Tubular reabsorption and acid base balance basics

Question 1

What is responsible for reabsorption and secretion in the nephron tubules

Answer 1

proteins positioned in the cell membranes in the nephron

Question 2

Why are the proteins in the cell membranes of the nephron important

Answer 2

-they are important sites for Rx targets

Question 3

How are small proteins that made it past glomerular filtration reabsorbed

Answer 3

typically via pinocytosis

Question 4

What are the 2 ways reabsorption can occur

Answer 4

1. Paracellular =passive, between adjacent tubule cells thought to account for 50% of reabsorption
2. Transcellular= passive and active, travels through tubule cell

Question 5

What is meant by obligatory water reabsorption

Answer 5

water follows solutes almost always, this is how most water is reabsorbed in the PCT and descending LOH

Question 6

Why does Glucosuria occur

Answer 6

Serum glucose is >200 mg/dL, renal symporters cannot work fast enough to reabsorb all the glucose so it is excreted in the urine

Question 7

What substances are secreted into the tubules

Answer 7

1. H ions
2. K ions
3. NH4
4. Creatinine
5. Certain drugs like Penicillin, elict drugs, anabolic steriods, EPO

Question 8

True or false the wall of the glomerular capsule, renal tubule and renal ducts are a single layer of epithelial cells

Answer 8

True

Question 9

What cell type compose the PCT

Answer 9

simple cuboidal epithelial cells with microvilli

Question 10

What are the microvilli in the PCT used for

Answer 10

increasing surface area for reabsorption and secretion

Question 11

What cell type compose the thin (descending and ascending) LOH

Answer 11

simple squamous epithelial cells

Question 12

What cell type compose the thick ascending LOH

Answer 12

simple cuboidal to low columnar cells

Question 13

What cell type compose the DCT

Answer 13

simple cuboidal cells

Question 14

What over cell types does the last part of the DCT have when compared to the rest of the DCT

Answer 14

All DCT is simple cuboidal but the last part contains:

1. Principle cells=have ADH and aldosterone receptors
2. Intercalated cells= play a role in blood pH

Question 15

What is the pH range of blood and ECF

Answer 15

7.35 to 7.45

Question 16

What kind of acidosis or alkalosis is caused by too little or too much bicrab (HCO3)

Answer 16

metabolic

Question 17

What kind of acidosis or alkalosis is caused by too little or too much partial pressure of carbon dioxide (pCO2)

Answer 17

respiratory

Question 18

What is the body’s first line system against acid-base abnormalities

Answer 18

extracellular (HCO3) and intracellular (pCO2) buffer systems

Question 19

Describe the extracellular buffer system

Answer 19

carbonic acid is dissociated to bicarb and H

Question 20

Describe the intracellular buffer system

Answer 20

CO2 is moved into the cell and combines with water to make carbonic acid which then dissociates to bicarb in the extracellular space

Question 21

What is the body’s second line system against acid-base abnormalities how does it react in an acidotic and alkalotic state

Answer 21

The respiratory system

• Acidosis=when pCO2 is high pH is low the body breathes off more pCO2 is low by increasing respiratory rate
• Alkalosis=when pCOs is low pH is high respiratory rate decreases

Question 22

What is the body’s third line system against acid-base abnormalities and how does it react in an acidotic and alkalotic state

Answer 22

The renal system, because it takes longer to compensate compared to the other 2 systems

• Acidosis= decreased HCO3 , more H is secreted into tubules
• Alkalosis=increased HCO3, less H is secreted into the tubules

Question 23

Remember ROME

Answer 23

respiratory opposites and metabolic equivalents