Physiology 1

Question 1

How many nephrons does each kidney have?

Answer 1

1 million

Question 2

When do nephron number start reducing?

Answer 2

30

Question 3

Consequences of high potassium?

Answer 3

V Fib (and death)

Question 4

Consequences of low potassium?

Answer 4

Weakness and malaise

Question 5

What does the kidney seek to regulate ahead of all else?

Answer 5

Water and Sodium

Question 6

Two hormones secreted from the kidney?

Answer 6

Renin

Erythropoitin

Question 7

What vitamin is secreted from the kidney?

What is its role?

Answer 7

Vit D3

Calcium re-absorption from the gut

Question 8

What prostaglandin is secreted by the kidnye?

Answer 8

PGI2 (prostacyclin)

- This lowers blood pressure it is a vasodilator

Question 9

What is the filtration unit of the kidney called?

Answer 9

The glomerulus

Question 10

Where is the initial filtrate from the kidney formed?

Answer 10

Bowman’s capsule

Question 11

What are the size of the holes in the capillaries in Bowman’s capsule?

Answer 11

2nm slits

Question 12

What prevents some molecules from moving through the capillaries in a healthy kidney?

Answer 12

Negative charge on the filtration slits which repels negatively charged ions.
This also allows some bigger positively charged proteins to get into the filtrate

Question 13

What is the most important negatively charged protein which is not filtered by the kidney?

Answer 13

Albumin

Question 14

What is the GFR per day and minute?

Answer 14

180L/day
125mls/min
= 60nL/min (per nephron)

Question 15

What is a feature of the proximal tubule?

Answer 15

It is convoluted (to give it extra length)

Question 16

What is the order of the segments of the kidney?

Answer 16

1. Bowman’s capsule
2. Proximal Tubule – pars recta and PCT (convoluted tubule)
3. Thin descending limb of Henle’s Loop – tDLH
4. Thin ascending limb of Henle’s Loop – tALH this is very short in superficial cortical nephrons It is long in JM nephrons
5. Thick Ascending limb – TAL
6. Distal Tubule –DT
7. Collecting Duct – CD

Question 17

What percentage of kidneys have a loop of Henle which delves into the medulla?

Answer 17

85% only delve to a shallow degree (short loops of henle)

15% have long nephrons which go down to the very tip of the medulla (the papilla)

Question 18

What happens are the junction between the ascending limb of the loop of Henle and the distal tubule?

Answer 18

Makes contact with its home glomerulus

It occurs in the crevice between the afferent and efferent arterioles

Question 19

What is the contact point between the between the ascending limb of the loop of Henle and the distal tubule as well as the glomerulus called?

Answer 19

Macula densa

Question 20

What is a feature of the distal tubule?

Answer 20

It is convoluted (gives it extra length)

Question 21

Where do the distal tubules end up?

Answer 21

The collecting ducts.

Several distal tubules generally form one collecting duct

Question 22

How much of the water and NaCl is absorbed by the proximal tubule?

Answer 22

65%

And majority of solutes

Question 23

Which section of the kidney is responsible for absorption of glucose, amino acids and metabolic intermediates (eg lactic acid)?

Answer 23

The proximal tubule (will absorb 100% of them)

Question 24

What is the role of the thin loops of Henle?

Answer 24

It concentrates the filtrate (4x the concentration of plasma)

Question 25

What does the thick ascending loop of Henle do?

Answer 25

It is the dilutor (gets down to pretty low osmolarity)

Question 26

What is the macular densa a part of?

Answer 26

The juxtaglomerular apparatus

Question 27

What is the role of the distal tubule?

Answer 27

It is the fine tuner - it reacts to specific needs and carries out alterations in the concentration of urine according to need. This also occurs through the collecting ducts

Question 28

What is the role of the collecting duct?

Answer 28

It is an aldosterone -dependant equilibrator

Question 29

What happens to the concentration of urine in the collecting duct?

Answer 29

If the permeability to water is high it will become concentrated. If the permeability to water is low it will stay dilute

Question 30

What dictates if the permeability to water in the collecting duct is high or low?

Answer 30

Aldosterone - They determine how many aquaporin channels are present

Question 31

How does water move from the collecting duct into the interstitium?

Answer 31

It is not by bulk flow as one might expect but rather by aquaporin channels which allow the movement of single molecules

Question 32

What are the two types of nephrons called?

Answer 32

Superficial Cortical Glomeruli | Juxtamedullary Glomeruli

Question 33

What are Superficial Cortical Glomeruli?

Answer 33

They are nephrons located close to the surface of the kidney and have short loops

Question 34

What are Juxtamedullary Glomeruli?

Answer 34

These are nephrons with long loops and are located close to the cortico-medullary junction though still in the cortex

Question 35

Which of the nephrons are responsible for forming the high concentrations?

Answer 35

Those that delve deepest into the papilla (JM)

Question 36

What are the vasa recta?

Answer 36

These are the capillaries which surround the nephron and absorb anything which leaves the nephron and goes into the interstitium

Question 37

What is the order of blood supply to the nephron?

Answer 37

Afferent arteriole Capillaries Reform into a Efferent arteriole Peritubular capillaries which surround the nephron at every point

Question 38

What is the only part of the nephron where there is no reabsorption?

Answer 38

Thin ascending limb of Henle

Question 39

How much urine is produced per day?

Answer 39

1-2 Litres (178-179 litres reabsorbed each day by the kidney)

Question 40

Aside from filtration how else can substances gain access to the lumen?

Answer 40

Secretion

Question 41

How does secretion occur?

Answer 41

It is an active process

Question 42

Where does secretion occur?

Answer 42

In the proximal tubule In the distal tubule In the collecting duct

Question 43

Secretion is an active process, which part of the kidneys are expending the energy?

Answer 43

Movement into the interstitium is passive (capillaries are very permeable). The active process is carried out by the epithelial cell lining the kidney tubule. It pumps the substance into the lumen

Question 44

How is excretion calculated?

Answer 44

Filtrate - reabsorbed + secreted = excreted | as long as something isn't made or broken down in the kidney, this is true for proteins

Question 45

When is secretion important?

Answer 45

Some xenobiotics where filtration does not remove them quick enough - in order to prevent them from rising from toxic levels they need to be both filtered and secreted

Question 46

How thick is the nephron?

Answer 46

All of it is one epithelial layer thick

Question 47

What are the two membranes of the nephron?

Answer 47

Luminal membrane | Basolateral membrane

Question 48

What is one function of the Macula densa?

Answer 48

It provides tubular globerular feedback