structure of the kidney

• the outermost layer is the cortex.

  the darker region is called the cortex, it contains many tiny blood vessels that branched from renal artery. it also contains microscopic tubes that are not blood vessels, they are filtering units called kidney tubules/nephrons.
• from the cortex, it ran down to the medulla where it has bulges called ‘pyramid’ pointing inwards toward the concave side of the kidney. The tubules in the medulla joined up and lead to the tips of these pyramids. The tips is where they empty urine into a tunnel like structure called pelvis.
• the pelvis connects with the ureter, carrying the urine to the bladder. 
• the nephron is across the cortex and medulla. Some part is in the cortex, more in the medulla.
• 1. blood is filtered in the cortex 
  2. medulla contains the renal pyramids, where the urine formation take place
  3. pelvis collects the urine produced in the kidney leading to ureters
• Renal artery: carry unfiltered blood from the aorta to the kidneys

  Renal Vein: carry filtered blood from the kidneys to the posterior vena cava.
• the kidney is the size of our fist and is the shape of a bean
• At the start of the nephron is a hollow cup of cells called the bowman’s capsule. It surrounds the glomerulus, capturing fluid leaking out of the glomerulus and returns it to the peritubular capillaries and participates in the filtration of blood from the glomerulus. Blood in the glomerulus and the space in the capsule is separated by two layers: the capillary wall, the wall of the capsule. Between these two cell layers is a third layer called Basement Membrane. 
•  Blood in the glomerulus and the space in the capsule is separated by two layers: the capillary wall, the wall of the capsule. Between these two cell layers is a third layer called Basement Membrane. It is not made of cells, it act like a filter, allowing water, ions and small molecules like glucose and urea to pass through. But holding back blood cells and large molecules such as protein.
• Ultrafiltration is a process where the filter separates different sized molecules under pressure
• Glomerulus filtrate is the fluid that enters the capsule space
• Glomerulus is a network of capillaries (smallest kind of blood vessel) where the blood is filtered. The thin walls allow smaller molecules, wastes and fluid mostly water to pass into the tubule. Larger molecules such as protein and blood cells, stay in the blood vessel.  
• The pressure of blood in the arteriole leading to the glomerulus is very high, because of the resistance to flow caused by the glomerulus. This pressure forces fluid from the blood through the walls of the capillaries and the bowman’s capsule, into the space in the middle of the capsule
• the first coiled tubule re absorb the nutrients and other chemicals the body needs. leaving behind the unwanted urea, salts and some water.
• the loop of henlé separate two coiled regions of the tubule in the cortex and reabsorb water and important nutrients in the filtrate.
• the collecting duct is the place where the final urine passes into the pelvis.