L17 - Histology of the Urinary system Flashcards Preview

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Flashcards in L17 - Histology of the Urinary system Deck (108):
1

What is the principal functions of the urinary system?

Maintenance of water, electrolyte and acid-base homeostasis

2

What is the normal expected urine volume per day?

1.25 L/day

3

What is Polyuria (too many) / oligouria (too little) a homeostatic disorder of?

Homeostasis of urine production

4

What are the most important toxic metabolites that require breakdown in body?

Nitorgen-containing compounds as products of protein breakdown

e.g. urea and creatinine

5

What actions of the urinary system do the principal functions involve? (what happens to the urine?)

Production, passage, storage and voiding of urine

6

What is secreted by the juxtaglomerular cells that regulate blood pressure?

renin (angiotensinogenase): cleaves angiotensinogen > makes angiotensin I > regulate blood pressure

7

What is the consequence on urine production volume by lack of ADH in Diabetes insipidus?

Lack of ADH > lose ability
to reabsorb water from distal convoluted tubule and collecting ducts >
large volume of urine production (up to 22 liters/day)

8

What are the four structures that make up the urinary system?

2 kidneys
2 ureters
urinary bladder
urethra

9

What is the kidneys' function?

Control urine production and urine composition

10

How are the ureters and urethra similar in function?

Both for passage of urine

11

What is the function of the urinary bladder?

storage and voiding of urine

12

How would you describe kidneys as an organ?

Kidneys are compound tubular glands covered by a thin capsule of dense connective tissue and embedded in a layer of fat

(renal capsule> perirenal fat >renal fascia> pararenal fat)

13

What is the location and level of the kidneys?

T12- L3
retroperitoneal
Right kidney is inferior to left kidney

14

What is the renal fascia made of?

thin layer of loose connective tissue

15

What passes through the hilum of the kidneys?

renal artery / vein (more anterior), nerves, ureter

16

What is the renal sinus?

cavity within the kidney

occupied by the renal pelvis, renal calyces, blood vessels, nerves and fat

17

What are the pyramids in the kidney?

The pyramids made of tubules that transport urine from the cortex to the calyces

18

Where and what is renal papilla?

where the renal pyramids in the medulla empty urine into the minor calyces

19

How is renal papilla duct formed?

medullary collecting ducts converging to form a papillary duct

20

How is the renal pelvis formed?

Fused major calyces

21

The kidney can be divided functionally into which two sections?

Transport portion
Filtration portion

22

What marks the start of the transport portion of the kidney?

major and minor calyces

23

What and where are the three physiological constrictions along the ureter?

Pelviureteric junction- after renal pelvis

Pelvic brim- crossing with external iliac artery

Uretero-vesical junction- before entrance into bladder

24

What artery does the renal artery branch from?

Aorta

25

What is the sequenc eof circulation from the renal artery to micro-circulation?

Renal artery > Segmental artery > InterLOBAR artery > Arcuate artery > interLOBULAR artery > microcirculation

26

What are the arteries before and after arcuate artery in kidney?

InterLOBAR is before
interLOBULAR is after

27

What preceeds interlobar artery in kidney?

Segmental artery

28

How are interlobar arteries arranged in kidney? (where does it lead to)

ascend within renal
columns toward cortex

29

Where are do arcuate arteries exist in kidneys?

arch over base of
pyramids

30

Where do interLOBULAR arteries end up in the kidney?

Renal cortex

31

Is the nephron open-ended or blind-ended?

Blind-ended

32

What is the uriniferous tubule of the kidney? What structures does it consist of?

The functional unit of the kidney that collects and conducts urine

Consists of a nephron + collecting tubule
(Renal corpuscle + PCT + Loop of Henle + DCT + collecting tubule)

33

Are the two components of the uriniferous tubule from the same embryonic origin?

No

34

Where are distal and proximal convoluted tubules located relative to the renal corpuscle?

PCT and DCT are adjacent to the renal corpuscle

35

What are the two types of nephrons? How are they distributed?

80% Cortical
20% Juxtamedullary

36

Does the loop of Henle of cortical nephron extend into the medulla? How about juxtamedullary nephrons' loop of Henle?

Cortical nephron: Yes but not deep into medulla

Juxtamed. nephron: Yes and deep into medulla

37

What forms the peritubular capillary network?

Efferent glomerular arterioles of the CORTICAL nephron

38

What is the difference in location between the renal corpuscle of cortical vs juxtamedullary nephron?

Cortical nephrons:
 Renal corpuscle nearer to periphery of cortex

Juxtamedullary nephrons:
 Renal corpuscle near cortical medullary border/ in the juxtamedullary cortex

39

What is the sequence for urine drainage inside the kidney?

nephron > collecting ducts > papillary ducts >
minor calyses > 3 major calyses > renal pelvis

40

What structures does the glomerular filtrate go through inside the uriniferous tubule?

Renal corpuscle > Proximal convoluted tubule > Loop of Henle > Distal convoluted tubule > Cortical Collecting duct > Medullary collecting duct

41

What is the Medullary Ray made of ?

Consists of Collecting tubule and segments of the loop of Henle of CORTICAL nephron

42

What is the difference between the structures formed from the efferent glomerular arteriole of the cortical and juxtamedullary nephrons?

Cortical nephron efferent glomerular arterioles form the peritubular capillary network

Juxtamed. nephron efferent glomerular arterioles form the VASA RECTA

43

What is the difference between the structures surrounded by the peritubular capillary network and Vasa Recta?

Peritubular capillary network surrounds the convoluted tubules of nephrons in the cortex

Vasa Recta surrounds the limbs of Loop of Henle

44

In which of the two types of nephrons is the Loop of Henle longer?

The juxtamedullary nephron has longer Loop of Henle

45

The cortex and medulla of kidneys is divided into which 4 sections?

Cortex- Outer cortex, juxtamedullary cortex

Medulla- Outer medulla, Inner medulla

46

What structures of nephron is prominent in the medulla?

Only Loop of Henle and Collecting duct

47

Are the renal corpuscle and convoluted tubules of juxtamedullary nephron located in the Medulla?

No, located in the juxtamedullary cortex

48

What is the sequence of venous vessels from microcirculation to inferior venan cava in the kidneys?

Microcirculation / peritubular capillaries > InterLOBULAR vein> Arcuate Vein> InterLOBAR vein> Renal Vein > Inferior VC

(No segmental vein)

49

Are the peritubular capillary networks continous with Vasa Recta?

Yes, the two capillary beds are linked
This is called Portal Circulation

50

What is the sequence of vessels in the microcirculation of the kidney?

Interlobular artery > Afferent arteriole > glomerulus > Efferent Arteriole > then to:
1) Peritubular capillaries > Vasa Recta > either arcuate vein or interlobular vein
2)Directly to interlobular vein
3)to Peritubular caplillaries > Interlobular vein

51

Which two veins can Vasa Recta lead to?

InterLOBULAR vein
Arcuate Vein

52

Which two vessels can Peritubular capillaries lead to?

Vasa Recta
InterLOBULAR vein

53

Which two vessels can efferent arteriole lead to?

interLOBULAR vein
Peritubular capillaries

54

What is the path that Vasa Recta (formed by juxtamedullar nephron efferent arterioles) takes in the kidneys?

course along with loops of Henle into the medulla > then to cortex

55

Where in the kidney are Arcuate A/V located?

Juxtamedullary cortex

56

What is located between renal pyramids?

Renal Columns

57

Is corticomedullary junction same as juxtamedullary cortex?

Yes

58

What are the epithelium types in parietal (outer) and visceral (inner) Bowman's capsule?

Parietal layer = simple squamous epithelium


Visceral layer = specialized podocytes, highly specialized simple squamous epithelium

59

What is the role of Mesangial matrix?

Produce Extra-cellular matrix for structural support of the glomerulus

60

What is glomerular tuft?

20-40 loops of fenestrated capillaries

61

In visceral epithelium, what structures does the plasma ultrafiltrate pass through from the glomerular capillary to urinary space?

Glomerular capillary endothelium > Fenetration > Basal Laminae (fused basement membrane between podocyte and endothelial > Filtration slit diaphragm between podocyte pedicels > Urinary space

62

What are pedicels of podocytes?

Finger-like projections, space between is called filtration slit

63

What 2 components make up renal corpuscle?

Glomerulus and Bowman's capsule

64

What structure faces the vasuclar pole and what faces the urinary pole?

Vascular pole: DCT, Afferetn and Efferent arterioles

Urinary pole: PCT

65

What are juxtaglomerular cells?

modified smooth
muscle cells of
AFFERENT arteriole

66

What is the role of juxtaglomerular cells?

Secretes renin
(converts angiotensinogen to angiotensin I > angiotensin II)

Act as mechanoreceptors, sensitive to BP

67

What are macula densa cells?

specialized / modified epithelial cells of distal
convoluted tubule

68

What is the role of macula dense?

Sensitive to osmolarity (e.g. amount of NaCl in distal
convulated tubules) and volume of filtrate =
regulates glomerular filtration rate

69

What cells has gap junction with juxtaglomerular cells and lies bteween macular densa and glomerulus?

Lacis cell (extraglomerular mesangial cells)

70

What is the Proximal convoluted tubule epithelium?
3 special features?

Simple cuboidal
epithelium with:
1) Microvilli (at luminal
brush border)
2) Mitochondria in basal infoldings/invaginations
3) Apical tight junctions + intercellular junctions (alternating ridges along basal part of cell)

71

What microscopy features do proximal convoluted cells have?

Brushed border
Cytoplasm: more
eosinophilic than DCT
No distinctive cell border

72

Does PCT reabsorb most of water and solutes?

Yes about 70% of all reabsorption

73

What is reabsorbed in the PCT?

Actively reabsorb Na+ ,amino acid, (small) proteins,glucose

Reabsorb water by osmosis

74

What is the pathway of reabsoption of PCT?

filtrate >
tubule cell >
interstitial fluid >
peritubular capillaries

75

What is the chang ein epithelium of Loop of Henle from descending limb to ascending limb?

1. Initial part of descending limb: simple cuboidal epithelium
2. Latter part of descending limb: simple squamous epithelium
3. Initial part of ascending limb: simple squamous epithelium
4. Distal part of ascending limb: simple cuboidal epithelium

Epithelial cells interlock with each other

76

What is the role of Loop of Henle?

Create hypertonicity gradient between collecting ducts and interstitium

77

When is renin secreted? What 2 cells is it made and secreted by?

When BP is low:

1) Detected by macula densa by decreased sodium concentration in DCT due to decreased glomerular filtration rate

or

2) Detected by Juxtamedullar cells (mechano-receptors)

78

What is the difference in water and solute permeability between ascending and descending limbs of the Loop of Henle?

Descending= impermeable to salt but permeable to water

Ascending pumps of salt but impermeable to water

79

What is the pairing of vasa recta to the limbs of the loop of henle?

Descending limb coupled with ascending Vasa Recta

Ascending limb coupled with descending Vasa Recta

Interstitium in between

80

DCT epithelium? 3 sepcial features?

Simple cuboidal epithelial cells with:
1) Mitochondria in basal folding/ invagination
2) Intercellular junction (impermeable to water)
3) Sparse microvilli

81

How does DCT cells compare to PCT cells morphological?

Morphology:
 Shorter, appear less in a section
 Pale stain
 Less brush border on luminal surface (few/sparse microvilli)
 More distinctive border
 Smaller size
 Less acidophilic

82

What is the function of the DCT?

Achieve acid-base and water balance by:

Absorption of water, Na+, HCO3-

Excretion of K+ and H+

83

Which of the DCT's membranes are responsible for transport of which ions?

 Apical membrane: countertransport (reabsorb Na+, Cl-; excrete H+, K+)

 Basal membrane: active transport/symport (reabsorb Na+, Cl-; excrete K+)

84

How do the lumens of PCT and DCT compare?

PCT=Thicker wall, Smaller lumen
DCT= Thinner wall, Bigger lumen

85

Collecting tubule/ duct function?

Controlled reabsoption of water under influence of ADH

86

What epithelium and cell types are in collecting ducts?

Simple Cuboidal epithelium

Principal and Intercalated (dark) cells

87

Function of medullary collecting tubules?

Water reabsorption

Hypothalamus synthesizes ADH > release from
posterior lobe of pituitary > collecting tubules respond to increase permeability to
water > water moves out > produce concentrated urine

88

What is the difference in function between the two types of collecting duct cells?

Principal (light) cells: mechanosensor of fluid flow and contents

Intercalated (dark) cells: Mediate acid-base transport, water impermeable

89

What are the two roles of interstitial cells?

Maintenance of renal architecture and production of erythropoietin

(Produces 1,25-dihydroxycholecalciferol/ active vitamin D to increase Calcium levels during UV exposure)

90

How does the DCT relate to renin/ angiotensin / aldosterone?

Angiotensinogen (liver) > angiotensin I > angiotensin II

Increased K+ + angiotensin II act on adrenal cortex > increase aldosterone secretion > reabsorb Na+, Cl-, excrete K+

91

Ureter epithelium?

transitional epithelium

92

How does transitional epithelium change?

Contracted (fat) and Distended (slim) states of viscus

Contracted/non-distended state of viscus:
Cuboidal basal, polygonal middle, columnar upper

93

Transitional epithelium vesicles role?

Reserve segments of surface membrane to incorporate into surface when lumen is distended

94

What are the layers and lumen of the ureter?

 Transitional epithelim (urothelium) >Lamina propria >Inner spiral (longitudinal) muscle >Outer spiral (circular) muscle> Outermost longitudinal layer (in lower third) >Adventitia



 Stellate-shaped lumen

95

What is the role of the ureter?

Hollow fibromuscular tubes that deliver urine from renal pelvis to urinary bladder via peristaltic smooth muscle contraction

96

What is the lamina propria of the ureter made of?

Dense collagenous and elastic connective tissue

97

What is the adventitia of ureter made of?

Loose connective tissue with autonomic nerve plexuses, clood vessels and lymphatics

98

Which muscle layer in ureter is for peristaltic movements to move urine?

Outermost longitudinal layer in lower third

99

What is the role of the urinary bladder?

Receive and stor urine until neural stimulation cause it to contract and expel urine via urethra

100

What three structures surrounding the male kidney is not found in female?

L/R ductus deferens
L/R seminal vesicle
Prostate

101

What is the lining of the bladder?

Transitional epithelium> Lamina propria > 3 layers of Detrusor muscle

102

What is the difference in neural control between the external detrusor muscle and the internal urethral sphincter?

External detrusor = Somatic NS
Internal urethral sphincter = Autonomic NS

103

Where is the trigone?

triangular area between entry of 2 ureters and exit of urethra

104

Compare male and female urethra location and length?

Length: Female shorter
Location:
- female: opens into vestibule anterior to vaginal opening
- male: from inferior part of urinary bladder through penis

105

3 sections of male urethra and epithelium?

Prostatic > Membranous > Spongy/penile

Transitional epithelium>
(pseudo-)stratified columnar
epithelium (most) >
Non-keratinized stratified squamous epithelium (tip of penis)

106

Is the change in epithelium in female urethra the same as in male?

Yes
Transitional > Pseudo. Col.> NKSS

107

How does urine movement change through the urinary system?

 Through nephron: hydrostatic pressure
 From renal pelvis > ureters > urinary bladder: peristalsis

108

How does neural control change frequency of urine movement?

 Parasympathetic stimulation: increases frequency
 Sympathetic stimulation: decreases frequency

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