0-1 Chapter 23 Urinary System Flashcards Preview

2 - Keiser A&P 2 > 0-1 Chapter 23 Urinary System > Flashcards

Flashcards in 0-1 Chapter 23 Urinary System Deck (224):
1

urinary system

principal means of waste removal

2

kidney functions

regulate blood volume and pressure, erythrocyte count, blood gases, blood pH, and electrolyte and acid base balance, eliminates wastes

3

urologists

treat both urinary and reproductive disorders

4

urinary system consists of 6 organs

2 kidneys, 2 ureters, urinary bladder, and urethra

5

Kidney

Secrete

secretes enzyme, renin, which activates hormonal mechanisms that control blood pressure and electrolyte balance
•secretes the hormone, erythropoietin, which stimulates the production of red blood cells
•final step in synthesizing hormone, calcitriol, which contributes to calcium homeostasis

6

waste

any substance that is useless to the body or present in excess of the body‟s needs

7

metabolic waste

waste substance produced by the body

8

urea formation

-proteins
-amino acids
-NH2 removed
-forms ammonia
- liver converts to urea

9

uric acid

product of nucleic acid catabolism

10

blood urea nitrogen (BUN)

expression of the level of nitrogenous waste in the blood

11

azotemia

elevated BUN
•indicates renal insufficiency

12

uremia

syndrome of diarrhea, vomiting, dyspnea, and cardiac arrhythmia stemming from the toxicity of nitrogenous waste

13

excretion

separation of wastes from body fluids and eliminating them

14

four body systems carry out excretion

respiratory system
integumentary system
digestive system
urinary system

15

respiratory system

CO2, small amounts of other gases, and water

16

integumentary system

water, inorganic salts, lactic acid, urea in sweat

17

digestive system

water, salts, CO2, lipids, bile pigments, cholesterol, other metabolic waste, and food residue

18

urinary system

many metabolic wastes, toxins, drugs, hormones, salts, H+ and water

19

Kidney

location

retroperitoneal along with ureters, urinary bladder, renal artery and vein, and adrenal glands

20

three protective connective tissue coverings

renal fascia
perirenal fat capsule
fibrous capsule

21

renal parenchyma

glandular tissue that forms urine
–appears C-shaped in frontal section
–encircles the renal sinus

22

renal sinus

contains blood and lymphatic vessels, nerves, and urine-collecting structures
•adipose fills the remaining cavity and holds structures into place

23

two zones of renal parenchyma

outer renal cortex
inner renal medulla

24

inner renal medulla

•renal columns –extensions of the cortex that project inward toward sinus
•renal pyramids –6 to 10 with broad base facing cortex and renal papilla facing sinus

25

lobe of the kidney

one pyramid and its overlying cortex

26

minor calyx

cup that nestles the papilla of each pyramid
•collects its urine

27

major calyces

formed by convergence of two or three minor calyces

28

renal pelvis

formed by convergence of two or three major calyces

28

ureter begins at

renal pelvis

29

ureter

a tubular continuation of the pelvis and drains the urine down to the urinary bladder

30

Blood Supply Diagram

Aorta, Renal a., Segmental a., Interlobar a., Arcuate a., Interlobular a.,Afferent arteriole ---
Glomerulus, Efferent arteriole, Peritubular capillaries-----Vasa recta
Interlobular v., Arcuate v., Interlobar v., Renal v., Inferior vena cava

31

renal fraction

kidneys account for only 0.4% of body weight, they receive about 21% of the cardiac output

32

renal artery divides into segmental arteries that give rise to

-interlobar arteries -up renal columns, between pyramids
-arcuate arteries -over pyramids
-interlobular arteries -up into cortex
-branch into afferent arterioles -each supplying one nephron
-leads to a ball of capillaries -glomerulus
-blood is drained from the glomerulus by efferent arterioles
-lead to either peritubular capillaries or vasa recta around portion of the renal tubule
-interlobular veins or directly into arcuate veins -interlobar veins

33

renal vein empties into

inferior vena cava

34

peritubular capillaries

in the cortex, peritubular capillaries branch off of the efferent arterioles supplying the tissue near the glomerulus, the proximal and distal convoluted tubules

35

vasa recta

in medulla, the efferent arterioles give rise to the vasa recta, supplying the nephron loop portion of the nephron

36

filtration unit of the kidney is the

nephron

37

Nephron
each composed of two principal parts:

–renal corpuscle –filters the blood plasma
–renal tubule –long coiled tube that converts the filtrate into urine

38

renal corpuscle consists of

the glomerulus and a two-layered glomerular (Bowman) capsule that encloses glomerulus

39

glomerular (Bowman) capsule

–parietal (outer) layer of Bowman capsule is simple squamous epithelium
–visceral (inner) layer of Bowman capsule consists of elaborate cells called podocytes that wrap around the capillaries of the glomerulus
–capsular space separates the two layers of Bowman capsule-collects filtrate

40

vascular pole

the side of the corpuscle where the afferent arteriole enters the corpuscle and the efferent arteriole leaves

41

urinary pole

the opposite side of the corpuscle where the renal tubule begins

42

renal (uriniferous) tubule

a duct that leads away from the glomerular capsule and ends at the tip of the medullary pyramid

43

divided into four regions –

proximal convoluted tubule, nephron loop, distal convoluted tubule –parts of one nephron
–collecting duct receives fluid from many nephrons

44

proximal convoluted tubule(PCT)

arises from glomerular capsule
–longest and most coiled region
–simple cuboidal epithelium with prominent microvilli for majority of absorption - increase surface area for absorption

45

nephron loop (loop of Henle)

long U-shaped portion of renal tubule
–descending limb and ascending limb

46

thick segments

have simple cuboidal epithelium
-water impermeable
•initial part of descending limb and part or all of the ascending limb
•heavily engaged in the active transport of salts and have many mitochondria

47

thin segment

has simple squamous epithelium
•forms lower part of descending limb
•cells very permeable to water

49

distal convoluted tubule (DCT)

begins shortly after the ascending limb reenters the cortex
–shorter and less coiled that PCT
–cuboidal epithelium without microvilli
–DCT is the end of the nephron

50

collecting duct

receives fluid from the DCTs of several nephrons as it passes back into the medulla
–numerous collecting ducts converge toward the tip of the medullary pyramid

51

papillary duct

formed by merger of several collecting ducts
•30 papillary ducts end in the tip of each papilla
•collecting and papillary ducts lined with simple cuboidal epithelium

52

becomes urine when it enters the

collecting duct

53

flow of fluid from the point where the glomerular filtrate is formed to the point where urine leaves the body:

glomerular capsule → proximal convoluted tubule → nephron loop → distal convoluted tubule → collecting duct → papillary duct → minor calyx → major calyx → renal pelvis → ureter → urinary bladder → urethra

54

cortical nephrons

–85% of all nephrons
–short nephron loops
–efferent arterioles branch into peritubular capillaries around PCT and DCT

55

juxtamedullary nephrons

–15% of all nephrons
–very long nephron loops, maintain salinity gradient in the medulla and helps conserve water
–efferent arterioles branch into vasa recta around long nephron loop

56

cortical nephrons have

peritubular capillaries

57

juxtamedullary nephrons have

vasa recta

58

renal plexus

nerves and ganglia wrapped around each renal artery
–follows branches of the renal artery into the parenchyma of the kidney
–issues nerve fibers to the blood vessels and convoluted tubules of the nephron

59

carries sympathetic innervation from the abdominal aortic plexus

•stimulation reduces glomerular blood flow and rate of urine production
•respond to falling blood pressure by stimulating the kidneys to secrete renin, an enzyme that activates hormonal mechanisms to restore blood pressure

60

carries parasympathetic innervation from the vagus nerve

increases rate of urine production

61

kidneys convert blood plasma to urine in three stages

glomerular filtration
–tubular reabsorption and secretion
–water conservation

62

glomerular filtrate

–fluid in capsular space
–blood plasma without protein

63

tubular fluid

–fluid in renal tubule
–similar to above except tubular cells have removed and added substances

64

urine

–once it enters the collecting duct
–only remaining change is water content

65

glomerular filtration

a special case of the capillary fluid exchange process in which water and some solutes in the blood plasma pass from the capillaries of the glomerulus into the capsular space of the nephron
NO REABSORPTION

66

filtration membrane

barriers

three barriers through which fluid passes

67

fenestrated endothelium of glomerular capillaries

•highly permeable

68

basement membrane

•proteoglycan gel, negative charge, excludes molecules greater than 8nm
•albumin repelled by negative charge
•blood plasma is 7% protein, the filtrate is only 0.03% protein

69

filtration slits

podocyte cell extensions (pedicels) wrap around the capillaries to form a barrier layer with 30 nm filtration slits
•negatively charged which is an additional obstacle for large anions

70

Filtration Membrane passes

•almost any molecule smaller than 3 nm can pass freely through the filtration membrane
–water, electrolytes, glucose, fatty acids, amino acids, nitrogenous wastes, and vitamins
•some substances of low molecular weight are bound to the plasma proteins and cannot get through the membrane
–most calcium, iron, and thyroid hormone
•unbound fraction passes freely into the filtrate

71

kidney infections and trauma

can damage the filtration membrane and allow albumin or blood cells to filter.

72

proteinuria (albuminuria

presence of protein in the urine

73

hematuria

presence of blood in the urine

74

blood hydrostatic pressure (BHP)

–much higher in glomerular capillaries (60 mm Hg compared to 10 to 15 in most other capillaries)
–because afferent arteriole is larger than efferent arteriole
–larger inlet and smaller outlet

75

hydrostatic pressure in capsular space

–18 mm Hg due to high filtration rate and continual accumulation of fluid in the capsule

76

colloid osmotic pressure (COP) of blood

about the same here as elsewhere -32 mm Hg
–glomerular filtrate is almost protein-free and has no significant COP

77

higher outward pressure of 60 mm Hg

opposed by two inward pressures of 18 mm Hg and 32 mm Hg

78

net filtration pressure

60out–18in–32in= 10 mm Hgout

79

glomerular filtration rate (GFR)

the amount of filtrate formed per minute by the 2 kidneys combined
–GFR = NFP x Kf125 mL / min or 180 L / day, male
–GFR = NFP x Kf105 mL / min or 150 L / day, female

80

total amount of filtrate produced equals

50 to 60 times the amount of blood in the body
–99% of filtrate is reabsorbed since only 1 to 2 liters urine excreted / day

81

GFR too high

–fluid flows through the renal tubules too rapidly for them to reabsorb the usual amount of water and solutes
–urine output rises
–chance of dehydration and electrolyte depletion

82

GFR too low

–wastes reabsorbed
–azotemia may occur

83

GFR controlled

by adjusting glomerular blood pressure from moment to moment

84

GFR control is achieved by three homeostatic mechanisms

–renal autoregulation
–sympathetic control
–hormonal control

85

renal autoregulation

the ability of the nephrons to adjust their own blood flow and GFR without external (nervous or hormonal) control
•enables them to maintain a relatively stable GFR in spite of changes in systemic arterial blood pressure

86

two methods of autoregulation

myogenic mechanism and tubuloglomerular feedback

87

myogenic mechanism

based on the tendency of smooth muscle to contract when stretched
–increased arterial blood pressure stretches the afferent arteriole
–arteriole constricts and prevents blood flow into the glomerulus from changing much
–when blood pressure falls
–the afferent arteriole relaxes
–allows blood flow more easily into glomerulus
–filtration remains stable

88

tubuloglomerular feedback

mechanism by which glomerulus receives feedback on the status of the downstream tubular fluid and adjust filtration to regulate the composition of the fluid, stabilize its own performance, and compensate for fluctuation in systemic blood pressure

89

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

90

three special kind of cells occur in the juxtaglomerular apparatus

macula densa
juxtaglomerular (JG) cells
mesangial cells

91

macula densa

patch of slender, closely spaced epithelial cells at end of the nephron loop on the side of the tubules facing the arterioles
–senses variations in flow or fluid composition and secretes a paracrine that stimulates JG cells

92

juxtaglomerular (JG) cells

enlarged smooth muscle cells in the afferent arteriole directly across from macula densa
–when stimulated by the macula
–they dilate or constrict the arterioles
–they also contain granules of renin, which they secrete in response to drop in blood pressure

93

mesangial cells

in the cleft between the afferent and efferent arterioles and among the capillaries of the glomerulus
–connected to macula densa and JG cells by gap junctions and communicate by means of paracrines
–build supportive matrix for glomerulus, constrict or relax capillaries to regulate flow

94

if GFR rises

–the flow of tubular fluid increases and more NaCl is reabsorbed
–macula densa stimulates JG cells with a paracrine
–JG cells contract which constricts afferent arteriole, reducing GFR to normal OR
–mesangial cells may contract, constricting the capillaries and reducing filtration

95

if GFR falls

–macula relaxes afferent arterioles and mesangial cells
–blood flow increases and GFR rises back to normal

96

Effectiveness of Autoregulation

•maintains a dynamic equilibrium -GFR fluctuates within narrow limits only
•renal autoregulation can not compensate for extreme blood pressure variation
–over a MAP range of 90 –180 mm Hg, the GFR remains quite stable

97

Sympathetic Control of GFR

•sympathetic nerve fibers richly innervate the renal blood vessels
•sympathetic nervous system and adrenal epinephrine constrict the afferent arterioles in strenuous exercise or acute conditions like circulatory shock

98

Renin-Angiotensin-Aldosterone Mechanism

•renin secreted by juxtaglomerular cells if BP drops dramatically
•renin converts angiotensinogen, a blood protein, into angiotensin I
•in the lungs and kidneys, angiotensin-converting enzyme (ACE) converts angiotensin I to angiotensin II, the active hormone

99

Angiotensin II

•potent vasoconstrictor raising BP throughout body
•constricts efferent arteriole raising GFR despite low BP
•lowers BP in peritubular capillaries enhancing reabsorption of NaCl & H2O
•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 & H2O intake

100

Tubular Reabsorption and Secretion

•conversion of glomerular filtrate to urine involves the removal and addition of chemicals by tubular reabsorption and secretion
–occurs through PCT to DCT
–tubular fluid is modified

101

Tubular Reabsorption and Secretion

steps involved include:

–tubular reabsorption
–tubular secretion
–water conservation

102

Proximal Convoluted Tubule

PCT reabsorbs about 65% of glomerular filtrate, removes some substances from the blood, and secretes them into the tubular fluid for disposal in urine
–prominent microvilli and great length
–abundant mitochondria provide ATP for active transport
–PCTs alone account for about 6% of one‟s resting ATP and calorie consumption

103

tubular reabsorption

process of reclaiming water and solutes from the tubular fluid and returning them to the blood

104

two routes of reabsorption

transcellular route

105

transcellular route

•substances pass through the cytoplasm of the PCT epithelial cells and out their base

106

paracellular route

•substances pass between PCT cells
•junctions between epithelial cells are quite leaky and allow significant amounts of water to pass through

107

solvent drag

water carries with it a variety of dissolved solutes

108

sodium reabsorption is the key to everything else

–creates an osmotic and electrical gradient that drives the reabsorption of water and other solutes
–most abundant cation in filtrate
–creates steep concentration gradient that favors its diffusion into the epithelial cells

109

two types of transport proteins in the apical cell surface are responsible for sodium uptake

–symports that simultaneously bind Na+ and another solute such as glucose, amino acids or lactate
–a Na+-H+ antiport that pulls Na+ into the cell while pumping out H+ into tubular fluid

110

sodium is prevented from accumulating in the epithelial cells by Na+-K+pumps in the basal surface of the epithelium

–pumps Na+out into the extracellular fluid
–picked up by peritubular capillaries and returned to the blood stream
–ATP consuming active transport pumps

111

secondary active transport

Na+transporting symports in apical cell membrane do not consume ATP, are considered an example of secondary active transport for their dependence on the Na+-K+pumps at the base of the cell

112

negative chloride ions follow the positive sodium ions by electrical attraction

–various antiports in the apical cell membrane that absorb Cl-in exchange for other anions they eject into the tubular fluid –K+-Cl-symport

113

potassium, magnesium, and phosphate ions

diffuse through the paracellular route with water

114

phosphate

phosphate Is also cotransported into the epithelial cells with Na+

115

some calcium is reabsorbed

through the paracellular route in the PCT, but most Ca2+reabsorption occurs later in the nephron

116

glucose

is cotransported with Na+by sodium-glucose transport (SGLT) proteins.

117

urea

diffuses through the tubule epithelium with water –reabsorbs 40 –60% in tubular fluid
–kidneys remove about half of the urea from the blood -creatinine is not reabsorbed at all

118

Water Reabsorption

•kidneys reduce 180 L of glomerular filtrate to 1 or 2 liters of urine each day
•two-thirds of water in filtrate is reabsorbed by the PCT

119

Reabsorption of all the salt and organic solutes makes the tubule cells and tissue fluid

hypertonic

120

aquaporins

water follows solutes by osmosis through both paracellular and transcellular routes through water channels called aquaporins

121

obligatory water reabsorption

in PCT, water is reabsorbed at constant rate called obligatory water reabsorption

122

Uptake by the Peritubular Capillaries

•after water and solutes leave the basal surface of the tubular epithelium, they are reabsorbed by the peritubular capillaries
–reabsorbed by osmosis and solvent drag

123

three factors promote osmosis into the capillaries

–accumulation of reabsorbed fluid around the basolateral sides of epithelial cell creates high interstitial fluid pressure that drives water into the capillaries
–narrowness of efferent arterioles lowers blood hydrostatic pressure in peritubular capillaries so there is less resistance to absorption
–proteins remain in blood after filtration, which elevates colloid osmotic pressure

124

Transport Maximum of Glucose

there is a limit to the amount of solute that the renal tubules can reabsorb
•limited by the number of transport proteins in the plasma membrane
•if all transporters are occupied as solute molecules pass
–excess solutes appear in urine

125

transport maximum is reached when

transporters are saturated
•each solute has its own transport maximum

126

glycosuria

any blood glucose level above 220 mg/dL results in

127

tubular secretion

process in which the renal tubule extracts chemicals from the capillary blood and secretes them into tubular fluid

128

two purposes in proximal convoluted tubule and nephron loop

waste removal
acid-base balance

129

waste removal

•urea, uric acid, bile acids, ammonia, catecholamines, prostaglandins and a little creatinine are secreted into the tubule
•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 3 to 4 times/day to keep pace with the rate of clearance

130

acid-base balance

•secretion of hydrogen and bicarbonate ions help regulate the pH of the body fluids

131

primary function of nephron loop

is to generate salinity gradient that enables collecting duct to concentrate the urine and conserve water

132

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 can not follow since thick segment is impermeable to water
–tubular fluid very dilute as it enters distal convoluted tubule

133

DCT and Collecting Duct

•fluid arriving in the DCT still contains about 20% of the water and 7% of the salts from glomerular filtrate
–if this were all passed as urine, it would amount to 36 L/day

134

DCT and collecting duct reabsorb variable amounts of water salt and are regulated by several hormones

–aldosterone, atrial natriuretic peptide, ADH, and parathyroid hormone

135

two kinds of cells in the DCT and collecting duct

principal cells
intercalated cells

136

principal cells

•most numerous
•have receptors for hormones
•involved in salt and water balance

137

intercalated cells

•involved in acid/base balance by secreting H+ into tubule lumen and reabsorbing K+

138

aldosterone

the “salt-retaining” hormone
–steroid secreted by the adrenal cortex
•when blood Na+concentration falls or
•when K+concentration rises
•or drop in blood pressure renin release angiotensin II formation stimulates adrenal cortex to secrete aldosterone

139

functions of aldosterone

–acts on thick segment of nephron loop, DCT, and cortical portion of collecting duct
•stimulates the reabsorption of more Na+and secretion of K+
•water and Cl-follow the Na+
•net effect is that the body retains NaCl and water
–helps maintain blood volume and pressure
•the urine volume is reduced
•the urine has an elevated K+concentration

140

atrial natriuretic peptide (ANP)

secreted by atrial myocardium of the heart in response to high blood pressure
•has four actions that result in the excretion of more salt and water in the urine, thus reducing blood volume and pressure

141

has four actions

–dilates afferent arteriole, constricts efferent arteriole -INCREASE GFR
–inhibits renin and aldosterone secretion
–inhibits secretion of ADH
–inhibits NaCl reabsorption by collecting duct

142

antidiuretic hormone (ADH)

secreted by posterior lobe of pituitary
•in response to dehydration and rising blood osmolarity
–stimulates hypothalamus
–hypothalamus stimulates posterior pituitary
•action -make collecting duct more permeable to water
–water in the tubular fluid reenters the tissue fluid and bloodstream rather than being lost in urine

143

parathyroid hormone

(PTH) secreted from parathyroid glands in response to calcium deficiency (hypocalcemia)
–acts on PCT to increase phosphate excretion
–acts on the thick segment of the ascending limb of the nephron loop, and on the DCT to increase calcium reabsorption
–increases phosphate content and lowers calcium content in urine
–because phosphate is not retained, the calcium ions stay in circulation rather than precipitating into the bone tissue as calcium phosphate
–PTH stimulates calcitriol synthesis by the epithelial cells of the PCT

144

Summary of Tubular Reabsorption and Secretion

----

145

PCT reabsorbs

65% of glomerular filtrate and returns it to peritubular capillaries
–much reabsorption by osmosis & cotransport mechanisms linked to active transport of sodium

146

nephron loop reabsorbs

another 25% of filtrate

147

DCT reabsorbs

Na+, Cl-and water under hormonal control, especially aldosterone and ANP
•the tubules also extract drugs, wastes, and some solutes from the blood and secretethem into the tubular fluid

148

DCT completes the process of

determining the chemical composition of urine

149

collecting duct

conserves water

150

Water Conservation

•the kidney eliminates metabolic wastes from the body, but also prevents excessive water loss as well
•as the kidney returns water to the tissue fluid and bloodstream, the fluid remaining in the renal tubules passes as urine, and becomes more concentrated

151

Collecting Duct Concentrates Urine

•collecting duct (CD) begins in the cortex where it receives tubular fluid from several nephrons
•as CD passes through the medulla, it reabsorbs water and concentrates urine up to four times
•medullary portion of CD is more permeable to water than to NaCl
•as urine passes through the increasingly salty medulla, water leaves by osmosis concentrating urine

152

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
–salt removed from the urine stays in the CD
–urine concentration may be as low as 50 mOsm/L

153

producing hypertonic urine

–dehydration causes the urine to become scanty and more concentrated
–high blood osmolarity stimulates posterior pituitary to release 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

154

If BP is low in a dehydrated person

GFR will be low.
–filtrate moves more slowly and more time for reabsorption –
–more salt removed, more water reabsorbed and less urine produced

155

vasa recta

capillary branching off efferent arteriole in medulla
–provides blood supply to medulla and does not remove NaCl and urea from medullary ECF

156

urinalysis

the examination of the physical and chemical properties of urine

157

appearance

clear, almost colorless to deep amber -yellow color due to urochrome pigment from breakdown of hemoglobin (RBCs) –other colors from foods, drugs or diseases
–cloudiness or blood could suggest urinary tract infection, trauma or stones

158

pyuria

pus in the urine

159

hematuria

blood in urine due to urinary tract infection, trauma, or kidney stones

160

odor

bacteria degrade urea to ammonia, some foods impart aroma

161

specific gravity

compared to distilled water
•density of urine ranges from 1.001 -1.028

162

osmolarity-

blood = 300 mOsm/L)
•ranges from 50 mOsm/L to 1,200 mOsm/L in dehydrated person

163

pH

range: 4.5 to 8.2, usually 6.0 (mildly acidic)

164

chemical composition:

95% water, 5% solutes

165

normal to find

urea, NaCl, KCl, creatinine, uric acid, phosphates, sulfates, traces of calcium, magnesium, and sometimes bicarbonate, urochrome and a trace of bilirubin

166

abnormal to find

glucose, free hemoglobin, albumin, ketones, bile pigments

167

Urine Volume - normal

normal volume for average adult -1 to 2 L/day

168

polyuria

output in excess of 2 L/day

169

oliguria

output of less than 500 mL/day

170

anuria

0 to 100 mL/day

171

diabetes

any metabolic disorder resulting in chronic polyuria

172

at least four forms of diabetes

–diabetes mellitus type 1, type 2, and gestational diabetes
–diabetes insipidus

173

diabetes mellitus type 1, type 2, and gestational diabetes

•high concentration of glucose in renal tubule
•glucose opposes the osmotic reabsorption of water
•more water passes in urine (osmotic diuresis)
•glycosuria –glucose in the urine

174

–diabetes insipidus

•ADH hyposecretion causing not enough water to be reabsorbed in the collecting duct
•more water passes in urine

175

diuretics

any chemical that increases urine volume
•commonly used to treat hypertension and congestive heart failure by reducing the body‟s fluid volume and blood pressure

176

some increase GFR

caffeine dilates the afferent arteriole

177

reduce tubular reabsorption of water

alcohol inhibits ADH secretion

178

act on nephron loop (loop diuretic)

inhibit Na+ -K+-Cl-symport
•impairs countercurrent multiplier reducing the osmotic gradient in the renal medulla
•collecting duct unable to reabsorb as much water as usual

179

Renal Function Tests

•tests for diagnosing kidney disease
•evaluating their severity
•monitoring their progress
•determine renal clearance
•determine glomerular filtration rate

180

renal clearance

the volume of blood plasma from which a particular waste is completely removed in 1 minute

181

represents the net effect of three processes:

+ glomerular filtration of the waste
+ amount added by tubular secretion
–amount removed by tubular reabsorption
renal clearance

182

kidney disease often results in

lowering of GFR –need to measure patient‟s GFR
–can not use clearance rate of urea
•some urea filtered by glomerulus is reabsorbed in the tubule
•some urea is secreted into the tubule

183

inulin

use inulin, a plant polysaccharide to determine GFR
–neither reabsorbed or secreted by the renal tubule
–inulin GFR = renal clearance on inulin

184

Urine Storage and Elimination

•urine is produced continually
•does not drain continually from the body
•urination is episodic –occurring when we allow it
•made possible by storage apparatus
•and neural controls of this timely release

185

ureters

retroperitoneal, muscular tube that extends from the kidney to the urinary bladder
–about 25 cm long
–passes posterior to bladder and enters it from below
–flap of mucosa acts as a valve into bladder
•keeps urine from backing up in the ureter when bladder contracts

186

3 layers of ureter

adventitia
muscularis
mucosa

187

adventitia

connective tissue layer that connects ureter to surrounding structures

188

muscularis

2 layers of smooth muscle with 3rdlayer in lower ureter
–urine enters, it stretches and contracts in peristaltic wave

189

mucosa

transitional epithelium
–begins at minor calyces and extends through the bladder

190

urinary bladder

muscular sac located on floor of pelvic cavity
–inferior to peritoneum and posterior to pubic symphysis

191

3 layers

parietal peritoneum,
muscularis
mucosa

192

parietal peritoneum,

superiorly, fibrous adventitia other areas

193

muscularis

detrusor muscle -3 layers of smooth muscle

194

mucosa

transitional epithelium

195

rugae

conspicuous wrinkles in relaxed bladder

196

trigone

smooth-surfaced triangular area marked with openings of ureters and urethra

197

capacity

moderately full is 500 ml, max. is 700 -800 ml
–highly distensible
–as it fills, it expands superiorly
–rugae flatten
–epithelium thins from five or six layers to two or three

198

renal calculus (kidney stone)

hard granule of calcium phosphate, calcium oxalate, uric acid, or a magnesium salt called struvite
•form in the renal pelvis
•usually small enough to pass unnoticed in the urine flow

199

causes

include hypercalcemia, dehydration, pH imbalances, frequent urinary tract infections, or enlarged prostate gland causing urine retention

200

treatment

includes stone dissolving drugs, often surgery, or lithotripsy–nonsurgical technique that pulverizes stones with ultrasound

201

lithotripsy

nonsurgical technique that pulverizes stones with ultrasound

202

Female Urethra

•3 to 4 cm long
•bound to anterior wall of vagina

203

external urethral orifice

–between vaginal orifice and clitoris

204

internal urethral sphincter

–detrusor muscle thickening
–smooth muscle under involuntary control

205

external urethral sphincter

–where the urethra passes through the pelvic floor
–skeletal muscle under voluntary control

206

Male Urethra

18 cm long
•3 regions of male urethra
–prostatic urethra (2.5 cm)
•passes through prostate gland
–membranous urethra (.5 cm)
•passes through muscular floor of pelvic cavity
–spongy (penile) urethra (15 cm)
•passes through penis in corpus spongiosum

207

internal urethral sphincter

detrusor muscle thickening

208

external urethral sphincter

part of skeletal muscle of pelvic floor

209

Urinary Tract Infection (UTI)

cystitis
pyelitis
pyelonephritis

210

cystitis

infection of the urinary bladder
–especially common in females due to short urethra
–frequently triggered by sexual intercourse
–can spread up the ureter causing pyelitis

211

pyelitis

infection of the renal pelvis

212

pyelonephritis

infection that reaches the cortex and the nephrons
–can result from blood-borne bacteria

213

Voiding Urine

•between acts of urination, the bladder is filling
–detrusor muscle relaxes
–urethral sphincters are tightly closed
•accomplished by sympathetic pathway from upper lumbar spinal cord
•postganglionic fibers travel through the hypogastric nerve to the detrusor muscle (relax) and internal urethral sphincter (excite)
–somatic motor fibers from upper sacral spinal cord through pudendal nerve to supply the external sphincter give us voluntary control

214

voluntary control

somatic motor fibers from upper sacral spinal cord through pudendal nerve to supply the external sphincter give us voluntary control

215

micturition

the act of urinating

216

micturition reflex

spinal reflex that partly controls urination

217

involuntary control

–filling of the bladder to about 200 mL excites stretch receptors in the bladder wall
–send sensory signals through fibers in pelvic nerve to sacral spinal cord (S2or S3)
–motor signals travel back from the spinal cord to the bladder by way of motor fibers in pelvic nerve and parasympathetic ganglion in bladder wall
–excites detrusor muscle and relaxes internal urethral sphincter
–results in emptying bladder
–if there was no voluntary control over urination, this reflex would be the only means of control

218

voluntary control

–nucleus integrates information about bladder tension with information from other brain centers
•urination can be prompted by fear
•inhibited by knowledge that the circumstances are inappropriate for urination
–fibers from micturition center descend the spinal cord
•through reticulospinal tracts
–some fibers inhibit sympathetic fibers than normally keep internal urethral sphincter contracted
–others descend farther to sacral spinal cord
•excite parasympathetic neurons that stimulate the detrusor to contract and relax the internal urethral sphincter
–initial detrusor contraction raises pressure in bladder, stimulate stretch receptors, bringing about more forceful contraction
–external urethral sphincter receives nerve fibers from cerebral cortex by way of corticospinal tract
•inhibit somatic motor neurons that normally keep that sphincter constricted

219

micturition center

nucleus in the pons that receives some input from bladder stretch receptors that ascends the spinal cord

220

Micturition Reflex

•urge to urinate usually arises at an inconvenient time
–one must suppress it
–stretch receptors fatigue and stop firing
•as bladder tension increases
–signals return with increasing frequency and persistence
•there are times when the bladder is not full enough to trigger the micturition reflex but one wishes to „go‟ anyway
–Valsalva maneuver used to compress bladder
–excites stretch receptors early getting the reflex started

221

renal insufficiency

a state in which the kidneys cannot maintain homeostasis due to extensive destruction of their nephrons

222

causes of nephron destruction

–hypertension, chronic kidney infections, trauma, prolonged ischemia and hypoxia, poisoning by heavy metals or solvents, blockage of renal tubules in transfusion reaction, atherosclerosis, diabetes, or glomerulonephritis

223

nephrons can

regenerate and restore kidney function after short-term injuries
–others nephrons hypertrophy to compensate for lost kidney function
•can survive with one-third of one kidney
•when 75% of nephrons are lost and urine output of 30 mL/hr is insufficient (normal 50 -60 mL/hr) to maintain homeostasis

224

hemodialysis

procedure for artificially clearing wastes from the blood
–wastes leave bloodstream and enter the dialysis fluid as blood flows through a semipermeable cellophane tube; also removes excess body water