Normal Kidney Anatomy And Fucntion Flashcards
Which side of the aorta does the left renal vein pass?
Anterior to the aorta, but posterior to the superior mesenteric
What the lymphatic drainage of the kidneys.
Lateral aortic nodes
What are the three layers that surround each kidney?
Renal capsule (innermost) Adipose capsule Renal fascia (outermost)
Describe the renal capsule.
Smooth, transparent, fibrous connective tissue membrane.
Connects with the outermost covering of the ureter at the hilum
Barrier for infection and trauma
Describe the adipose capsule.
Mass of fatty tissue
Protects the kidney against blows and holds it firmly in place in the abdominal cavity
Describe the renal fascia
Thin layer of fibrous connective tissue
Anchors the kidney to the surrounding structure and abdominal wall
How many renal pyramids make up the medulla of the kidney?
8-18
Describe the renal pyramids.
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
What is the name of the cortex that separates the renal pyramids?
Renal columns
What structures does urine pass through to reach the bladder?
Minor calyces - one at the base of each pyramid Major calyces - 2 or 3 in total Renal pelvis Ureter Bladder
What are the layers of the filtration barrier?
Single-called capillary endothelium
Collagen based glomerular basement membrane
Podocytes
What are the cell type of the JGA and what do they secrete in response to increased or decreased luminal flow rate?
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
What is the action of adenosine?
It constricts the afferent arteriole into the bowmans capsule, so reducing the overall pressure inside the capsule, and less fluid is filtered.
Where is the JGA found?
The JG cells are found lining the afferent arteriole.
The macula densa are found at the junction between the DCT and TALH
Name the eight functions of the kidney.
Excretion of small solutes Excretion of drugs Salt and water balance Blood pressure control Electrolyte balance Acid base balance EPO Vitamin D activation
What is the effect of EPO?
Increases the mass of red blood cells, so they can carry more oxygen
What hydroxylation of vitamin D occurs in the kidneys?
25 DHCC becomes 1,25 DHCC
Explain how serum creatinine can be used to measure creatinine.
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
What are the problems with serum creatinine as a measure of kidney function?
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
What are the pros of using serum creatinine.
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
Describe how urine creatinine can be used to assess GFR.
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
What can an ultrasound show a clinician?
Kidney size - should be bigger than 10cm Shape Location Number Structure - polycystic kidney disease Drainage and obstruction Renal blood flow
Describe radioisotope scanning.
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
Describe the different urinalysis tests.
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)
How can urine protein be detected?
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
Which renal artery is longer (left or right) and why?
The right, because it has to pass behind the IVC to reach to right kidney. This also means it has a shorter renal vein.
