Case 7 Flashcards
What is the difference in onset between type 1 and type 2 diabetes?
type one is usually in childhood and adolescence, type two is typically in adulthood.
What is the difference in the weight of people with type one diabetes?
They typically lose weight in the run up to diagnosis.
What is the difference between blood insulin levels in type one and type 1 and type 2 diabetes?
There is a progressive decrease in type 1 whereas in type 2 they start particularly high and then there is a moderate to normal decrease in the later stages
What is the difference in the appearance of the islets of langerhans in type 1 and type 2 diabetes?
There is insulitis (inflamatory infiltrate of T cells and macrophages) in type 1 which is not present in type 2 in type two there is also amyloid deposits in the islets.
What is the mechanism and indication for Thiazides (e.g. bendroglumethiazide) and thiazide like drugs (e.g.indapamide)
They inhibit the sodium-chloride transporter in the distant tubule, this transporter only reabsorbs 5% of filtered Na so is less effective than loop diuretics, they are mostly used in small doses for the treatment of hypertension.
What is the mechanism and indication for loop diuretics (e.g. Furosemide, Bumetanide, Torasemide)
They inhibit the sodium-potassium-chloride transporter in the thick ascending limb, this transporter is responsible for 25% of Na re-absorption so has a strong effect, these drugs are used to treat heart failure and fluid retention in chronic kidney disease.
What is the mechanism for potassium sparing diuretics? (e.g. amiloride, triamterene) What advantage do they pose over loop diuretics
Some antagonize the work of aldosterone in the distal segment of the distal tubule causing more sodium and water to be into the collecting duct and be excreted in urine, the advantage of this is that there is no risk of hypoalkemia as potassium is not unnecessarily lost.
What is the relationship of the kidneys to the peritoneum?
They are retroperitoneal
Which kidney is slightly lower than the other? Why is this?
The right kidney is slightly lower than the left kidney to make up for the space the liver takes up
What vertebral level do the kidneys begin and extend to?
They extend from T12 to roughly L4
What are the rough proportions of the kidney?
10cm long, 5cm wide and 2.5cm thick
What are the three layers of supportive tissue that surround the kidneys? list them from most superficial to deep
The renal fascia, the perirenal fat capsule and the fibrous capsule
What is the purpose of the perirenal fat capsule?
It acts as a shock absorber protecting the kidney from physical blows
How do the shapes and positions of the two kidneys differ from one another?
The left kidney is longer and more slender, it is also closer to the midline. The right kidney is lower than the left due to the space the liver takes up
What is the role of the fibrous capsule of the kidney?
It prevent infection in the regions surrounding the kidney from spreading to it
What is the name of the extensions of the renal cortex that extend into the renal medulla?
renal columns
How do the renal columns effect the shape of the medulla? What structure does this form?
The renal columns divide the medulla into discontinuous triangular sections called renal pyramids
What surrounds each renal pyramid? What makes up a lobe of a kidney?
renal pyramids are surrounded by a shell of cortex that together for each lobe of the kidney
What is at the end of each renal pyramid what surrounds it?
Each renal pyramid has a renal papilla at its apex surrounded by a minor calyx
What is the name for portions of nephron that extend beyond the renal pyramids into the renal cortex?
medullary rays
What forms the renal pelvis?
minor calyxes of the renal pyramids combine to form major calyxes which themselves converge creating the renal pelvis
Name the sequence of arteries that arise originally from the abdominal aorta to supply the kidney from largest to smallest
abdominal aorta, renal artery, segmental, interlobular, arcuate, cortical radiate, afferent arterioles
What are the series of venous vessels that help drain the kidneys, name them from smallest to largest
capillaries, efferent venules interlobular veins, arcuate veins, interlobar veins renal veins
What i the innervation of the kidney?
renal nerves whose fibers are derived mostly sympathetic post ganglionic fibers from the celiac plexus and inferior splanchnic nerves
What is the effect of sympathetic innervation on the kidney?
Modulation of urine production by altering blood flow and pressure at the nephron level. Stimulation of renin release restricting loss of water and salt in urine by stimulating reabsorption
What is the lymphatic drainage of the kidney?
lateral aortic lumbar nodes surrounding the origin of each renal artery
Roughly how many nephrons and collecting ducts are in each kidney?
1.2 million nephrons and thousands of collecting ducts
What proportion of nephrons are cortical nephrons?
85%
What is a cortical nephron?
A cortical nephron is a nephron that is almost entirely within the superficial cortex of the kidney. It has a short nephron loop and its associated efferent arteriole delivers blood to a network of peritubular capillaries
What is a juxtamedullary nephron?
A nephron with a long nephron loop that extends deep into the medulla and have peritubular capilaries that are connected to vasa recta
What is the other name for a glomerular capsule?
Bowman’s capsule
What are the two layers of the Bowman’s capsule?
An external parietal layer that helps contain the glomerular filtrate and a visceral layer that clings to the glomerulus helping filtration
What type of cell composes the visceral membrane of the glomerular capsule?
modified branching epithelial cells called podocytes
What is the name for the openings between the foot processes of podocyte?
filtration slits
What is the name for the supporting cells that have actin like filaments surrounding adjacent capilaries in glomeruli that can contract under the stimulation of various hormones helping to modify capilary diameter/blood flow
mesangial cells
What are the three main hormones that effect the contractility of mesangial cells?
angiotensin II, vasopressin and histamine
What are the three layers of the ultrastructure of the glomerrular membrane?
capillary membrane, basement membrane and Bowman’s visceral epithelium
The capillary membrane of the glomerulus is fenestrated with capilaries how large?
70-90nm
What composes the basement membrane of the glomerulus?
thick glycoproteins and mucopolysaccharides
How large are the filtration slits?
25nm
How long is a typical renal tubule?
3cm
What are the three main parts of a renal tubule, what does it drain into?
proximal convoluted tubule, loop of henle, distal convoluted tubule. it drains into a collecting duct
What is the role of the proximal convoluted tubule?
To reabsorb organic nutrients, ions water and if present plasma proteins from the glomerular filtrate and to secrete them into the peritubular fluid where they can be returned to the blood
What type of epithelium linesthe proximal convoluted tubule?
a simple cuboidal epithelium with microvilli on its apical surface
Both the descending and ascending limb of the loop of Henle have thick and thin segments how do the epithelium of each of these differ from one another?
Thick segments have cuboidal epithelium thin segments have squamous epithelium
What is the role of the thick segments of the loops of henle?
They pump sodium and chloride ions out of the tubular fluid
What is the role of the thin segments of the loops of henle?
They are permeable to water but not ions, water moves out of these into peritubular fluid condensing the tubular fluid
What are two ways the distal convoluted tubules are different in structure from proximal convoluted tubules?
They have a smaller diameter and their epithelial cells lack microvilli
What are the three processes that happen in the distal convoluted tubule?
Active secretion of ions, acids, drugs and toxiins into the tubule, the selective reabsorption of Na ions and calcium ions from the tubular fluid and the selective re-absorption of water from the tubule helping to concentrate the tubular fluid
Where are the epithelial cells of the DCT tallest? what other other unique arrangement do they have in this area?
near the renal corpuscle (the region is known as the macula densa) they also have their nuclei clustered together
What is the name of the unusual smooth muscle fibers in the afferent arterioles?
juxtaglomerular cells
What composes the juxtaglomerular complex? what does it secrete?
juxtaglomerular cells and the macula densa. It secretes the the hormone erythropoietin and the enzyme renin
Which convoluted tubule has leaky tight junctions between its cells?
proximal
Which convoluted tubule has tight tight junctions between cells?
distal