Urinary System Flashcards
1
Q
Kidney Functions
A
filter blood plasma, reg. blood volume and pressure, the osmolarity of body fluids, secretes enzyme (renin), secretes erythropoietin, reg. PCO2 and acid-base balance, detoxify, promotes glucogenesis, completes step in calcitrol
2
Q
waste vs metabolic waste
A
Waste- Any substance that is useless to the body
Toxins
Drugs
Hormones
Salts
Hydrogen ions
Excess water
Metabolic waste- produced by the body
CO2
Nitrogenous wastes
3
Q
Cell process for prodcuing nitrogenous wastes
A
Urea
50% of nitrogenous wastes
protein catabolism
proteins→amino acids →NH2 removed →forms ammonia → liver converts to urea
Uric acid
nucleic acid catabolism
Creatinine
creatinine phosphate catabolism
4
Q
Azotemia
A
build up of nitrogenous wastes in the blood
5
Q
Uremia
A
toxic effects as wastes accumulate
6
Q
excretion
A
Separation of wastes from body fluids and eliminating them
7
Q
Waste of respiratory system
A
CO2
8
Q
waste of integumentary system
A
water, salts, lactic acid, urea
9
Q
waste of digestive
A
water, salts, CO2, lipids, bile pigments, cholesterol
10
Q
waste of urinary system
A
many metabolic wastes, toxins, drugs, hormones, salts, H+ and water
11
Q
three layers of connective tissue of a kidney
A
Renal Fascia
Perirenal fat (adipose) capsule
Fibrous (renal) capsule
12
Q
Renal parenchyma
A
glandular tissue that forms urine
2 Zones
Cortex – outer 1 cm
Medulla – pyramids
13
Q
renal sinus
A
cavity within the kidney
contains blood & lymphatic vessels, nerves, urine collecting ducts and fat
14
Q
renal columns
A
Renal columns – extensions of cortex that project toward the renal sinus
divide medulla into renal (medullary) pyramids
15
Q
renal pyramids
A
6 to 10 with the broad base facing cortex and renal papilla facing sinus
16
Q
lobe
A
one pyramid and its overlying cortex
17
Q
Minor Calyx
A
cup that nestles the papilla of each pyramid and collects its urine
18
Q
Major calyces
A
formed by the convergence of two or three minor calyces
19
Q
Renal pelvis
A
formed by the convergence of two or three major calyces
20
Q
Ureter
A
tubular continuation of the pelvis that drains the urine down to the urinary bladder
21
Q
Kidneys account for only .4% of body weight, but they receive about _____ of the cardiac output (renal fraction)
A
21%
22
Q
A
- interlobar arteries - up renal columns, between pyramids
- arcuate arteries - over pyramids
- cortical radiate arteries - up into cortex
Branch into afferent arterioles: each supplying one nephron
This leads to a ball of capillaries—glomerulus
23
Q
Renal vein empties into ______
A
inferior vena cava
24
Q
Blood is drained from the glomerulus by
A
efferent arterioles
-lead to peritubular capillaries
or vasa recta
-cortical radiate veins
-arcuate veins
-interlobar veins
25
cortex you find
peritubular capillaries
26
medulla you find
vasa recta
27
Nephron
-functional unit of kidneys
28
part of the nephron: Renal corpuscle
filters the blood plasma
- contains a glomerulus & glomerular (Bowman’s) capsule that encloses glomerulus
29
Part of the nephron: Renal tubule
a long coiled tube that converts the filtrate into urine
-contains a duct that leads away from the glomerular capsule and ends at the tip of the medullary pyramid
30
Collecting duct
receives fluid from many nephrons
31
Collecting duct vs Papillary duct
-receives fluid from the DCTs of several nephrons as it passes back into the medulla
-merger of several collecting ducts
30 papillary ducts end in the tip of each papilla
Collecting and papillary ducts lined with simple cuboidal epithelium
32
Nephron Loop
long U-shaped portion of renal tubule
-Descending limb
-Ascending limb
Thick segments -active transport of salts
many mitochondria
Thin segment - very permeable to water
33
flow of fluids
glomerular capsule - glomerular filtrate
pct - tubular fluid
nephron loop - tubular fluid
dct - tubular fluid
collecting duct - urine all below
papillary duct
minor calyx
major calyx
renal pelvis
ureter
urinary bladder
urethra
34
4 processes of urine production
1.Glomerular filtration
plasma-like filtrate
2. Tubular reabsorption
returns solutes to the bloodstream
3. Tubular secretion
removes additional wastes from the blood
4. Water conservation
returns water to the bloodstream
35
How much of the glomerular filtrate is reabsorbed back into the blood?
99%
36
Mechanism of glomerular filtration
capillary fluid exchange process
water and some solutes in the blood pass from the capillaries of the glomerulus into the capsular space of the nephron ( pass thru are water, electrolytes, glucose, fatty acids, amino acids, nitrogenous wastes, and vitamins)
37
Filtration membrane
-fenestrated endothelium - small enough to exclude blood cells
-Basement membrane - proteoglycan gel
a few large particles may penetrate, but most are held back
negatively charged
blood plasma 7% protein, glomerular filtrate 0.03%
-Filtration slits
podocyte arms have pedicels with negatively charged filtration slits to exclude large anions
38
pass through filtration membrane
Water
Electrolytes
Glucose
Amino acids
Fatty acids
Vitamins
Urea
Uric acid
Creatinine
39
can't pass the filtration membrane
Blood cells
Plasma proteins
Large anions
Protein-bound
minerals and
hormones
Most molecules
>8nmin
diameter
40
Proteinuria (albuminuria)
protein in urine
41
Hematuria
blood in the urine
42
why would protein be found in the urine
Distance runners and swimmers often experience temporary proteinuria or hematuria
prolonged, strenuous exercise greatly reduces perfusion of the kidney
glomerulus deteriorates under prolonged hypoxia
43
Blood hydrostatic pressure (BHP)
Much higher in glomerular capillaries
60 mm Hg compared to 10-15 in most other capillaries
An afferent arteriole is larger than efferent arteriole
larger inlet and smaller outlet
44
Hydrostatic pressure (CP)
in capsular space
18 mm Hg due to high filtration rate and continual accumulation of fluid in the capsule
45
Colloid osmotic pressure (COP) of blood
- 32 mm Hg
filtrate is almost protein-free no significant COP
46
Net filtration pressure:
60out – 18in – 32in = 10 mm Hg out
47
effect of high glomerulus blood pressure
hypertension
rupture of glomerular capillaries
scarring of the kidneys (nephrosclerosis)
atherosclerosis of renal blood vessels
renal failure
48
Avg. glomerular filtration rate in males and females
males: 180 L/day
females: 150 L/day
49
how many liters of urine are excreted daily?
1-2 Liters of urine a day
50
If the glomerular filtration rate is too high what happens?
-Fluid flows through the renal tubules too rapidly for them to reabsorb the usual amount of water and solutes
-Urine output rises
dehydration and electrolyte depletion
51
If the glomerular filtration rate is too low what happens?
-Too much waste is reabsorbed
azotemia may occur
52
the glomerular filtration rate is controlled by ....
adjusting glomerular blood pressure
53
the glomerular filtration rate is controlled by what three mechanisms?
-Renal autoregulation
-Sympathetic nervous system control
-Hormonal control
54
renal autoregulation
the ability of the nephrons to adjust their own blood flow and GFR without external (nervous or hormonal) control
55
Contrast the myogenic mechanism and tubuloglomerular feedback
Myogenic mechanism—based on the tendency of smooth muscle to contract when stretched
Tubuloglomerular feedback—the mechanism by which the glomerulus receives feedback on the status of the downstream tubular fluid and adjusts filtration
56
Juxtaglomerular apparatus
complex structure found at the very end of the nephron loop where it has just reentered the renal cortex
Loop comes into contact with the afferent and efferent arterioles at the vascular pole of the renal corpuscle
57
3 kinds of cells occur in the juxtaglomerular apparatus
Macula densa— Senses variations in flow or fluid composition and secretes a paracrine that stimulates JG cells
Juxtaglomerular (JG) cells:
dilate or constrict arterioles when stimulated by the macula
secrete renin in response to a drop in blood pressure
Mesangial cells:
constrict or relax glomerular capillaries to regulate the flow
58
sympathetic control of glomerular filtration rate
-Reduces GFR and urine output
-Redirects blood from the kidneys to the heart, brain, and skeletal muscles
-GFR may be as low as a few milliliters per minute
59
hormones that regulate GFR and describe the functions
1.Renin is secreted by the kidneys when they sense a drop in blood pressure
first step in pathway to angiotensin II
2.Angiotensin II
Potent vasoconstrictor raising BP throughout body
Constricts efferent arteriole raising GFR despite low BP
-Angiotensin II stimulates adrenal cortex to secrete aldosterone promoting Na+ and H2O reabsorption in DCT and collecting duct
-Stimulates posterior pituitary to secrete ADH which promotes water reabsorption by collecting duct
-Stimulates thirst and H2O intake
60
How much glomerular filtrate becomes urine?
1%
61
Tubular secretion
wastes from the blood to the tubular fluid
62
Tubular reabsorption
-useful substances from tubular fluid back to the blood
reabsorbs 65% of GF to peritubular capillaries!
63
Structure of proximal convoluted tubule
-Great length, prominent microvilli, and abundant mitochondria for active transport
-Reabsorbs a greater variety of chemicals than other parts of the nephron
64
Two routes of reabsorption
1.Transcellular route
Substances pass through the cytoplasm of the PCT epithelial cells
2.Paracellular route
Substances pass between PCT cells
Junctions between epithelial cells are quite leaky and allow significant amounts of water to pass through
Solvent drag—water carries with it a variety of dissolved solutes
3.Taken up by peritubular capillaries
65
Why is there a solute transport maximum?
Limited by # of TRANSPORT PROTEINS ; If all transporters are occupied as solute molecules pass, then excess solutes appear in urine
66
Tubular secretion
Extracts additional chemicals/wastes from capillary blood and secretes them into tubular fluid
1.Waste removal
Urea, uric acid, bile acids, ammonia, catecholamines, prostaglandins, and a little creatinine
Secretion of uric acid compensates for its reabsorption earlier in PCT
Clears blood of pollutants, morphine, penicillin, aspirin and other drugs
explains need to take prescriptions multiple times/day to keep pace with the rate of clearance
2. Acid-base balance
Secretion of hydrogen and bicarbonate ions help regulate pH of body fluids
67
structure of nephron loop
-Only the thin segment is permeable to water
Electrolyte reabsorption from filtrate
-Thick segment reabsorbs 25% of Na+, K+, and Cl−
Ions leave cells by active transport and diffusion
-NaCl remains in the tissue fluid of renal medulla
Water cannot follow since thick segment is impermeable
68
tubular fluid is very dilute as it enters the
distal convuloted tubule
69
tubular fluid in the dct
DCT still contains about 20% of the water and 7% of the salts from the glomerular filtrate
70
Hormones that act of the DCT
1.Aldosterone acts on thick segments and cause absorb of Na+ and excretion of K+
2.Atrial Natriuretic Peptide- reduces blood vol and pressure; causes excretion of salt and water in urine
3.ADH-collecting duct more permeable to water so that it can enter the tissues
4.Parathyroid hormone- dct increase calcium concentration and pct excrete phosphate
71
_____ completes the process of determining the chemical composition of urine
distal convuloted tubule
72
water absorption by collecting duct
starts in the cortex and receives fluid from many nephrons
As CD passes through the medulla, it reabsorbs water & concentrates urine up to 4X
The medullary portion of CD is more permeable to water than to NaCl
73
Water diuresis
drinking large volumes of water will produce a large volume of hypotonic urine
-Cortical portion of CD reabsorbs NaCl, but it is impermeable to water
Urine concentration may be as low as 50 mOsm/L
74
hypertonic urine
-Dehydration causes the urine to become scanty and more concentrated
-High blood osmolarity stimulates release of ADH and then an increase in synthesis of aquaporin channels by renal tubule cells
-More water is reabsorbed by collecting duct
-Urine is more concentrated
75
If BP is ____, GFR will be ____
low, low (more salt removed and more water reabsorbed; less urine produced)
76
The Countercurrent Multiplier
-The ability of the kidney to concentrate urine depends on the salinity gradient in the renal medulla
-Four times as salty in the renal medulla than the cortex
77
how does the nephron loop act as a countercurrent multiplier?
Multiplier: continually recaptures salt and returns it to extracellular fluid of medulla which multiplies the salinity in adrenal medulla
Countercurrent : because of fluid flowing in opposite directions in adjacent tubules of nephron loop
78
recycling of urea
-lower end of CD permeable to urea
Urea contributes to the osmolarity of deep medullary tissue
-Continually cycled from collecting duct to the nephron loop and back
-Urea remains concentrated in the collecting duct and some of it always diffuses out into the medulla adding to osmolarity
79
Contrast countercurrent multiplier and countercurrent exchange
Countercurrent multiplication is something the tubule does to create the high interstitial osmolality, and a large osmolality gradient between the renal medulla and the renal cortex. The countercurrent exchange mechanism is something the vasa recta do to maintain this gradient.
80
the function of the countercurrent multiplier
reabsorb water from the tubular fluid and produce concentrated urine.
81
beavers have little need to conserve water so they would have ____nephron loops
shorter
82
appearance of urine
Clear to deep amber is normal
Urochrome - yellow pigment produced from breakdown of hemoglobin of dead RBCs
Pink, green, brown, black
-food, vitamins, drugs, metabolic disease
Cloudy
– bacterial growth
83
pyuria
pus present due to kidney/bladder infection
84
hematuria
blood present
-caused by infection, trauma, kidney stones
85
odor of urine
-Should normally have little odor
Pungent odor – bacteria
bacteria convert urea to ammonia
Foods may cause odor
ie. asparagus
Sweet, fruity odor – glucose present
diabetes
Foul odor - infection
86
specific gravity of urine
1.001-1.035
87
chemical composition of urine
95% water, 5% solutes
Normal solutes
urea, NaCl, createnine, uric acid, phosphates, sulfates calcium, magnesium, bicarbonate, H+
Abnormal solutes
Glucose
Free hemoglobin or whole RBCs
Albumin
Ketones (ok during pregnancy)
Bile pigments
88
normal urine volume
1-2 liters a day
89
polyuria
excess of 2L/day
disease long term (ie. Diabetes)
drugs - temporary
90
Oliguria
less than 500 mL/day
91
Anuria
- 0 to 100 mL
disease
dehydration
circulatory shock
enlarged prostate gland (males only)
92
pH of urine
range: 4.5-8.2
usually 6.0, which is slightly acidic
93
diuretics
any chemical that increases urine volume
94
caffeine effect
dilate the afferent arteriole
95
alcohol inhibits ____
adh
96
what is diuretics used for
treat hypertension & congestive heart failure by reducing the body’s fluid volume and blood pressure
97
diuretics' effect on urine volume
increase GFR, reduce tubular reabsorption of water, act on nephron loop Impairs countercurrent multiplier reducing the osmotic gradient in the renal medulla
98
ureters
-Muscular tube from renal pelvis of kidney to bladder
-passes dorsal to bladder and enters it from below
-about 25 cm long
99
3 tissues of the ureter
1.adventitia - CT
2.muscularis - 2 layers of smooth muscle
urine enters, it stretches & contracts in peristaltic wave
3.mucosa - transitional epithelium
lumen very narrow, easily obstructed
100
urinary bladder
Muscular sac on floor of pelvic cavity
3 layers
Parietal peritoneum on flat superior surface
Fibrous adventitia everywhere else
Muscularis (detrusor muscle) - smooth muscle
Mucosa with rugae (wrinkles)
relaxed bladder in wrinkled – highly distensible
101
Trigone
triangular area on floor where ureters enter and urethra exits
102
male vs female urethra
female - 4 cm long, has an external urethral orifice (b/w vaginal orifice and clitoris)
male - 18 cm long
102
male vs female urethra
female - 4 cm long , has a external urethral oriface (b/w vaginal orifice and clotris)
male - 18 cm long
103
Micturition
voiding the bladder
104
Micturition reflex in infants
1) 200 ml urine in bladder - stretch receptors send signal to spinal cord
2) parasympathetic reflex arc from spinal cord - stimulates contraction of detrusor muscle
3) relaxation of internal urethral sphincter
4) voids bladder
105
Micturition in adults
If urination is appropriate, pons sends signal for stimulation of detrussor and relaxes internal urethral sphincter
If urination is inappropriate, impulses sent to external urethral sphincter keep it contracted
When urination becomes appropriate, the impulses are inhibited and the external urethral sphincter will relax
106
Valsalva maneuver
Valsalva maneuver
aids in expulsion of urine by ↑ pressure on bladder
activates micturition reflex voluntarily when there is no urge to void bladder
107
what are kidney stones made of ?
Renal Calculi
Calcium, phosphate, uric acid and protein crystallize
Form in the renal pelvis
Most are small, but some can be several centimeters
Causes blockages that destroy nephrons
Jagged pain and hematuria
108
causes of kidney stones
hypercalcemia
dehydration
pH imbalance
frequent urinary infections
enlarged prostate (males only)
109
treatments of kidney stones
stone-dissolving drugs, surgery and/or lithotripsy (ultrasonic vibrations)
110
UTI's more common in females because
they have a shorter urethra
111
Cystitis
infection of the urinary bladder
112
Pyelitis
infection of the renal pelvis
113
Pyelonephritis
infection that reaches the cortex and the nephrons
114
Acute Glomerularnephritis
-destruction of glomeruli
autoimmune disease
may follow an infection
usually temporary – most recover
115
Hydronephrosis
increased fluid pressure due to blockage in kidney
116
Nephroptosis
- floating kidney
>too little body fat to hold kidney in place (ie anorexia)
>prolonged vibration – truck drivers, jackhammer operators
117
Nephrotic Syndrome
- glomerular injury causes large amounts of protein to be excreted in urine
causes hypotension, edema, increased susceptibility to infection
118
Acute Renal Failure
sudden onset traumatic damage to nephrons
great blood loss
119
Chronic Renal Failure
slow, progressive
irreversible loss of nephrons
trauma
metal poisoning
glomeruli blocked by protein
atherosclerosis
120
Urinary Incontinence
inability to control urination
causes :
Bladder irritation due to infection
Pressure during pregnancy
Incompetence of urethral sphincters
Obstruction
121
Stress incontinence
uncontrollable urination due to brief surges in bladder pressure
laughter, coughing, sneezing
122
With hyperglycemia and glycosuria (DIABETES)
1.diabetes mellitus I and II- insulin hyposecretion/insensitivity
2.gestational diabetes - 1 to 3% of pregnancies
3.pituitary diabetes - hypersecretion of GH
4.adrenal diabetes - hypersecretion of cortisol
123
With glycosuria but no hyperglycemia
renal diabetes - hereditary deficiency of glucose transporters
124
With no hyperglycemia or glycosuria
diabetes insipidus - ADH hyposecretion; CD ↓ water reabsorption
