Physiology 4 - Reabsorption and Secretion

Question 1

The vast majority of reabsorption occurs at which point in the neprhon?

Answer 1

Proximal convoluted tubule

Question 2

What percentage of water and salt is reabsorbed by the kidneys?

Answer 2

99%

Question 3

Which two substances are normally 100% reabsorbed in the kidneys?

Answer 3

Glucose and amino acids

Question 4

What percentage of urea is reabsorbed in the kidneys?

Answer 4

50%

Question 5

What is the osmolarity of tubular fluid going into the proximal convoluted tubule?

Answer 5

300mosmol/l

Question 6

What is the osmolarity of tubular fluid coming out of the proximal convoluted tubule?

Answer 6

300mosmol/l

Question 7

Where are glucose and amino acids reabsorbed?

Answer 7

Proximal convoluted tubule

Question 8

Where is creatinine secreted into the nephron?

Answer 8

Proximal convoluted tubule

Question 9

Where are drugs to be excreted secreted into the nephron?

Answer 9

Proximal convoluted tubule

Question 10

Where are hydrogen ions secreted into the nephron?

Answer 10

Proximal and distal convoluted tubules

Question 11

Where are potassium ions secreted into the nephron?

Answer 11

Distal convoluted tubule

Question 12

‘Energy from the hydrolysis of ATP is used to move the substance against its concentration gradient’ describes which type of membrane transport?

Answer 12

Primary active transport

Question 13

‘The carrier molecule is transported coupled to the concentration gradient of an ion’ describes which type of membrane transport?

Answer 13

Secondary active transport

Question 14

‘Passive carrier mediated transport of a substance down its existing concentration gradient within the cell membrane’ describes which type of membrane transport?

Answer 14

Facilitated transport

Question 15

Under normal circumstances, in what direction is the sodium concentration gradient?

Answer 15

Inward

Question 16

Under normal circumstances, in what direction is the potassium concentration gradient?

Answer 16

Outward

Question 17

Sodium ions are reabsorbed in all regions of the nephron except where?

Answer 17

Descending limb of the loop of Henle

Question 18

The reabsorption of sodium is driven by the presence of the Na+/K+ pump at which membrane of the cell?

Answer 18

Basolateral

Question 19

What type of transporter is the Na+/K+ ATPase pump?

Answer 19

Primary active transporter

Question 20

Within the Na+/K+ ATPase, does sodium enter or exit the cell?

Answer 20

Exit

Question 21

Within the Na+/K+ ATPase, does potassium enter or exit the cell?

Answer 21

Enter

Question 22

Sodium is positively charged and so when it moves across a cell via the transcellular route in the proximal convoluted tubule it sets up an electrochemical gradient for the passive reabsorption of what via the paracellular route?

Answer 22

Chloride

Question 23

Via what route is water reabsorbed in the proximal convoluted tubule?

Answer 23

Paracellular

Question 24

Why is there no overall change in osmolarity at the beginning and end of the proximal convoluted tubule?

Answer 24

Water and salt are reabsorbed in equal concentrations

Question 25

When glucose is reabsorbed in the proximal convoluted tubule via the transcellular route, this sets up an osmotic gradient for the reabsorption of what via the paracellular route?

Answer 25

Water

Question 26

At what blood glucose level will the transport mechanisms in the proximal convoluted tubule become saturated?

Answer 26

10-12mmol/l

Question 27

2/3rds of water and salt are reabsorbed where in the nephron?

Answer 27

Proximal convoluted tubule

Question 28

Which segment of the loop of Henle is highly permeable to water?

Answer 28

Descending limb

Question 29

Which segment of the loop of Henle is relatively impermeable to water?

Answer 29

Ascending limb

Question 30

Salt (i.e. sodium and chloride) is reabsorbed in which segment of the loop of Henle?

Answer 30

Ascending limb

Question 31

Which segment of the loop of Henle does not reabsorb salt?

Answer 31

Descending limb

Question 32

Is salt reabsorption in the thin ascending loop of Henle active or passive?

Answer 32

Passive

Question 33

Is salt reabsorption in the thick ascending loop of Henle active or passive?

Answer 33

Active

Question 34

Where is the Na+/K+/Cl- triple co-transporter found?

Answer 34

Thick ascending loop of Henle

Question 35

On which membrane of the cell is the Na+/K+/Cl- triple co-transporter found?

Answer 35

Apical

Question 36

What drug group blocks the Na+/K+/Cl- triple co-transporter?

Answer 36

Loop diuretics

Question 37

What is the tonicity of tubular fluid compared to the interstitial fluid when it leaves the loop of Henle?

Answer 37

Hypotonic

Question 38

If a person is dehydrated, what happens to the levels of ADH?

Answer 38

Increased

Question 39

Describe the urine which is produced when a person is dehydrated?

Answer 39

Small volumes of concentrated urine

Question 40

If a person is over-hydrated, what happens to the levels of ADH?

Answer 40

Decreased

Question 41

Describe the urine which is produced when a person is over-hydrated?

Answer 41

Large volumes of dilute urine

Question 42

Hormones which affect reabsorption act on which parts of the nephron?

Answer 42

Distal convoluted tubule and collecting ducts