L22 - Renal Function 1: Excretion

Question 1

Is K, PO4, urea and creatinine more concentrated in the urine or the plasma?

Answer 1

more concentrated in the urine

Question 2

Is HCO3, glucose and albumin more concentrated in the urine or the plasma?

Answer 2

more concentrated in the plasma

Question 3

Why is glucose and HCO3 not found in the urine?

Answer 3

completely reabsorbed by the kidney

Question 4

Why is albumin not found in the urine?

Answer 4

the molecule is too large to be filtered into the urine

Question 5

How many nephrons are in each kidney?

Answer 5

approximately one million

Question 6

Where does filtration occur in the kidney?

Answer 6

at the glomerulus where blood flows in and out

Question 7

Which structures are found in the nephron in order?

Answer 7

glomerulus, proximal convoluted tubule, descending limb, loop of Henle, thick ascending limb, distal convoluted tubule, connecting tubule, collecting duct

Question 8

Why must the glomerulus be positioned right next to the thick ascending limb?

Answer 8

enables cells of the glomerulus to sample from the thick ascending limb and determine if there is adequate urine filtration / reabsorption

Question 9

What is Bowman’s capsule?

Answer 9

space where filtrate comes out from the capillaries i.e. where filtration occurs

Question 10

How is the amount of solute excreted?

Answer 10

amount filtered - amount reabsorbed + amount secreted = amount of solute excreted

Question 11

Where does reabsorption and secretion occur?

Answer 11

between the peritubular capillaries and the nephron

Question 12

Where does filtration occur?

Answer 12

between the glomerulus and the rest of the nephron

Question 13

Which substances are filtered and reabsorbed in the body?

Answer 13

water, sodium, potassium, calcium, phosphate, glucose and urea

Question 14

Which substance is only filtered into urine and not reabsorbed?

Answer 14

creatinine

Question 15

Which substance is secreted into the nephron?

Answer 15

potassium

Question 16

What are podocytes and what is their role?

Answer 16

foot processes which surround each capillary in the glomerulus and leave slits through which filtration can take place

Question 17

What is the role of mesangial cells?

Answer 17

provide structure to the capillaries so that they are suspended in the glomerulus

Question 18

Why are podocytes important?

Answer 18

provides a size barrier of what can be filtered and what can’t

Question 19

What are the steps behind glomerular filtration?

Answer 19

1. plasma volume enters afferent arteriole = 100%
2. 20% of volume filters in the glomerulus
3. 19% of fluid is reabsorbed by the efferent arteriole
4. > 99% of plasma entering kidney returns to systemic circulation
5. <1% of volume is excreted to external environment

Question 20

What is oncotic pressure in Bowman’s capsule?

Answer 20

zero, if it was greater than zero, this means albumin is present in Bowman’s capsule resulting in oncotic pressure drawing fluids inward

Question 21

What is the glomerular filtration rate?

Answer 21

volume of plasma filtered through the glomerulus per unit time

Question 22

What is the most important force that affects glomerular filtration rate?

Answer 22

hydrostatic pressure in the glomerulus