Flashcards in F214:02:04 The Kidney Deck (34):
Where are the kidneys positioned?
each side of the spine, just below the lowest rib
From which vessels does the blood enter and leave the kidneys
From the renal artery and is drained by the renal vein
What is the role of the kidneys?
to remove waste products from the blood and produce urine.
Where does urine go once it has left the kidneys?
Down the ureter to the bladder where it is stored until it is ready to be releasedaaa
What can you see when you take a longitudinal section of the kidney?
- an outer region (cortex)
- an inner region (medulla)
- Central pelvis
Surrounded by a tough capsule
Where does the pelvis lead to?
What does the bulk of the kidneys consist of?
tiny tubules called nephrons
How many nephrons are there in a kidney?
around 1 million
What are nephrons closesly associated with?
tiny blood capillaries
Where does each nephron start?
In the cortex
What is a nephron?
a functional unit of the Kidney
It is a microscopic tubule that receives fluid from the blood capillaries in the cortex and converts this to urine, which drains into the ureter
What is the glomerulus?
a fine network of capillaries that increases the local blood pressure to squeeze fluid out of the blood.
It is surrounded by a cup / funnel shaped capsule which collects the fluid and leads into the nephron
Where is the glomerulus found?
In the cortex
What is the Bowmans capsule?
The cup shaped structure surrounding the glomerulus
What is ultrafiltration?
The process by which fluid from the blood is pushed into the Bowmans capsule
What are the four parts of the nephron which the capsule leads into?
- proximal convoluted tube
- distal convoluted tube
- loop of Henle
- collectinf duct
What happens as the fluid moves along the nephron?
Its composition is altered due to seletive absorption
What is the proximal tubule?
The part of the nephron closest to the glomerulus
What is the distal tubule?
The part of the neurone furthest from the glomerulus
What is the convoluted tube?
The part of the nephron that is bent and coiled
What happens to the substances in the nephron as it passes through the convoluted tube?
The useful substances are reabsorbed back into the tissue fluid and blood capillaries surrounding the nephron tubule.
What is the final product in the collecting duct, after the fluid has passed through the nephron?
How does urine leave the kidneys?
It is the final product left in the distal convoluted tube, which then passes to the collection duct, which passes down into the pelvis and down the ureter to the bladder
What is the afferent arteriole?
The arteriole leading blood to the glomerulus
What is the efferent arteriole?
The arteriole leading away from the glomerulus
How does the composition of fluid change in the proximal convoluted tube?
sugars, most salts and some water are reabsorbed
85% of fluid is reabsorbed
How does the composition of fluid change in the descending limb of the loop of Henle? (in terms of water potential)
The water potential of the fluid is decreased by the addition of salts and the removal of water
How does the composition of fluid change in the ascending limb of the loop of Henle? (in terms of water potential)
Water potential is increased as salts are removed by active transport
How does the composition of the fluid change in the collecting duct? (in terms of water potential)
Decreases by the removal of water
Why is water removed to lower the water potential in the collecting duct?
To ensure that urine has a low water potential, and to ensure that urine has a higher concentration of solutes than is found in the blood and tissue fluid
What is selective reabsorption?
Where useful substances are reabsorbed from the nephron into the blood stream which other excretory substances remain in the nephron
Suggest why the nephrons are convoluted
To increase the length for greater SA for absorption
Why are there many capillaries round each nephron?
So that materials reabsorbed from the fluid in the tubule can re-enter the blood