Renal Anatomy and Blood Supply Flashcards
What are the 3 functions in which the kidneys work?
- as excretory organs
- as regulatory organs
- endocrine organs
How do the kidneys function as excretory organs?
They ensure that those substances in excess or that are harmful are excreted in urine in appropriate amounts
How do the kidneys function as regulatory organs?
They maintain a constant volume and composition of the body fluids by varying the excretion of solutes and water
How do the kidneys function as endocrine organs?
They synthesize and secrete 3 hormones: renin, erythropoietin, and 1,25-dihydroxycholecalciferol
What are the 3 main regions of the kidneys in the sagittal section?
- the cortex is the outer region
- the medulla is the central region
- the papilla is the innermost tip of the inner medulla
What do the papillae empty into?
pouches called minor and major calyces
The minor and major calyces are extensions of what?
The ureter
What is the functional unit of the kidney?
The nephron
Each kidney contains approximately how many nephrons?
1 million
What does a nephron consist of?
A glomerulus and a renal tubule
What surround the glomerular capillaries?
the Bowman’s capsule
What are the 5 segments that comprise the renal tubule?
- the proximal convoluted tubule
- the proximal straight tubule
- the loop of Henle
- the distal convoluted tubule
- the collecting ducts
What is unique about the cells of the proximal convoluted tubule?
They have an extensive development of microvilli, called a brush border, on their luminal side
What is the function of the brush border?
It provides a large surface area for the major reabsorptive function of the proximal convoluted tubule
What are the 2 types of nephrons?
- superficial cortical nephrons
- juxtamedullary nephrons
Where do superficial cortical nephrons have their glomeruli?
In the outer cortex
Where do juxtamedullary nephrons have their glomeruli?
near the corticomedullary border
Which type of nephrons have higher filtration rates? Explain why
The juxtamedullary nephrons because their glomeruli are larger than those of the superficial cortical nephrons
Superficial cortical nephrons have ____ loops of Henle. Juxtamedullary nephrons have ____ loops of Henle.
short
long
Describe the path blood takes as it enters the kidneys
Blood enters via the renal artery, which branches into interlobar arteries, arcuate arteries, and then cortical radial arteries
What do the smallest arteries (cortical radial arteries) subdivide into?
The first set of arterioles, the afferent arterioles
Where do the afferent arterioles deliver blood to?
The first capillary network, the glomerular capillaries
What occurs across the glomerular capillaries?
ultrafiltration
Blood leaves the capillaries via what?
a second set of arterioles, the efferent arterioles
Where do the efferent arterioles deliver blood to?
To the secondary capillary network, the peritubular capillaries
What occurs across the peritubular arteries?
Solutes and water are reabsorbed into the from the nephron
Where does blood flow after exiting the peritubular arteries?
Into small veins and then into the renal vein
How does juxtamedullary nephron blood flood differ?
The peritubular capillaries have a specialization called the vasa recta, which are long, hairpin-shaped blood vessels that follow the same course as the loop of Henle
What do the vasa recta serve as?
Osmotic exchangers for the production of concentrated urine
