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

0-1 Chapter 23 Urinary System Flashcards

1
Q

urinary system

A

principal means of waste removal

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2
Q

kidney functions

A

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

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3
Q

urologists

A

treat both urinary and reproductive disorders

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4
Q

urinary system consists of 6 organs

A

2 kidneys, 2 ureters, urinary bladder, and urethra

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5
Q

Kidney

Secrete

A

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

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6
Q

waste

A

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

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7
Q

metabolic waste

A

waste substance produced by the body

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8
Q

urea formation

A
  • proteins
  • amino acids
  • NH2 removed
  • forms ammonia
  • liver converts to urea
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9
Q

uric acid

A

product of nucleic acid catabolism

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10
Q

blood urea nitrogen (BUN)

A

expression of the level of nitrogenous waste in the blood

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11
Q

azotemia

A

elevated BUN

•indicates renal insufficiency

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12
Q

uremia

A

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

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13
Q

excretion

A

separation of wastes from body fluids and eliminating them

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14
Q

four body systems carry out excretion

A

respiratory system
integumentary system
digestive system
urinary system

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15
Q

respiratory system

A

CO2, small amounts of other gases, and water

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16
Q

integumentary system

A

water, inorganic salts, lactic acid, urea in sweat

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17
Q

digestive system

A

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

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18
Q

urinary system

A

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

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19
Q

Kidney

location

A

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

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20
Q

three protective connective tissue coverings

A

renal fascia
perirenal fat capsule
fibrous capsule

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21
Q

renal parenchyma

A

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

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22
Q

renal sinus

A

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

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23
Q

two zones of renal parenchyma

A

outer renal cortex

inner renal medulla

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24
Q

inner renal medulla

A
  • 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
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25
Q

lobe of the kidney

A

one pyramid and its overlying cortex

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26
Q

minor calyx

A

cup that nestles the papilla of each pyramid

•collects its urine

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27
Q

major calyces

A

formed by convergence of two or three minor calyces

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28
Q

renal pelvis

A

formed by convergence of two or three major calyces

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28
Q

ureter begins at

A

renal pelvis

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29
Q

ureter

A

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

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30
Q

Blood Supply Diagram

A

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

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31
Q

renal fraction

A

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

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32
Q

renal artery divides into segmental arteries that give rise to

A
  • 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
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33
Q

renal vein empties into

A

inferior vena cava

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34
Q

peritubular capillaries

A

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

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35
Q

vasa recta

A

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

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36
Q

filtration unit of the kidney is the

A

nephron

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37
Q

Nephron

each composed of two principal parts:

A

–renal corpuscle –filters the blood plasma

–renal tubule –long coiled tube that converts the filtrate into urine

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38
Q

renal corpuscle consists of

A

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

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39
Q

glomerular (Bowman) capsule

A

–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

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40
Q

vascular pole

A

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

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41
Q

urinary pole

A

the opposite side of the corpuscle where the renal tubule begins

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42
Q

renal (uriniferous) tubule

A

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

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43
Q

divided into four regions –

A

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

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44
Q

proximal convoluted tubule(PCT)

A

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

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45
Q

nephron loop (loop of Henle)

A

long U-shaped portion of renal tubule

–descending limb and ascending limb

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46
Q

thick segments

A

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

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47
Q

thin segment

A

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

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49
Q

distal convoluted tubule (DCT)

A

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

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50
Q

collecting duct

A

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

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51
Q

papillary duct

A

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

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52
Q

becomes urine when it enters the

A

collecting duct

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53
Q

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

A

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

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54
Q

cortical nephrons

A

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

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55
Q

juxtamedullary nephrons

A

–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

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56
Q

cortical nephrons have

A

peritubular capillaries

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57
Q

juxtamedullary nephrons have

A

vasa recta

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58
Q

renal plexus

A

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

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59
Q

carries sympathetic innervation from the abdominal aortic plexus

A
  • 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
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60
Q

carries parasympathetic innervation from the vagus nerve

A

increases rate of urine production

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61
Q

kidneys convert blood plasma to urine in three stages

A

glomerular filtration
–tubular reabsorption and secretion
–water conservation

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62
Q

glomerular filtrate

A

–fluid in capsular space

–blood plasma without protein

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63
Q

tubular fluid

A

–fluid in renal tubule

–similar to above except tubular cells have removed and added substances

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64
Q

urine

A

–once it enters the collecting duct

–only remaining change is water content

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65
Q

glomerular filtration

A

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

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66
Q

filtration membrane

barriers

A

three barriers through which fluid passes

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67
Q

fenestrated endothelium of glomerular capillaries

A

•highly permeable

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68
Q

basement membrane

A
  • 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
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69
Q

filtration slits

A

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

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70
Q

Filtration Membrane passes

A

•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

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71
Q

kidney infections and trauma

A

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

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72
Q

proteinuria (albuminuria

A

presence of protein in the urine

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73
Q

hematuria

A

presence of blood in the urine

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74
Q

blood hydrostatic pressure (BHP)

A

–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

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75
Q

hydrostatic pressure in capsular space

A

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

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76
Q

colloid osmotic pressure (COP) of blood

A

about the same here as elsewhere -32 mm Hg

–glomerular filtrate is almost protein-free and has no significant COP

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77
Q

higher outward pressure of 60 mm Hg

A

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

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78
Q

net filtration pressure

A

60out–18in–32in= 10 mm Hgout

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79
Q

glomerular filtration rate (GFR)

A

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

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80
Q

total amount of filtrate produced equals

A

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

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81
Q

GFR too high

A

–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

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82
Q

GFR too low

A

–wastes reabsorbed

–azotemia may occur

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83
Q

GFR controlled

A

by adjusting glomerular blood pressure from moment to moment

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84
Q

GFR control is achieved by three homeostatic mechanisms

A

–renal autoregulation
–sympathetic control
–hormonal control

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85
Q

renal autoregulation

A

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

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86
Q

two methods of autoregulation

A

myogenic mechanism and tubuloglomerular feedback

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87
Q

myogenic mechanism

A

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

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88
Q

tubuloglomerular feedback

A

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

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89
Q

juxtaglomerular apparatus

A

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

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90
Q

three special kind of cells occur in the juxtaglomerular apparatus

A

macula densa
juxtaglomerular (JG) cells
mesangial cells

91
Q

macula densa

A

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
Q

juxtaglomerular (JG) cells

A

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
Q

mesangial cells

A

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
Q

if GFR rises

A

–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
Q

if GFR falls

A

–macula relaxes afferent arterioles and mesangial cells

–blood flow increases and GFR rises back to normal

96
Q

Effectiveness of Autoregulation

A

•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
Q

Sympathetic Control of GFR

A
  • 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
Q

Renin-Angiotensin-Aldosterone Mechanism

A
  • 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
Q

Angiotensin II

A
  • 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
Q

Tubular Reabsorption and Secretion

A

•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
Q

Tubular Reabsorption and Secretion

steps involved include:

A

–tubular reabsorption
–tubular secretion
–water conservation

102
Q

Proximal Convoluted Tubule

A

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
Q

tubular reabsorption

A

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

104
Q

two routes of reabsorption

A

transcellular route

105
Q

transcellular route

A

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

106
Q

paracellular route

A
  • substances pass between PCT cells

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

107
Q

solvent drag

A

water carries with it a variety of dissolved solutes

108
Q

sodium reabsorption is the key to everything else

A

–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
Q

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

A

–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
Q

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

A

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

111
Q

secondary active transport

A

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
Q

negative chloride ions follow the positive sodium ions by electrical attraction

A

–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
Q

potassium, magnesium, and phosphate ions

A

diffuse through the paracellular route with water

114
Q

phosphate

A

phosphate Is also cotransported into the epithelial cells with Na+

115
Q

some calcium is reabsorbed

A

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

116
Q

glucose

A

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

117
Q

urea

A

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
Q

Water Reabsorption

A
  • 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
Q

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

A

hypertonic

120
Q

aquaporins

A

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

121
Q

obligatory water reabsorption

A

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

122
Q

Uptake by the Peritubular Capillaries

A

•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
Q

three factors promote osmosis into the capillaries

A

–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
Q

Transport Maximum of Glucose

A

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
Q

transport maximum is reached when

A

transporters are saturated

•each solute has its own transport maximum

126
Q

glycosuria

A

any blood glucose level above 220 mg/dL results in

127
Q

tubular secretion

A

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

128
Q

two purposes in proximal convoluted tubule and nephron loop

A

waste removal

acid-base balance

129
Q

waste removal

A

•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
Q

acid-base balance

A

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

131
Q

primary function of nephron loop

A

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

132
Q

electrolyte reabsorption from filtrate

A

–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
Q

DCT and Collecting Duct

A

•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
Q

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

A

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

135
Q

two kinds of cells in the DCT and collecting duct

A

principal cells

intercalated cells

136
Q

principal cells

A
  • most numerous
  • have receptors for hormones
  • involved in salt and water balance
137
Q

intercalated cells

A

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

138
Q

aldosterone

A 
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
Q

functions of aldosterone

A

–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
Q

atrial natriuretic peptide (ANP)

A

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
Q

has four actions

A

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

142
Q

antidiuretic hormone (ADH)

A

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
Q

parathyroid hormone

A

(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
Q

Summary of Tubular Reabsorption and Secretion

A
145
Q

PCT reabsorbs

A

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

146
Q

nephron loop reabsorbs

A

another 25% of filtrate

147
Q

DCT reabsorbs

A

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
Q

DCT completes the process of

A

determining the chemical composition of urine

149
Q

collecting duct

A

conserves water

150
Q

Water Conservation

A
  • 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
Q

Collecting Duct Concentrates Urine

A
  • 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
Q

water diuresis

A

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
Q

producing hypertonic urine

A

–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
Q

If BP is low in a dehydrated person

A

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

155
Q

vasa recta

A

capillary branching off efferent arteriole in medulla

–provides blood supply to medulla and does not remove NaCl and urea from medullary ECF

156
Q

urinalysis

A

the examination of the physical and chemical properties of urine

157
Q

appearance

A

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
Q

pyuria

A

pus in the urine

159
Q

hematuria

A

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

160
Q

odor

A

bacteria degrade urea to ammonia, some foods impart aroma

161
Q

specific gravity

A

compared to distilled water

•density of urine ranges from 1.001 -1.028

162
Q

osmolarity-

A

blood = 300 mOsm/L)

•ranges from 50 mOsm/L to 1,200 mOsm/L in dehydrated person

163
Q

pH

A

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

164
Q

chemical composition:

A

95% water, 5% solutes

165
Q

normal to find

A

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

166
Q

abnormal to find

A

glucose, free hemoglobin, albumin, ketones, bile pigments

167
Q

Urine Volume - normal

A

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

168
Q

polyuria

A

output in excess of 2 L/day

169
Q

oliguria

A

output of less than 500 mL/day

170
Q

anuria

A

0 to 100 mL/day

171
Q

diabetes

A

any metabolic disorder resulting in chronic polyuria

172
Q

at least four forms of diabetes

A

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

–diabetes insipidus

173
Q

diabetes mellitus type 1, type 2, and gestational diabetes

A
  • 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
Q

–diabetes insipidus

A
  • ADH hyposecretion causing not enough water to be reabsorbed in the collecting duct
  • more water passes in urine
175
Q

diuretics

A

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
Q

some increase GFR

A

caffeine dilates the afferent arteriole

177
Q

reduce tubular reabsorption of water

A

alcohol inhibits ADH secretion

178
Q

act on nephron loop (loop diuretic)

A

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
Q

Renal Function Tests

A
  • tests for diagnosing kidney disease
  • evaluating their severity
  • monitoring their progress
  • determine renal clearance
  • determine glomerular filtration rate
180
Q

renal clearance

A

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

181
Q

represents the net effect of three processes:

A

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

182
Q

kidney disease often results in

A

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
Q

inulin

A

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

184
Q

Urine Storage and Elimination

A
  • 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
Q

ureters

A

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
Q

3 layers of ureter

A

adventitia
muscularis
mucosa

187
Q

adventitia

A

connective tissue layer that connects ureter to surrounding structures

188
Q

muscularis

A

2 layers of smooth muscle with 3rdlayer in lower ureter

–urine enters, it stretches and contracts in peristaltic wave

189
Q

mucosa

A

transitional epithelium

–begins at minor calyces and extends through the bladder

190
Q

urinary bladder

A

muscular sac located on floor of pelvic cavity

–inferior to peritoneum and posterior to pubic symphysis

191
Q

3 layers

A

parietal peritoneum,
muscularis
mucosa

192
Q

parietal peritoneum,

A

superiorly, fibrous adventitia other areas

193
Q

muscularis

A

detrusor muscle -3 layers of smooth muscle

194
Q

mucosa

A

transitional epithelium

195
Q

rugae

A

conspicuous wrinkles in relaxed bladder

196
Q

trigone

A

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

197
Q

capacity

A

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
Q

renal calculus (kidney stone)

A

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
Q

causes

A

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

200
Q

treatment

A

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

201
Q

lithotripsy

A

nonsurgical technique that pulverizes stones with ultrasound

202
Q

Female Urethra

A
  • 3 to 4 cm long

* bound to anterior wall of vagina

203
Q

external urethral orifice

A

–between vaginal orifice and clitoris

204
Q

internal urethral sphincter

A

–detrusor muscle thickening

–smooth muscle under involuntary control

205
Q

external urethral sphincter

A

–where the urethra passes through the pelvic floor

–skeletal muscle under voluntary control

206
Q

Male Urethra

A 
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
Q

internal urethral sphincter

A

detrusor muscle thickening

208
Q

external urethral sphincter

A

part of skeletal muscle of pelvic floor

209
Q

Urinary Tract Infection (UTI)

A

cystitis
pyelitis
pyelonephritis

210
Q

cystitis

A

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
Q

pyelitis

A

infection of the renal pelvis

212
Q

pyelonephritis

A

infection that reaches the cortex and the nephrons

–can result from blood-borne bacteria

213
Q

Voiding Urine

A

•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
Q

voluntary control

A

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

215
Q

micturition

A

the act of urinating

216
Q

micturition reflex

A

spinal reflex that partly controls urination

217
Q

involuntary control

A

–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
Q

voluntary control

A

–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
Q

micturition center

A

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

220
Q

Micturition Reflex

A

•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
Q

renal insufficiency

A

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

222
Q

causes of nephron destruction

A

–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
Q

nephrons can

A

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
Q

hemodialysis

A

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

2 - Keiser A&P 2 (15 decks)

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