Normal Kidney Anatomy And Fucntion

Question 1

Which side of the aorta does the left renal vein pass?

Answer 1

Anterior to the aorta, but posterior to the superior mesenteric

Question 2

What the lymphatic drainage of the kidneys.

Answer 2

Lateral aortic nodes

Question 3

What are the three layers that surround each kidney?

Answer 3

Renal capsule (innermost)
Adipose capsule 
Renal fascia (outermost)

Question 4

Describe the renal capsule.

Answer 4

Smooth, transparent, fibrous connective tissue membrane.
Connects with the outermost covering of the ureter at the hilum
Barrier for infection and trauma

Question 5

Describe the adipose capsule.

Answer 5

Mass of fatty tissue

Protects the kidney against blows and holds it firmly in place in the abdominal cavity

Question 6

Describe the renal fascia

Answer 6

Thin layer of fibrous connective tissue

Anchors the kidney to the surrounding structure and abdominal wall

Question 7

How many renal pyramids make up the medulla of the kidney?

Answer 7

8-18

Question 8

Describe the renal pyramids.

Answer 8

Striated appearance from straight tubules
The bases of the pyramids face the cortex
The tips point towards the centre of the kidney and are called renal papillae

Question 9

What is the name of the cortex that separates the renal pyramids?

Answer 9

Renal columns

Question 10

What structures does urine pass through to reach the bladder?

Answer 10

Minor calyces - one at the base of each pyramid 
Major calyces - 2 or 3 in total
Renal pelvis
Ureter
Bladder

Question 11

What are the layers of the filtration barrier?

Answer 11

Single-called capillary endothelium
Collagen based glomerular basement membrane
Podocytes

Question 12

What are the cell type of the JGA and what do they secrete in response to increased or decreased luminal flow rate?

Answer 12

The JG cells secrete renin when the macula densa senses a decreased flow rate
The macula densa cells secrete adenosine in response to an increase flow rate

Question 13

What is the action of adenosine?

Answer 13

It constricts the afferent arteriole into the bowmans capsule, so reducing the overall pressure inside the capsule, and less fluid is filtered.

Question 14

Where is the JGA found?

Answer 14

The JG cells are found lining the afferent arteriole.

The macula densa are found at the junction between the DCT and TALH

Question 15

Name the eight functions of the kidney.

Answer 15

Excretion of small solutes
Excretion of drugs 
Salt and water balance
Blood pressure control
Electrolyte balance
Acid base balance 
EPO
Vitamin D activation

Question 16

What is the effect of EPO?

Answer 16

Increases the mass of red blood cells, so they can carry more oxygen

Question 17

What hydroxylation of vitamin D occurs in the kidneys?

Answer 17

25 DHCC becomes 1,25 DHCC

Question 18

Explain how serum creatinine can be used to measure creatinine.

Answer 18

Creatinine is an endogenous substance produced daily by normal wear and tear on muscles.
- it is however dependent on muscle mass
It has been found that serum creatinine has an inverse exponential relationship with kidney function.
The more serum creatinine there is in the blood, the lower the eGFR

Question 19

What are the problems with serum creatinine as a measure of kidney function?

Answer 19

Inverse relationship means you can lose 70% of kidney function before creatinine spikes (suddenly rises at less than 60ml/min)
It’s dependent on muscle mass so it overestimates the eGFR of low mass muscle groups (women, amputees, elderly, muscle wsting disease)
Not used for chrildren

Question 20

What are the pros of using serum creatinine.

Answer 20

Although it’s not accurate, when it changes, it still means there is a change in the true GFR.
It’s quick and easy and cheap

Question 21

Describe how urine creatinine can be used to assess GFR.

Answer 21

It’s quite a good method because it’s freely filtered by the glomerulus and not reabsorbed into the blood (however small amount of tubular secretion)
Creatinine clearance is roughly equal to GFR
But is quite cumbersome, so plasma creatinine is normally used

Question 22

What can an ultrasound show a clinician?

Answer 22

Kidney size - should be bigger than 10cm
Shape 
Location 
Number
Structure - polycystic kidney disease
Drainage and obstruction 
Renal blood flow

Question 23

Describe radioisotope scanning.

Answer 23

Injection of radio-isotope tracer
- Tc-99 DMSA if you want to see structure
- Tc-99 DTPA if you want to see obstruction or perfusion
Can show how much of the total kidney function is being done by each kidney

Question 24

Describe the different urinalysis tests.

Answer 24

Microscopic examination of urine - microscopic blood
Dipstick test - can detect protein, blood, ketones, pus, bacteria and sugar (UTIs, CKD, diabetes, bladder infections and kidney stones)

Question 25

How can urine protein be detected?

Answer 25

Any detection of proteinuria needs to be confirmed with an albumin specific dipstick test.
This can detect even trace amounts of albumin and can diagnose microalbuminuria

Question 26

Which renal artery is longer (left or right) and why?

Answer 26

The right, because it has to pass behind the IVC to reach to right kidney. This also means it has a shorter renal vein.