The kidneys Flashcards
What are the functions of the kidneys?
Excrete waste products
Regulate water potential of blood
Explain the process of ultrafiltration
As blood passes through the capillaries in the cortex of the kidneys, substances are filtered out of the blood and into long tubules that surround the capillaries
Explain the process of selective reabsorption?
Useful substances are reabsorbed back into the blood
Where do the unwanted substances go?
They pass along to the bladder and are excreted as urine
Where does blood from the renal artery enter?
It enters smaller arterioles in the cortex of the kidney
What does each arteriole split into?
Glomerulus
What is a glomerulus?
A bundle of capillaries looped inside a hollow ball called a Bowman’s capsule
Where does ultrafiltration take place?
Glomerulus
What is the afferent arteriole?
The arterioles that takes blood into each glomerulus
What is the efferent arteriole?
The arteriole that takes the filtered blood away from each glomerulus
Which arteriole has the smaller dimeter?
Efferent arteriole
Is the blood in the glomerulus under low or high pressure?
High pressure
What does the high pressure result in?
Forces liquid and small molecules in the blood out of the capillaries and into the Bowman’s capsule
What 3 layers does the liquid and small molecules pass through to get into the Bowman’s capsule and enter the nephron tubules?
Capillary wall
Membrane
Epithelium of Bowman’s capsule
What is the glomerular filtrate?
The molecules that enter the Bowman’s capsule
What happens to larger molecules like proteins and plasma?
Remain in the blood
What happens to the glomerular filtrate?
It passes along the rest of the nephron and useful substances are reabsorbed along the way
Where does the filtrate flow through before passing out of the kidney?
Collecting duct
What are nephrons?
The long tubules along the bundle capillaries where the blood is filtered
When does selective reabsorption take place?
Takes place as the glomerular filtrate flows along the proximal convoluted tubule (PCT), through the loop of Henle and along the distal convoluted tubule (DCT).
Where do the useful substances leave and enter?
Leave: tubules of nephron
Enter: capillary network
What do the microvilli in the epithelium of the wall of the proximal convoluted tubule do?
Provide a large surface area for the reabsorption of useful materials from the glomerular filtrate into the blood
How are useful solutes reabsorbed along the proximal convoluted tubule?
By active transport and facilitated diffusion
Where is water reabsorbed?
PCT
Loop of Henle
DCT
Collecting duct
What is urine usually made up of?
Water
Dissolved salts
Urea
Hormones
Excess nutrients
What isn’t usually found in urea?
Proteins
Blood cells
Glucose
