Urinary System Flashcards
(104 cards)
1
Q
major excretory organs
A
kidneys
also lungs and skin participate
2
Q
main functions of the kidney
A
- filter 180-200L of blood daily to allow toxins, wastes, and excess ions to leave the body as urine
- regulate blood volume and chemical make up
- water and salt balance, and acid base balance
3
Q
other renal functions
A
- gluconeogenesis- during prolonged fasting glucose is made from glycerol and amino acids; happens in kidney cortex
- rennin production- help regulate bp and erythropoietin to stimulate RBC production
- Activation of vitamin D
4
Q
urinary bladder
A
provides a temporary storage reservoir for urine
5
Q
paired ureters
A
transport urine from the kidneys to the bladder
6
Q
urethra
A
transports urine from bladder to outside the body
7
Q
external anatomy of the kidney
A
- right kidney is lower than the left because it is crowded by the liver
- lateral surface is convex, medial surface is concave
- the renal hilum leads to the renal sinus cont calyces and renal pelvis
- ureters, renal bv, lymphatics, and nerves enter/exit at the hilum
8
Q
renal/fibrous capsule
A
fibrous capsule that prevents kidney infection
9
Q
perirenal fat/adipose capsule
A
fatty mass that cushions the kidney and helps it attach to the body wall
also for energy
if kidneys lose this fat they can fall and compress the ureter backing up urine causing ptosis
10
Q
renal fascia
A
outer layer of dense fibrous CT that anchors the kidney
11
Q
internal kidney anatomy
cortex
A
light colored granule superficial region
most vascularized region of the kidney
12
Q
internal kidney anatomy
medulla
A
exhibits cone shaped medullary (renal) pyramids separated by columns
the medullary pyramid and its surrounding capsule constitute a lobe
13
Q
internal kidney anatomy
major calyces
A
large branches of the renal pelvis
collect urine draining from the renal papillae
empty urine into renal pelvis
14
Q
internal kidney anatomy
renal pelvis
A
flat funnel shaped tube lateral to the hilum within the renal sinus
15
Q
internal kidney anatomy
minor calyces
A
branches of the major calyces that collect urine formed in the papilla draining from the medullary pyramid
16
Q
amount of the cardiac output that flows through the kidneys each minute
A
1/4 (1200mL) of systemic cardiac output
17
Q
nerve supply to the kidney
A
renal plexus-sympathetic nerves
18
Q
renal vascular pathway
A
aorta—renal artery—segmental artery—interlobar artery—arcuate artery—cortical radiate artery—afferent arteriole—glomerulus capillaries—efferent arteriole—peritubular capillaries and vasa recta—cortical radiate vein—arcuate vein—interlobar vein—renal vein—inferior vena cava
19
Q
nephron
A
structural and functional units that form urine
consist of a glomerulus and renal tubules
20
Q
glomerulus
A
tuft of capillaries associated with a renal tubule
21
Q
renal tubules
A
made of the glomerular capsule, PCT, DCT, and loop of henle
22
Q
renal corpuscle
A
the glomerulus and its bowmans capsule
23
Q
anatomy of the renal corpuscle
glomerular epithelium
A
fenestrated epi
allows solute rich virtually protein free filtrate to pass from the blood into the glomerular capsule
24
Q
anatomy of the renal corpuscle
glomerular/bowmans capsule
A
blind cup shaped end of a renal tubule that completely surrounds the glomerulus
25
glomerular/bowmans capsule
| external parietal layer
simple squamous epithelium
| is a structural layer
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glomerular/bowmans capsule
| visceral layer
modified, branching epithelial podocytes
| extensions terminate in foot processes
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glomerular/bowmans capsule
| filtration slits
openings between the foot processes that allow filtrate to pass into the capsular space
28
whatever is made in the renal corpuscle goes to the
renal tubules because they are a continuation of eachother
29
renal tubule
| PCT
composed of cuboidal cells with numerous microvilli and mitochondria
reabsorbs water and solutes from filtrate and secretes substances into it
30
renal tubule
| loop of henle
a hairpin shaped loop of the renal tubule
proximal part is similar to the PCT and then is followed by thin segment of simple squamous cells (water) and the thick segment of cuboidal/columnar cells (salt)
31
renal tubule
| DCT
cuboidal cells without microvilli that function more in secretion that reabsorption
less mitochondria-no villi
less reabsorbtion
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connecting tubules
the distal portion of the DCT that is nearer to the collecting ducts
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important cell types in the collecting tubules
intercalated cells- cuboidal cells with microvilli that funct in maintaining the acid base balance of the body
principal cells- cuboidal cells without microvilli that help maintain the bodies water and salt balance
34
cortical nephrons
85% of the nephrons
| located in the cortex
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juxtamedullary nephrons
15%
located at the cortex medulla junction
have loops of henle that deeply invade the medulla
have extensive thin segments (hold more H20 when dehydrated)
involved in the production of concentrated urine
36
every nephron has 2 capillary beds
glomerulus
| peritubular capillaries
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glomerular capillary bed
each glomerulus is fed by an afferent arteriole and drained by an efferent arteriole
fluids are forced out of the blood throughout the entire length of the glomerulus
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blood pressure is high in the glomerulus because
arterioles are high resistance vessels
afferent arterioles have larger diameters than efferent arterioles
blood is coming in at a faster rate than leaving
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peritubular beds are low pressure, porous capillaries adapted for absorption that
arise from efferent arterioles
cling to adjacent renal tubules
and empty into the renal venous system
absorb 99% of the filtrate
cortical nephrons
40
vasa recta
long straight efferent arterioles of juxtamedullary nephrons that play a role in forming concentrated urine
41
juxtaglomerular apparatus of the nephron
where the distal tubule lies against the afferent (sometimes efferent) arteriole
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juxtaglomerular cells in the arterial walls
enlarged smooth muscle cells
have secretory granules containing renin
act as mechanoreceptors
if renin is needed to increase the blood pressure then bp coming here is low
43
JGA
| macula densa
tall closely packed distal tubule cells
lie adjacent to the juxtaglomerular cells
function as chemoreceptors or osmoreceptors (can change how we reabsorb sodium)
44
JGA
| mesanglia cells
have phagocytic and contractile properties
influence capillary filtration
they clean up the capsule so there are no road blocks in filtration
45
filtration membrane of the nephron
filter that lies between the blood and the interior of the glomerular capsule, composed of 3 layers
1. fenestrated endothelium of glomerular capillaries
2. visceral membrane of the glomerular capsule (podocytes)
3. basement membrane composed of fused basal lamina of the other layers
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the kidneys filter the body's entire plasma volume
60 times each day
| consume 20-25% of 02
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the filtrate contains
contains all plasma components except plasma protein
| looses water, nutrients, and essential ions to become urine
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the urine contains
metabolic wastes and unneeded substances
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urine formation and adjustment of blood composition involves 3 major processes
glomerular filtration
tubular reabsorption
secretion
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glomerular filtration
| glomerulus is more efficient than other capillary beds because
1. its filtration membrane is more permeable
2. glomerular bp is higher
3. the glomerulus has a higher net filtration pressure
51
glomerular filtration
| plasma proteins are not filtered because
they are used to maintain oncotic pressure of the blood
52
glomerular filtration
| net filtration pressure
the pressure responsible for filtrate formation
equals the glomerular hydrostatic pressure (HPg) minus the osmotic pressure of glomerular blood (OPg) ocmbined with the capsular hydrostatic pressure (HPc)
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NFP=
HPg- (OPg+HPc)
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glomerular filtration
| glomerular filtration rate
the total amount of filtrate formed per minute by the kidneys 120-125mL/min
directly proportional to the NFP
changes in GFR normally result from changes in glomerular blood pressure
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glomerular filtration
| factors governing filtration rate at the capillary bed are
total surface area available for filtration
filtration membrane permeability
net filtration pressure
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if the GFR is to high
needed substances cannot be reabsorbed quickly enough and are lost in the urine
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if the GFR is to low
everything is reabsorbed, including wastes that are normally disposed of
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3 mechanisms that control the GFR
```
renal autoregulation (intrinsic system)
neural controls (sympathetic)
hormonal mech (renin-angiotensin system)
```
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Intrinsic control of GFR
under normal conditions renal autoregulation mainains a nearly constant glomerular filtration rate
autoregulation entails 2 types of ctrl
-myogenic-resp to changes in pressure of renal bv
-flow dependent tubuloglomerular fedback- senses changes in the juxtaglomerular apparatus
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myogenic intrinsic GFR ctrl
decrease in bp= decrease in GFR
vasodilation of afferent arterioles
increases glomerular hydrostatic pressure
increases GFR
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flow dependent tubuloglomerular feedback intrinsic GFR ctrl
```
increase in GFR
sodium stays high in the filtrate
macula densa cells release a vasoconstrictor
afferent arterioles constrict
lower BF= lower hydrostatic pressure
decrease in GFR
```
62
extrinsic ctrl of GFR
| when sympathetic nervous system is at rest
renal bv are maximally dialated
| autoregulation mechanisms prevail
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extrinsic ctrl of GFR
| under stress
norepinephrine is released by sympathetic nervous system
epinephrine is released by adrenal medulla
afferent arterioles constrict and filtration is inhibited
64
extrinsic ctrl of GFR
| sympathetic stimulation of renin-angiotensin mechansim
triggered when Juxtaglomerular cells release renin
renin acts on angiotensinogen to release angiotensin I
angiotensin I is converted to angiotensis II
angiotensin II causes mean arterial pressure to rise, stimulates adrenal cortex to release aldosterone (for sodium reabsorption), both systemic and glomerular hydrostatic pressure rises
65
tubular reabsorption
the second step in urine production
most tubule contents are returned to the blood
transported substances move through 3 membranes (luminal and basolateral membranes of tubule cells, and endothelium of peritubular capillaries)
can be an active or passive process
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tubular reabsorption cont
only ca2+, Mg2+, K+, and some Na+ are reabsorbed via paracellular pathways
all organic nutrients are reabsorbed
water and ion reabsorption is hormonally controlled
67
tubular reabsorption
| sodium
almost always by active transport
it enters the tubule cells at luminal membrane
actively transported out of the tubules by NaK+ atpase pump
then moves to peritubular capillaries due to low hydrostatic pressure or high osmotic pressure of blood
sodium reabsorption provides the energy to reabsorb most other solutes
68
tubular reabsorption by PCT cells
| the active pumping of sodium drives the reabsorption of
water by osmosis, aided by aquaporins
cations and fat soluble substances by diffusion
organic nutrients and selected cations by secondary active transport
69
non reabsorbed substances/transport maximum
reflects the number of carriers in the renal tubules available, exists for every substance actively absorbed
when carriers are saturated the excess is excreted
70
substances are not reabsorbed if
lack of carriers
not lipid soluble
too large to pass through the membrane pores
71
most important non reabsorbed substances
urea, creatinine, uric acid
the end products of protein/nucleic acid metabolism
urea can be partially reabsorbed
72
substances reabsorbed in the PCT include
sodium, all nutrients, cations, anions, water
urea and lipid soluble solutes
small proteins
73
the loop of henle reabsorbs
water in the descending limb -is not coupled with solute reabsorption, movement thru osmosis+aquaporins (simple squamous epi)
Ca2+, Cl-, K+, Mg2+, Na+ in the ascending limb (simple cuboidal)
NaCl through active transport
74
DCT reabsorbs
Na+ through primary active transport
Cl- by secondary active transport
mostly regulated by hormones from now on
ADH-water
Aldosterone-Na
PTH- Ca
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collecting ducts absorb
water-controlled by ADH
Na+ through primary active transport
HCO3-, Cl-, K+, and H+ through passive and secondary transport
76
tubular secretion
3rd step in urine formation
| essentially reabsorption in reverse, where substances move from peritubular capillaries or tubular cells into filtrate
77
tubular secretion is important for
1. disposing of substances NOT already in the filtrate
2. eliminating undesirable substances such as urea and uric acid
3. ridding the body of excess potassium ions
4. controlling the blood pH
78
the PCT secretes
H+, urea, uric acid, and creatinine
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loop of henle secretes
urea
80
DCT secretes
H+ and K+
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collecting tubule secretes
H+ and K+
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osmolality
the number of solute particles dissolved in 1L of water
reflects the solutions ability to cause osmosis
osmotic activity is determined by the number of particles that do NOT pass through the semipermeable membrane
83
the kidneys keep the solute load of body fluids constant at about
300 mOsm
84
the countercurrent mechanism that keeps solute load at 300
interaction between the flow of filtrate through the loop of henle (countercurrent multiplier) and the flow of blood through the vasa recta bv (countercurrent exchanger
85
loop of henle
| countercurrent multiplier
descending LOH
relatively impermeable to solutes (no NaCl)
permeable to water- aquaporins
collecting ducts in deep medullary regions are permeable to urea
86
loop of henle
| countercurrent exchanger
vasa recta is countercurrent exchanger that maintains the osmotic gradient and delivers blood to the cells in the urea
87
hormonal regulation of urine conc and volume
| renin-angiotensin system
renin released by JGA in response to decrease in renal blood pressure- the most important function of the JGA
angiotensin II
proximal- reabsorption of Na+, Cl- and secretion of H+
stimulates cortex---aldosterone- more reabsorbtion of Na, Cl and secreate K+ into collecting ducts
major regulator of K+ in the blood
decreases glomerular filtration by causing vasoconstriction of afferent arterioles
88
hormonal regulation of urine conc and volume
| ANP-the aldosterone antagonist
inhibits the reabsorption of Na+, Cl-, and H20 by tubules so that blood volume decreases and GFR increases
more water and salt in the urine
lowers the blood volume
89
hormonal regulation of urine conc and volume
| ADH-
major hormone to regulate water reabsorption by negative feedback
affects the permeabililty of collecting ducts to water
hypothal stimulates posterior pit to decrease the water in blood
last part of distal and collecting ducts are affected when blood volume decreases so more water is reabsorbed
ADH decreases-low permeability- more urine
ADH increases-high permeability-less urine
inserts proteins that function as water channels into plasma membranes
90
physical characteristics of urine
| color and transparency
clear, pale to deep yellow due to urochrome from the breakdown of hemoglobin to form bilirubin
the more concentrated the deeper the color
drugs, vit, and diet can change color
cloudy urine can indicate UTI
91
phys char of urine
| odor
fresh urine is slightly aromatic
standing urine develops ammonia odor bc of bacteria
some drugs and veggies like asparagus alter the odor
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phys char of urine
| pH
```
slightly acidic (6) with range of 4.5-8
diet can alter pH
```
93
phys char of urine
| specific gravity
ranges from 1.001 to 1.035
| dependent on solute concentration
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chemical comp of urine
95% water and 5% solutes
has nitrogenous wastes: urea, uric acid, and creatinine
other normal solutes: sodium, potassium, phosphate, and sulfate ions
calcium, magnesium, and bicarbonate ions
95
abnormally high concentrations of any urinary constituents may indicate
pathology
96
transport of urine
```
glomerulus-
renal pelvis-
PCT-
DLOH-
ALOH-
DCT-
collecting duct
minor calyx
major calyx
renal pelvis
ureter
bladder
urethra
```
97
ureters transport
pass under the bladder causing compression and preventing backflow when pressure builds up during urine production
actively propel urine to the bladder via the response of smooth muscle stretch
98
ureters have a tri layered wall
1. transitional epithelium mucosa- inner mucosa made of transitional epi and goblet cells to make mucus to prevent contact bt urine and cells
2. smooth muscle muscularis- for peristalsis
3. fibrous CT adventititia- with bv, nerves, and lymphatic vessels
99
urinary bladder
hollow muscular organ that stores urine
smaller in female because of uterus
ureters located at the base with uretral openings
distensible and collapses when empty
and can expand as urine accumulates without signimcant rise in internal pressure
100
trigone
triangular area outlined by the openins for the ureters and the urethra
clinically important because infections tend to persist here
101
bladder wall has 3 layers
1. transitional epithelium mucosa-transitional epi+goblet cells
2. thick muscular layer-detrusor muscle- with 3 layers of smooth muscle
3. fibrous adventitia (outer)- peritoneum superior surface forming an outer coat, and a fibrous outercovering
102
fullness of the bladder
moderate- 500 ml
max 800-1000
overstretch can cause burst
103
urethra
for elimination of urine
females-embedded in front wall of vagina
males- for sperm and urine, passes through prostate, urogenital diaphragm, then penis
closed by sphinters when not urinating
internal- involuntary-made of smooth muscle at the bladder urethra junction
external- voluntary-made of skeltal muscle surrounds the urethra as it passes through urogenital diaphragm
104
micturation
the act of emptying the bladder
from increase in pressure and stretch receptors
parasympathetic- contraction of detrusor muscle, relaxation of internal urethral sphincter, inhibition of motor neurons and relaxation of skeletal muscle sphincter
