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Semester 3 > Urinary > Flashcards

Urinary Flashcards

1
Q

What are the functions of the kidney/ urinary system?

A

homeostasis volume, osmolarity and pH

excretion of waste

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2
Q

Where is the 40Litres of water in the body?

A

intracellular- 25L
interstitial- 12L
Intravascular- 3L
Lymph and transcellular (synovial pleural etc)

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3
Q

Describe the venous drainage of the kidneys

A

Communicate with the IVC. This is the most superficial of the hiatus anteriorly. The left renal vein is longest as the IVC is situated on the right side of the aorta. The left side passes under the superior mesenteric artery.

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4
Q

Describe the arterial supply to the kidneys

A

Pair of arteries that branch of the abdominal aorta that pass posteriorly to the IVC. The right side is longer than the left.

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5
Q

Describe the arrangements of vessels within the kidney

A

Abdominal aorta
renal artery
anterior and posterior branches
segmental arteries pass along the renal columns.
Interlobar arteries pass along the edge of the pyramid.
At the base of the pyramid it arcs round the base becoming the arcuate arteries.
At 90% to the arcuate are the interlobular which branch off.
Branches off to give rise to the afferent arteriole and then the glomerulus.
Vasa recta comes from efferent in juxta medullary arteriole that goes all the way down the loop of henle communicating with venous drainage that drains then into the interlobular arteriole
In cortical nephrons the efferent arteriole forms the peritubular capillaries which drains into the interlobular veins.

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6
Q

Describe the gross histology of the kidney

A

Cortex surround the medullary pyramids. The pyramids are ionically rich and towards the hilum of the kidney i.e close to the pelvis. The pelvis takes drainage from the minor –>major calyx and drains into the ureter.

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7
Q

Describe the course of the ureters

A

Pelvouretal junction. When it leaves the pelvis.
Travels down towards the division of the common iliac into the internal and external iliac arteries.
It then travels down and joins with the bladder.

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8
Q

How does change in extracellular volume affect the body?

A

Will cause a change in BP, and a change in tissue fluid and cell function.

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9
Q

How does lack of homeostasis of osmolarity affect the cells of the body?

A

Will lead to changes in cell volume.

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10
Q

Describe what is meant by hypotonic

A

With a conc lower than a reference fluid

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11
Q

Describe what is meant by hypertonic

A

With a conc higher than a reference fluid

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12
Q

Describe what is meant by isotonic

A

Equal conc to the reference fluid.

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13
Q

Define osmolality

A

Solute per Kg of solvent.

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14
Q

Define osmolarity

A

Number of osmoles of solute per litre

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15
Q

What volume of ultrafiltrate is produced per day and how much isn’t recovered?

A

180L

1.5L

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16
Q

What blood flow does the kidney need?

A

4ml/g/min (approx 25% of the cardiac output)

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17
Q

What height are the kidneys at?

A 
L= 11th rib
R= 12th rib
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18
Q

What is the parenchyme of the kidney?

A

The medulla and cortex

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19
Q

How many nephrons are in each kidney?

A

1.5 million

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20
Q

What is the role of the glomerulus?

A

To filter the blood plasma. the fluid is similar in composition to filtration across other capillary beds i.e similar ionically to blood but lacking the large proteins and high molecular weight molecules however the rate in the kidneys is massively higher.

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21
Q

Describe the arrangement of cells in the glomerulus

A

At the vascular pole there is a hilum for the efferent and afferent arteriole. In communication with this are the macula densa cells of the distal tubule. Surrounding the afferent arteriole is the Juxtaglomerular apparatus. Within the bowman’s capsule podocytes are on the exterior of the epithelium of the capillaries, this is known as the visceral layer of bowman’s capsule. The parietal layer of bowman’s capsule is the outside of the capsule. In the middle of the bowman’s capsule are mesangial cells.

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22
Q

How does the epithelium of the capillaries differ in the glomerulus?

A

They are fenestrated in nature and are lined with basement membrane and a layer of podocyte foot processes except at the mesangial cells in the centre where they have neither.The fenestrations don’t restrict anything except for cellular movement.

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23
Q

What is the glomerular basement membrane’s composition and how does it function?

A

Lamina rara interna-contains heparan sulphate so restricts movement of -ve ions
Lamina densa- restricts size to 1 kDa
Lamina rara externa-contains heparan sulphate so restricts movement of -ve ions

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24
Q

What are the roles of the kidney?

A

Hormone production, electrolyte balance, pH balance, fluid balance, excretion.

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25
Q

What is the renal corpuscle? Function? Made of ?

A

The glomerulus and bowman’s capsule.
To produce the ultrafiltrate from between the pseudopodia of the podocytes.
Made from a meshwork of capillaries in glomerulus which are formed between the efferent and afferent arterioles at the vascular pole. Endothelium line them here which are fenestrated to allow passage of particulates. Beneath which is a triple layer basement membrane high in glycoproteins to trap anions. Beneath again are the podocytes which interdigitate to provide a further meshwork.
This is a very leaky barrier however particulates exceeding 14 kDa experience great resistance in passing the layers.

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26
Q

What do collecting ducts drain into?

A

Ducts of bellini.

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27
Q

What properties do that cells have in the PCT?

A

It links the bowman’s capsule to the loop of henle.
Made from simple cuboidal epithelium.
They have a very prominent brush border on the apical/luminal membrane. This increases surface area allowing for increased rates of absorption.
The cells are densely packed with mitochondria found largely in the basal region of the plasma membrane. This gives the cells a very acidophillic appearance. This is needed fro Na+ transport.
Between the cells are tight junctions preventing unwanted diffusion between the lumen and ECF. However the tightness of the junctions increases from proximal to distal.

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28
Q

Describe the thin limbs of loop of henle

A

Low number of mitochondria.
Composed of simple squamous epithelium.
Ascending: partially water permeable, relatively permeable to salts.
Descending: 100% water permeable, but only partially solute permeable.

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29
Q

Describe the thick limbs of the loop of henle

A

Composed of simple cuboidal epithelium with no brush border.
Impermeable to water and have numerous NKKC2 channels in the apical membrane. There are also many K+ channels in the apical membrane allowing K+ to pass into the lumen. This creates a +ve charge in the lumen and is a driving force for both transcellular movement of Na+ and also provides the substrate for the NKKC2 channel.

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30
Q

Describe the Distal convuluted tubule

A

Makes contact with the glomerulus via macula densa cells. They have a role of producing prostaglandin in the presence of small amounts of NaCl and producing adenosine in the presence of high NaCl.
They contain many mitochondria.

31
Q

What is contained within the juxtaglomerular apparatus?

A

Macula densa cells,juxtaglomerula cells, lacis cells

32
Q

Describe the ultrastructure of the ureter

A

a muscular tube. 2 layers of smooth muscle from the top and a 3rd appears in the bottom 1/3. lined by specialised epithelium.

33
Q

describe the layers of muscle in the bladder

A

3 layers of smooth muscle. spiral, longitudinal and circular.

34
Q

What mesoderm forms the kidneys and urinary system?

A

The intermediate mesoderm.

35
Q

What are the three kidney systems that are present in various stages of embryological development? time of being present? distinctive features?

A

Pronephros. start-4th week-finish. and is present in the cervical region as 7-10 cell populations. Has a duct that extends down to the cloaca that drives the next stage of development.
Mesonephros: starts at regression of the pronephros at the end of the 4th week and lasts until the end of the 2nd month where all is gone in the female and most in the male. Forms s shaped tubules which acquire tufts of capillaires and laterally they drain into the mesonephric duct. This is all contained within the urogenital ridge of which medially is the region of the future gonads. It sprouts the ureteric bud which induces the developement of the definitive kidney.
Metanephros is induced from intermediate mesoderm by the ureteric bud. The collecting system is derived from the ureteric bud and the excretory component is derived from the mesoderm.

36
Q

Describe ascent of the kidney

A

they pass through the fork produced by the umbilical arteries. If they touch as they move up they can fuse forming a horseshoe kidney.

37
Q

Describe the molecular regulation of the kidney’s developement

A

The mesenchyme expresses a WT1 transcription factor allowing it to be induced by the ureteric bud. FGF2 is also a key signal between the two. Conversion of the mesenchyme to an epithelium is also induced by the ureteric bud.

38
Q

Why do accessory arteries develop in the kidneys?

A

Due to persistence of embryonic vessels.

39
Q

What are the effects of a duplication of the ureteric bud?

A

Typically can result in ectopic urethras and extra urethral openings i.e not just into the bladder.

40
Q

Describe cystic disease of the kidneys

A

multicystic- bilateral in 30% of cases, oligohydramnios,
dominant polycystic- 1 in 500 live births, no ethnical preference, bilateral and progressive. Due to
recessive polycystic- 1 in 20,000 live births, hypoplasia in 30% mortality in neonates, dilatations of the collecting ducts from the medulla to cortex.

41
Q

Describe the parts of the gut tube and their relationship to the developing kidney.

A

Cloaca is the primitive end of the gut tube. This is then split by the uro-rectal septum which splits the urinary and digestive regions. The bladder is connected to the allantois via the urachus which can persist in adults (being patent)

42
Q

Describe the division of the urogenital sinus

A

in 3 parts. Largest part is future bladder, bottom part is the pelvic and and a small outcropping on the pelvic part is the phallic part.

43
Q

How does the mesonephric duct and Ureteric bud interact at the bladder during development?

A

Initially just the MD joins the bladder. Ureteric bud is on the MD. As the bladder grows it absorbs a portion of the MD until the MD and UB both have their own orifices. Smooth muscle is present on the bladder at this point.
The MD is then at the base of the bladder and in males it remains present communication with the prostate and in women it regresses.

44
Q

What are the 4 parts of the male urethra?

A

preprostatic, prostatic, membranous, spongy/phallic

45
Q

What is the role of SRY?

A

Sex determining region on Y is the y chromosome’s contribution to sexual dimorphism.

46
Q

what is the path of the primordial germ cells?

A

start in the epiderm and migrate through the primitive streak into the endoderm adjacent to the allantois. During the 4th week they travel along the dorsal mesentery until they reach the genital ridges in the 6th week inducing gonadal development.

47
Q

describe the developement of the external genitallia

A

in the 3rd week mesenchyme from the primitive streak migrate to the cloacal membrane and form a pair of elevated folds. cranial to the membrane the fold unite to form the genital tubercle. caudally the folds are subdivided into urethral and anal folds.
Another pair of elevations form adjacent to the urethral folds and are the genital swellings.
In men. Rapid development of the genital tubercle causes the lateral walls of the urethral groove to form. At 3 months the folds close over to give the penile urethra.

48
Q

What is the weight of the kidney? the % of cardiac output? resting blood flow per gram?

A

300 grams,
22%,
4ml/gram min.

49
Q

Describe the two types of nephron

A

Cortical. Short loop of henle, disordered blood supply and glomerulus is high in the cortex.
Juxtamedullary. Glomerulus on the border of the medulla and has a long loop of henle that descends deep into the medulla. Has a well ordered blood supply from the vasa recta which operates a counter current multiplier.

50
Q

What % of blood volume passes into the bowman’s space?

A

20%

51
Q

describe the barrier between the glomerular vessels and the bowman’s space

A 
Endothelium
Basement membrane (3 layers)
Podocyte (pseudopodia)
52
Q

How are species filtered in the glomerulus?

A

-ve charge repelled by glycoproteins
Endothelium is fenestrated
All electrolytes able to move unimpeded.
Cells and large molecules above 14kDa cannot pass the layers.

53
Q

What are the 3 forces in opposition across the glomerulus?

A

hydrostatic pressure out
Hydrostatic pressure in
Osmotic/coloid pressure in.
Net pressure out

54
Q

What proportion of Na+ is reabsorbed in the PCT?

A

67%

55
Q

How is Na+ reabsorbed in the PCT?

A

using a NHX and a glucose symporter (SGLUT).

Low internal Na+ from basolateral membrane having Na/K atpase

56
Q

What are the two ways that substrate can be reabsorbed from the lumen of the PCT?

A

Trans/paracellularly.

57
Q

Describe glucose absorption in the PCT

A

Moves against the concentration gradient however it uses the energy from the Na+ gradient to move through a symporter, SGLUT. Usually its 100% absorbed however if the levels exceed 200mg/100ml then glycosuria occurs. Basolateral side of cells have channels for the glucose to diffuse down into the ECF and then blood.

58
Q

Describe hyperaminaciduria

A

An increase in the renal excretion of amino acids.
This can be owed to any number of homeostatic derangements.
Pre-renal high arginine can result in it being present in the urine. Also the transporter for Arg is the same for Lys and ornithine so they are elevated in the urine as well.
Renal- vary based on the amino acid properties i.e can be anionic, cationic or neutral aminoacidurias.
Fanconi syndrome- a generalised aminoaciduria that is due to an impairment of the PCT. This can be due to a number of factors. Not only AA are compromised in terms of reabsorption.

59
Q

How does the fluid at the end of the PCT compare to the blood plasma at the same level?

A

Iso osmotic.

60
Q

What does the macula densa cells release upon high [NaCl] and what effect does this have?

A

Release of prostaglandin which induces contraction of the afferent arterioles to reduce renal blood flow.

61
Q

What % of HCO3 is absorbed in the PCT?
H2O-
K+
Cl-

A

80-90%
65%
65%
50%

62
Q

What is secreted into the tubular lumen of the PCT?

A

H+, K+ organic ions and cations

63
Q

What do loop diuretics block? example of?

A

NKKCl2 channels

Furosemide

64
Q

How are organic cations transported across the apical membrane in the PCT lumen?

A

Using a H+ antiport.

65
Q

How to calculate volume of ultrafiltrate formed per minute?

A 
renal blood volume per minute=1.1L/min
minus haemtocrit (1.1-0.45)=0.605L/min=RPF
RPF/5=125ml/min
filtration fraction=20%.
66
Q

How do we measure GFR clinically? why do we need to measure it?

A

It is an indicator of overall kidney function.

We need to calculate the clearance rate.

67
Q

What are the ranges for GFR?

A

men 115-125

women- 90-100

68
Q

How do we calculate clearance?

A

clearance is asking what volume of plasma is cleaned of the substance we are measuring.

GFR[plasma]=Urine rate[urine]
ONLY IF THERE IS NO SECRETION, ABSORPTION OR METABOLISM.

69
Q

What are the assumptions for using an item’s clearance as an indicator of GFR?

A

not secreted, absorbed or metabolised whilst in the kidneys.

70
Q

What is the exact species to use know the value of GFR and an approximation of GFR?

A

Inulin

Creatinine

71
Q

When does clearance rate not equal GFR?

A

when there are changes to the substance being measured whilst in transit.
Overestimate of GFR if secreted or synthesized.
underestimate if absorbed or metabolised.

72
Q

What is filtered load?

A 
volume of a substance that is contained within ultrafiltrate.
Calculated from mg/ml of plasma
then filtration fraction with RPF.
so 0.605x0.2-->125ml/min
x conc--> filtered load.
73
Q

Describe myogenic autoregulation in the kidneys

A

The blood flow in the kidneys is kept relatively constant through smooth muscle contractions opposing a change in. So an increase in blood pressure is met with a contraction of smooth muscle in the afferent arterioles.

Semester 3 (6 decks)

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