Urinary System Flashcards
components of the urinary system
kidneys, ureters, urinary bladder and urethra
blood supply to the kidneys
25% of total blood pumped by the heart goes to the kidneys at rest
- need such a large blood supply because the kidneys filter the plasma, returning most water and solutes to the bloodstream
functions of the kidneys
excretion regulation of blood volume and pressure regulation of solute concentration in blood regulation of pH regulation of RBC synthesis vitamin D synthesis
excretion as a function of the kidneys
urea
urobillin (a waste product from the heme group of RBC)
toxins
drugs and waste products
regulation of blood volume and pressure as a function of the kidneys
flow=pressure/resistance
so if you have a greater volume of blood, BP increases and causes flow to increase.
thus, when you decrease blood volume (by removing fluids) you also decrease BP
regulation of solute concentration in the blood as a function of the kidneys
regulates solute concentration of ions such as Na+, K+, Cl-
regulation of pH as a function of the kidneys
H+ ion balance is regulated in the kidneys
they work with the bicarbonate system to regulate blood pH
regulation of RBC synthesis as a function of the kidneys
erythropoietin, the hormone responsible for RBC synthesis, is produced in the kidney
vitamin D synthesis as a function of the kidneys
active form of vitamin D is created by kidneys and aids in calcium absorption from the gut into the blood
where are the kidneys found in the body
- they are positioned above the wait
- are retroperitoneal, protected by 11th and 12th floating ribs
- right kidney is slightly lower than the left because the liver is located predominantly on the right side
3 layers of CT that surround the kidney
(superficial to deep)
- peritoneum on anterior and lateral sides of kidney
1. renal fascia
2. adipose capsule
3. renal capsule
renal fascia
- most superficial layer around the kidney
dense irregular CT layer that connects the kidney to abdominal cavity and other organs on the abdominal wall
adipose capsule (CT layer around kidney)
middle layer of protection
- might be thicker in obese people
- surrounds entire kidney, cushions with essential fat
renal capsule
innermost layer of protection around the kidney
- surrounding dense irregular CT that gives strength in many directions
- maintains and gives kidney its bean shape and holds everything together
renal hilum
medial curved part of kidney where blood vessels and ureters enter/exit the kidney
renal cortex
the part of the kidney close to the outside
- some dips down towards hilum called the renal column
renal column
parts of renal cortex that dip down between pyramids
renal medulla
highly organized into pyramids that are cone shaped structures on the inside of the kidney (deep to cortex)
- a person has 8-18 pyramids
- larger portion is the base of the pyramid, apex is called the renal papilla
nephron
functional portion of the kidney where filtration happens
- highly supplied with blood
- long tube, most of it located in cortex, loop runs into medullary region
- most filtrate produced in 1st portion of the nephron
path of urine drainage in the kidney
collecting duct > papillary duct > minor calyx > major calyx > renal pelvis > ureter > urinary bladder
renal lobe
functional unit of the kidney that produces urine, incl the cortex and medulla surrounding a pyramid
blood supply of the kidney
renal artery > segmental arteries > interlobar arteries > arcuate arteries > cortical radiate arteries > afferent arterioles > glomerular capillaries > efferent arterioles > peritubular capillaries > cortical radiate veins > arcuate veins > interlobar veins > renal vein
renal sinus
region where renal artery starts branching and smaller veins merge to become renal vein
vasa recta
carries mixed oxygenated and deoxygenated blood
- highly organized capillaries in medullary cavity surrounding the loop of Henle in the nephron
glomerulus
a bunch of capillaries that form a ball/network where filtrate is produced when blood passes through (lots of surface area here)
- pulls about 20% of plasma from blood
- endothelial cells are fenestrated here
parts of the nephron
2 parts:
renal corpuscle
renal tubule
renal corpuscle
- located in cortex, is the site of plasma filtration where glomerular filtrate is produced
- includes the glomerulus, and Bowman’s (glomerular capsule which catches filtrate)
renal tubule
- conveyor belt idea where it picks and chooses what to keep and add 3 portions: - proximal convoluted tubule - nephron loop - distal convoluted tubule
proximal convoluted tubule
first part of renal tubule
- located in cortex, comes off of renal corpuscle
- very bendy, giving lots of SA
- reabsorbs about 65% of what gets dumped into the tubule
nephron loop
aka loop of Henle
- dips down into medulla and comes back into the cortex
distal convoluted tubule
last part of renal tubule
- bendy, also found in cortex
collecting ducts
where distal convoluted tubules all join together
papillary ducts
reach papillary region and drip urine into minor calyx
types of nephrons
2 types:
cortical nephron
juxtamedullary nephron
cortical nephron
80-85% of nephrons
- most of nephron found in cortex
- corpuscle is closer to CT outer part of cortex
- shorter loop of Henle, with ascending and descending limbs of equal thickness
- blood supply to the loop is via peritubular capillaries which aren’t very organized
juxtamedullary nephron
15-20% of nephrons
- means beside medullary region
- corpuscle located near medulla in cortex close to the base of the pyramid
- long nephron loop that runs from the base of pyramid to papilla and back again
- loops ahs descending and thin (1st half) and thick (2nd half) ascending limbs
- can produce dilute or concentrated urine dependant upon the concentration gradient that in generates
podocytes
modified simple squamous cells that adhere to glomerulus
- have projections called pedicels which form a sieve like pattern for filtration
pedicels
the projections on podocytes
capsular space
where glomerular filtrate accumulates
glomerular capillaries
arise from afferent arterioles and from a ball before emptying into the efferent arteriole
- the blood is essentially the same, just with 20% less plasma in it
juxtaglomerular apparatus
- structure where afferent arteriole make contact with the ascending limb of the nephron loop
- helps regulate BP in kidneys
- components include macula densa, and juxtaglomerular cells
macula densa
thickened part of the ascending limb
- monitor water and ion concentrations in filtrate
- if we need to change this, they send a signal to juxtaglomerular cells when too much water is being release in the filtrate
juxtaglomerular cells
modified smooth muscle cells in afferent arteriole which contract when they get a signal from the macula densa that we are losing too much fluids
mesangial cells
are in contact with afferent and efferent arterioles and some are in contact with capillaries
- change SA of arterioles by constricting when losing too much fluids, thus less filtrate gets made
layers of the filtration membrane and what they filter
3 layers:
- fenestration of glomerular endothelial cell: filter RBC, WBC and platelets, allowing components of plasma to pass through
- basal lamina of glomerulus: prevents filtration of large proteins
- slit membrane b/w pedicels: prevents filtration of medium proteins
cell type found in proximal convoluted tubule (PCT)
simple cuboidal with brush border microvilli
cell type found in descending limb and thin ascending limb of nephron loop
simple squamous, allow free movement of things along their concentration gradients
- lots of water absorbed back into blood here
cell type found in thick ascending limb of nephron loop
simple cuboidal to low columnar
- highly regulate what moves through
cell type found in distal convoluted tubule (DCT) - only in the first part
simple cuboidal
- highly selective
cell type found in last part of DCT and collecting duct
simple cuboidal and some specialized cells mixed in that are regulated by hormones (principal and intercalated cells)
principal cells
help regulate pH
- found in last part of DCT and CD
- activity regulated by hormones
intercalated cells
help regulate blood volume through movement of Na+, K+
- found in last part of DCT and CD
- activity regulated by hormones
