Renal System Flashcards
What are the kidneys?
Humans have 2, one either side of the vertebral column. A tough renal capsule covers each one. It receives blood from the renal artery and returns it through a renal vein. The blood is filtered in the outer layer, the cortex, at the Bowmans capsule and the medulla contains the loop of Henle and the collecting ducts that carry the urine to the pelvis. The pelvis empties the urine into the ureter which goes to the bladder.
What is the calyx?
The first unit in the system of ducts in the kidney carrying urine from the renal pyramid of the medulla to the renal pelvis for excretion. There is the minor renal calyx with several others which drains into the major renal calyx which in turn joins other major calyces to form the pelvis.
What is the cortex?
Where small molecules are filtered from the blood and where most are returned to blood before leaving the kidney.
What is the medulla?
Helps in control of water content of blood. The renal pyramids are a part of the medulla in which urine drains into the pelvis. The pelvis is the white region at the top of the ureter that urine drains into. The ureter carries urine from kidneys to bladder.
What do the renal arteries and veins do?
Renal artery brings blood from the heart to the kidney. Renal vein carries blood from the kidney to the inferior vena cava.
What are the 2 main roles and 4 minor roles of the kidney?
Main: osmoregulation and excretion.
Minor: control of water balance, regulation of blood pressure, regulation of electrolyte balance and excretion of metabolic wastes like urea.
Where are the nephrons located?
They start in the cortex, loop down into the medulla and back into the cortex and join to form the ureter.
What is the bowmans capsule?
At the start of the nephron and Holds the glomerulus.
What is the glomerulus?
A network of blood capillaries, where blood enters at high pressure from the afferent arteriole from the renal artery.
Describe ultrafiltration.
In the glomerulus. Blood is at such high pressure that solutes and water are forced out through the fenestrae of capillaries, through the basement membrane and through filtration slits between pedicels into the cavity of the Bowmans capsule. The solutes and water that filter out constitute the glomerular filtrate and includes glucose, water, salts, urea and amino acids.
What happens at the proximal convoluted tubule?
Where most of the reabsorption happens. The solutes move from the filtrate to the blood and because this then lowers the water potential of the outside, water is followed by osmosis. Most of the water is reabsorbed.
What happens in the loop of Henle?
The ascending limb is impermeable to water, and ions actively transport out which reduces the water potential of the medulla. The descending limb is relatively permeable to water and because of the reduced water potential of the medulla due to the ascending limb, water moves out.
What happens at the distal convoluted tubule?
This is the area most affected by ADH. This controls the amount of water reabsorbed into the blood and therefore the concentration of the urine. This is osmoregulation.
What happens at the collecting duct?
The filtrate now has very little water, urea and salts/ions. It goes into the collecting duct, out of the renal pelvis, through the ureter and into the bladder.
Briefly describe urine production.
Blood enters glomerulus and water and solutes are forced out due to high BP - filtrate forms - reabsorption happens at the PCT - concentration increases at the loop of Henle - amount of water is modified to meet the bodies needs at DCT - some reabsorption occurs at the collecting duct - leaves through ureter.
