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1 multiple choice question
The kidneys are supplied
with blood by a:
a) single artery and a single vein
b) single artery, a
ureter and a vein
c) single artery and two veins
Answer: Option (a)
2 What are the two types of kidney nephron and what are the key structural differences between them?
Answer: There are two general types of nephron, cortical and juxtamedullary, with distinction based on the length and location of their associated loop of Henle. A cortical nephron has its loop of Henle situated in the renal medulla at the junction with the renal cortex, while in the case of the juxtamedullary nephron the loop of Henle is located near the medulla but still within the cortex, hence the term ‘juxtamedullary’.
3
What is the structure of the juxtaglomerular apparatus (JGA) and how does this part of the kidney nephron help to control blood pressure and volume?
Answer: The JGA is composed of cells that are really best
described as modified smooth muscle cells. It is these cells that
produce the renin which is part of the rennin-angiotensin
system/network. Structurally, the JGA is composed of three
components:
Juxtaglomerular cells. These are the
modified smooth muscle cells that are located in the walls of the
afferent arterioles. Functionally they detect changes in blood
pressure and secrete the enzyme renin under the appropriate
stimulus.
Extraglomerular mesangial cells (Lacis
cells): These cells are flat cells that support the
JGA.
Macula densa cells: This area of the JGA is associated with the glomerulus because it loops back into the cortex, with the cells becoming taller and more densely packed. These cells are thought to detect sodium ion concentration changes within the distal convoluted tubule (DCT) and relay this to the juxtaglomerular cells.
Control of blood pressure in the juxtaglomerular apparatus involves the following:
- Lacis cells of the juxtaglomerular apparatus sense a decrease in blood pressure and secrete the enzyme renin.
- Renin circulates in the blood and converts circulating angiotensinogen to angiotensin I and then angiotensin II.
- Angiotensin II causes the cells of the adrenal cortex to release aldosterone, a hormone that acts on the DCT and the collecting duct of the kidney to retain more sodium and thus water.
4: multiple choice question.
Bladder epithelium is
composed of:
a) Stratified squamous epithelium
b) Transitional epithelium
c) Columnar epithelium
d) Ciliated columnar epithelium
Answer: (b)
5 What are the main types of pathology that can affect the kidney?
Answer:
Broadly speaking, kidney disease involves damage to, or some form of attack on, the functional unit of the kidney, the nephron. In chronic kidney disease the causative factors may include reaction to medicines (iatrogenic change), or a genetic defect that causes increased susceptibility to kidney problems; for example, the development of an autoimmune condition or a defined trauma that caused a direct injury to the kidney(s). More acute problems can be classified under a) cancer, b) stones, c) cysts, or d) infections