Chapter 25 Urinary Flashcards
1
Q
Kidneys filter 200 liters of blood daily allowing
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toxins, metabolic wastes, and excess ions to leave the body in urine
2
Q
Kidneys regulate volume and chemical makeup of the
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blood
3
Q
Kidneys maintain proper balance between
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water and salts, and acids and bases
4
Q
Gluconeogenesis happens during
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prolonged fasting
5
Q
Production of rennin to help regulate blood pressure and
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erythropoietin to stimulate RBC production
6
Q
Activation of
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Vitamin D
7
Q
Urinary bladder
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provides a temporary storage reservoir for urine
8
Q
Paired ureters
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transport urine from the kidneys to the bladder
9
Q
Urethra
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transports urine from the bladder out of the body
10
Q
The kidneys lie in a retroperitoneal position
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in the superior lumbar region
11
Q
The right kidney is lower than the left because
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it is crowded by the liver
12
Q
The lateral surface is convex the medial
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surface is concave
13
Q
The renal hilus leads to the
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renal sinus
14
Q
Ureters, renal blood vessels, lymphatics, and nerves
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enter and exit at the hilus
15
Q
Renal capsule
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a fibrous capsule that prevents kidney function
16
Q
Adipose capsule
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fatty mass that cushions the kidney and helps attach it to the body wall
17
Q
Renal facia
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the outer layer of dense fibrous connective tissue that anchors the kidney
18
Q
Cortex
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the light-colored, granular superficial region
19
Q
Medulla
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exhibits-cone shaped medullary (renal) pyramids separated by columns
20
Q
The medullary pyramid and its surrounding capsule
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constitute a lobe
21
Q
Renal pelvis
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flat funnel-shaped tube lateral to the hilus within the renal sinus
22
Q
Major calyces
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large branches of the renal pelvis
23
Q
Major calyces
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- collects uring draining from papillae
* empties urine into the pelvis
24
Q
Urine flows through the pelvis and ureters to the
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bladder
25
Approximately one-fourth (1200ml) of systematic cardiac output
flows through the kidneys each minute
26
Arterial flow into and venous flow out of kidneys
follow similar paths
27
The nerve supply is via
the renal plexus
28
Nephrons are the structural and functional units that
form urine, consisting of: Glomerulus, Glomerular (Bowman's) capsule, Renal corpuscle, and Glomerular endothelium.
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Glomerulus
a tuft of capillaries associated with a renal tubule
30
Glomerular (Bowman's) capsule
blind, cup-shaped end of a renal tubule that completely surrounds the glomerulus
31
Renal corpuscle
the glomerulus and its Bowman's capsule
32
Glomerular endothelium
fenestrated epithelium that allows solute-rich, virtually protein-free filtrates to pass from the blood into the glomerular
33
Anatomy of the Glomerular Capsule
* The external parietal layer is a structural layer
* The visceral layer consists of modified, branching epithelial podocytes
* extensions of the octopus-like podocytes terminate in foot processes
* Filtration slits-openings between the foot process that allow filtrate to pass into the capsular space
34
Proximal convoluted tubule (PCT)
composed of cuboidal cells with numerous microvilli and mitochondria
35
Proximal convoluted tubule (PCT)
composed of cuboidal cells with numerous microvilli and mitochondria
*resorbs water and solutes from filtrate and secretes substances into it
36
Loop of Henle
a hairpin-shaped loop of the renal tubule
* proximal part is similar to the proximal convoluted tubule
* proximal part is followed by the thin (descending limb) segment (simple squamous cells) and the thick (ascending limb) segment (cuboidal to columnar cells)
37
Distal convoluted tubule (DCT)
cuboidal cells without microvilli that function more in secretion than reabsorption
38
Connecting tubules
| The distal portion of the distal convoluted tubule nearer to the collecting ducts.
*Two important cell types are found here-intercalated cells and principal cells
39
Intercalated Cells
* cuboidal cells with microvilli
| * function in maintaining the acid-base balance of the body
40
Principal cells
* cuboidal cells without microvilli
| * help maintain the body's water and salt balance
41
Cortical nephrons
85% of nephrons; located in the cortex
42
Juxtamedullary nephrons
* are located at the cortex-medulla junction
* have loops of Henle that deeply invade the medulla
* Have extensive thin segments
* are involved in the production of concentrated urine
43
Every nephron has two capillary beds
* Glomerulus
| * Peritubular capillaries
44
Each glomerulus is:
* fed by an afferent arteriole
| * drained by an efferent arteriole
45
Blood pressure in the glomerulus is high because:
* Arterioles are high-resistance vessels
| * Afferent arterioles have larger diameters than efferent arterioles
46
Fluid and solutes are forced out of the blood throughout
the entire length of the glomerulus
47
Peritubular beds are low-pressure, porous capillaries adapted for absorption that:
* arise from efferent arterioles
* cling to adjacent renal tubules
* empty into the renal venous system
48
Vasa recta-
long, straight efferent arterioles of juxtamedullary nephrons
49
Juxtaglomeular Apparatus (JGA)
*where the distal tubule lies against the afferent (sometimes efferent) arteriole
50
Arteriole walls have juxtaglomeular (JG) cells
* enlarged, smooth muscle cells
* Have secretory granules containing renin
* act as mechanoreceptors
51
Macula densa
* tall, closely packed distal tubule cells
* lie adjacent to JG cells
* function as chemoreceptors or osmoreceptors
52
Mesanglial cells
* have phagocytic and contractile properties
| * influence capillary filtration
53
Filtration membrane
*Filter that lies between the blood and the interior of the glomerular capsule
54
The filtration membrane is composed of three layers:
* fenestrated endothelium of the glomerular capillaries
* visceral membrane of the glomerular capsule (podocytes)
* basement membrane composed of fused basal laminae of the outer layers
55
Mechanisms of Urine Formation
* The kidneys filter the body's entire plasma volume 60 times each day
* They filtrate:
* contains all plasma components except protein
| * loses water, nutrients, and essential ions to become urine
56
The urine contains metabolic wastes and
unneeded substances
57
Glomerular Filtration
| *Principles of fluid dynamics that account for tissue fluid in all capillary beds apply
to the glomerulus as well
58
The glomerulus is more efficient than other capillary beds because:
* its filtration membrane is more permeable
* Glomerular blood pressure is higher
* it has a higher net filtration pressure
59
Plasma proteins are not filtered and are used to maintain
oncotic pressure of the blood
60
Net Filtration Presure (NFP)
* The pressure responsible for filtrate formation
* NFP equals the glomerular hydrostatic pressure (HPg) minus the oncotic pressure of glomerular blood (OPg) combined with the capsular hydrostatic pressure (HPc)
NFP=HPg-(OPg+HPc)
61
Glomerular Filtration Rate (GFR)
The total amount of filtrate formed per minute by the kidneys
62
Factors governing the filtration rate at the capillary bed are:
* Total surface area available for filtration
* Filtration membrane permeability
* Net filtration pressure
63
GFR is directly proportional
to the NFP
64
Changes in GFR normally result from
changes in glomerular blood pressure
65
If the GFR is too high:
Needed substances cannot be reabsorbed quickly enough and are lost in the urine
66
If the GFR is too low:
Everything is reabsorbed, including wastes that are normally disposed of
67
Three mechanisms that control the GFR:
* Renal autoregulation (intrinsic system)
* Neural controls
* Hormonal mechanism (the renin-angiotensin system)
68
Tubular Reabsorption
a transepithelial process whereby most tubule contents are returned to the blood
69
Transported substances move through three membranes
* Luminal and basolateral membranes of tubule cells
| * Endothelium of peritubular capillaries
70
Only Ca2+, Mg2+, K+, and some Na+ are reabsorbed
via paracellular pathways
71
All organic nutrients are
reabsorbed
72
Water and ion reabsorption is
hormonally controlled
73
Reabsorption may be
an active (requiring ATP) or passive process
74
Substances reabsorbed in PCT include:
* sodium, all nutrients, cations, anions, and water
* urea and lipid-soluble solutes
* small proteins
75
Loop of Henle reabsorbs:
* H2O, Na+, Cl-, K+ in the descending limb
| * Ca2+, Mg2, and Na+ in the ascending limb
76
DCT absorbs:
*Ca2+, Na+, H+, K+, and water
77
Collecting duct absorbs:
water and urea
78
Osmolality
* the number of solute particles dissolved in 1L of water
| * reflects the solution's ability to cause osmosis
79
Body fluids are measured in
milliosmols (mOsm)
80
The kidneys keep the solute load of body fluids
constant at about 300 mOsm
81
This is accomplished by the
countercurrent mechanism
82
Countercurrent mechanism
interaction between the flow of filtrate through the loop of Henle (countercurrent multiplier) and the flow of blood through the vasa recta blood vessels (countercurrent exchanger)
83
Countercurrent mechanism
* The solute (solid) concentration in the loop of Henle ranges from 3000 mOsm to 1200 mOsm
* Dissipation of the medullary osmotic gradient is prevented because the blood in the vasa recta equilibrates with the interstitial fluid
84
Loop of Henle: Countercurrent Multiplier
| The descending loop of Henle:
* is relatively impermeable to solute
| * is permeable to water
85
Loop of Henly: Countercurrent Multiplier
| The ascending loop of Henle
* is permeable to solutes
| * is impermeable to water
86
Collecting ducts in the deep medullary regions
are permeable to urea
87
Loop of Henley: Countercurrent Exchanger
| The vasa recta is countercurrent exchanger that:
* Maintains the osmotic gradient
| * Delivers blood to the cells in the area
88
Formation of Dilute Urine
| Filtrate is diluted in the
ascending loop of Henle
89
Dilute urine is created by allowing this
filtrate to continue into the renal pelvis
90
This will happen as long as
antidiuretic hormone (ADH) is not being secreted
91
Collecting ducts remain impermeable to water;
no further water reabsorption occurs
92
Sodium and selected ions can be
removed by active and passive mechanisms
93
Urine osmolality can be as low as
50 mOsm (one-sixth that of plasma)
94
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Formation of Concentrated Urine
Antidiuretic hormone (ADH)
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inhibits diuresis (increased or excess production of urine)
95
In the presence of ADH,
99% of the water in filtrate is reabsorbed
96
ADH-dependent water reabsorption is called
facultative water reabsorption
97
ADH is the signal to produce
concentrated urine
98
The kidneys' ability to respond depends upon
the high medullary osmotic gradient
99
Chemicals that enhance the urinary output include:
* any substance not reabsorbed
* substances that exceed the ability of the renal tubules to reabsorb it
* substances that inhibit Na+ reabsorption
100
Osmoric diuretics include:
* High glucose levels-carries water out with the glucose
* Alcohol-inhibits the release of ADH
* Caffeine and most diuretic drugs-inhibit sodium ion reabsorption
* Lasix and Diuril-inhibit Na+ -associated symporters
101
Color and transparency:
* clear, pale to deep yellow (due to urochrome)
* concentrated uring has a deeper yellow color
* drugs, vitamin supplements, and diet can change the color of urine
* cloudy urine may indicate an infection of the urinary tract
102
Odor
* Fresh urine is slightly aromatic
* standing urine develops an ammonia odor
* some drugs ard vegetables (asparagus) alter the usual odor
103
pH
* slightly acidic (pH 6) with a range of 4.5 to 8.0
| * diet can alter pH
104
Specific gravity
* ranges from 1.001 to 1.035
| * is dependent on solute concentration
105
Urine is
95% water and 5% solutes
106
Nitrogenous wastes:
urea, uric acid, and creatinine
107
Other normal solutes include:
* sodium, potassium, phosphate, and sulfate ions
| * calcium, magnesium, and bicarbonate ions
108
Abnormally high concentrations of any
urinary constituents may indicate pathology
109
Ureters
| *Slender rubes that convey urine from
the kidneys to the bladder
110
Ureters enter the base of the bladder through the posterior wall.
*this closes their distal ends as bladder pressure increases and prevents backflow of urine into the ureters
111
Ureters have a trilayered wall
* Transitional epithelial mucosa
* smooth muscle muscularis
* fibrous connective tissue adventitia
112
Ureters actively propel urine to the bladder via
response to smooth muscle stretch
113
Urinary Bladder is
smooth, collapsible, muscular sac that stores urine
114
The urinary bladder lies
retroperitoneally on the pelvic floor posterior to the pubic symphysis
* males-prostate gland surrounds the neck inferiorly
* females-anterior to the vagina and uterus
115
Trigone-
triangular area outlined by the openings for the ureters and the urethra
*Clinically important because infections tend to persist in this region
116
The bladder wall has three layers:
* transitional epithelial mucosa
* a thick muscular layer
* a fibrous adventitia
117
The bladder is distensible (able to stretch and expand) and
collapses when empty
118
As urine accumulates
the bladder expands without a significant rise in internal pressure
119
Urethra
muscular tube that:
* drains urine from the bladder
* conveys it out of the body
120
Sphincters keep the urethra closed when urine is not being passed
* internal urethral sphincter-involuntary sphincter at the bladder-urethra junction
* external urethral sphincter-voluntary sphincter surrounding the urethra as it passes through the urogenital diaphragm
* levator ani muscle-voluntary urethral sphincter
121
The female urethra is tightly bound to the
anterior vaginal wall
122
Its external opening lies anterior to the vaginal opening and
posterior to the clitoris
123
The male urethra has three named regions:
* Prostatic urethra-runs within the prostate gland
* membranous urethra-runs through the urogenital diaphragm
* spongy (penile) urethra-passes through the penis and opens via the external urethral orifice
