Renal 3

Question 1

How much fluid is excreted in the body

Answer 1

180L/day is filtered and less than 1% is actually excreted, Most of it reabsorbed

Question 2

Purpose of Reabsorbtion

Answer 2

It allows kidneys to selectively regulate ions and water to the plasma to maintain homeostasis

Question 3

Why do you filter 180L if only 1% is eliminated

Answer 3

Because many foreign substances filtered into tubules but not reabsorbed
Frequent filteration of ions and water into the tubules simplifies regulation and allows it to occur rapidly

Question 4

Is reabsorbtion active or passive

Answer 4

Both

Question 5

Steps of fluid reabsorbtion

Answer 5

Na + is reabsorbed by active transport
Anions follow due to the positive in ECF
Electrochemical gradient drives anion reabsorbtion
Water moves by osmosis, following solute reabsorbtion. Concentrations of other solutes increase as fluid volume in lumen decreases
Permeable solute are reabsorbed by diffusion through membrane transporters or by the paracellular pathway

Question 6

Transepithelial Transport

Answer 6

Substances cross the apical and basolateral membrane of the tubule cells to enter the ECF

Question 7

Paracellular Transport

Answer 7

Substances pass through the cell to cell junctions between 2 adjacent tubule cells

Question 8

2 types of Active Transport Na+

Answer 8

1. Basolateral Na+ Active Transport
2. Secondary Active Transport: Symport with Na+

Question 9

Basolateral Na+ Transport

Answer 9

1. Moves through various membrane proteins and moves down its electrochemical gradient (Apical Side)
2. Na + is pumped out the basolateral side of cell by the Na+ K+ ATPase

Question 10

Secondary Active Transport: Symport with Na+

Answer 10

1. Na+ moving down its concentration gradient
2. Glucose diffuses out the basolateral side of the cell using the GLUT protein
3. Na+ is pumped out by Na K+ ATPase

Question 11

Passive Absorbtion

Answer 11

urea (Nitrogenous waste product)
Due to the movement of sodium into the ECF, the concentration of Urea in the filtrate goes up. Which creates a contration gradient for urea to move into the ECF

Question 12

Endocytosis

Answer 12

very small plasma proteins or peptides using megalin

Question 13

Example of Endocytosis in reabsorbtion

Answer 13

Receptor mediated endocytosis
Receptor binding plasma proteins known as megalin
- Once the cell the proteins are digested by lysomes

Question 14

How are majority of the substances transported in the nephron

Answer 14

They use membrane proteins

Question 15

Saturation

Answer 15

The maximum rate of transport that occurs when all available carriers are occupied
In an average individual you never reach saturation

Question 16

How does saturation effect in filteration

Answer 16

Amount of glucose filtered depends on the plasma glucose

Question 17

How does saturation effect in reabsorbtion

Answer 17

• The transport rate at saturation is the transport maximum
• Excess glucose filteres = more glucose than transporters and some glucose is excerted (diabetes)

Question 18

Renal threshold

Answer 18

When solute starts to show up in urine
Occurs at transport maximum

Question 19

When does renal threshold occur

Answer 19

occurs at Transport maximum

Question 20

Amount Exerted

Answer 20

Amount filtered - amount reabsorbed + amount secreted

Question 21

Glucose excreted

Answer 21

Glucose filtered - glucose absorbed

Question 22

Glycosuria

Answer 22

• Glucose appearing in urine
• Occurs with elevated blood glucose
• Rare genetic disorder with reduced transporters

Question 23

Which pressures favor reabsorbtion

Answer 23

Peritubular capillary pressures

Question 24

What drives reabsorbtion

Answer 24

Sodium in the proximal tubule

Question 25

Pathway of reabsorbtion

Answer 25

Proximal Tubule lumen - Epithelial cells of nephron - Extracellular fluid

Question 26

Apical membrane

Answer 26

Faces the lumen of nephron

Question 27

Basolateral membrane

Answer 27

Faces the extracellular fluid

Question 28

Filtrate and plasma both

Answer 28

Are isosmotic Same solute concentration No concentration gradient

Question 29

Where does active transport of sodium occur

Answer 29

At the Basolateral membrane using Sodium pottasium ATPase

Question 30

ENac

Answer 30

Sodium transporters through just a simple concentration gradient (Fascilitated diffusion)

Question 31

Glucose is low

Answer 31

In ECF and filterate

Question 32

Where does secondary active sodium transport occur

Answer 32

Through symport using SGLT protein

Question 33

Concentration of urea in ECF and filterate is

Answer 33

Equal

Question 34

What kind of transport does urea use

Answer 34

Paracellular Transport

Question 35

Majority of reabsorbtion happens due to the finite amount of

Answer 35

membrane proteins

Question 36

The amount of glucose filtered depends on the

Answer 36

Plasma Concentration

Question 37

As plasma glucose concentration goes up

Answer 37

Reabsorbtion goesup and Glucose transport into ECF goes up

Question 38

Transport maximum

Answer 38

When saturation reached

Question 39

More glucose than trasnporters

Answer 39

Lose glucose in urine (Diabetes)

Question 40

hydrostatic pressure at peritubular cappilaries

Answer 40

10mmHg and its low

Question 41

Second part of reabsorbtion

Answer 41

Peritibular pressure in 10 lower then oncotic pressure of 30 This creates a gradient for blood to travel into the peritubular capillaries

Question 42

net pressure at peritubular pressure

Answer 42

20mmHg

Question 43

Secretion

Answer 43

Transfer of molecules from ECF into the lumen of the nephron

Question 44

Secretion depends on

Answer 44

Membrane transport proteins

Question 45

What kind of transportation process does secretion use

Answer 45

Only Active process

Question 46

Why does secretion occur

Answer 46

Homeostatic regulation of K+ and H+ (Distal) Organic compoind removal

Question 47

Amount Excreted =

Answer 47

Amount filtered - amount reabsorbed + amount secreted

Question 48

Where does secretion occur

Answer 48

Proximal Tubule

Question 49

Primary active transport during secretion

Answer 49

Happens at basolateral membrane to keep intracellular Na concentration low

Question 50

Secondary Indirect Active Transport during secretion

Answer 50

Happens at apical membrane and basolateral membrane. Uses NaDC cotransporter

Question 51

teritary active transport

Answer 51

Happens both at apical and basolateral membrane (OAT 1-3)

Question 52

Excretion

Answer 52

Tells us what the body is eliminating