glomerular filtration

Question 1

what are the basic renal processes?

Answer 1

Filtration: the formation at the glomerular capillaries of an essentially protein-free filtrate of plasma, (~20%)

Reabsorption: Substances that the body wants are reabsorbed, those it doesn’t want stay in the tubule and are excreted

Secretion: Substances may be specifically removed from the body in this way.

Question 2

what is the glomerular filtration rate?

Answer 2

very high = 180 l/day

Question 3

what significance does having a high glomerular filtration rate have?

Answer 3

This means that the kidney has ample opportunity to precisely regulate ECF volume and composition and eliminate “nasty” substances.

Question 4

how much blood flow do the kidneys receive?

Answer 4

1200mls/min, ie 20-25% of total cardiac output.

Question 5

true or false:

None of the red cells and only a fraction of the plasma is filtered through into Bowman’s capsule

Answer 5

true

Question 6

what is therenal plasma flow?

Answer 6

55% of total BV

Question 7

what does the glomerular filtration dependent on?

Answer 7

the balance between the hydrostatic forces favouring filtration and the oncotic pressure forces favouring reabsorption. (Starling’s forces).

Question 8

why is glomerular capillary pressure higher than in most of the capillaries in the body?

Answer 8

because the afferent arteriole is short and wide and offers little resistance to flow. So the blood arriving at the glomerulus still has a high hydrostatic pressure.

Question 9

what is the golden rule of the circulation?

Answer 9

If you have a high resistance, hydrostatic pressure upstream is increased, while the pressure downstream is decreased