tubule?
Reabsorption - facilitated by Na+/K+ ATPase in the basolateral membranes
What is reabsorbed in the proximal convoluted tubule?
Most of the water Most of the Na+/Cl- All of the amino acids All of the glucose Some bicarbonate HCO3-
What is the function of the loop of Henle?
Creates and maintains the high ionic concentration of the medulla required for the control of urine concetration
What are the two components of the loop of Henle and what are their functions?
Thick ascending limb:
Actively transports Na+/Cl- out of the tubule
Is impermeable to water
So the concentration of the medulla is becoming higher and lower in the tubule and a concentration gradient is established
Thinner descending limb:
SO due to the high water potential and osmotic pressure in the medulla, water is readily absorbed into the descending limb and is reabsorbed from the medulla, along with some Na+/Cl-
SO THIS SYSTEM ALLOWS for the reabsorption of water from the medulla which was lost at the glomerulus
What is the function of the distal convoluted tubule?
Fine regulation of electrolyte and acid-base balance: Na+, K+, H+
Regulation ofl water balance involving ADH
What is the juxtaglomerular apparatus?
Where the distal convoluted tubule bends back and meets the glomerulus
What is the function of the juxtaglomerular apparatus?
Regulation of blood pressure and volume via the release of the enzyme renin
The Na+ concentration is sensed by the macula densa cells
What is the function of the collecting duct?
Final concentration of urine - ADH sensitive
Electrolyte and acid-base balance - aldosterone sensitive
