Urinary Flashcards

1
Q

How much of the body is made up of water? Intracellular? extracellular?

A

60%
ICF 40%
ECF 20%

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2
Q

How much water is roughly taken in by food and metabolism (ml/day)

A
food = 500
metabolism = 400
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3
Q

How much water output is from skin, respiration and faeces (ml/day)

A
skin = 400
respiration = 400
faeces = 100
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4
Q

What is water intake variation

A

type of food

water availability

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5
Q

What is water output variation

A

lactation
exercise
environmental conditions
disease/infection

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6
Q

What are four common causes of fluid loss

A

diarrhoea/vomiting
hyperventilation
fever
sweating

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7
Q

Most abundant cation in extracellular fluid? anion?

A
cation = Na+
Anion = Cl-
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8
Q

Nine symptoms of dehydration

A
extreme thirst
dark coloured urine/zero output
fatigue
dizziness/headache
dry mouth, lips and eyes
poor skin turgor
low blood pressure
rapid heart beat
slow capillary refill
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9
Q

What happens to the plasma osmolarity, plasma Na+, ECV, and ICV when you lose equal amounts of water and salt (isotonic) and what is the typical cause

A
Plasma osmolarity = normal
Plasma Na+ = normal
ECV = decreases
ICV = normal 
Causes = acute diarrhoea
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10
Q

What happens to the plasma osmolarity, plasma Na+, ECV, and ICV when you lose more water than salt (hypertonic) and what are the typical causes

A
Plasma osmolarity = increases
Plasma Na+ = increases
ECV = Decreases
ICV = decreases 
Causes = burns/fever/respiratory infection
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11
Q

What happens to the plasma osmolarity, plasma Na+, ECV and ICV when you lose more salt than water (hypotonic) and what are the typical causes

A
Plasma osmolarity = decreases
Plasma Na+ = decreases
ECV = decreases
ICV = increases
Causes = chronic vomiting/diarrhoea
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12
Q

Typical concentration of electrolytes in extracellular fluid: sodium, osmolarity, chloride, bicarbonate, potassium, calcium and pH

A
Sodium ~142mmol/l
Osmolarity ~290mosmol/l
Chloride ~102mmol/l
Bicarbonate ~25mmol/l
Potassium ~4.2mmol/l
Calcium ~1.2mmol/l
pH ~7.4
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13
Q

How many nephrons in a singular kidney

A

about 1 million (each 5 cm long)

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14
Q

What does a nephron do

A

contains a glomerulus that filters your blood and a tubule which returns needed substances to your blood and pulls out additional waste

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15
Q

What is the renal pelvis, what is it lined with and what does it do

A

Where two or three major calyces join
Lined with mucous membrane covered with transitional epithelium
Acts as a funnel for urine flowing to the ureter

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16
Q

What are the ureters and how do they function

A

Narrow tubes carry urine from the kidney to the bladder
Muscles in their walls contract and relax to force urine down (if urine backs up, or is allowed to stand then a kidney infection can occur)

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17
Q

Two roles of bladder, and how much can it store

A

temporary storage of urine and assists in expulsion of urine

Holds 400-600ml

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18
Q

Four parts of male urethra

A

pre-prostatic, prostatic, membranous, spongy

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19
Q

What is the glomerular filtration rate

A

test used to see how well kidneys are working

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20
Q

What is the typical rate at glomerular filtration occurs

A

~90-125ml/min (across both kidneys)

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21
Q

What does the glomerular filtrate contain

A

no cells
trace amount of protein
ions and small organic substances in same concentrations as plasma

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22
Q

What does the renal artery branch into and what do they branch into

A

branches into segmental arteries which branch into interloper arteries which branch into arcuate arteries, cortical radiate arteries, afferent arterioles

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23
Q

What is the blood supply to the nephrons

A

afferent arterioles

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24
Q

What does the rate of filtration of a given substance depend on

A

its molecular weight
electrical charge
shape

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25
Q

What happens at the glomerulus

A

main function is to filter plasma to produce glomerular filtrate which passes down the length of the nephron tubule to form urine

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26
Q

What is tubular reabsorption

A

process by which the nephron removes water and solutes from the tubular fluid and returns them to the circulating blood

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27
Q

What is tubular secretion

A

used to remove drugs, toxins, or other natural compounds in excessive amounts (K+, H+, urea) out of blood plasma

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28
Q

What is hyperkalaemia

A

higher potassium than normal

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29
Q

ECG changes with hyperkalaemia

A

tall, peaked T waves with a narrow base, shortened QT interval, and ST depression

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30
Q

What are starling forces

A

opposing forces that affect glomerular filtration: hydrostatic and oncotic pressure

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31
Q

What is autoregulation

A

ability to maintain relatively constant blood flow despite changes in perfusion pressure

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32
Q

Where are sodium ions most likely to be reabsorbed

A

proximal convoluted tubule

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33
Q

Definition of paracellular

A

transfer of substances across an epithelium by passing through the intercellular space between the cells

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34
Q

Definition of transcellular

A

substances travel through the cell, passing through both apical and basolateral membranes

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35
Q

What are some general properties of the proximal convoluted tubule

A
longest segment of nephron
contain brush border microvilli
lots of mitochondria (active-transport)
reabsorbs 60-70% glomerular filtrate
Reabsorption is isosmotic
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36
Q

What does isosmotic mean

A

having the same osmotic pressure

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37
Q

Describe tubular transport of sodium

A

most is done via secondary active transport
most reabsorbed in exchange for H+
driven by ionic gradients across apical membrane and ATPase on basolateral membrane

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38
Q

Describe tubular transport of calcium and potassium

A

most potassium ion reabsorption is via paracellular route passively down ionic gradient
Calcium reabsorption is via transcellular and paracellular routes down ionic gradient

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39
Q

Describe tubular transport of amino acids and glucose

A

occurs against concentration gradient via secondary active transport (co-transport)
dependent on sodium gradient on apical membrane
facilitated diffusion of basolateral membrane
when transport maximum is reached the rest is secreted in the urine

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40
Q

Describe tubular transport of water

A

occurs down osmotic gradient
transcellular reabsorption on apical and basolateral membranes via aquaporins
paracellular reabsorption via gap junctions
also occurs in loop of Henle, distal tubules, and collecting ducts

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41
Q

Describe tubular transport of bicarbonate and hydrogen

A

bicarbonate combines with hydrogen for indirect reabsorption in presence of carbonic anhydrase
In distal tubules new bicarbonate is formed and hydrogen is secreted via buffers

42
Q

What do longer loops of Henle create

A

create a larger osmotic gradient so their parent kidney can produce more concentrated urine

43
Q

What is the distal nephron composed of

A

distal convoluted tube
cortical portion of collecting duct
medullary portion of collecting duct

44
Q

What does aldosterone do in the plasma concentration of potassium

A

targets the distal nephron where it increases K+ secretion (secreted to the urine)

45
Q

What is hypovolaemia

A

decrease of blood volume and venous return

46
Q

What does hypovolaemia decrease

A

Stroke volume, cardiac output and hence arterial blood pressure

47
Q

How do kidneys deals with hypovolaemia

A

sense reduced blood pressure and reduced renal blood flow
they reduce sodium loss in urine
reduce, by osmotic retention, water loss in urine

48
Q

What are the high blood pressure sensors

A
arterial baroreceptors (carotid sinus/aortic arch)
juxtaglomerular apparatus of kidney
49
Q

What are the low blood pressure sensors

A

(useful for excretion of excess, retained plasma fluid)
cardiac atria
pulmonary vasculature

50
Q

Explain juxtaglomerular apparatus and renin

A

complex structure where distal tubules makes close contact with the glomerulus and its vasculature
juxtaglomerular secrete a hormone renin, in response to low blood flow
Renin has a direct role in Na+ secretion and hence water reabsorption in the distal tubules

51
Q

Describe the renin-angiotensin-aldosterone system (RAAS)

A

key in regulating blood volume by controlling NaCl and hence water reabsorption by the nephron
Renin is a proteolytic enzyme its substrate is circulating angiotensin produced by the liver
the result is angiotensin I
angiotensin I is converted into angiotensin II by an angiotensin converting enzyme (ACE)

52
Q

What 3 things does angiotensin II do

A

exerts a vasoconstrictor response
stimulate ADH release and hence water reabsorption by the kidney
stimulates aldosterone release from the adrenal cortex to increase Na+ retention by the kidney

53
Q

What is aldosterone

A

steroid hormone secrete from the zona glomerulosa of the adrenal glands under the stimulation of angiotensin II

54
Q

What happens when there is an increase in circulating aldosterone

A

they bind to a receptor which forms a complex that stimulates transcription of apical Na+ channels
Increases NaCl reabsorption via principal cells in the distal tubules/collecting ducts
Na+ uptake from the lumen is enhanced, Cl- and then water follow

55
Q

What does atrial natriuretic peptide (ANP) do ?

A

causes natriuresis=excretion of Na+ as NaCl and hence water

56
Q

Why is plasma osmolarity regulated

A

to stop cells shrinking or swelling

57
Q

How is plasma osmolarity regulated

A

by controlling water influx and efflux

58
Q

What is normal plasma osmolarity

A

290mosmol.kg^-1

59
Q

What happens if there is a change in plasma osmolarity

A

osmoreceptors in hypothalamus detect the change
hypothalamus initiates changes to pituitary gland and/or thirst centre
pituitary gland releases ADH and thirst centre changes the thirst response
Release of ADH changes the urine concentration and changes in thirst response changes water intake

60
Q

Where is ADH secreted from

A

posterior pituitary gland

61
Q

Alternative name for ADH

A

vasopressin

62
Q

3 actions of ADH on the kidney

A

increases water permeability at the collecting duct
increases NaCl reabsorption in the thick ascending limb of the loop of Henle
increases urea permeability in the inner medullary region of the collecting duct

63
Q

Where is ADH produced

A

in the supraoptic and paraventricular nuclei neurones

64
Q

What portion of the nephron is impermeable to water

A

the ascending limb of the loop of Henle

65
Q

What is the net result of the counter-current mechanism in the loop of Henle

A

osmolarity gradient is generated in the medullary
interstitium
fluid entering the distal tubules and collecting duct is hypo-osmotic

66
Q

What is diabetes insipidus caused by

A

abnormality in the functioning of the ADH hormone

67
Q

What is plasma concentration of H+ like?

A

very low

68
Q

3 reasons as to why it is important to regulate arterial pH

A

enzyme structure may be impaired
Acidosis can decrease cardiac contractility and lead to life-threatening arrhythmia’s
handling of other cations (K+ and Ca2+) can lead to neuromuscular dysfunction

69
Q

What is the bronstead and Lowry theory

A

than an acid is a proton donor and a base is a proton acceptor
and when an acid loses a proton it forms a conjugate base

70
Q

Difference between strong and weak acids

A

strong acids fully dissociate in water and weak acids only partially dissociate

71
Q

What do buffer pairs consist of

A

a weak acid and its conjugate base

72
Q

What is the Henderson hasselbach equation

A

pH = pK + log [A-]/[HA]

73
Q

What determines PaCO2

A

rate of carbon dioxide production by metabolism divided by rate of carbon dioxide removal by alveolar ventilation

74
Q

Where is bicarbonate filtered

A

at the glomerulus

75
Q

What does vomiting cause? how?

A

metabolic alkalosis

by excessive loss of [H+]

76
Q

What does diarrhoea cause? how?

A

metabolic acidosis

by excessive loss of bicarbonate

77
Q

what does insulin deficiency cause? how?

A

metabolic acidosis

by excessive production of H+

78
Q

What does shock cause? how?

A

metabolic acidosis

by excessive production or ingestion of H+

79
Q

When assessing renal function what 6 things should you assess?

A
production of urine
sodium and water homeostasis
filtration
blood flow
endocrine functions
information about other systems (glucose, bilirubin and ketones)
80
Q

What should you look for on observation of urine tests

A

colour
clarity
volume

81
Q

What are you looking for on a dipstick examination of urine

A
blood
ketone
nitrites
pH
glucose
proteins
82
Q

What do lab tests look for on urine tests

A

omsolarity
sodium
creatine

83
Q

Four tests on blood

A
U & E's (sodium, potassium, urea and creatine)
osmolarity
pH
bone profile 
full blood count
84
Q

What makes urine tests abnormal?

A

infection - kidney, UTI
Saturation of filtration system - glucose in diabetes
metabolism of fats - ketones
renal failure

85
Q

What are the variables used in the CKD-EPI equation

A

gender
ethnicity
creatine
age

86
Q

How do you perform a urine dipstick test

A
urine should be collected in sterile container
Urine should be collected midstream
do a visual analysis: colour and clarity
apply sample to dipstick 
record results immediately
87
Q

What are the endocrine functions of the kidney

A

aldosterone and ADH - water homeostasis
parathyroid hormone - increase calcium absorption and phosphate excretion
Erythropoietin - stimulates bone marrow to produce RBC

88
Q

What does the parathyroid hormone (PTH) do in the kidney? in the bone?

A
Kidney:
increases calcium absorption in the distal tubules
increases phosphate excretion
increases formation of active Vit D
Bone:
stimulates bone resorption
89
Q

What does vitamin D do in the bone? Intestine?

A
Bone:
stimulates bone resorption 
Intestine:
stimulates calcium absorption
stimulates phosphate absorption
90
Q

What are sunken fontanelles a sign of in children

A

dehydration

91
Q

Why is creatinine used to assess renal function

A

because it is an easily measured byproduct of muscle metabolism that is excreted unchanged by the kidneys

92
Q

What does U & E stand for

A

urea and electrolytes

93
Q

During urine storage what nerves are suppressed/active?

A
pelvic nerve (S2-S4) is suppressed
Pudendal nerve is active (S2-S4) is active
94
Q

During urine voiding what nerves are suppressed/active?

A
pelvic nerve (S2-S4) is active 
pudendal nerve is suppressed (S2-S4)
95
Q

What is nitrogen found in

A
mostly nucleic acids and proteins
but also:
cofactors such as NAD+
hormones such as adrenaline
neurotransmitters such as serotonin
96
Q

what is a negative nitrogen balance and what is it indicative of

A

when you lose more nitrogen than you take in

indicative of: malnutrition, or recent/ongoing trauma

97
Q

What is a positive nitrogen balance and what is it indicative of

A

when you gain more nitrogen than you lose

indicative of pregnancy, growth

98
Q

Why does amino acid breakdown take precedence over breakdown of excess carbs and fat

A

because excess amino acids cannot be stored

99
Q

How are amino acids transported to the liver

A

as alanine or glutamine

100
Q

What is the toxic immediate product of amino acid breakdown

A

ammonium/ammonia

101
Q

Difference between glucogenic amino acids and ketogenic amino acids

A

glucogenic amino acids can be converted into pyruvate and other glucose precursors
ketogenic amino acids can be converted into acetyl CoA and acetoacetyl CoA