Week 1 - overview

Question 1

How can you identify the ureters on an x-ray?

Answer 1

-Runs down tips of transverse processes

Question 2

Describe the macroscopic structure of the kidney

Answer 2

• Parenchyma is the muscle and supporting tissue
• Cortex lays just inside the capsule
• Medulla is organised into pyramids

Question 3

Are the kidneys intraperitoneal or retroperitoneal?

Answer 3

-Retroperitoneal

Question 4

What % of TBW is water?

Answer 4

-60% (approx 40L)

Question 5

Describe the distribution of fluid within the body

Answer 5

• ICF = 25L

- ECF = 15L (divided into interstitial>plasma>lymph>transcellular)

Question 6

What is osmolality?

Answer 6

-Solute per Kg of solvent

Question 7

What is osmolarity?

Answer 7

• number of osmoles per litre

Question 8

What happens to the water in cells with high ECF osmolarity?

Answer 8

-Moves out of cells into ECF

Question 9

How much urine produced on average per day?

Answer 9

-1.5L

Question 10

What is the functional unit of the kidney?

Answer 10

-nephron

Question 11

Which part(s) of nephron in cortex and medulla?

Answer 11

• PCT and DCT in cortex

- Loop and CD in medulla

Question 12

How much water is recovered in normal balance?

Answer 12

-over 99%

Question 13

How much Na and Cl recovered in normal electrolyte balance?

Answer 13

-99%

Question 14

How much bicarb, a’a and glucose recovered in normal water and electrolyte balance?

Answer 14

-100%

Question 15

What determines GFR?

Answer 15

-The pressure in the afferent and efferent arterioles

Question 16

What is bulk transport?

Answer 16

-The mass movement of water which is reabsorbed in the PCT following Na reabsorption

Question 17

How much Na and H2O reabsorbed in PCT?

Answer 17

= approx. 67%

Question 18

Where is the major site of glucose reabsorption?

Answer 18

-PCT (100%)

Question 19

How come the filtrate remains isotonic in PCT even though Na removed?

Answer 19

-Water follows down concentration gradient

Question 20

Why are the epithelial cells of tubules polarised?

Answer 20

-Allows transport across epithelium

Question 21

Why are there tight gap junctions between tubule epithelia?

Answer 21

-The reduce fluidity and prevent channels and transporters moving to opposite sides

Question 22

What pump is present on the basolateral side of all tubule cells?

Answer 22

-NaKATPase

Question 23

Describe Na reabsorption in PCT

Answer 23

• NaKATPase pumps 3Na out and 2K in
• Creates Na gradient
• Na enters across apical membrane down its concentration gradient.

Question 24

How does Na movement in PCT drive movement of other ions and molecules?

Answer 24

-Energy from Na movement drives reabsorption of other substanced such as glucose and a’a via symporters

Question 25

What is the major function of loop of henle?

Answer 25

-Create gradient of increasing osmolarity in the medulla by counter current multiplication

Question 26

What is the major function of DCT?

Answer 26

• Fine tune and alter reabsorption of electrolytes and water

- Actively secretes H+ ions

Question 27

How is concentrated urine produced? (in brief)

Answer 27

• Hypotonic filtrate from DT enters collecting duct
• CD, under influence of ADH, is permeable to water and thus large volumes of water leaves as the CD passes through high osmolarity environment of medulla
• Hypertonic, concentrated urine produced

Question 28

By what mechanism is excess Na recovered after the PCT?

Answer 28

-RAAS in the DCT

Question 29

What controls the recovery of water in late DCT and CD?

Answer 29

-Anti-diuretic hormone