The Kidneys Flashcards
vena cava :
main vein returning blood to the heart
renal vein :
takes “cleaned” blood away from kidneys
aorta :
main artery supplying oxygenated blood to body
renal artery :
brings blood containing “waste” to the kidneys
urethra :
carries urine out of the body
ureter :
carry urine to the bladder
bladder :
muscular sac that stores urine (~ 700 cm)
sphincter muscle :
keeps bladder close
medulla :
lighter middle layer of kidney
pelvis :
central cavity which collects urine
cortex :
darker outer layer
nephron :
filtration unit (where the urine is produced)
The main function of the kidney is to ….
get rid of waste such as:
• Urea
• Excess water
• Excess salt (mineral ions)
Substances found in uncleaned blood :
urea, proteins, cells, glucose, amino acids, salt and water
Substances found in urine :
urea and some salt and water
Substances found in cleaned blood :
proteins, cells, glucose, amino acids, some salt and water and very little urea
It is important to remove urea because …
it is toxic
It is important to remove excess water because …
of its osmotic effect
It is important to remove excess salt because …
of its osmotic effect
When you compare the composition of blood and urine, you can see that some substances are ….
more abundant in urine than in blood
The substances more abundant in urine than in blood are …
waste substances, such as urea, which the body doesn’t want
There is about 60 times more urea …
in urine than in blood
The explanation is that as the blood passes through the kidney …
urea is taken out of it and passed into the urine.
However, the kidneys do more than simply …
cleanse the blood of urea
. They also regulate the …
amount of water and salt in the blood and also make sure that the pH of the blood is constant
The concentration of water and salt in our blood changes depending on …
what you eat and drink
If you drink a lot of water …
it is absorbed from your gut into the bloodstream and it has a diluting effect on the blood. The diluted blood reaches the kidney, which takes out more water than usual and pass it into the urine, thereby producing more urine, which is dilute.
If you eat a lot of salt,
the solute concentration in your blood increases. To counteract this, the kidneys take out less water from the blood and pass it into the urine, therefore producing less urine
By regulating the water and salt concentrations …
the kidneys make sure that the concentration of the blood stays more or less the same all the time
Regulating the water and salt concentration is important …
so that also the solute concentration in our body cell is constant. Otherwise, osmosis would occur and our cells would not function properly
Regulating the water and salt concentration is known as ….
osmoregulation and is an example of homeostasis.
Explain what happen when some food (chicken) is eaten.
o mechanically broken by mouth from chicken to protein
o in the digestive system protein is chemically broken down into amino by protease
o most of the amino acids are absorbed into blood but excess is transported to the liver, where it is converted to urea
o via the kidney, it will leave the body as urine
Urine production in the nephron - Step One :
Ultrafiltration
Ultrafiltration occurs in the …
glomerulus and the Bowman’s capsule
Step One : Ultrafiltration
o blood arrives at a high pressure in the glomerulus
o small molecules are squeezed through pores in the walls of the glomerulus and into the Bowman’s capsule
o large molecules and cells stay in blood (too large to fit through pores)
o result : filtrate contains small molecules
Urine production in nephron - Step Two :
Selective Reabsorption
Step Two occurs in the …
first coiled tubule
The first coiled tubule is also known as the …
proximal convoluted tube
Step Two : Selective Reabsorption
o useful molecules such as glucose, amino acids and salts are reabsorbed into the bloodstream by active transport
o some filtrate water moves back into the blood via osmosis
o urea stays in the filtrate
o result : filtrate containing urea
Where is blood water level adjusted by the kidneys?
o Some water is filtered into the nephron from blood
o In the PCT some water is reabsorbed into the blood
o In the Loop of Henle more water is reabsorbed into the blood
o In the collecting duct, water levels are finally adjusted and more water is reabsorbed into the blood
o Some water is excreted in urine
Water homeostasis : being thirsty
o ADH is secreted
o collecting duct becomes more permeable to water
o more water is reabsorbed into the bloodstream
o less urine is produced
Water homeostasis : when hydrated
o less ADH is secreted
o collecting duct is less permeable to water
o less water is reabsorbed into the bloodstream
o more urine is produced
