Microscopic anatomy of the urinary tract Flashcards
Water is actively pumped in the kidneys, true or false?
False
Briefly, how does water move in the kidneys?
Na is moved and water follows by osmosis
The _____ is the functional unit of the kidney
Nephron
What constitutes a nephron?
The Bowmans capusle, PCT, Loop of Henle, DCT, collecting tubules and ducts
Were do the collecting ducts drain to?
Renal pelvis
Where does urine pass after it enters the renal pelvis?
Ureter
Where does urine pass after the ureter?
Bladder
Where does urine pass after the bladder?
Urethra
What are the two different types of nephron?
Cortical
Juxtamedullary
What is the difference between cortical and juxtamedullary nephrons?
Cortical nephrons glomeruli are in the outer cortex, LOH only enters the outer medulla, whereas juxtamedullary nephrons have glomerulus in the inner cortex and LOH enter the inner medulla
The gross structure of the kidney is directly related to its appearance. The amount of _____ present in the medulla regions gives the variation in colour seen on histology and in life. The _____ medulla has th most tubules within, hence the darker colour, whereas the _____ has less, accounting for the paler colour.
Tubules
Outer
Inner
The greater the amount of nephrons in the kidney, the greater the _____ _____ for the exchange of fluid and the formation of urine.
Surface area
The glomerulus is also known as the _____ _____.
Renal corpuscle
The glomerulus is a vascular tuft or capillary bundle that enters the _____ _____.
Bowmans capsule
Outline the blood supply of the glomerulus.
Afferent arteriole to the glomerulus
Exits via efferent arteriole
Passes to the peritubular capillaries (i.e. surrounding the PCT, LOH and DCT)
What structure results in the fenestrations seen on the surface of the glomerulus?
Podocytes
What is the function of the podocytes covering the glomerulus?
Prevents proteins from leaving the blood, ensures filtration of fluids only
What makes up the visceral layer of the Bowmans capsule?
The podocytes covering the glomerulus.
What makes up the parietal layer of the Bowmans capsule?
Epithelial cells
The glomerulus is made up of lots of parallel capillaries with lots o interconnections, true or false?
True
Where are the glomeruli found within the kidney?
The cortex
Exchange of substances between the peritubular capillaries and the _____ _____ are important in determining the concentration and volume of _____.
Collecting ducts
Urine
What structure do the peritubular capillaries empty into?
Venules
What structure do the peritubular capillaries empty into?
Venules
What is the spaces between the two layers of the Bowmans capsule called?
Urinary space or Bowmans space
What are the peritubular capillaries that follow the course of the LOH in juxtamedullary nephrons called?
Vasa recta
What cells are found between the endothelium and basal lamina of capillaries of the glomerulus?
Mesangial cells
What are the three main properties of mesangial cells?
1.
2.
3.
Contractile smooth muscle cells
Immune functions
Structural support
How can mesangial cells influence the diameter of the glomerular capillaries, rate of blood flow through the glomerular capillaries and filtration rate?
They can contract, increasing the diameter of the capillaries, thus increasing flow rate and filtration rate
How do mesangial cells contribute to immune functions?
They can take up immune complexes and participate in inflammatory processes through the production of cytokines and phagocytose foreign material to help clean the glomerular basal lamina
What makes up the filtration apparatus in the nephron?
Fenestrated capillary endothelium
Glomerular basement membrane
Podocytes
The fenestrations in the endothelium allow fluids and ions to pass through, but not _____
Cells
The glomerular basal lamina is made up of collagen and glycoprotein fibres restricts the passage of _____ _____.
Plasma proteins
Podocytes are found within the inner epithelial layers of the Bowmans capsule. They are in contact with the _____ _____.
Basal lamina
Anions are not able to pass into the filtrate because the basal lamina of the glomerulus is _____ _____.
Negatively charged
Outline the three different stages fluid in the glomerular capillaries have to pass through to get to the urinary space.
1.
2.
3.
Through the fenestrations in the endothelial cells of the capillaries
Through the basal lamina of the capillaries
Through the spaces between the pedicels of the podocytes
Podocytes have primary and secondary process known as _____ that act as filtration slits.
Pedicles
The PCT is very _____ as lots of pumping of solutes and solution occurs here.
Active
Name the two different segments of the PCT.
Convoluted (S1 and S2)
Straight (S3)
In what region does the majority of transport of materials occur?
PCT
Why are there lots of different mitochondria present in this region?
Very active region that uses oxidative process for the transport of materials to occur
What structures aids bulk absorption in the PCT?
Brush border cells
Basal striations
How does a brush border aid in bulk absorption?
Increases the SA for absorption