Renal Anatomy & Microanatomy Flashcards
urinary system
*involves the organs responsible for producing, storing, and excreting urine
*includes: kidneys, ureters, urinary bladder, & urethra
kidneys - overview
*filter the blood, removing water and most small molecules (sodium, potassium, glucose), then reabsorb the water & molecules that are needed for homeostasis
*sit at about T12 (left) and L3 (right)
*retroperitoneal structures
renal capsule - overview
*outer layer of the kidneys
*made up of fibrous connective tissue that gives the organ a smooth, firm surface
ureters - overview
*tubular, smooth muscle-lined structures
*connect the kidneys to the urinary bladder
*begin at the hilum of the kidneys and descend anteriorly to the psoas muscles before crossing the common iliac vessels to enter the pelvis; connect to the posterior wall of the urinary bladder
urinary bladder - overview
*a muscular structure that receives urine from the 2 ureters, stores it, then expels it during coordinated micturition
urethra (males) - overview
*an opening in the bladder neck inferiorly connects to the urethra, which carries the urine to the outside
*male urethra divided into segments: preprostatic, prostatic, membranous, penile (spongy)
*opens at the urethral meatus
urethra (females) - overview
*an opening in the bladder neck inferiorly connects to the urethra, which carries the urine to the outside
*female urethra is very short and promptly exits anterior to the vaginal opening
gross anatomy of the kidney
- renal cortex - location of most nephrons
- renal medulla - cortical nephrons dip into slightly; medullary nephrons travel through
- renal pelvis - contains draining structures that ultimately flow into the ureter, plus renal artery & vein
cortical vs. juxtamedullary nephrons
*85% of nephrons are cortical (loop of henle dips slightly into the medulla)
*15% of nephrons are juxtamedullary (loop of henle dips far into medulla; important for production of concentrated urine)
segments of the nephron
- glomerular capillaries & bowman’s space
- proximal convoluted tubule (PCT)
- proximal straight tubule
- thin descending limb (of loop of henle)
- thin ascending limb (of loop of henle)
- thick ascending limb (of loop of henle)
- macula densa
- distal convoluted tubule (DCT)
- connecting tubule
- cortical collecting duct
- outer medullary collecting duct
- inner medullary collecting duct
vasculature of the glomerulus
*glomerulus is fed by an afferent arteriole, which drains into glomerular capillary tuft, then back into an efferent arteriole, which gives rise to some of the capillaries (peritubular or vasa recta)
*major site of regulation of renal blood flow (constriction or dilation of afferent/efferent arterioles)
path of blood flow through renal blood vessels
aorta → renal artery → segmental artery → interlobar artery → arcuate artery → cortical radiate artery → afferent arteriole → glomerulus (capillaries) → efferent arteriole → peritubular capillaries or vasa recta → cortical radiate vein → arcuate vein → interlobar vein → renal vein → inferior vena cava
effects of arteriolar diameter change on filtration
*constriction of afferent arteriole → decreased glomerular filtration rate (GFR), decreased renal blood flow
*constriction of efferent arteriole → increased glomerular filtration rate (GFR), decreased renal blood flow
anatomy of the glomerulus/Bowman’s capsule
*afferent arteriole feeds blood into glomerular capillaries, then the blood continues into the efferent arteriole
*glomerular capillaries are surrounded by Bowman’s Capsule
*Bowman’s Capsule is a thin layer of cells in which the filtrate enters, then drains into the PCT
filtration membrane - components
- glomerular capillary endothelium (with fenestrations)
- glomerular basement membrane (type IV collagen)
- foot processes of podocyte of glomerular capsule
note - filtration membrane is negatively charged, and the size of molecules matters (smaller molecules enter the filtrate, while larger molecules are retained in the plasma)
