Renal system: L32 - Overview of Urinary system Flashcards
What is the function of the kidneys? How do they generally achieve this?
Maintain chemical and water balance in the body. They do this by their ability to selectively filter, reabsorb and secrete substances (water, salts, wastes, toxins, drugs) contained in the blood, and to excrete wastes in urine.
How much blood flows through the kidneys?
1200ml/min
What endocrine functions does kidney have?
Renin secreted to maintain blood pressure and EPO to regulate RBC production.
What are the major components of the urinary system?
2 kidneys, 2 ureters, urinary bladder, urethra, regulatory nerves and muscles.
Describe the position of the kidneys, including relativity to other structures.
Kidneys lie against the posterior abdominal wall, and are retroperitoneal (behind the peritoneal cavity) organs. Their anterior surface is covered in peritoneum. They are located between T12 and L3. They are protected by the 11th and 12th ribs and surrounded in fat. The liver pushes the right kidney lower than the left. The right kidney is posterior to the liver and left kidney is posterior to the spleen. The adrenal glands sit on top of the kidneys.
Describe the orientation and shape of the kidneys.
The kidneys are bean-shaped with their convex surface lying laterally, and their concave surface lying medially. The medial surface has a notch called the hilum. This is an entry and exit point for structures such as arteries, veins, lymphatics, nerves and ureters.
Describe the cortex layer of the kidneys.
The outer continuous layer of the kidneys, the cortex sends in divisions called renal columns which lie between medullary pyramids.
Describe the medulla layer of the kidneys.
The inner layer of the kidneys, divided into approximately 7 medullary pyramids, each of which ends in in a pointy papilla that urine is emptied into. Each pyramid corresponds with an outer region of cortex to form a lobe, 5-11 lobes per kidney.
Describe the renal pelvis.
Urine from each papilla collects in a minor calyx. These calyces join together to form major calyces which join to form the renal pelvis. The renal pelvis then narrows to form a ureter which exits the hilum of the kidney and conducts urine down to the bladder.
Briefly describe the nephron.
The kidney’s most basic functional unit is the nephron. Nephrons consist of a renal corpuscle (site of filtration), a looped renal tubule (where reabsorption occurs) and a collecting duct (which empties urine into the papillae), and serve the purpose of making urine, regulating excretion of other wastes, and maintenance of correct electrolyte levels.
Explain the blood supply route to the kidneys from branch to branch.
Abdominal aorta –> Renal arteries (enter the kidneys)–> segmental arteries –> lobar arteries –> interlobar arteries –> arcuate arteries (arch around medullary pyramids) –> interlobular arteries (penetrate kidney cortex) –> afferent arterioles –> glomerulus (where blood is filtered) –> efferent arterioles –> peritubular capillaries and vasa recta for juxtamedullary nephrons –> veins (similarly named pathway).
Explain the nerve supply to the kidneys.
Sympathetic nervous system division of the autonomic nervous system. Sympathetic nerves feed into the renal plexus, which is a network of nerves and associated ganglia located on renal arteries. The ‘renal plexus’ controls the level of vasoconstriction of renal arterioles and in this way alters resistance to control blood flow to the kidneys.
