The kidneys Flashcards
How does blood enter the kidneys?
Through the renal artery
What is ultrafiltration?
The filtering of substances out of the blood when the blood passes through the capillaries in the cortex
What substances are reabsorbed into the blood?
Useful substances
Glucose and the right amount of water
What is selective reabsorption?
The reabsorption of useful substances
After selective reabsorption, where do the unwanted substances go to?
They pass through the bladder and are excreted as urine
What are nephrons?
Long tubules alone with the bundles of capillaries where the blood is filtered
Roughly how many nephrons are there in each kidney?
One million
What do the smaller arterioles which go into the cortex of the kidney split into?
Glomerulus
What are Glomerulus?
A bundle of capillaries looped inside a hollow ball called a Bowman’s capsule
Where does ultrafiltration take place?
In the Bowman’s capsule
What is the arteriole that takes blood into each glomerulus called?
Afferent arteriole
What is the arteriole that takes filtered blood away from each glomerulus?
Efferent arteriole
Which arteriole is smaller in diameter? What is the effect of this?
Efferent arteriole
The blood in the glomerulus is under high pressure
What is the effect of the high pressure?
Forces liquid and small molecules in the blood out of the capillary and into the Bowman’s capsule
What three layers does the liquid and the small molecules pass through to get into the bowman’s capsule and the nephron tubules?
the capillary endothelium
a membrane
the epithelium of the Bowman’s capsule
What molecules cant pass through the three layers?
Large molecules such as proteins and blood cells
What is the glomerular filtrate?
The substances that enter the Bowman’s capsule
Where does selective reabsorption take place?
As the glomerular filtrate flows along the proximal convoluted tubule (PCT), through the loop of Henle and along the distal convoluted tubule
Where do useful substances that leave the nephrons go?
Into the capillary network wrapped around them
What does the epithelium of the wall of the PCT have?
Microvilli to increase the surface area for the reabsorption of useful materials from the glomerular filtrate into the blood
How are useful substances reabsorbed?
Through active transport and facilitated diffusion
How does water enter the blood? How does this happen?
Osmosis
The water potential of the blood is lower than that of the filtrate
Where is water reabsorbed?
PCT
loop of Henle
DCT
Collecting duct
What is urine usually made up of?
Water Dissolved salts Urea Hormones Excess vitamins
