Week 5: Anatomy and Histology of the Kidney Flashcards

1
Q

Where are the kidneys located?

A

retroperitoneally

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 6 functions of the kidneys?

A

The main function of the kidneys is the production of urine

It also excretes metabolic wastes

It is in charge of regulation of water and acid-base balance of the blood

It regulates body fluid osmolarity and electrolyte concentration

Regulates arterial pressure

Secretes hormones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are the 3 regions of the kidney

A

The cortex- contains nephrons, medulla- and pelvis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

describe the blood supply of the kidneys

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are the two main components of the nephron and what do they contain?

A

Corpuscle

This is comprised of a glomerular tuft (which are spherical structures that get bigger the closer they get to the medulla)

This glomerular is encapsulated by bowman’s space, which is held together by bowman’s capsule

Tubule

Contains PCT, Descending limb, DCT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are the two different types of nephrons and where are they located in the kidneys?

A

Juxtamedullary

Because they exist closer to the medulla (closer to the centre)

These have a long thin loop of Henle

The blood vessels that supply the loop of Henle are known as the Vasa Recta

Cortical

Have shorter loops of Henle

Exist in the outer cortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the structure of the renal corpuscle

A

Is comprised of a glomerulus that is surrounded by bowman’s capsule

In relation to the glomerulus, this structure is made up by a penetrating afferent arteriole (the bigger of the two) which forms the capillary network (the glomerulus), and then leaves as the efferent arteriole

Where these structures enter the renal corpuscle is known as the vascular pole

Opposite this is the urinary pole which drains the filtrate from the podocytes into the proximal convoluted tubule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the 3 types of cells in the glomeruli and their function

A

Podocytes

These are parietal cells that line the outside of capillaries

These are quite large cells with foot processes that reach out and interlock with each other

The little gaps between each of these interlocking foot processes is where the fluid will pass through (whilst stopping large structures like proteins)

Mesangial cells

Are the cell that structural supports the glomerular tuft

These are the cells that bind two capillaries together, providing structural support to the capillaries

These are less important in terms of filtration

Endothelial cells

Is the lining of the capillaries that forms part of the filtration barrier

It has a very spotty appearance, which actually are tiny holes known as fenestrations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the histology of the PCT

A

Is made up of simple cuboidal epithelium

These have a special apical cell surface specialisation of microvilli, or finger like projections that reach into the tubule (which stain a very light pink)

These are usually referred to as a brush border (makes the lumen very messy)

This plays a major role in reabsorption

Have a ‘brush border’ which is the bright pink border which are thousands of micro villi à trying to increase surface area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

describe the histology of the loop of henle

A

Simple squamous epithelium

There are thick and thin descending limbs, a hairpin turn, then a thin ascending limb before it expands to a thick ascending limb

Those nephrons that are close to the medulla (or juxtamedullary nephrons) have particularly long loops of Henle (as opposed to those in the cortex that are little)

Is heavily involved in water retention

different regions have different permeabilities to water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the histology of the DCT

A

Cuboidal

Is the last segment of the nephron

It has no brush border, it is important in acid-base balance

It is the site of ion exchange

Site of salt and water regulation

This then connects to the collecting duct (which is not part of the nephron)

Has macula densa (or juxtamedullary) cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

In a nephron, which 3 structures are in the cortex and which 3 are in the medulla

A

The structures that are contained within the cortex are (left side of image);

Renal Corpuscle (glomerular tuft, bowmen’s space and bowman’s capsule)

Post convoluted Tubules

Distal convoluted Tubule

The structures that are contained within the medulla are (right side of image);

Loop of Henle

Collecting ducts

Vasa Recta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what are the 3 types of kidney variations

A

Fused ectopia (when kidneys fuse into one)

Horseshoe kidneys (when they are joined inferiorly by either kidney tissue or fibrous tissue). These result in higher rates of;

Obstructions and infections

Trauma (road accidents from seat belt)

Recurrent calculus

Pancake tissue is when both are joined inferiorly and superiorly creating one large shape. These result in higher rates of;

Uteropelvic junction obstruction

Recurrent infection

Recurrent calculus

Increased malignancy incidence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the macula densa cells, where are they located and what is their function?

A

These are special cells which line the distal convoluted tubule as it comes into close proximity to the afferent arteriole

These cells detect salt levels within the distal convoluted tubule, an elevated amount of sodium within the filtrate will then tell the afferent arterioles to constrict (reducing the amount of blood going through the capillaries, reducing the filtration rate of salt)

At the same time these cells tell the juxtaglomerular cells to produce renin, which will increase blood pressure through the renin-angiotensin aldosterone system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe the 3 sets of nephric structures to develop of kidneys

A

Pronephroi: transient, no excretory capacity, continuous with Wolffian duct, degenerates

Mesonephroi: excretory organs, open into Wolffian ducts and cloaca, function briefly, have glomeruli and tubules, degenerate end of 1st trimester (in males become efferent ductules of testes)

Metanephroi: produces urine week 10, excreted into amniotic cavity, permanent kidneys from uretic bud and metanephric mesenchyme

17
Q

what does the uretic bud give rise to?

A

CD, calcyes, renal pelvis and ureter

18
Q

what does the metanephric mesenchyme give rise to?

A

nephron and interstitium

19
Q

Describe nephrogenesis

A

Induced by signals form ureteric epithelium

Renal vesicle forms à into nephron

Capillary becomes associated with nephron

20
Q

What positional change do the kidneys undergo?

A

rotate 90 degrees.

21
Q

What is characteristic about the ureter as they enter the bladder and what is the clinical significance of this?

A

The ureters descend to the base of the bladder where it turns medially and obliquely through the posterior bladder wall (an important structural mechanism which prevents backflow)

This backflow is prevented by the contraction of the smooth muscle of the bladder

As the urinary bladder fills, it compresses the ureter. (See diagram)

This function protects the kidney from spread of infections

22
Q

Where are the 3 locations that renal calculi (kidney stones) may lodge?

A

Where the renal pelvis narrows is the region that the ureter begins, and is one potential zone where a renal calculi or kidney stone may lodge

Further down, the region where the ureter passes over the pelvic brim, and passes over the external iliac artery and vein, there is opportunity for kidney stones to lodge due to a slight kink

Where it passes through the bladder wall itself

23
Q

What type of epithelium line the major calyces, renal pelvism ureters, bladder and urethra?

A

Transitional epithelium

24
Q
A
25
Q

Why do males have increase accuracy of urination?

A

These two sphincters (internal and external) open in opposite directions, this creates a spiralling effect of urine which increases accuracy of urination (like a bullet out of a gun)

26
Q

Describe the histology of the male urethra

A

Starts out as transitional epithelium and then becomes stratified columnar and then towards the distal end it becomes stratified squamous

27
Q

how long is the male urethra and female urethra?

What is the clinical significance of the length of the female urethra

A

20 cm and 4 cm

due to short length -much more prone to infection (e.g. e-coli during poor wiping.)

28
Q

describe the histology of the female urethra

A

stratified colomnar epithelium

29
Q

which kidney sits more cranially and why?

A

left sits higher than right as the right needs to make room for the liver

30
Q

what are two functions of the type of epithelium that lines the ureter and what epithelium is it?

A

transitional epithelium, allows for stretch and prevents against toxicity of urine

31
Q

why are women more susceptible to bladder infections

A

urethra only 4cm long

32
Q

what components of the kidney are derived from the metanephric mesenchyme?

A

nephron and intersitium

33
Q

what is the part of the medulla which is made up of a collection of tubules which drain into the minor calyx?

A

Renal pyramid