Kidneys

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Slide 1

Kidney in Detail

Standard Grade Biology

Slide 2

Excretion by the Kidney

Urea

-nitrogenous waste

-made by liver

-excess amino acids in blood

-toxic

Why must nitrogenous waste be excreted?

Slide 3

1 – Filtration by the Kidney

Renal artery

Ureter

Renal vein

Supplied with blood from renal artery

Inside it splits into many fine capillaries

Each capillary supplies blood to hundreds of thousands of tiny filtration units called nephrons

Lets have a look at a nephron!!!

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Slide 6

Glomerulus brings a large surface area of blood capillaries in close contact with Bowman’s capsule

2. Liquid filtered from blood under pressure (filtration)

Glomerular filtrate produced containing:

-water

-glucose

-salts

-urea

(Protein molecules and red blood

cells do not pass into tubule as

they are TOO BIG!!!!)

Blood from renal artery enters wide capillary

Blood travels through narrow capillary towards renal vein

Glomerular filtrate

Filtration

Slide 7

Think…

Which feature of the glomerulus helps the process of filtration?

Which 4 components of unfiltered blood appear in the glomerular filtrate?

Why do blood cells and protein molecules not appear in the glomerular filtrate?

Slide 8

Key Words!!

Nephron: structure in the kidney that acts as a microscopic filtration unit

Glomerulus: dense mass of very fine blood capillaries at the nephron that act as a filter

Bowman’s capusle: cup-shaped part of the nephron that holds a glomerulus and collects the products of filtration from it

Glomerular filtrate: liquid removed from the blood by filtration in the kidney

Slide 9

2 – Reabsorption by the Kidney

Once the main components of glomerulur filtrate enter the bloodstream

-they are no longer in bloodstream

If nothing more happened in the nephron then all the useful stuff would be lost in the urine!

Therefore, glucose, water and some salts need to be reabsorbed!

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