Unit 5 Lecture 36

Question 1

What % of solutes and water was reabsorbed into blood by the end of the DCT

Answer 1

90-95%

Question 2

What are the 2 cells found in the collecting ducts?

Answer 2

principal cells and intercalated cells

Question 3

Function of principal cells

Answer 3

• reabsorb Na+ and water

- secrete K+

Question 4

What hormones effect the functions of principal cells and what do they individually control?

Answer 4

aldosterone - effects Na+ and K+

ADH - effects water

Question 5

Function of intercalated discs

Answer 5

• reabsorb K+ and bicarbonate ions

- secrete H+

Question 6

What direction does Na+ move across a membrane?

Answer 6

Filtrate –> blood

Question 7

What does Na+ first pass through to get into a principal cell?

Answer 7

leakage channels

Question 8

What does Na+ pass through to leave principal cells into ISF?

Answer 8

Na+/K+ pumps

Question 9

What direction does K+ move across a membrane?

Answer 9

ISF –> filtrate

Question 10

What two things must K+ pass through (in order) to get into filtrate?

Answer 10

1. Na+/K+ pump
2. K+ leakage channel

(opposite of Na+)

Question 11

What does aldosterone do to principal cells and how??

Answer 11

Increases Na+/ water reabsorption and K+ secretionby adding new pumps and channels into membrane

Question 12

What does ADH do to principal cells and how?

Answer 12

Inceases water reabsorption by inserting aquaporins into apical membrane

Question 13

Function of intercalated cells in the collecting duct?

Answer 13

regulates pH of body fluids by secretion of H+ and reabsorption of HCO3-

Question 14

What is needed in intercalated discs to secrete H+ and reabsorb HCO3- and what does it make?

Answer 14

CO2 and water

*they bond together to make carbonic anhydrase –> carbonic acid which then dissociates into H+ and HCO3-

Question 15

What direction does H+ move from intercalated cells?

Answer 15

intercalated cells –> filtrate

Question 16

How does H+ pass through the membrane into filtrate?

Answer 16

proton pumps (ATPases)

Question 17

Is urine acidic or basic?

Answer 17

ACIDIC

Question 18

How are acidic H+ buffered once it gets into filtrate?

Answer 18

bonds with either (HPO4)2- or NH3

Question 19

What does CO2 and water make when bonded together in intercalated cells?

Answer 19

carbonic anhydrase –> carbonic acid

Question 20

What direction does bicarbonate (HCO3-) move across intercalated cells?

Answer 20

Intercalated cell –> peritubular capillary

Question 21

What must bicarbonate travel through to get to blood?

Answer 21

Cl-/HCO3- antiporters

Question 22

What direction does Cl- move across Cl-/HCO3- antiporters?

Answer 22

ISF –> intercalated cells

Question 23

What happens to pH when HCO3- enters blood?

Answer 23

pH rises

Question 24

What do intercalated cells do when blood pH drops (gets more acidic)?

Answer 24

1. forms more carbonic acid
2. secretes more H+ into filtrate
3. exchanges more Cl- for HCO3-
4. More HCO3- enters blood, raising blood pH

Question 25

Why is it important that intercalated cells control blood pH?

Answer 25

Although they are slow at changing blood pH vs. respiratory system, they are they only system that can counter act the acidity of nonvolatile acids like sulfuric acid by excreteing H+ in urine

Question 26

Define diuretics

Answer 26

substances that slow the reabsorption of water in blood --> greater urine flow rate

Question 27

What are 3 examples of diretics?

Answer 27

Caffeine, Alcohol, meds

Question 28

What does caffeine do urine production?

Answer 28

Inhibits Na+ reabsorption

Question 29

What type of water reabsorption process is inhibited due to caffeine?

Answer 29

obligatory water reabsorption

Question 30

What does alcohol do to urine production?

Answer 30

Inhibits secretion of ADH

Question 31

What type of water reabsorption process is inhibited due to alcohol?

Answer 31

facultative water reabsorption

Question 32

What does some prescription meds do to urine production?

Answer 32

effects the PCT, loop of Henle or DCT

Question 33

Define micturition

Answer 33

urination

Question 34

What type of fibers cause detrusor muscles in the urinary bladder to contract and initiate micturition?

Answer 34

parasympathetic fibers

Question 35

What must the internal and external sphincters do for micturition?

Answer 35

relax

Question 36

What type of control do we have over the internal and external sphincters?

Answer 36

internal - involuntary (smooth muscle) external - voluntary (skeletal muscle)

Question 37

What brain structure can initiate or delay micturition for a period of time?

Answer 37

Cerebral cortex