Urinary/renal systems 2

Question 1

How many nephrons are there in each kidney

Answer 1

Approx. 1 million

Question 2

What are the two types of nephrons

Answer 2

Cortical nephrons - 85%

Juxtamedullary nephrons

Question 3

What is the main different between the two types of nephrons

Answer 3

Cortical lies mainly in cortex and Juxtamedullary extends deep into the medulla

Question 4

What is the juxtamedullary nephrons important for

Answer 4

Formation of concentrated urine

Question 5

What are the functions of the nephron

Answer 5

Selective blood filtering
Return anything to be kept to blood
Carry waste away for storage and expulsion

Question 6

What is each nephron comprised of

Answer 6

Glomerular capsule
Renal tubules
Collecting duct

Question 7

What is each nephrons associated with

Answer 7

Glomerulus

Peritubular capillaries

Question 8

Describe glomerular capillaries (what makes up glomerulus)

Answer 8

Thin walled single layer of fenestrated endothelial cells - specialised for filtration

Question 9

What do arterioles do for glomerular capillaries

Answer 9

Feed and drain them

Question 10

Describe where peritubular capillaries are

Answer 10

Wrap around renal tubules - specialised for absorption

Question 11

What do peritubular capillaries do

Answer 11

Receive reabsorbed filtrate from nephron

Some non-filtered solutes needing to be excreted can pass into nephrons

Question 12

What are vasa recta

Answer 12

Extensions that follow loops of Henle deep into medulla - only in Juxtamedullary

Question 13

Describe the renal corpuscle

Answer 13

The glomerulus enclosed by the glomerular capsule - where capillary and capsule meet - filtration barrier

Question 14

What are the two layers of the glomerular capsule (Bowman’s)

Answer 14

Outer parietal - simple squamous

Inner visceral - podocytes

Question 15

What is between the two layers of the glomerular capsule

Answer 15

Capsular space - receives filtrate

Question 16

Where are podocytes located

Answer 16

Surrounding the glomerular capillaries

Question 17

Describe podocytes

Answer 17

Very branched specialised epithelium - forms intertwining food processes - pedicles

Question 18

What forms between Pedicels

Answer 18

Filtration slits - Filtered blood moves through and passes into capsular space

Question 19

Describe the filtration barrier

Answer 19

Between blood and capsular space

Question 20

What does and doesn’t the filtration barrier allow through

Answer 20

Allows free passage of water and small molecules

Restricts most proteins and RBC (not filtered into nephron)

Question 21

What are the three layers of the filtration barrier

Answer 21

Fenestrated endothelium (glomerular capillary)
Fused basement membrane 
Filtration slits between pedicels of podocytes

Question 22

Is everything that’s filtered secreted

Answer 22

No

Question 23

What happens after filtration

Answer 23

Urine is waste fluid
Solutes filtered from blood
Some filtrate reabsorbed
Some not unfiltered secreted into nephron

Question 24

What does urine equal

Answer 24

Urine = filtered - reabsorbed + secreted

Question 25

What does the Proximal convoluted tubule (PCT) do

Answer 25

Bulk absorption - surrounded by peritubular capillaries

Question 26

Describe the structure of the Proximal convoluted tubule (PCT)

Answer 26

``` Cuboidal epithelial Dense microvilli on luminal membrane Highly folded basolateral membrane Lots of mitochondria Leaky epithelium ```

Question 27

Where is the nephron loop located

Answer 27

Loops down into medulla | Surrounded by vasa recta (juxtamedullary)

Question 28

What is the length of the nephron loop important in

Answer 28

Production of dilute/concentrated urine

Question 29

Describe the structure of the nephron loop

Answer 29

Thick descending and ascending limb - Similar to DCT structure Thin descending and ascending limb - Simple squamous epithelium

Question 30

Why are different area of the nephron loop different thicknesses

Answer 30

So they can have different permeabilities to water and sodium

Question 31

Describe the distal convoluted tubule (DCT)

Answer 31

Fine tuning | Cuboidal epithelium - thinner than PCT

Question 32

Describe the structure of the distal convoluted tubule (DCT)

Answer 32

No brush boarder (few microvilli) | Fewer mitochondria

Question 33

What is reabsorption in the DCT mostly influenced by

Answer 33

Aldosterone - hormone

Question 34

Describe the collecting duct

Answer 34

Fine tuning | Filtrate from several DCT's into one collecting duct

Question 35

Where do collecting ducts empty

Answer 35

At the Papilla

Question 36

Describe the structure of the collecting duct

Answer 36

Simple cuboidal epithelium

Question 37

What are the two main cells in the collecting duct

Answer 37

Principle - reabsorption | Intercalated - Acid/Base balance

Question 38

What is the juxtaglomerular apparatus (JGA)

Answer 38

Specialised zone in every nephron - located where DCT lies against afferent arteriole

Question 39

What are the specialised cells in the DCT of the juxtaglomerular apparatus (JGA)

Answer 39

DCT - Macula densa cells - chemoreceptors (sodium levels)

Question 40

What are the specialised cells in the DCT of the juxtaglomerular apparatus (JGA)

Answer 40

Afferent arteriole - Juxtaglomerular cells - Mechanoreceptors (blood pressure