Anatomy of the Kidney

Study Notes

The kidney is a paired organ, with one located on each side of the spine in the retroperitoneal space.
Each kidney is surrounded by a fibrous capsule and is divided into the following regions:
- Cortex: outer layer, contains nephrons (functional units of the kidney)
- Medulla: inner layer, contains renal pyramids (collecting ducts and blood vessels)
- Renal pelvis: funnel-shaped structure that collects urine from the calyces (cup-like structures)

Excretion: remove waste and excess substances from the blood, including urea, creatinine, and water
Regulation of electrolytes: maintain homeostasis of electrolytes like sodium, potassium, and calcium
Blood pressure regulation: control blood pressure through the renin-angiotensin-aldosterone system
Erythropoiesis: produce erythropoietin, a hormone that stimulates red blood cell production
Vitamin D activation: convert vitamin D into its active form, calcitriol

The kidneys receive about 20-25% of the total cardiac output
Renal arteries branch off from the abdominal aorta and divide into smaller segments
Renal veins drain into the inferior vena cava

Functional units of the kidney, responsible for filtration, reabsorption, and secretion
Each nephron consists of:
- Renal corpuscle (Bowman's capsule and glomerulus)
- Proximal convoluted tubule (PCT)
- Loop of Henle
- Distal convoluted tubule (DCT)
- Collecting duct

Glomerular filtration: the process by which the glomerulus filters the blood, producing a filtrate
Tubular reabsorption: the process by which the PCT and DCT reabsorb water, electrolytes, and nutrients back into the bloodstream
Tubular secretion: the process by which the PCT and DCT secrete waste and excess substances into the filtrate
Urine formation: the final product of the filtration and reabsorption processes, containing waste and excess substances.

The kidney is a paired organ located on each side of the spine in the retroperitoneal space, surrounded by a fibrous capsule.
Each kidney is divided into three regions: cortex, medulla, and renal pelvis.

Inner layer of the kidney containing renal pyramids (collecting ducts and blood vessels).

Funnel-shaped structure that collects urine from the calyces (cup-like structures).

Excrete waste and excess substances from the blood, including urea, creatinine, and water.
Regulate homeostasis of electrolytes like sodium, potassium, and calcium.
Control blood pressure through the renin-angiotensin-aldosterone system.
Produce erythropoietin, a hormone that stimulates red blood cell production.
Convert vitamin D into its active form, calcitriol.

The kidneys receive 20-25% of the total cardiac output.
Renal arteries branch off from the abdominal aorta and divide into smaller segments.
Renal veins drain into the inferior vena cava.

Glomerular filtration: the process by which the glomerulus filters the blood, producing a filtrate.
Tubular reabsorption: the process by which the PCT and DCT reabsorb water, electrolytes, and nutrients back into the bloodstream.
Tubular secretion: the process by which the PCT and DCT secrete waste and excess substances into the filtrate.
Urine formation: the final product of the filtration and reabsorption processes, containing waste and excess substances.