143 - Renal Histology

Question 1

Ureters role

Answer 1

Connect kidneys and bladder

Question 2

Kidney dimensions

Answer 2

11 cm x 4-5 cm x 1-2 cm

Question 3

Where does the ureter originate?

Answer 3

At the hilum, from renal pelvis

Question 4

Where do blood vessels and veins enter and leave the kidney?

Answer 4

At the hilum

Question 5

Blood vessels at the boundary between the cortex and medulla

Answer 5

Arcurate vessels

Question 6

Number of nephrons per kidney

Answer 6

0.3 to 1.5 million per kidney

Question 7

Renal corpuscle

Answer 7

Bowman’s capsule + glomerulus

Question 8

What does the nephron consist of?

Answer 8

Renal corpuscle and tubule

Question 9

What do tubules drain into?

Answer 9

Collecting duct

Question 10

Layers of kidney

Answer 10

Capsule, cortex, medulla

Question 11

*Microscopic view of cortex

Answer 11

Blood vessels, tubules, renal corpuscles

Question 12

Location in kidney of renal corpuscles

Answer 12

In cortex

Question 13

Location in kidney of tubules

Answer 13

Loop down into medulla from the cortex, then return

Question 14

Where do tubules join collecting ducts?

Answer 14

In the cortex, then collecting duct drains into renal pelvis

Question 15

Two sorts of nephron

Answer 15

1. Juxta medullary- base of cortex with tubule that loops deep into the medulla (15%) 2. Cortical - higher in cortex, tubule loops halfway into medulla (85%)

Question 16

*Appearance of juxtamedullary and cortical nephrons

Answer 16

Question 17

Is there much connective tissue in the kidney?

Answer 17

No

Question 18

What lines the interior of Bowman’s space?

Answer 18

Podocytes line capillaries. Parietal cells cover interior of Bowman’s capsule.

Question 19

Role of mesangial cells

Answer 19

Support glomerulus, provide limited connective tissue

Question 20

Urinary space

Answer 20

Bowman’s space

Question 21

Vascular space

Answer 21

Lumen of glomerular capillaries

Question 22

Filtration in the glomerulus

Answer 22

Movement of fluid, solutes from vascular space into urinary space

Question 23

Vascular pole

Answer 23

Where capillaries enter Bowman’s capsule

Question 24

Urinary pole

Answer 24

Where tubule drains Bowman’s space

Question 25

Orientation of vascular pole and urinary pole

Answer 25

Always 180 degrees from one another

Question 26

Epithelial type of Bowman's capsule

Answer 26

Squamous parietal cells

Question 27

Epithelial type of tubule

Answer 27

Cuboidal epithelium

Question 28

Crucial point at which ultrafiltrate is formed in kidneys

Answer 28

Interdigitations between podocytes (glycocalyx and slit membranes)

Question 29

Cell type of podocytes

Answer 29

Epithelial

Question 30

Filtration barrier

Answer 30

Basal lamina plus slit membrane

Question 31

\*Filtration barrier on glomerular capillaries

Answer 31

Question 32

Size of molecules that can be filtered

Answer 32

Basal lamina traps molecuels over 69kDa

Question 33

Aspects of filtration barrier 1 2 3 4

Answer 33

1) Fenestrated capillaries lack diaphragms 2) Basal lamina is very thick 3) Slit membranes have pores of around 3-5 nM 4) Basal lamina traps molecules above 69kDa

Question 34

Relative thickness of walls of proximal/distal tubules, loop of Henle

Answer 34

Proximal tubule is thick walled Loop of Henle is mainly thin walled Distal tubule is thick walled

Question 35

Role of kidney tubule 1 2 3 4

Answer 35

• Tubule modifies ultrafiltrate • Recovers water, electrolytes, glucose amino acids, proteins • Secretes creatinine, potassium, protons, ammonium, foreign molecules (eg penicillin) • Result is hyperosmotic urine, rich in urea

Question 36

Structure of proximal tubule 1 2 3 4 5

Answer 36

• Cuboidal epithelium • Abundant microvilli • Interdigitating cell boundaries • Resorb glucose, aa’s and protein • Part in cortex is proximal convoluted tubule

Question 37

Ion movement across epithelial cells of proximal tubule 1 2 3 4 5

Answer 37

• Basal membrane folded with many Na+K+ATPases • Na+K+ATPases pump Na+ across cell • Cl- and H2O follow • Na+, Cl- and H2O passively move across apical membrane • Energy hungry - ATP

Question 38

Which limb of loop of Henle is more water-permeable?

Answer 38

Descending limb more permeable to water

Question 39

What are walls of loop of Henle permeable to?

Answer 39

Urea, electrolytes

Question 40

Cell type in thin limbs of loop of Henle

Answer 40

Squamous

Question 41

Cell type in distal tubule

Answer 41

Cuboidal

Question 42

Features of distal tubule 1 2 3 4 5 6 7

Answer 42

• Part in cortex is distal convoluted tubule • Cells are cuboidal, lack microvilli • Larger lumens • Have infoldings of basal membrane, more mitochondria than proximal tubules • Impermeable to water and urea but have Cl- and Na+ pumps • Ion pumps make extracellular space hyperosmotic • Blood vessels sweep away recovered water and salts

Question 43

Aspects of collecting duct 1 2 3 4

Answer 43

• Large lumen, cuboidal cells • Normally impermeable to water and urea • Antidiuretic hormone (vasopressin) makes them permeable to water • Empty into renal pelvis

Question 44

When can collecting duct become permeable to water?

Answer 44

When dehydrated. Antidiuretic hormone (vasopressin) makes walls permeable to water

Question 45

Nephrons that can make urine more concentrated than blood

Answer 45

Juxtaglomerular nephrons (not cortical)

Question 46

What are juxtamedullary nephrons essential for?

Answer 46

Hyperosmotic urine

Question 47

Role of juxtaglomerular apparatus 1 2 3

Answer 47

• Macula densa is specialised cells of distal tubule wall • Monitor filtrate volume and Na+ concentration • Cause juxtaglomerular cells to release renin

Question 48

Effect of renin

Answer 48

Acts on angiotensinogen, makes it into angiotensin I, then into angiotensin II

Question 49

Juxtaglomerular cells cell type

Answer 49

Modified smooth muscle cells

Question 50

Juxtaglomerular cell role 1 2

Answer 50

• Release renin (enzyme) • Renin converts angiotensinogen (inactive) into angiotensin I, which is converted by other enzymes into angiotensin II, a potent vasoactive hormone

Question 51

Role of extraglomerular mesangial cells

Answer 51

Unknown

Question 52

Location of vasa recta 1 2

Answer 52

• Capillaries from efferent arteriole envelope tubule – form vasa recta • Form hairpin loops in medulla among loops of Henle

Question 53

Role of vasa recta

Answer 53

Crucial in concentrating urine

Question 54

Organisation of the medulla 1 2 3 4

Answer 54

• Medulla consists of: • Thin and thick walled loops of Henle • Collecting ducts • Capillaries of vasa recta

Question 55

Epithelial type of ureters

Answer 55

Lined with transitional epithelium

Question 56

Wall of ureters. 1 2 3

Answer 56

• Lined with transitional epithelium • Distinct lamina propria • Thick muscularis of smooth muscle

Question 57

Role of muscularis propria in ureters

Answer 57

Smooth muscle contracts in peristaltic waves to force urine into bladder

Question 58

Role of thick lamina propria in ureters

Answer 58

Prevents escape of urine from ureters

Question 59

Epithelial lining of bladder

Answer 59

Transitional epithelium

Question 60

Nervous system controlling bladder

Answer 60

Autonomic nervous system

Question 61

Epithelial type of urethra

Answer 61

Transitional epithelium and stratified squamous epithelium

Question 62

Part of body that acts as sphincter in urethra

Answer 62

Where urethra penetrates pelvic floor

Question 63

Things complicating male urethra

Answer 63

Male urethra also penetrates prostate gland and has a variety of glands, as well as the ejaculatory ducts, emptying into it