Human Kidneys Flashcards
What are the three layers on the outside of the kidneys?
- Renal Capsule
- Adipose Capsule
- Renal Fascia
What is the renal capsule and its function?
It is the outermost layer of the kidney, formed by connective tissue adhering to the outside of the kidney
It forms a physical barrier around the kidney, as well as maintaining the shape of the kidneys
What is the adipose capsule and its function?
It is padding surrounding the renal capsule, providing physical protection and maintaining the position of the kidneys in the body
What is the renal fascia and its function?
It is a connective tissue layer that anchors the kidney to surrounding structures
How does the kidney interact with blood?
It collects the fluid (filtration), and changes the composition of the fluid, selectively returning some substances to the blood, others to body fluid, and the rest into urine.
Why is the kidney multilobar?
It contains many lobes
What is the layer deep to the renal capsule?
The renal cortex
What are the renal columns?
Extensions of the cortex + fat, separating the medullary pyramids
What is the medulla?
The layer of the kidney deep to the renal cortex
What is the papilla?
The tip of the pyramid formed by the medullary pyramids. They are attached to the minor calyces
What forms a lobe within the kidney?
The medullary pyramid, its ortex and half of each renal column
How many lobes are there in the kidney?
8-12
What is interlobar?
The area between lobes of the kidney
How is the medulla broken up?
Into small cones- all together they look like bunches of flowers. These are called medullary pyramids
What is the functional unit of the kidney?
The nephron
How many nephrons are there in a kidney?
Approx. 1 million
Where do nephrons empty into?
The collecting duct
Where do collecting ducts empty into?
The papillary duct
Where is the papillary duct?
The tube within the papilla of the medullary pyramid
Where do papillary ducts empty into?
The minor calyces
Where do the minor calyces enter into?
The major calyces
Where do the major calyces enter into?
The pelvis
Where does the pelvis continue?
Through the ureter to the urinary bladder
What are lobules?
Miniature lobes within the renal cortex and medulla
Where are blood vessels in the kidneys?
The enter the renal artery and vein, the renal columns, the renal cortex and between lobules
What is the pathway of blood through the kidneys?
O2 blood—> Renal Artery –> Interlobar arteries –> arcuate arteries –> interlobular arteries –> Afferent Arterioles –> glomerular capillaries –> efferent arteriole –> (Descending vasa recta –> peritubular capillaries of the medulla –> Ascending vasa recta) OR )Peritubular capillaries of the cortex) —> Interlobular vein –> arcuate vein –> interlobar vein –> Renal vein –> DeO2 blood
What is the renal hilum?
The region of the kidney where many blood vessels enter and exit
What defines a lobule?
The area between an interlobular artery and vein
What are the 2 pathways the blood in an efferent arteriole can take?
The vasa recta pathway, or go to the peritubular capillaries of the cortex
What is the function of the descending vasa recta?
Supports the tubular portion of the renal medulla with Oxygen
What is the function of the peritubular capillaries of the medulla?
Supplies the hoop of henle with Oxygen
What is the parenchyma?
The functional portion of the kidney
What are juxtamedullary nephrons?
Nephrons extending into both the cortex and the medulla
What is the progress of ‘urine’ from glomerular capsule to to minor calyx?
Glomerular capsule –> Proximal Convoluted tubule –> Thick descending loop of henle –> Thin descending loop of henle –> Thin ascending loop of henle–> thick ascending loop of henle –> Distal convoluted tubule –> collecting duct –> papillary duct –> minor calyx
What parts of the nephron are in the medulla vs. the cortex?
Cortex: Proximal convoluted tubule, renal corpuscle, distal convoluted tubule
Medulla: Thick and thin ascending and descending loops of henle, papillary duct
Both: Collecting duct
What makes up the renal corpuscle?
Glomerulus
Glomerular capsule
What is the glomerulus?
A specialized know of capillaries, formed of endothelium. It is found inside the glomerular capsule
What is the glomerular capsule?
AKA bowman’s capsule
Has 2 parts:
- Visceral: Podocytes
- Parietal: forms the outer wall of the capsule in simple squamous epithelium, continuous with the rest of the nephron
What are podocytes?
Specialized epithelial cells with interlocking foot processes. They are continuous with the parietal layer of the glomerular capsule
What is the hollow group of cells between the afferent and efferent arterioles?
The distal convoluted tubule, able to give feedback about filtrate composition. Its layer of cells closest to the renal corpuscle are the macula densa, the cells just beyond that are mesanglial cells, while a circle of cells surrounding the arterioles are the granular cells.
What is notable about the cells of the proximal convoluted tubule?
It contains cells with microvilli to increase the surface area available for the reabsorption of nutrients and electrolytes before they reach the loop of henle.
What makes up the filtration membrane of the renal corpuscle?
Fenestrations in glomerular (capillary) cells
Basal lamina between both
Slit membrane between pedicels
What are pedicels?
Foot-like processes of the podocytes that are interdigitated.
How does the fenestrated capillary membrane help filtration in the kidneys?
It permits all sizes of proteins through, but not cells
How does the basal lamina of the renal corpuscle help filtration in the kidneys?
It permits medium and small proteins through, but not large proteins.
It isn’t uniform, and is formed by the combination of the basement membrane of the endothelium and podocytes
How does the slit membrane between the pedicels help filtration in the kidneys?
It allows small proteins through, but not medium proteins.
What is the overall purpose of the filtration membrane in the kidneys?
It allows gradation of filtrates, with only small proteins and molecules getting through into the filtrate. This allows much of the necessary plasma components to remain in the blood, while preventing clogging
What happens to the plasma components not allowed through the filtration membrane?
They make their way back into the blood.