urinary system Flashcards

1
Q

what are the major structures in the urinary system

A

2 kidneys
2 ureters
bladder
urethra

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2
Q

what are the functions of the urinary system

A

filter blood plasma (conc of ions and remove toxins)

conserves valuable nutrients (prevent loss thru urine)

regulates blood volume and pressure (decrease fluid > decrease blood vol > decrease BP)

regulates blood pH and glucose levels (remove H+ and glucose > maintain homeostasis)

release hormones (erythropoietin and calcitriol)

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3
Q

describe the anatomical position of the kidneys

A

either side of vertebral column
left slightly superior to right
retroperitoneal
protected by 11th and 12th ribs

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4
Q

what are the 4 structures going in/out of the kidney

A

renal artery
renal vein
hilum
ureter

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5
Q

what are the 3 CT layers around the kidney

A

fibrous capsule = collagen fibres

perirenal fat = cushioning layer of adipose tissue

renal fascia = fibrous layer that anchors kidney to surrounding structures

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6
Q

what is the renal cortex

A

outermost 1cm of the kidney

where filtration and reabsorption occurs

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7
Q

what is the renal medulla

A

2-3cm below the cortex

regulate concentration of urine

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8
Q

what is the renal sinus

A

central cavity that contains renal pelvis, renal calyces, blood vessels and fat

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9
Q

what are renal pyramids

A

in the medulla

extends from cortex to the renal sinus

transport urine from cortex to sinus

apex = renal papilla

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10
Q

what are renal columns

A

in the medulla

bands of tissue that separate adjacent renal pyramids

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11
Q

what are kidney lobes

A

in the medulla

they are functional units > where urine is produced

consist of renal pyramid, overlying renal cortex, and adjacent tissues of the renal columns

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12
Q

how is filtrate drained into the sinus

A

renal papilla >

minor calyces (collects urine produced by a single kidney lobe) >

major calyces (fusion of 4-5 minor calyces / collects urine from minor calyces >

renal pelvis (continuous w ureter) >

ureter (drains urine from kidney to bladder using peristaltic waves)

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13
Q

what are ureters

A

muscular tubes that go from the kidneys to the posterior wall of the bladder

sit retroperitoneal and are firmly attached to the posterior abdominal wall

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14
Q

what are the histological layers of the ureters

A

muscosa > transitional epithelium ie urothelium > expansion of ureter

muscularis > peristalsis / upper 2/3 has 2 layers of smooth muscle and bottom 1/3 has 3 layers of smooth muscle

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15
Q

what are the histological layers of the bladder

A

mucosa > urothelium + rugae > expansion

muscularis > expulsion of urine / 3 layers of smooth muscle

sphincters > bands of skeletal muscle that control urine flow, like valves

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16
Q

what are the 2 sphincters in the bladder

A

internal urethral (involuntary)
external urethral (voluntary)

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17
Q

what does the urethra do

A

transport urine from bladder to exterior of body

females = urine only
males = urine + semen

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18
Q

what are the histological layers of the urethra

A

mucosa > proximal = stratified transitional epithelium / middle = stratified columnar / distal = stratified squamous

muscularis > expulsion of urine / 2 layers of smooth muscle

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19
Q

what do the kidneys do

A

produce urine

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20
Q

what do the ureters do

A

carry urine from kidney to bladder

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21
Q

what does the bladder do

A

receives and stores urine

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22
Q

how does blood flow in the kidney

A
  1. O2 rich blood via renal artery
  2. renal artery divides into segmental arteries in renal sinus
  3. segmental arteries branch into interlobar arteries in renal columns
  4. interlobar arteries branch into small vessels > culminate in afferent arterioles that supply each nephron > blood enter glomerulus
  5. efferent arteriole carries blood from glomerulus to peritubular capillaries
  6. peritubular capillaries surround renal tubule
  7. peritubular capillaries drain into cortical veins > filtered back to IVC
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23
Q

what is a nephron

A

functional units of the kidney

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24
Q

what are the two types of nephrons

A

cortical - renal cortex / excrete waste product

juxtamedullary - long nephron loops in renal medulla / produce concentrated urine

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25
Q

what are the three main components of the nephron

A

renal corpuscle
renal tubule
collecting system

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26
Q

what does the renal corpuscle do

A

site of blood filtration

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27
Q

what does the renal tubule do

A

site of filtrate modification

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28
Q

what does the collecting system do

A

urine from each nephron empties into collecting system and then into minor calyces

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29
Q

what are the 3 distinct physiological process kidneys use to maintain homeostasis

A

filtration
reabsorption
secretion

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30
Q

what does the filtration structure in the renal corpuscle consist of

A

glomerulus (afferent and efferent arterioles)

glomerular capsule/bowmans capsule

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31
Q

why do efferent arterioles have a smaller diameter than afferent

A

increase the glomerular pressure which is needed as a driver for filtration to occur as it forces water and solutes out of glomerular capillaries into renal tubule

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32
Q

how does filtrate from the blood get filtered and passed onto the glomerulus capsule from the glomerulus

A

through a filtration membrane

filtrate move into capsular space while non filterable components exit glomerulus via efferent arteriole

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33
Q

what is the filtration membrane comprised of

A

fenestrated endothelium - stops cells and platelets

basement membrane - stops large proteins

filtration slits b/w pedicels (processes from podocytes) - stops medium sized proteins

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34
Q

what enhances filtration

A

thinness of filtration membrane
large SA of glomerular capillaries
higher glomerular BP

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35
Q

what is glomerular filtration rate (eGFR)

A

based on creatinine levels > gives estimation on kidney function

> GFR90 is normal
GFR 60-90 = CKD1

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36
Q

what are mesangial cells

A

b/w adjacent capillaries

contract and relax to control capillary diameter and blood flow rate

phagocytosis to keep glomerular filter free of debris

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37
Q

what are the three main parts of the renal tubule

A

proximal convoluted tubule (PCT)

loop of henle

distal convoluted tubule (DCT)

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38
Q

what is the function and structure of the PCT

A

reabsorbs most of filtrate (e.g glucose and small proteins)

has microvilli to increase SA, mitochondria for active transport, centrally located nucleus and pink appearance

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39
Q

what is the function and structure of loop of henle

A

urine concentration

descending limb
thin ascending limb
thick ascending limb
has vasa recta

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40
Q

how does the countercurrent multiplier mechanism work in the loop of henle

A

descending limb is permeable to water > water leaves descending limb into ISF of medulla

this causes a conc gradient to be established in medulla

the ascending limb is not permeable to water, so in response to ISF becoming dilute, ions such as Na+ and Cl- and K+ are actively transported out into the ISF to make it ‘salty’

this creates a conc gradient again so that water exits the DCT and collecting duct

all this, allows for increase water reabsorption

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41
Q

what is the function and structure of the DCT

A

Na+ reabsorbed due to release of aldosterone > increase blood Na+ > water reabsorption > increase blood volume and pressure

K+ secreted due to aldosterone release

bicarbonate ions reabsorbed

ADH/vasopressin

has few microvilli, many mitochondria

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42
Q

what is the function of collecting tubules and ducts

A

tubules unite to form ducts

concentrates urine by passive reabsorption of water into medulla (increase by ADH)

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43
Q

what is the juxtaglomerular apparatus (JGA)

A

regulates systemic blood pressure using RAAS

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44
Q

what are the components of the JGA

A

Jg cells = endocrine cells in afferent arteriole > produce renin > aldosterone > increase Na+ reabsorption in DCT

Macula densa (part of DCT) = monitor Na+ level in filtrate

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45
Q

what are diuretics

A

increase excretion of sodium and water

e.g caffeine, alcohol, medications

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46
Q

what are three main metabolic waste products

A

urea (by-product of AA breakdown)

creatinine (breakdown of creatine phosphate)

uric acid (byproduct of recycling nitrogenous bases of RNA)

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47
Q

how is dilute urine formed

A

decrease ADH > decrease water reabsorption in DCT and collecting ducts > dilute urine

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48
Q

how is concentrated urine formed

A

increase ADH > increase water reabsorption in DCT and collecting ducts > concentrated urine

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49
Q

what affect does podocytes contracting have on glomerular filtration

A

sympathetic stimulation > contract > decrease filtration coefficient and GFR

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50
Q

what is the normal range of GFR

A

90-140 ml/min

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51
Q

is GFR same for males and females

A

no, females are on the lower side of the range

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52
Q

does GFR change w age

A

10% reduction for every 10 years over 20

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53
Q

why is it important to keep GFR within a specific range

A

maintain fluid and electrolyte balance

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54
Q

does GFR change w changes in BP

A

typically not, within the autoregulatory range

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55
Q

what starling forces are involved in GFR

A

glomerular blood hydrostatic pressure = 55mmHg

capsular hydrostatic pressure = 15mmHg

blood colloid osmotic pressure = 30mmHg

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56
Q

how is net filtration pressure measured (NFP)

A

GBHP - CHP - BCOP

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57
Q

what is the consequence of being unable to regulate glomerular pressure

A

rapid decline in kidney function

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58
Q

how does vasoconstriction in the afferent arteriole affect GFR

A

vasoconstrict > decrease blood flow into glomerulus > decrease glomerular capillary BP > decrease net filtration pressure > decrease GFR

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59
Q

how does vasodilation in the afferent arteriole affect GFR

A

vasodilation > increase blood flow into glomerulus > increase glomerular capillary BP > increase net filtration pressure > increase GFR

60
Q

what are the main factors affecting GFR

A

radius of afferent arteriole

extrinsic sympathetic stimulation

hormonal regulation of AngII and ANP

auto regulation

myogenic mechanism

tubuloglomerular feedback

61
Q

what is the myogenic mechanism

A

increase afferent arteriole pressure causes stretch that in turn causes the vessel to constrict, increasing resistance and reducing flow

62
Q

what is the tubuloglomular feedback (TGF)

A

macula densa sense increase Na+ > release ATP > decrease GFR (maintains normal filtered load) and decrease renin secretion (which allows more Na+ excretion)

macula densa sense decrease Na+ > release NO and prostaglandins > increase GFR and increase renin secretion (conserves Na+)

63
Q

how is renal blood flow measured

A

PAH or inulin are molecules that are not reabsorbed in the tubules so RPF is equal to plasma clearance rate/GFR

RPF = concentration PAH = Urinary PAH x volume / plasma PAH

64
Q

why is inulin clinically important

A

it is freely filtered ie no tubular reabsorption so it is ideal to use for the measurement of GFR

65
Q

what is plasma clearance

A

volume of plasma cleared of a particular substance each minute in the kidney

66
Q

why is creatinine often used as a reasonable estimate of GFR

A

breakdown product of creatine phosphate in muscle > usually produced at a fairly constant rate

67
Q

what are the components of body fluids

A

water, protein, electrolytes, etc.

68
Q

what are the functions of body functions

A

transport/carriage, colloid osmotic pressure, membrane excitability buffering

69
Q

what proportion of fluids in the body are ICF

A

2/3

70
Q

what proportion of fluids in the body are ECF

A

1/3

71
Q

what percentage of ECF is ISF

A

80%

72
Q

what percentage of ECF is plasma

A

20%

73
Q

what is plasma

A

fluid component of blood

74
Q

what separates plasma and ISF

A

capillary wall

> mvmt across this is passive via pores due to both sides of the wall having similar compositions

75
Q

what separates ISF and ICF

A

plasma membrane

> mvmt across this is passive and active due to both sides of wall having different compositions

76
Q

how is fluid gained

A

ingested liquids, ingested food, metabolic production

77
Q

how is fluid lost

A

urinary loss, sweating, respiratory evaporation, GI losses

78
Q

how does the thirst mechanism work

A

dehydration > increase blood osmolarity > stimulates osmoreceptors in hypothalamus > stimulates thirst centre in hypothalamus > increases thirst > increases water intake > increase body water level

79
Q

how is the resp system key in short term acid-base regulation

A

increase RR > decrease CO2 > decrease H+ (alkalosis)

decrease RR > increase CO2 > increase H+ (acidosis)

80
Q

how can opioids lead to acidosis

A

depress CNS > decrease RR > increase CO2 > increase H+ (acidosis)

81
Q

what is the normal pH range

A

7.35 - 7.45

82
Q

why is such a narrow range of pH a must

A

maintenance of normal excitability of nerve and muscle cells

preservation of structure of proteins and enzymes

83
Q

what is the upper and lower ‘border’ of pH that leads to death

A

6.8 and 8.0

84
Q

what can acidosis lead to

A

coma

85
Q

what can alkalosis lead to

A

seizures, spasms

86
Q

what is the juxtaglomerular apparatus

A

specialised cells within the nephron

87
Q

the JGA responds when there is a change in…

A

blood pressure (stretch)

blood osmolality (Na+)

88
Q

the JGA is responsible for the release of…

A

Renin from granular cells

89
Q

outline how the renin-angiotensin-aldosterone system works

A

angiotensinogen (liver) + renin (kidney) > angiotensin I + angiotensin-converting enzyme > angiotensin II > vasopressin (ADH) + thirst + arteriolar vasoconstriction

aldosterone (adrenal cortex) > aldosterone > stimulate kidney > Na+ reabsorption > increase Na+ conserved > Na+ osmotically hold more H2O in ECF > increase H2O conserved

90
Q

what does aldosterone act on and what does it do

A

principal cells of distal convoluted tubule

promotes Na+ retention and K+ secretion

91
Q

what are diuretic drugs

A

drugs which increase urine production

92
Q

what are the major uses of diuretic drugs

A

correction of fluid oedema states

reduction of BP in hypertension

93
Q

how do diuretics work

A

act on specific targets on renal tubular cells

inhibit sodium reabsorption

94
Q

what are loop diuretics

A

diuretics used for oedematous states (e.g chronic heart failure) which act (inhibit) on luminal part of Na+/K+/2Cl- co-transporter

95
Q

what are examples of loop diuretics

A

furosemide

bumetanide

96
Q

how is the suitability of the use of which loop diuretic to use determined

A

if one is allergic to furosemide

97
Q

what can occur due to the use of loop diuretics that need to be communicated

A

dramatic diuresis
postural hypotension
need for monitoring

98
Q

what is monitored when prescribed loop diuretics

A

electrolytes ie decrease in K and H
renal function
edema
weight

99
Q

what are thiazides

A

diuretics used for milder oedematous states (e.g hypertension) which act (inhibit) on the luminal part of the Na+/K+/2Cl- co-transporter in the DCT

100
Q

what are examples of thiazides

A

hydrochlorothiazide
chlorthalidone
indapamide

101
Q

how is suitability of thiazides determined

A

allergy to thiazide
postural hypotension
hyponatremia
gout

102
Q

what effects on thiazide needs to be communicated

A

mild diuresis
postural hypotension

103
Q

what needs to be monitored when prescribed thiazide

A

postural hypotension
electrolytes ie decrease in Na, K and H
renal function
edema
weight

104
Q

what are mineralocorticoid antagonists

A

diuretics used in cases of oedema driven by increase aldosterone (e.g severe heart failure) which bind to mineralocorticoid receptors in collecting tubular cells

105
Q

what is an example of mineralocorticoid receptor antagonist

A

spironolactone

106
Q

how is the suitability of the use of mineralocorticoid receptor antagonists determined

A

renal impairment
elevated K

107
Q

what effects of mineralocorticoid receptor antagonists need to be communicated

A

gynaecomastia
need for monitoring

108
Q

what needs to be monitored when prescribed mineralocorticoid receptor antagonists

A

electrolytes ie decrease Na and H and increase K
renal function
edema
weight

109
Q

what are potassium sparing diuretics

A

diuretics used in cases where mild diuretic efficacy is required and to treat low K by inhibiting Na/K exchange in distal nephron

110
Q

what is an example of a potassium sparing drug

A

amiloride

111
Q

how is the suitability of the use of potassium sparing drugs determined

A

renal impairment
elevated K

112
Q

what effects of potassium sparing drugs need to be communicated

A

need for monitoring

113
Q

what needs to be monitored when prescribed potassium sparing drugs

A

electrolytes ie decrease Na and increase in K and H
renal function

114
Q

what are ACE inhibitors

A

most commonly used cardiovascular medicines w indications including hypertension, chronic systolic heart failure, diabetic nephropathy etc

generally end in -pril e.g perindopril and ramipril

115
Q

how do ACE inhibitors work

A

prevent angiotensin I from being converted into angiotensin II, which can lead to the build up of bradykinin resulting in side effects like a cough, angioedema, hyperkalemia etc

116
Q

what are angiotensin receptor blockers

A

similar uses to ACE
prevents angiotensin II binding to AT1 receptors on adrenal gland

end in -sartan e.g candesartan and irbesartan

117
Q

what are neprolysin inhibitors

A

neprolysin = neutral endopeptidases

inhibition > increase BNP leading to decrease BP, sympathetic tone, fibrosis, hypertrophy / increase bradykinin > increase angiotensin II

118
Q

what is ARNI (angiotensin receptor antagonist + neprolsyin inhibitor)

A

combination of neprolysin inhibitor w angiotensin II receptor blocker (e.g sacubitril + valsartan) for patients w heart failure w reduced ejection fraction

119
Q

at what volume of bladder filling do we get the urge to urinate

A

around 200 mL

120
Q

at what volume of bladder filling do the detrusor muscle contractions force the urethral sphincter to open

A

around 500mL

121
Q

how does the micturition reflex work

A
  1. receptors detect stretch and sends this message to the brain through the spinal cord (not direct part of the reflex as a reflex can be generated by just the spinal cord)
  2. spinal cord signals detrusor muscle to contract bladder > relaxes internal sphincter (this is the micturition reflex)
  3. message from brain goes through spinal cord to external sphincter telling it to relax or contract (voluntary)
122
Q

how is the bladder innervated

A

sympathetic innervation through hypogastric nerves in L1 L2 and L3

parasympathetic innervation through pelvic nerves in S2 S3 and S4

somatic innervation (of external urethral sphincter) through pudendal nerves in S2 S3 and S4

123
Q

how is the detrusor muscle in the bladder wall innervated

A

sympathetic hypogastric nerves release NA onto beta-3 receptors > relaxes the detrusor muscle

parasympathetic pelvic nerves ACh into M3 receptors > contracts detrusor muscle

124
Q

how is the internal urethral sphincter innervated

A

sympathetic hypogastric nerves release NA onto alpha-1 receptors > contracts internal urethral sphincter

125
Q

what happens to the three muscles during bladder filling and what is their dominant neural input

A

detrusor muscle - relaxed - sympathetic

internal sphincter - contracted - sympathetic

external sphincter - contracted - SNS

126
Q

what happens to the three muscles during bladder voiding and what is their dominant neural input

A

detrusor muscle - contracted - parasympathetic

internal sphincter - relaxed - reduced sympathetic outflow

external sphincter - relaxed - SNS

127
Q

what are the three main centres involved in micturition

A

cortical centre (inhibitory to pontine centre)

brainstem centre (pons is facilitatory to micturition)

spinal cord (parasympathetic reflex evacuation)

128
Q

what effect would a beta 3 receptor agonist have on bladder/IUS tone

A

relaxation of the detrusor muscle > contraction of IUS

129
Q

what effect would muscarinic receptor antagonist have on bladder/IUS tone

A

relaxation of detrusor muscle > contraction of IUS

130
Q

what effect would alpha 1 adrenergic antagonist have on IUS tone

A

relax the IUS

131
Q

what are 3 types of renal pathologies

A

UTI
kidney stones
renal failure (chronic and acute)

132
Q

what causes a UTI

A

bacterial infection in any part of the urinary system

133
Q

what is affected in a lower UTI

A

bladder, urethra
(less serious)

134
Q

what is affected in an upper UTI

A

kidneys, ureters
(serious)

135
Q

how can a UTI be treated

A

drink lots of water, antibiotics

136
Q

what are kidney stones

A

crystallisation of minerals and salts in urine that can affect any part of the urinary system

137
Q

what can happen if kidney stones get stuck in the ureters

A

block flow of urine > swelling of kidneys and ureteric spasms

138
Q

what can cause kidney stones

A

excess Ca2+, dehydration, etc.

139
Q

how can kidney stones be treated

A

drinks lots of water, pain relief, ultrasonic waves, surgery

140
Q

what is renal failure

A

when the kidneys cannot filter waste from the blood meaning homeostasis cannot be maintained which leads to issues in all systems of the body, resulting in things like increase BP, dev of anaemia, and CNS problems

141
Q

what is acute renal failure

A

filtration suddenly stops or slows > kidneys may regain partial or complete function

142
Q

what can cause acute renal failure

A

renal ischemia, urinary obstruction, trauma, nephrotoxic drugs

143
Q

what is chronic renal failure

A

kidney function deteriorates gradually > cannot be reversed

144
Q

what can cause chronic renal failure

A

co-morbidities such as unmanaged diabetes and hypertension

145
Q

what is dialysis

A

procedure to remove waste products and excess fluid from blood when kidneys stop working properly by using an artificial membrane (which has pores allowing diffusion of ions, nutrients, and wastes but not plasma proteins)

two types: haemodialysis and peritoneal dialysis