Glomerular Filtration

Question 1

3 main functions of the kidney

Answer 1

Filtration - the formation of an essentially protein-free filtrate
Reabsorption - Substances that the body wants are reabsorbed
Secretion - Substances may be specifically removed from the body in this way.

Question 2

What substances are reabsorbed

Answer 2

NaCl
Water
Amino Acids
Sugars

Question 3

What substances are excreted

Answer 3

Organic ions
Drugs
K+ and H+

Question 4

Where are NaCl, water, amino acids and sugars reabsorbed

Answer 4

The proximal tubule

Question 5

Where are NaCl and water reabsorbed only

Answer 5

The distal tubule

Question 6

Where are orgainc ions and drugs secreted

Answer 6

Proximal tubule

Question 7

Where are H+ and K+ secreted

Answer 7

The distal tubule

Question 8

What happens at the thin loop

Answer 8

Passive water and NaCl exchange

Question 9

Where does the blood go after the glomerulus

Answer 9

The efferent arterioles ->peritubular capillaries -> the renal vein

Question 10

How much of the total blood volume does plasma make up

Answer 10

~55%

Question 11

Normal Glomerular Filtration Rate (GFR)

Answer 11

125ml/min

Question 12

How much of the renal plasma becomes glomerular filtrate

Answer 12

~19%

Question 13

What two forces is Glomerular Filtration dependent on

Answer 13

balance between hydrostatic forces and oncotic pressure forces

Question 14

What force favours filtration and what force favours Reabsorption

Answer 14

Hydrostatic forces = Filtration

Oncotic pressure forces = Reabsorption

Question 15

What effects a particles ability to filtered

Answer 15

Size, shape and charge

Question 16

“Golden rule of circulation”

Answer 16

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

Question 17

Where are afferent and efferent arterioles in relation to the glomerulus ie before or after

Answer 17

Afferent = before 
Efferent = after

Question 18

What is the effect of increased afferent arterioles resistance

Answer 18

Decreased; Renal blood flow, capillary blood pressure and GFR

Increased blood flow to other organs

Question 19

What is the effect of increased resistance of efferent arterioles

Answer 19

Decreased RBF

Increased capillary blood pressure and GFR

Question 20

What is the effect of decreased afferent arteriole reistance

Answer 20

Increaed; RBF, capillary blood pressure and GFR

Question 21

What blood pressure is the glomeruli’s autoregulation effective over

Answer 21

60-130mmHg

Question 22

What happens when blood pressure reaches 50mmHg

Answer 22

No more filtration

Question 23

What’s the response to increased mean arterial pressure

Answer 23

Constriction of afferent arterioles

Question 24

What’s the response to decreased mean arterial pressure

Answer 24

Dilatation of afferent arterioles

Question 25

What blood vessels are responsible for Reabsorption

Answer 25

Peritubular capillaries

Question 26

Pressure in peritubular capillaries

Answer 26

~15mmHg

Question 27

What is different about the blood in the efferent arterioles and the peritubular capillaries compared to systemic circulation

Answer 27

It has a higher concentration of plasma proteins

Question 28

What is different about the blood in the efferent arterioles and the peritubular capillaries compared to systemic circulation

Answer 28

It has a higher concentration of plasma proteins (therefore a higher oncotic pressure?) Due to this difference Reabsorption is favoured

Question 29

How much water, Na+, glucose and urea are reabsorbed

Answer 29

Water = 99% 
Na+ = 99.55
Glucose = 100%
Urea = 50%
Mainly at the proximal convoluted tubule