Week 9- Genitourinary System

Question 1

On an average day what is salt and water consumption like?

Answer 1

More than we need so that excess must be excreted

Question 2

What is the function of the kidney?

Answer 2

Excretion of metabolic products, foreign substances
Regulation of body fluids, electrolytes and acid base balance
Control of blood pressure
Secrete hormones

Question 3

What is the function of the detrusor muscle?

Answer 3

Contracts to build up pressure in the bladder to support urination

Question 4

What is the function of the trigone?

Answer 4

Stretching of this region to its limit signals to the brain about the need for urination

Question 5

Describe the flow through a nephron

Answer 5

Glomerulus, bowmans capsule, proximal convoluted tubule, loop of henle, distal convoluted tubule, collecting duct

Question 6

At the proximal convoluted tubule where does water flow and why?

Answer 6

Out of the tubule because sodium and proteins are pumped out so water follows

Question 7

What is special about primary and distal convoluted tubule epithelial cells?

Answer 7

They have a lot of mitochondria

Question 8

What is special about ascending loop of henle epithelial cells?

Answer 8

They have few mitochondria

Question 9

What are the 2 cell types in the collecting duct and how do they differ?

Answer 9

Principal cells- low mitochondrial density

Intercalated cells- rich in mitochondria

Question 10

What are the 2 types of nephron?

Answer 10

Superficial and juxtamedullary

Question 11

What type of nephron is more abundant and by how much?

Answer 11

Superficial- 10 times as many

Question 12

What makes up the juxtaglomerular apparatus?

Answer 12

Macula densa (distal convoluted tubules)
Extraglomerular mesangial cells
Juxtaglomerular cells (afferent arterioles)

Question 13

What is the function of the juxtaglomerular apparatus?

Answer 13

GFR regulation through tubulo-glomerular feedback mechanism

Renin secretion for regulating blood pressure

Question 14

Is glomerular filtration active or passive?

Answer 14

Passive

Question 15

How permeable are glomerular capillaries?

Answer 15

Semi permeable

Question 16

Where does glomerular filtrate go through to?

Answer 16

Bowmans capsule

Question 17

How is net ultrafiltration pressure calculated?

Answer 17

Hydrostatic pressure in glomerular capillaries - hydro pressure in bowmans capsule - oncotic pressure of plasma proteins in glomerular capsule

Question 18

What is glomerular filtration rate (GFR)?

Answer 18

The amount of fluid filtered from the glomeruli into the Bowmans capsule per unit time

Question 19

What is the unit for GFR?

Answer 19

mL/min

Question 20

How is GFR calculated?

Answer 20

Sum of filtration rate of all functioning nephrons
Pressure of ultrafiltration x ultrafiltration coefficient (membrane permeability and surface area available for filtration)

Question 21

Describe the myogenic mechanism of regulation of GFR?

Answer 21

Arterial pressure increases, afferent arteriole stretches, arteriole contracts, vessel resistance rises, blood flow reduces, GFR stays the same

Question 22

What is renal clearance?

Answer 22

The number of litres of plasma that are completely cleared of substance per unit time

Question 23

How is renal clearance calculated?

Answer 23

(conc of substance in urine x rate at which urine is produced)/ conc of substance in plasma

Question 24

What are the units of renal clearance?

Answer 24

mL/min

Question 25

why is liv such a legend?

Answer 25

who knows? theories are still being thought up- maybe it's her biochemistry, the very molecules she is made from? more likely its the fact she is an anomaly and has the love of her one and only wifey xox

Question 26

Describe renal blood supply through the kidney

Answer 26

``` renal artery segmental artery interlobar artery arcuate artery interlobular artery afferent arteriole glomerular capillary efferent arteriole peritubular capillary interlobular vein arcuate vein interlobar vein renal vein ```

Question 27

What is the function of the internal sphincter?

Answer 27

Involuntary control to prevent urination

Question 28

What is the function of the external sphincter?

Answer 28

Voluntary control to prevent urination

Question 29

What is the function of the bulbourethral gland?

Answer 29

Produces a thick lubricant that mixes with watery semen to promote survival of sperm

Question 30

How do the descending and ascending limbs of the loop of Henle differ?

Answer 30

Descending limb: water moves out, impermeable to sodium | Ascending limb: impermeable to water, sodium pumped out at the top

Question 31

Describe osmolarity at the lowest point of the loop of Henle

Answer 31

High osmolarity (hyperosmolar), this can be adjusted to change the amount of water that is conserved

Question 32

Describe osmolarity at the top of the loop of Henle

Answer 32

Iso-osmolar to blood plasma

Question 33

What are the 4 main renal processes?

Answer 33

``` Glomerular filtration Secretion Reabsorption Excretion Different substances undergo a different combination of these processes ```

Question 34

Why is glomerular filtration a passive process?

Answer 34

Because its driven by the hydrostatic pressure of the heart

Question 35

Describe the glomerular basement membrane

Answer 35

It is around 70nm in diameter, permeable to water and small solutes but impermeable to cells and proteins

Question 36

What 2 pressures influence glomerular filtration?

Answer 36

Hydrostatic (pushes fluid out) and oncotic (draws water in)

Question 37

What is the average GFR for males?

Answer 37

90-140 mL/min

Question 38

What is the average GFR for females?

Answer 38

80-125 mL/min

Question 39

What is the main feature of renal failure?

Answer 39

A fall in GFR with a build of excretory products in the plasma

Question 40

Describe the tubulo- glomerular feedback mechanism of regulation of the GFR

Answer 40

Increase/decrease in GFR Increase/decrease in Nacl in loop of Henle Change detected by macula densa Increase/decrease in ATP or adenosine discharged Afferent arteriole constricts/dilates GFR stabilises

Question 41

What are the 2 ways substances leave the kidneys?

Answer 41

Via excretion or to recirculate

Question 42

Why can GFR be measured by measuring the renal clearance of a molecule?

Answer 42

If a molecule isn't resorbed or secreted in the nephron, then the vol filtered is equal to the vol secreted so renal clearance displays GFR

Question 43

What is the ideal molecule for measuring GFR and what are its limitations?

Answer 43

Inulin, it is freely filtered, not secreted, measurable in urine and plasma BUT not found in mammals so needs to be infused

Question 44

What molecule is commonly used to measure GFR and what are its limitations?

Answer 44

Creatinine (a waste product from creatine in molecule metabolism) , amount released is fairly constant BUT a small amount is secreted in the nephron- this can be accounted for in calculations

Question 45

What happens to creatinine clearance and plasma creatinine during renal failure?

Answer 45

Creatinine clearance is low | Plasma creatinine is high

Question 46

What is filtration fraction?

Answer 46

The ratio of the amount of plasma which is filtered and the amount which arrives via the afferent arteriole

Question 47

What is the usual filtration fraction?

Answer 47

0.15-0.20

Question 48

What are the 3 passive transport mechanisms in renal tubules?

Answer 48

Diffusion, osmosis and electrical gradient difference

Question 49

What are the 2 types of active transport mechanisms in renal tubules?

Answer 49

Primary active and secondary active/coupled transport (movement of one solute along its electrochemical gradient provides energy for the other solute to move against it)

Question 50

What are the 2 types of primary active transport mechanisms in renal tubules?

Answer 50

Using a pump | Endocytosis eg small proteins in the PCT

Question 51

What are the 2 types of secondary active transport mechanisms in renal tubules?

Answer 51

Symport (both move in the same direction across the membrane) Antiport (both move in opposite directions across the membrane)

Question 52

Describe how sodium and bicarbonate are resorbed in the proximal convoluted tubule

Answer 52

Water and co2 combine to form carbonic acid via carbonic anhydrase which dissociates H+ ions move out of the cell via Na+/H+ antiporter so Na+ enters cell Na+ and biacrb move out of cell into blood via symporter

Question 53

Describe how glucose is resorbed in the proximal convoluted tubule

Answer 53

Na+ and glucose move into the cell via Na+-glucose symporter Gluscose moves out of cell and into blood via glucose transporter

Question 54

What hormone regulates Na+ resorption and how?

Answer 54

Angiotensin II, it increases Na+-H+ antiporters

Question 55

What substances are resorbed in the proximal convoluted tubule?

Answer 55

Na+, Cl-, HCO3-, 100% glucose, water, amino acids, urea

Question 56

What substances are secreted in the proximal convoluted tubule?

Answer 56

Drugs, ammonia, bile salts, prostaglandins, vitamins (folate and ascorbate)

Question 57

What substances are resorbed in the loop of Henle?

Answer 57

Na+, Cl-, water

Question 58

How are Na+ and Cl- resorbed in the ascending limb of the loop of Henle?

Answer 58

Na+, 2x Cl- and K+ move into the cell via symporter, Na+ then moves out into the blood via Na+/K+ ATPase pump and K+ and Cl- move out into the blood via symporter

Question 59

How are Na+ and Cl- reabsorbed in the distal convoluted tubule?

Answer 59

They enter the cell via symporter, Na+ leaves and enters blood via Na+ K+ ATPase pump and Cl- moves into the blood via K+ Cl- symporter

Question 60

How is Ca2+ actively resorbed in the early distal convoluted tubule?

Answer 60

Via Na+ Ca 2+ antiporter | Via Ca 2+ ATPase pump

Question 61

How does aldosterone regulate Na+ reabsorbtion?

Answer 61

It increases apical Na+ channels and basolateral Na+/K+ ATPase pumps

Question 62

How does ADH regulate water reabsorption?

Answer 62

It increases apical aquaporins

Question 63

What cells are involved with maintaining the acid base balance and where are they found?

Answer 63

Intercalated cells (alpha and beta), they are found in the distal convoluted tubule

Question 64

How do the 2 different intercalated cells maintain acid base balance?

Answer 64

Alpha intercalated cell- reabsorption of HCO3- and H+ secretion Beta intercalated cell- H+ reabsorption and HCO3- secretion

Question 65

How is renal clearance calculated?

Answer 65

(Urine conc of Y x Urine vol) / Plasma conc of Y

Question 66

What is the difference between accuracy and precision?

Answer 66

Accuracy: being able to get to where you want Precision: consistently being able to get where you want

Question 67

What substance is almost completely secreted in the kidney?

Answer 67

PAH (para amino hippuric acid)