Module 5: Renal/Urinary system Flashcards
how much percent of males is water
60%
how much percent of females is water
55%
extracellular fluid makes how much of TBW
1/3
intracellular fluid makes how much of TBW
2/3
how much blood flows through the kidneys every minute
1200mL
how much urine does a person produce daily
800-2000mL
what is urine
waste product excreted to maintain balance within the body
what makes up normal urine
water, salts, metabolites and small proteins
what is found in abnormal urine
large proteins, RBCs, glucose
main components of the urinary system are
2 kidneys, 2 ureters, urinary bladder and urethra
the structure of the kidney allows for
blood to be brought in close proximity to the nephron for filtering, allows blood to leave the kidney and a pathway for urine to be stored and excreted
where are the kidneys located
between T12-L3 vertebrae
what passes through the hilum
blood vessels, lymphatics, nerves and ureter
what gland sits on top of the kidney
adrenal
retroperitoneal means
located on posterior abdominal wall covered on anterior side by peritoneum
three regions of the kidney
cortex, medulla and pelvis
what is the protective layer of the kidney
fibrous capsule
the inner medullar is divided
into pyramids and each pyramid ends in a papilla
the outer cortex is
a continuous layer and contains renal columns
how many lobes are in each kidney
5-11
a kidney lobe contains
one pyramid and all the cortex that surrounds it
kidney lobes are mainly made from
approx 1 million nephrons
function of nephrons
filter blood and create urine
urine travels–>
papilla–> minor calyx–> major calyx–> renal pelvis–> ureter
function of afferent arteriole in nephron
deliver blood from the arteries to the glomerulus
what is the glomerulus made of and what is it function
glomerular capillaries and is the site of filtration
function of efferent arteriole in nephron
carries blood from the glomerulus to the peritubular capillaries
function of peritubular capillaries
allow us to change our mind of what we want filtered and reabsorb stuff we want back in the blood which carry blood to veins
flow of blood from the cortex to be filtered
abdominal aorta–> renal artery–> series of arteries–> afferent arteriole–> glomerular capillary
flow of blood away from the cortex after being filtered
glomerular capillary–> efferent capillary–> peritubular capillaries–> series of veins–> renal vein–> inferior vena cava
nerve supply in kidneys
innervation is from a network of autonomic nerves and ganglia called the renal plexus
nephron is
microscopic functional unit of the kidney
renal corpuscle
where blood and nephron meet/ site of filtration
proximal convoluted tubule
close to renal corpuscle and wiggly
nephron loop
loop at bottom of nephron
distal convoluted tubule
further away from renal corpuscle and wiggly
collecting duct
runs down and papilla’s connect to it
types of nephron
cortical and juxtamedullary
what nephron is the most abundent
cortical (85%)
where do cortical nephrons mainly lie
cortex
function of juxtamedullary nephron
extend deep into medulla and are important for the formation of concentrated urine
each nephron is comprised of
a glomerular capsule, renal tubules and a collecting duct
structure of glomerular capillaries
thin walled single layer of fenestrated endothelial cells
what are vasa recta and where are they found
extensions that follow nephron loop deep into the medulla only found within juxamedullary nephron
the renal corpuscle contains
glomerulus enclosed by the glomerular capsule and is where capillary and nephron meet and is the site of filtration
two layers of the glomerular capsule
outer parietal layer of simple squamous cells and inner visceral layer of podocytes
podocytes
surround the glomerular capillaries which have branches called pedicels
function of pedicels
filtration slits that filter blood
filtration barrier is also known as
the blood-urine barrier or glomerular capsular membrane
what does the blood-urine barrier allow free passage of
water and small molecules
what does the filtration barrier restrict passage of
proteins and RBCs
three layers of the filtration barrier from blood side to nephron side
fenestrated endothelium of glomerular capillary, fused basement membrane and filtration slits between the pedicels of the podocytes
urine=
filtered- reabsorbed + secreted
function of PCT
bulk reabsorption
structure of PCT
cuboidal epithelial, dense microvilli, highly folded basolateral mitochondria and leaky epithelium
function of nephron loop
length is important in production of dilute/ concentrated urine
structure of thick descending limb
like PCT
structure of thin descending limb
simple squamous epithelium
structure of thin ascending limb
simple squamous epithelium
structure of thick ascending limb
like DCT
function of DCT
fine tuning- not bulk reabsorption
structure of DCT
cuboidal epithelium but thinner than PCT, few microvilli, few mitochondria
reabsorption in DCT is regulated by
aldosterone
function of collecting duct
fine tuning- filtrate from several DCTs drain into one collecting duct
structure of collecting duct
wall of simple cuboidal epithelium, principal cells, intercalated cells
principal cells
reabsorption
intercalated cells
acid/base balance
reabsorption in collecting duct is regulated by
ADH and aldosterone
Juxtaglomerular apparatus
specialised zone in every nephron
where is the JGA located
where DCT lies against afferent arteriole
Macula densa cells
chemoreceptors detect sodium levels
juxtaglomerular cells
mechanoreceptors detect stretch therefore blood pressure
transitional epithelium
stratified, round cells which flatten when stretched
function of transitional epithelium
protection
how is urine moved into bladder
peristaltic waves
three layers of ureter from inner to outer
transitional epithelium, muscularis (inner longitudinal and outer circular), adventitia
transitional epithelium
found anywhere that needs extra protection
adventitia
outer covering of fibrous connective tissue
ureters can act as a ___ : compressed by ___ bladder pressure to prevent ___
sphincter; increased; backflow
function of bladder
collapsible muscular sac that stores and expels urine
ureters
carry urine from kidneys to bladder
bladder wall
contains muscle for expulsion of urine
rugae
folds that allow bladder to expand
trigone
triangular region between 2 openings of entry of ureters and 1 opening for urethra
urethra
carries urine out of bladder
description of empty bladder
pyramidal and lies within the pelvis
description of filling–> full bladder
becomes more spherical and expands superiorly
location of bladder in males
anterior to rectum and superior to prostate gland
location of bladder in females
anterior to vagina and uterus
thick smooth muscle layer in bladder
detrusor
urethra epithelium changes
transitional near bladder, columnar then stratified squamous near external opening
internal urethral sphincter
junction of bladder and urethra, involuntary
externa urethral sphincter
located where urethra passes through the urogenital diaphragm, voluntary control
urination
bladder fills with urine and expands, AP from stretch receptors to brain, signal increases with urgency, internal sphincter relaxes we need to consciously relax external sphincter
glucose in urine is a signal of
diabetes
protein in urine is a signal of
broken filtration barrier
blood in urine is a signal of
UTI
kidney failure/ disease
hyperkalaemia
what is the main buffer of the blood neutralising acids from metabolism
bicarbonate
how is bicarbonate concentration controlled
by the lungs exhaling CO2 and kidneys reabsorbing bicarbonate and secreting hydrogen ions
filtration in nephron
creates a plasma-like filtrate of blood
reabsorption in nephron
removes useful solutes from the filtrate and returns them back to the blood
secretion in nephron
adds additional wastes from the blood to the filtrate
four forces/ pressures determining net filtration pressure
glomerular hydrostatic pressure, blood colloid osmotic pressure, capsular hydrostatic pressure, capsular colloid osmotic pressure
favouring forces are
glomerular hydrostatic pressure, blood colloid osmotic pressure
opposing forces are
capsular hydrostatic pressure, capsular colloid osmotic pressure
glomerular hydrostatic pressure
blood pressure (+50mmHg)
blood colloid osmotic pressure
albumin (-25mmHg)
capsular hydrostatic pressure
corpuscle embedded in tissues (-15mmHg)
capsular colloid osmotic pressure
no protein in capsular space (0mmHg)
net filtration pressure
(10mmHg)
clearance of a substance
S
Clearance =
concentration of S in urine x volume of urine produced per unit time / concentration of S in plasma
Cs=
Us x V / Ps (mL/min)
GFR
glomerular filtration rate
GFR is
the amount of fluid filtered per unit time
Inulin
polysaccharide not metabolised by body-sugar–> not found in body but has to be injected
Creatinine
waste product produced by muscles already in body so most commonly used clinically
plasma creatinine is low if
both kidneys are working
plasma makes up how much of the ECF
1/5
interstitial fluid makes up how much of the ECF
4/5
tonicity is based on
the effect of the solution on cells
how much of sodium chloride foes back into blood
99%
how much sodium reabsorption occurs in the PCT
67%
how much sodium reabsorption occurs in the TAL
25%
how much sodium reabsorption occurs in the DCT
5%
how much sodium reabsorption occurs int he CD
3%
water is reabsorbed in the
thick descending limb
in a hypertonic solution cells
shrivel
in an isotonic solution cells
remain the normal shape
in a hypotonic solution cells
swell
hormone released from posterior pituitary
ADH
ADH synthesis
in cell body of central neurons (hypothalamus) , axonal transport to posterior pituitary
ADH release
in posterior pituitary and into bloodstream
major stimuli for release of ADH
increased ECF osmolarity and decreased blood volume
obligatory water reabsorption
not regulated, accounts for 92% of total water reabsorption
facultative water reabsorption
tight epithelia, only transcellular, regulated by ADH, accounts for 2-8% of total water reabsorption
diuresis
large amount of urine
antidiuresis
not a lot of urine produced
