Structure and function of the kidney Flashcards
What is the cortex?
The outer region of the kidney; extensions of the cortical tissue, contains about one million blood filtering nephrons
What is a nephron?
the filtration units in the kidneys
What is the medulla?
Inner region of the kidney, which contains 8-12 renal pyramids
These pyramids empty into the calyx
Medullary pyramids are formed by the collecting ducts, which is the inner part of the kidney
What is the calyx?
An extension of the renal pelvis, they channel urine from the pyramids to the renal pelvis
What is the ureter?
Muscular tubes that collect, filtrate urine and transport it from each kidney to the bladder
What is the function of the renal artery?
It branches off of the aorta, bringing waste filled blood into the kidney, where it can be filtered in the nephrons
The artery is further subdivided into several branches inside the kidney, and it receives 20% of blood pumped by the heart each minute
What is the function of the renal vein?
It removes filtered blood from the kidneys to the inferior vena cava
What is the function of the urethra?
A narrow passageway where urine passes from the bladder to the outside of the body, through urination
What is the function of the bladder?
A sac that collects and holds urine that comes from the ureters
How does blood travel through the kidneys?
Blood travels in through the renal artery
Waste products are filtered out and nutrients are absorbed
The balance of water in the body is regulated
The renal vein takes the blood away
Waste products in the urine move down to the bladder
What are the key functions of the kidney? (what I need to know)
removal of urea regulation of water levels ultrafiltration reabsorption osmoregulation parts of the nephron involved in this
What is the glomerulus?
The beginning of the nephron A network (tuft) of capillaries that performs the first step[ of filtering blood using diffusion
What is the Bowman’s capsule?
Fluids from the blood in the glomerulus are collected in the Bowman’s capsule
What is ultrafiltration?
(The Glomerulus filtrate), - Bowman’s capsule.
Blood is further processed along the nephron to form urine. This is called ultrafiltration
How is urea removed from blood?
Parts of the kidney nephrons in each kidney called the glomerulus and the bowman’s capsule act like a filter.
Blood enters the glomerulus at a high pressure, and the plasma is forced out through the capillary walls, into the Bowman’s capsule.
This rapid exit of the plasma is known as ultrafiltration, and removes waste, nutrients and water from the plasma, leaving blood proteins and cells behind.
Much of what is in the filtrate is needed by the body and so must be taken back into the blood. These red blood cells and proteins remain in the glomerulus and are not found in the urine of a healthy person. Reabsorption of these products occurs in the proximal tubule. 95% of water from the former plasma is reabsorbed, along with glucose, amino acids, vitamins and most mineral salts
Although glucose is removed, it is always reabsorbed back into the blood
What is urea?
A waste product formed by the liver and transported to the kidneys by the blood
What is water regulation known as?
osmoregulation
What could happen if we lose water?
This would increase the concentration of blood and if left uncorrected it could result in our cells losing water by osmosis, as water diffuses into the now concentrated plasma. This could be lethal
What is the role of the hypothalamus in water regulation?
The hypothalamus in the brain detects the rise in blood concentration and sends the impulses to neighbouring pituitary gland, which results in the release of a hormone ADH. (Antidiuretic hormone). This travels all over the body but it’s target cells lie in the walls of the kidneys collecting ducts
A specialised blood supply keeps the medulla region of the kidney salty by remaining salt from the urine in the loop of Henle
The collecting ducts are also located in this salty medulla
In the presence of ADH, water can pass through the walls of the collecting ducts, so water in the urine diffuses out of the ducts into the salty medulla and from there back into the blood
Where does reabsorption of salts and glucose happen?
The proximal tubule and reabsorption of salts occurs in the distal tubule
Where is most of the water reabsorbed?
loop of Henle. The result is a return to the correct blood concentration and the production of a concentrated urine
What happens if you drink too much water and it is cold outside?
If you drink lots of water and it is a cold day out, your blood can become too diluted. The risk is blood and cells taking up water by osmosis, swelling and possibly bursting
under these circumstances the hypothalamus is not stimulated and the pituitary gland does not produce ADH, and the water remains in the urine, passed to the bladder, causing us to urinate more
Urine from the nephrons flow into a collecting duct, leading to the renal pelvis which is drained by the ureter
