ANAPHY LEC Flashcards
What is the Urinary System?
What are the Organs of the Urinary System?
Kidneys
Ureters
Urinary Bladder
Urethra
Location and Dimension of the Kidneys.
Dimensions
Reddish-brown, bean shaped
12cm long, 6cm wide, 3cm thick
High on posterior abdominal wall
at the level of T12 to L3- superior lumbar region
Retroperitoneal & against the dorsal body wall
The right kidney is slightly lower than the left, convex laterally
Attached to ureters, renal blood vessels, and nerves at renal hilus (medial indention)
Atop each kidney is an adrenal gland
What is the Adipose Capsule?
Surrounds the kidney
Provides protection to the kidney
Helps keep the kidney in its correct location against muscles of posterior trunk wall
Ptosis-kidneys drop to a lower position due to rapid fat loss, creating problems with the ureters.
Ptosis can lead to hydronephrosis, a condition where urine backs up the ureters and exerts pressure on the kidney tissue.
What is the Renal Capsule?
Surrounds each kidney
What is the Renal Cortex?
outer forms an outer shell
What are Renal Columns?
extensions of cortex material inward
What is the Renal medulla?
inside the cortex, contains medullary (renal) pyramids
What are the Medullary Pyramids?
triangular regions of tissue in the medulla, appear striated
What is the Renal Pelvis?
inner collecting tube, divides into major and minor calyces.
What are Calyces?
cup-shaped structures enclosing the tips of the pyramids that collect and funnel urine towards the renal pelvis
What are the functions of the Urinary System?
Elimination of waste products
filtering gallons of fluid from the bloodstream every day creating “filtrate”
“filtrate” includes: metabolic wastes, ionic salts, toxins, drugs
Maintenance of the circulation
Red blood cell production- by producing hormone erythropoietin to stimulate RBC production in bone marrow
Blood pressure (vessel size)- by producing renin which causes vasoconstriction
Blood volume (water balance)- ADH released from Anterior Pituitary targets the kidney to limit water loss when blood pressure decreases or changes in blood composition
Blood composition (electrolyte balance)- water follows salt; aldosterone reclaims sodium to the blood
Blood pH- regulates H+ ions and HCO3- ions
Blood Flow in the Kidneys
Rich blood supply to filter blood and adjust blood composition
~¼ of blood supply passes through the kidneys each minute
Blood enters the kidneys under extremely high pressure
Renal artery arises from abdominal aorta, divides into Segmental artery at hilus
Inside renal pelvis, Segmental artery divides into Lobar artery, which branch into Interlobar artery travelling thru the renal column to reach the renal cortex
At the medulla-cortex junction, the Interlobar artery curves over the medullary pyramids as the Arcuate artery.
Small Interlobular arterioles branch off of the Arcuate artery and move away from the renal cortex and into the Nephron of the kidney
The final branches of the interlobular arteries are called afferent arterioles.
Afferent arterioles lead to the glomerulus, a network of capillaries that are involved in filtration.
Leading away from the glomerulus, blood less filtrate travels through the efferent arterioles and into the peritubular capillaries.
From there, blood moves through similar veins that parallel the arteries at their respective locations.
In simple terms, illustrate the blood flow in the kidneys.
Aorta - Renal Artery - Segmental Artery - Lobar Artery - Interlobar Artery - Arcuate Artery - Interlobular Artery - Afferent Arteriole - Glomerulus Capillaries - Efferent Arteriole - Peritubular capillaries - Interlobular vein - Arcuate vein - Interlobar vein - Renal vein - Inferior Vena Cava
What is a Nephron?
The structural and functional units of the kidneys
Over 1 million
Responsible for forming urine
Consist of renal corpuscle and renal tubule
Renal corpuscle composed of a knot of capillaries called the Glomerulus (a.k.a. Bowman’s Capsule)
Renal tubule- enlarged, closed, cup-shaped end giving rise to the PCT, dLOH, aLOH, DCT, and CD.
What is the Glomerulus?
A specialized capillary bed fed and drained by arterioles.
Glomerular capillaries filter fluid from the blood into the renal tubule
Capillaries attached to arterioles on both sides in order to maintain high pressure
Large afferent arteriole-arises from interlobular artery (feeder vessel); large in diameter, high resistance vessels that force fluid & solutes (filtrate) out of the blood into the glomerular capsule.
Narrow efferent arteriole-merges to become the interlobular vein; draining vessel.
Glomerular capillaries are covered with podocytes from the inner (visceral) layer of the glomerular capsule.
Podocytes have long, branching processes called pedicles that intertwine with one another and cling to the glomerular capillaries.
Filtration slits between the pedicles form a porous membrane around the glomerular capillaries.
The glomerular capillaries sit within a glomerular capsule (Bowman’s capsule)
Expansion of renal tubule
Receives filtered fluid
Renal tubule coils into the PCT, then the dLOH, aLOH, DCT and finally, the CD.
Along the PCT, much of the filtrate is reclaimed