Exam 4: Urinary System Flashcards
functions of urinary system (primary and associated both have 2)
primary: fluid and electrolyte balance and excretion of metabolic waste (bilirubin, urea)
associated: pH regulation (H+ and bicarb) and endocrine function (RAAS, erythropoetin)
4 components of urinary system
paired kidneys
paired ureters
urinary bladder
urethra
function of kidneys
carry out all urinary functions
release urine to rest of system for excretion
function of ureters
use peristalsis to direct urine to the urinary bladder - goes around and enters at bottom of urinary bladder
function of urinary bladder
holds urine until triggered by stretch receptors to release contents into the urethra
release is controlled by both involuntary and voluntary sphincters
internal sphincter: smooth muscle, opens from stretch receptors
external sphincter: you have control over
function of urethra
excretes urine from body
o the male: path for sperm ejaculation
location of kidneys
retroperitoneally in abdominal cavity
-in abdominal cavity but parietal peritoneum goes over them, not behind them
kidneys themselves have capsule that protects them with loose CT over it infiltrated with adipose tissue to anchor them to the back wall of cavity
inside of kidney
outer cortex and inner medulla layer
cortical extensions coming from it - columns break it up into lobes
filtration units- nephrons
development of kidneys
develop as multiple lobes that fuse into one
nephron function and types
longer (juxtaglomerular) - for additional reabsorption to get volume down
medullary and cortical
all put filtrate into collecting tubes that deposit it into membranous center, renal pelvis
renal pelvis
has funnel like extensions that go down
shape of lobes of kidneys
come to point - renal pyramid
each point comes down to a minor calix
2 or more minor calices use into major calices with fuse into renal pelvis
sometimes if lots of filtrate with particulate it sits - can get stones if pH is off aggregates and kidney stone formation in any area where renal pelvis or calices are
urinary system pathway
kidney filters blood and concentrate urine
- can do for solute but if well hydrated concentration means dec in volume not solute
urine collected from kidneys is transported by ureters usinf peristalsis to the urinary bladder
urinary bladder temporarily holds urine until it is excreted through urethra
nephron
unit of filtration
each kidney has ~ 1 million nephrons
total filtration: 180L/day
urine production 1-2L/day
most are cortical (short)
10-15% are juxtamedullary nephrons
- these inc reabsorption
blood flow through kidney
aorta renal artery segmental artery interlobar artery arcuate artery cortical radiate artery
nephron
cortical radiate vein arcuate vein interlobar vein renal vein inferior vena cava
blood flow through nephron of kidney
arcuate arches over renal pyramid, cortical radiate artery and then afferent arteriole to the nephron - goes into capillary bed, glomerulus is where filtration occurs
then efferent arterioles go to another capillary bed that is plexus of many branches - peritubular capillary plexus - reabsorption
vasa recta
aka peritubular capillary plexus
takes in all the branches
renal corpuscle
filtration
glomerulus: capillary bed and bowman capsule that gather filtrate from capillary bed
glomerular filtrate comes out and forms the vasa recta
proximal convoluted tubules
reabsorbs nutrients (organics, ions, water - aquaporins) we want to keep from the filtrate, now known as tubular fluid
convoluted: bends backwards on itself, does a LOT of work
thicker areas: tube same size but walls are thicker
do not recapture urea
excretion of H+ !!
countercurrent Na+ in and H+ out
open channels: allow Na+ in
Na/K ATPase pump
throw bicarb out with some Na
nephron loop (loop of henle)
establishes osmotic gradient in renal medulla
promotes water reabsorption from tubular fluid in nephron system
ascending loop: passage of salt
descending loop: passage of water
ascending influences the descending
distal convoluted tubule
secretion and reabsorption
hormonally - ADH and aldosterone
if dehydrated can pull in more salt or let some go into collecting tubules into calices and then out
what is the primary force of filtration in the glomerulus
hydrostatic P that will overcome the oncotic P in blood
mesangial cells
supportive
involved in regulating glomerular filtration rate (GFR) and repairing damage
GFR less than 60 =
GFR less than 15 =
less than 60=renal disease
less than 15= renal failure
as GFR goes down, metabolic wastes are staying in the body
podocytes
specialized cells of glomerulus, wrap around blood vessel and give extra filtration, slits to go through
why should you be careful with certain medications, autoimmune crisis, cancer treatments, antibody antigen complexes
when lots of debris you have stuff coming through that normally would not
can damage podocytes, can get bigger openings and blood cells or large proteins going through
inflammation closing off area, hard to filter
actions of the loop of henle
set up an osmotic gradient through countercurrent flow and differential permeability btw the descending and ascending limbs
ascending limb
permeable to salt AND urea, NOT water
thick ascending limb in loop of Henle actions
- uses NKCC symporter to move ions from tubule
- Na/K ATPase pumps move Na into renal medulla/vasa recta
- antiporters exchange bicarb for Cl-
- K+ and Cl- passively move through facilitative diffusion
distal convoluted tubule (DCT) actions
impermeable to water
continues Na and bicarb reabsorption
secretes K+ and NH4+
produces hypo-osmotic filtrate; filtrate 100mOsmol, medulla 300mOsmol
collecting duct
contains ADH regulated aquaporins
depending on need to regulate aid or base:
-actively secretes H+
-antiport exchanger for Cl- and bicarbonate
ureters
take urine through peristalsis waves to be collected into the bladder
micturition (urination) reflex has 2 sphincters
internal and external
internal urinary sphincter
in smooth muscle, under parasympathetic control
external urinary sphincter
visceral striated, under voluntary control
when does the stimulus of stretch receptors begin
when bladder has 200ml
causes contractions in the detrusor muscle and continues with every 100ml increase
at 500ml the voluntary control is overridden and you will urinate
median umbilical ligament - urakus
remnant of umbilical
from midline of bladder right to the abdominal wall
on top of bladder this is the apex
