Lecture 37: Renal Systems 2

Question 1

What does the final composition of urine excreted from the body depend on?

Answer 1

1. What is FILTERED into the nephrons from the blood
2. What is SECRETED into the nephrons via the blood
3. What is REABSORBED from the nephron into the blood

Question 2

Where are substances filtered in the kidney?

Answer 2

Renal corpuscle (glomerulus) excep for substances bound to protein
- Many substances are filtered at a constant rate

Question 3

What substances need to be partly reabsorbed?

Answer 3

Na+, K+

Question 3

What substances need to be entirely reabsorbed?

Answer 3

Glucose

Question 3

What substances need to be entirely secreted?

Answer 3

PAH - drugs

Question 4

How does blood enter and exit the glomerulus?

Answer 4

Blood flows into the glomerulus through the afferent arterioles and leaves the glomerulus through the efferent arterioles

Question 5

What structure exits the bowman’s capsule?

Answer 5

Proximal tubule

Question 6

Which ions/substances move from blood into the nephron?

Answer 6

• Small substances (low molecular mass) are freely filtered into the nephron
• Large substances (high molecular mass) are not filtered and stay in the blood

Question 7

What are the filtration driving forces?

Answer 7

1. Blood pressure (PGC) drives filtration
2. Osmotic pressure in glomerular capillary (πGC) opposes filtration
3. Fluid pressure in Bowman capsule (PBS) opposes filtration

Question 8

What is the tonicity of primary urine?

Answer 8

Isotonic

Question 9

What are the properties of a substance that determines the filtration rate?

Answer 9

• Freely filtered
• NOT reabsorbed
• NOT secreted
• NOT metabolised
• NOT toxic

Question 9

What would indicate that the filtration barrier is damaged?

Answer 9

Blood cells or protein in the urine

Question 10

What 2 substances can be used to determine filtration rate?

Answer 10

1. Insulin (exogenous)
2. Creatinine (endogenous metabolite)