Anatomy of the urinary system Flashcards
What are the functions of the kidneys and urinary tract?
- Excretion of waste products and drugs
- Regulation of body fluid volume and ionic compounds
- Synthesis of renin, erythropoietin, and prostaglandins
- Metabolisation of vitamin D to its active form
- Catabolism of low-molecular-weight proteins such e.g. insulin, parathyroid hormone, calcitonin
What is the anatomical location of the kidneys?
- Retroperitoneum on the posterior abdominal wall, either side of the vertebral column.
- Located between the T12 and L3 vertebra.
- Partially protected by ribs 11 and 12
- Hilum at L1
What is the size of an average kidney?
- 11cm long x 6 cm wide
- Left and right kidney should be roughly the same size.
Why is the right kidney lower than the left kidney?
- Because of the presence of the liver
How are the kidneys held in position within the abdomen?
- Nothing tethers the kidneys in place
- Lots of fat surrounds the kidneys, holding them still and cushioning them.
Where do kidneys receive their blood supply from?
- The abdominal aorta
- The right renal artery is longer than the left renal artery because it has to stretch over the inferior vena cava.
Where does the blood drain from the kidneys?
- Directly into the inferior vena cava
- The left renal vein is longer than the right renal vein because it must stretch over the aorta.
Outline the structure of the kidneys
- Cortex is the outer region
- Medulla is the inner region
- Medulla is divided into renal pyramids
- A renal lobe is the renal pyramid and the cortex above it.
- Blood vessels are found within the renal columns located in between each renal lobe.
Outline the path taken by urine as it drains to reach the ureter
Minor calyces ==> major calyces ==> renal pelvis ==> ureter
Why is there high osmolality in the medulla of the kidney?
- Allows very concentrated urine to be made
What are the 2 different types of renal corpuscle?
- Cortical (85%) has a short loop of Henle that only dips down into the outer medulla
- Juxtamedullary (15%) has a long loop of Henle that reaches the inner medulla.
- This allows different concentrations of urine to be produced - longer loop of Henle makes more concentrated urine.
What structures are found within the glomerulus?
- Afferent arteriole which breaks down into a network of capillaries to allow filtration.
- Efferent arteriole - 2 arterioles allow the blood pressure within the capillaries to be altered.
- Podocytes - lots of foot processes mesh together to form gaps that assist in filtration.
Which cells are found in the juxtaglomerular apparatus?
- Macula densa cells
- Extraglomerular mesangial cells
- Granular cells (release renin)
What do macula densa cells do?
- Sense the composition of fluid as it moves into the distal convoluted tubule.
- It then sends signals to change the rate at which we filter blood.
- This alters BP.
Why is the superior mesenteric artery an important landmark>
- It stops the kidney from moving too high up during embryological development.
