Week 1 - anatomy of the urinary system Flashcards
What is the overall function of the urinary system?
The urinary system is designed, both structurally and functionally, to handle fluids in the body
- Allows filtration and selective reabsorption
- Controls concentration of substances in the extracellular fluid
What are the functions of the kidney?
- Control osmolarity
- Control volume of ECF
- Help to control pH
- Excrete some waste products
How does the kidney achieve its functions?
- Filters a large amount of extra cellular fluid
- 180 L/day
- Each litre is filtered over 10 times a day
- Recovers most of the substances
o > 99% of filtered water
o >99% of filtered Na+ and Cl-
o 100% of Hydrogen Carbonate
o 100% of Glucose and Amino Acids - Actively secretes some substances (H+)
- A few waste products are not recovered
What is the ureter?
- A smooth muscle tube
- Connects the kidneys to the bladder
- Each kidney has 1
What is the bladder?
- A sac of smooth muscle
- Used for storage of urine
- Empties periodically via the urethra
Describe the anatomical position of the kidneys
- Retro peritoneal
- Left and right of vertebral column
- Left: T11-L2, right: T12-L3
- Right kidney is lower because of the liver
Describe the anatomical position of the bladder
- Anterior
- In the pelvic cavity
- Distends upwards when it fills with urine
- Right behind the pelvic bone in an adult, above it in a child
Describe the anatomical position of the prostate
- Inferior to the neck of the bladder
- Superior to the external urethral sphincter
- The ampulla of the rectum lies posterior to it
Describe the course of the ureters
- Arise from the renal pelvis at the ureteropelvic junction
- Descend down the abdomen along the anterior surface of the psoas major
- Cross the pelvic brim at the area of the sacroiliac joints, entering the pelvic cavity and also crossing the bifurcation of the common iliac arteries
- Run down the lateral pelvic wall
- Turn anteromedially at the ischial spines, towards the bladder
- Pierces the lateral wall of the bladder
Where are the most common places for kidney stones to cause a blockage in the ureter?
- Ureteropelvic junction
- Pelvic brim
- Where the ureter enters the bladder
Describe the renal arterial supply
- Renal arteries are a branch of the abdominal aorta at L2/3, just inferior to the mesenteric arteries
- Right renal artery is longer than the left and passes posterior to the IVC
- Renal arteries divide to give segmental branches
- Segmental arteries divide to give interlobar arteries
- Interlobar arteries divide to give arcuate arteries
- Arcuate arteries give off the interlobular arteries at 90 degrees to themselves
- Interlobular arteries divide to form afferent arterioles
- Afferent arterioles form the glomerulus (capillary network)
- The capillaries come together to form the efferent arterioles
Describe the renal venous drainage
Drained by the left and right renal veins, which drain directly into the IVC
What is the kidney encased in?
Layers of fascia and fat:
- Renal capsule
- Perirenal fat
- Renal fascia
- Pararenal fat
How is the renal parenchyma split?
Into the medulla and cortex
- Cortex: forms a continuous smooth outer zone
- The cortex projects into the medulla, creating pyramids (renal pyramids)
- The apex of a renal pyramid is called a renal papilla
- Each renal papilla is associated with a minor calyx, which collects urine from the pyramids
- The minor calyces can merge to form a major calyx
- Urine passes through a major calyx into the renal pelvis
What is the renal hilum?
A deep fissure where structures enter/exit the kidney
- Found on the medial margin of the kidney
