Formation of filtrate Flashcards

1
Q

What is the ultrafiltrate?

A

Blood filtered as it enters from glomerulus into the Bowman’s capsule

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2
Q

What is the diameter of the glomerular capillaries?

A

200 micrometers

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3
Q

What is the length of the glomerular capillaries?

A

19 km in total

1 nephron = 1 cm

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4
Q

What is the surface ares of the capillaries?

A

1 metre squared

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5
Q

What is the histology of the filtration barrier on the side of the glomerulus?

A

Endothelial cells contain endothelial pores

Allow small molecules to move across the filtration barrier

Fenestrae can be plugged with glycocalyx

Glycocalyx is attached to the basal lamina

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6
Q

What is the role of the glycocalyx?

A

Prevent macromolecules from entering Bowman’s capsule

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7
Q

What is glycocalyx made of?

A

Glycoprotein - polysaccharide covering

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8
Q

What is the basal lamina made up of?

A

Negatively charged glycoprotein sheets

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9
Q

What is the histology of the filtration barrier on the side of the Bowman’s space?

A

Glomerular capillary is surrounded by podocytes

Between the podocytes is a diaphragm made by the protein nephrin

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10
Q

How do the podocytes surround the glomerular capillaries?

A

Podocytes are made up of arm-like structures called primary processes

The primary processes -> secondary processes -> finger-like projections that extend over all capillaried to form a sheet

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11
Q

What is the diaphragm of podocytes made up of?

A

The protein nephrin

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12
Q

What disease is caused by a mutation in the protein nephrin?

A

Congenital nephrotic syndrome

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13
Q

How wide is the diaphragm of the podocytes?

A

4 nm

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14
Q

Which factors determine glomerular filterability of molecules?

A

Electrical charge

Molecular weight

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15
Q

How does electrical charge determine filterability of a molecule?

A

Filtration membrane is made up of negatively charged glycoproteins

Repels negatively charged solutes

Attract positively charged solutes

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16
Q

How does molecular weight determine filterability of a molecule?

A

Small molecules are freely filtered

As molecules increase in size - filtration ratio decreases

17
Q

What is the equation for net ultrafiltration pressure?

A

Net ultrafiltration pressure = net hydrostatic pressure - net oncotic pressure

18
Q

What creates net hydrostatic pressure in the capillaries?

A

Heart

19
Q

What creates net oncotic pressure in the capillaries?

A

Proteins

20
Q

What is the equation for net hydrostatic pressure?

A

Glomerular hydrostatic pressure - Bowmans space hyrdrostatic pressure

21
Q

What happens to the net hydrostatic pressure as you go from the afferent to the efferent arterioles?

A

Net hydrostatic pressure = net oncotic pressure

22
Q

What does net hydrostatic pressure do?

A

Drives filtration of salt, water and other components from the glomerulus to the Bowman’s space

23
Q

What happens when net hydrostatic pressure = net oncotic pressure?

A

No filtration happens

24
Q

What can alter the rate of glomerular filtration?

A

Change in any pressure can alter ultrafiltrate pressure

Decrease in hydrostatic pressure following haemorrhage

Increase in hydrostatic pressure following kidney stone

Increase in oncotic pressure folowing dehydration